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RNA-seq approach to discriminate gene expression profiles in RIXI overexpressing transgenic rice
PENG Yaoyao, HOU Chunxiao, ZHAN Yihua, HUANG Yingying, SUN Xiangyu, WENG Xiaoyan
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 643-653.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.142
To investigate whether RIXI overexpressing transgenic plants influence the expression of other genes, we analyzed transcriptomic changes between R7 (RIXI overexpression transgenic line 7) plants and WT (wild-type) plants using deep RNA sequencing combined with digital gene expression profile analysis. The differentially expressed genes between the WT and R7 libraries were identified by DEG-Seq (differentially expressed genes from RNA-seq) software. The profiling analysis revealed that the overexpression of RIXI in rice resulted in numerous changes in gene expressions, including upregulation of 391 genes and downregulation of 905 genes. These differentially expressed genes were categorized into 30 groups with broad functions using gene ontology (GO) assignments. Among the 30 groups, five groups (singleorganism metabolic process, biological regulation, anion binding, small molecule binding and nucleotide binding） had more differentially expressed genes. Biological pathways affected by RIXI overexpression were mapped using the detected genes to reference canonical pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG). The differentially expressed genes were assigned to 98 KEGG pathways, and four enriched pathways were identified: metabolic, biosynthesis of secondary metabolites, plantpathogen interaction and plant hormone signal transduction. The measurement of agronomic traits of R7 showed that the overexpression of RIXI did not influence the growth and development of rice. Thus, we conclude that the xylanase inhibitor gene RIXI may play a role in activation of a complex signal transduction network in response to various biotic and abiotic stresses, but does not have a negative influence on growth and development of rice plants.
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Isolation and screening of an electrochemically active strain Bacillus cereus sp. WL027 using phenol as fuel and preliminary study on its mechanism of electricity production
WANG Lili, GUO Wei, FU Chunna, YAN Hong
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 654-664.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.111
Microbial fuel cell (MFC) is an economic and effective way for wastewater treatment, which enables not only degradation of phenol but also conversion of biomass energy into electricity. Selection and breeding of electricigens from anode of a microbial fuel cell is the premise and foundation of MFC research; meanwhile, the problem of low energy efficiency can also be solved. Electronic delivery mechanisms of electricigens included biofilm mechanism and electron shuttle mechanism. Biofilm mechanism refers to the electricigens being attached to the electrode surface and then use cytochrome C or “nanowires” to transfer intracellular electrons to the electrode through the biofilm. Electronic shuttle mechanism concerns the use of a redox mediator to transfer electrons between the cell and the electrode. Currently, most Gram-negative bacteria with cell walls rich in cytochrome C, have been found to use cytochrome C to transfer electrons, such as Geobacter sulfurreducens, Aeromonas hydrophila and Rhodoferax ferrireducens, etc. In the process of electron transfer, the use of redox mediator for the electron transfer between the cell and the electrode is called electron shuttle mechanism. According to the source of redox mediator, it can be divided into exogenous redox mediator and endogenous redox mediator (cell autocrine). So far, little was known about the potential of Bacillus cereus to produce electricity.
In this work, an efficient phenoldegrading electricigenic bacterium was separated and screened, and its MFC was built using the obtained strain, and the efficiencies of phenol degradation and electricity production were further investigated. Meanwhile, the anode carbon felt was analyzed by scanning electron microscopy, and the cyclic voltammetry curve of the obtained strain was measured during the four growth stages (7, 18, 31 and 52 h), to explore the potential related mechanism of electricity production.
Twentyone pure strains with potential ability of electricity production were isolated, of which WL013, WL024 and WL027 strains could produce electricity, and the WL027 was the favorite electricityproducing strain. Hence, the strain WL027 was selected as the dominant strain. Based on the combination results of 16S rDNA and physiological and biochemical characteristics, the strain WL027 was identified as Bacillus cereus. This strain WL027 was electrochemically active, and its electricity was mainly generated at the stable phase during the growth of the strain. When the strain WL027 was inoculated into the MFC, the maximum voltage increased by 179 mV compared with the start voltage, with Coulombic efficiency of 64.25% and phenol degradation rate of 68.62%. The intracellular and extracellular concentrations of riboflavin were 6.10×10-3 and 1.32×10-2 mg/L respectively during the process of electricity production. The voltage was increased by 18 mV when the riboflavin was added to the MFC at the stable phase. Therefore, it can be speculated that the strain WL027 could promote the electron transport through the secretion of riboflavin in microorganisms.
In conclusion, the MFC constructed by Bacillus cereus not only can degrade phenol efficiently, but also has obvious advantages in energy conversion efficiency. Besides, the strain WL027 can promote the electron transport through the secretion of riboflavin in microorganisms.
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Effects of drinking water distribution system on Vibrio amounts in biofilm
SHI Ya, SHI Xiaofeng, ZHANG Yongjing, LIU Jingqing, CHENG Dongqing
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 665-670.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.271
With the development of modern industries, drinking water in residential area and public building were supplied by water distribution systems. The drinking water distribution system is the final step from water plants to the users, and therefore is essential to assure drinking water safety for customers. Previous studies confirmed that many bacteria in the drinking water distribution systems existed as biofilm, which could induce corrosion and scaling of the pipe walls, reduce the water quality and water-carrying capacity of the pipelines. Moreover, as the pathogens growing in the biofilms transferred in the pipelines, the risks caused by these microorganisms would increase. Vibrio species is an estuarine bacterium widely distributed in the natural aquatic environment around the world. Among the discovered 76 kinds of Vibrio species, at least 12 kinds have pathogenic effect on human, and often result in severe diarrhea and dehydration. We found the Vibrio species in our previous survey of pathogenic bacteria in biofilm, indicating that the residents were at potential risk from Vibrio species. Therefore, the effect of pipe materials, pipe ages, and pipe diameters on amount of Vibrio species in biofilm of drinking water distribution system was necessary to investigate.
In this study, 12 biofilm samples were collected from the drinking water distribution system in east China. Vibrio was isolated using thiosulfate-citrate-bile salts-sucrose (TCBS) agar medium and was identified according to their biochemical reaction characteristics using biochemical identification kit for Vibrionaceae GYZ9V. The amounts of total bacteria were determined by a spreadplating method according to the Ministry of Health Standard Examination Methods for Drinking Water (2006). Samples and their dilutions were spread on Petri dishes with nutrient agar medium. Analysis of variance (ANOVA) by a least significant difference test was used to compare Vibrio counts from different pipe materials, ages and diameters.
The results showed that Vibrio species could be detected in nodular cast iron, galvanized steel and stainless steel clad pipes, but not in plastic pipe. The Vibrio species amount on the biofilm attached to the nodular cast iron pipe (212±39.40 CFU/cm2) was significantly higher than those attached to the galvanized steel pipe (4.85±1.03 CFU/cm2) and stainless steel clad pipe (0.66±0.21 CFU/cm2). However, the rank of total bacteria amount was galvanized steel pipe > nodular cast iron pipe ≈ plastic pipe > stainless steel clad pipe. Pipe age had little influence on Vibrio amounts from galvanized steel and nodular cast iron pipes. Nodular cast iron pipe with a nominal diameter of 200 mm had the highest amount of Vibrio species (2.65×103±204 CFU/cm2), followed by 150 mm (212±39.40 CFU/cm2) and 300 mm (44.20±6.88 CFU/cm2), and the tendency of total bacteria amount was similar with Vibrio species.
In conclusion, contamination from Vibrio species with varying levels is observed in nodular cast iron, galvanized steel and stainless steel clad pipes, but not in plastic pipe. The different pipe materials, especially nodular cart iron pipe, have strong influence on Vibrio species amount in biofilm from drinking water distribution system; therefore, the potential risks of Vibrio species from nodular cast iron pipe should be taken into consideration while laying the pipelines.
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Identification of pathotype of Verticillium dahliae isolates on cotton in Zhejiang Province and phenotypic analysis on inhibitory effect by high temperature
SUN Xiaoting, LU Xiuyun, ZHANG Jingze, ZHU Shuijin
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 671-678.
https://doi.org/10.3785/j.issn.1008-9209.2015.11.161
China is the largest cotton producing country in the world. Zhejiang Province owned cotton growing area of about 17 264 hectares in 2013, was not major cotton producing area in China. Verticillium wilt, caused by Verticillium dahliae, is one of the most important disease of cotton and causes great economic losses in almost all cotton producing areas, but has not been found in fields in Zhejiang region. However, in 2014, the serious verticillium wilt disease of cotton was observed in the experimental field of Zhejiang University. The disease began to appear in the early June and occurred seriously in the early July. The disease caused the serious defoliation on the middle and lower parts of plants and the diseased plants were significantly dwarf. However, the disease became to remit gradually in the early August during high temperature in summer and dwarf phenomenon of the diseased plants was not obvious with new leaf formation. Since then, the diseased plants were still able to bloom and produce bolls. The symptom of the disease was similar to that caused by the defoliating pathotype strains of V. dahliae but in the later period, not identical to that.
Based on the importance of verifying pathotype of pathogen and understanding the phenomenon of high temperature inhibiting disease for disease control, we detected the isolates causing the verticillium wilt disease of cotton by using the specific primers of defoliation and nondefoliation pathotypes of V. dahliae and characteristics of microsclerotia. Meanwhile, the effect of temperature on growth and development of pathogen was determined and the reason for the phenomenon of high temperature inhibiting disease was analyzed as well.
Results of polymerase chain reaction (PCR) amplification using the specific primers showed that the isolates (VD-h1, VD-h2, VD-h6, VD-h3 and VD-h5) obtained all belonged to the defoliating pathotype. The results of observation for characters of microsclerotia formation confirmed that the difference of microsclerotia length-to-width ratio between defoliating and nondefoliating pathotype isolates was remarkable. Temperature had a significant influence on Verticillium isolates. The optimal growth temperature of two isolates (VD-h1 and VD-h6) from Zhejiang was 22-28 ℃ and two (VD-101 and VD-086) from Xinjiang was 22-26 ℃, whereas at 32 ℃, fungal hyphal growth was all inhibited. At the same time, the numbers of produced conidial decreased and conidial germination was delayed. Combining biological properties of fungus and meteorological data, research results indirectly verified that the reason for disappearance of disease symptoms was that the growth and reproduction of pathogen were inhibited under the condition of high temperature in summer.
In sum, this study provides important scientific data for studying the regulation of disease occurrence in future.
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Functional analysis of stress-related transcription factor gene PsDREB from Paeonia suffruticosa
LIU Huichun, MA Guangying, ZHU Kaiyuan, ZOU Qingcheng, ZHOU Jianghua, TIAN Danqing
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 679-686.
https://doi.org/10.3785/j.issn.1008-9209.2015.05.152
Peony (Paeonia suffruticosa) is one of the most famous traditional flowers with profound cultural connotation in China. With the fast development of gardenflower industry, the application of peony increased dramatically for the purpose of landscaping or medicinal uses. However, stress resistance of peony has been poor due to artificial domestication for thousands of years, which greatly restricted the development of peony. With the significant interest of adding new vitality into the flower industry by successfully introducing and cultivating peony in southern China, improving the tolerance of peony cultivars to stress has become crucial. The dehydration responsive element binding protein (DREB) gene is one of the most important transcription factors that was found to be related to adversity resistance. The objective of this study was to analyze the biological function of DREB gene from peony, named as PsDREB, with methods of yeast one-hybrid assay and transgenic technology.
In this study, the ability of PsDREB protein binding with DRE and its transcriptional activation activity were tested by yeast onehybrid assay. Results showed that the PsDREB protein was able to combine specifically with the DRE, but unable to combine with the mutated DRE (mDRE), showing a strong transcriptional activity. Subsequently, the PsDREB gene was transferred into tobacco and was mediated by Agrobacterium to determine its biological function in response to adversity. Thereafter, the tolerance ability of the transgenic tobacco was detected under manipulated drought, low temperature, high salt, and abscisic acid (ABA) treatments, as compared to controls.
In conclusion, the PsDREB protein has strong binding and transcriptional activities. The overexpression of PsDREB can obviously enhance plant resistance to abiotic stresses, especially for drought and high salt treatments. These results lay the foundation for further research on the function mode of PsDREB transcription factor, and also supply theoretical and material evidence for excavating more possible stressresistant genes from peony so as to breed out highly stress-tolerant transgenic peony.
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Leaf characteristics and geographical distribution of Berberis amurensis and B. anhweiensis of Berberidaceae
SHI Xiaoping, YUAN Sen, LI Xinhua, XING Guipei
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 687-693.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.252
Within the genus Berberis L., B. amurensis Rupr. and B. anhweiensis Ahrendt are easily confused in the main taxonomic characters, and the demarcation between these two species usually depends on the site information of their living plants or specimens.
In order to further reveal their interspecific relationship, the leaf morphological and micromorphological features of B. amurensis and B. anhweiensis were studied by means of field surveys and experimental observation, and their geographical distribution patterns were also mapped and analyzed based on specimen check and literature analysis.
The results showed that, although the leaf shape of both B. amurensis and B. anhweiensis varied greatly, continuous variation patterns still existed in both species, and obvious similarities were found between the two species in features of leaf shape, dense spinescent teeth on the leaf margin, and the reticulate venation.
Light microscopy observation showed that, the outline of the periclinal walls of the leaf adaxial epidermal cells was approximately tetragonal to hexagonal in both B. amurensis and B. anhweiensis , but the anticlinal walls of the leaf adaxial epidermal cells were undulate or approximately straight in B. amurensis, and nearly straight or slightly undulate in B. anhweiensis. The outline of the periclinal walls of the leaf abaxial epidermal cells was irregularly polygonal in B. amurensis, and its anticlinal walls were undulate. The outline of the periclinal walls of the leaf abaxial epidermal cells was regularly polygonal in B. anhweiensis, and its anticlinal walls were nearly straight or slightly undulate. Both the two species were hypostomatic, and their stomata were all actinocytic and anomocytic.
Scanning electron microscope observation revealed that, the leaf adaxial epidermis of B. amurensis was nearly smooth, or was covered with dense granular wax ornamentation, and the outline of the periclinal walls of the epidermal cells was irregularly polygonal, and the anticlinal walls were undulate; the leaf abaxial epidermis was nearly smooth, or was covered with dense granular wax ornamentation and remarkable bifurcate ridges. The leaf adaxial epidermis of B. anhweiensis was covered with dense fine granular wax ornamentation, and the outline of the periclinal walls of the epidermal cells was irregularly polygonal, and the anticlinal walls were undulate or approximately straight; the leaf abaxial epidermis was covered with dense granular or short filiform wax ornamentation and notable bifurcate ridges. The outline of the periclinal walls and the anticlinal walls of the leaf abaxial epidermal cells were all obscure in both B. amurensis and B. anhweiensis, and the inner margin of the outer stomatal ledges was nearly smooth or partially notched.
There existed no obvious disjunctive geographical distribution between B. amurensis and B. anhweiensis in China, and the populations of B. amurensis might have extended its distribution from North China, via Qinling Mountains and Funiu Mountains, southward to Dabie Mountains, located across Central and East China, and spread closely to the distribution areas of B. anhweiensis in East China.
Berberis anhweiensis was reported by AHRENDT in 1961, although AHRENDT considered that this species resembled B. chekiangensis Ahrendt; in fact, B. anhweiensis was much more similar to B. amurensis. Because of the considerable similarities between B. amurensis and B. anhweiensis in the morphological and micromorphological characteristics of leaves, together with the notable resemblances in other key taxonomic characters
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Progress and application of salinomycin-induced cell autophagy in anti-cancer treatment
CHEN Siyuan, HU Ji’an
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 694-702.
https://doi.org/10.3785/j.issn.1008-9209.2016.07.123
Autophagy is a cell self-eating process that allows the orderly degradation and recycling of misfolded proteins and damaged organelles through lysosome. It plays a vital role in cells’ adaptation to metabolic stress and homeostasis as well as the formation, development and treatment of tumors. Autophagy is a doubleedged sword, both suppressing and facilitating tumorigenesis. For example, multiple benign tumors formed in the liver when autophagy gene Atg5 was mosaically deleted in mice. But at the same time, cancer cells can upregulate autophagy to survive under microenvironmental stress, promote tumor dormancy and increase their growth and aggressiveness.
Salinomycin is a polyether ionophore antibiotic isolated from Streptomyces albus. Compared with lasalocid and monensin, salinomycin is less toxic, lower priced and less susceptible to drug resistance, which enables worldwide use to prevent chicken coccidiosis and promote the growth of ruminants. As an antimicrobial drug, salinomycin acts as an ionophore for K+ and Na+ ions and is able to alter cytoplasmic and mitochondrial membrane potentials, thereby inhibiting oxidative phosphorylation. Besides, salinomycin can activate a MutS homolog 1-dependent cell cycle checkpoint, leading to the ultimate death of the coccidial parasites.
In 2009, salinomycin was reported to exert a powerful effect on breast cancer stem cells (CSCs), and it reduced the proportion of CSCs by more than 100 folds relative to paclitaxel. Up to now, it has been shown that salinomycin could effectively kill a variety of CSCs and multi-drug resistant cell lines by inhibiting Wnt/β-catenin signaling pathways, curbing cell cycle progression and reversing epithelial-mesenchymal transformation. Anticarcinogen can directly trigger apoptosis, autophagy and necrosis simultaneously. Most of cancer cell lines utilize autophagy to protect themselves from death after treatment with salinomycin. However, inhibiting autophagy through siRNA or PI3K inhibitor partially prevents cell death upon the addition of salinomycin in SW620 cells, indicating that autophagy induced by salinomycin can provoke cell death. The process of autophagy induced by salinomycin is complicated. Salinomycin can activate autophagy through different ways: 1) increasing intracellular reactive oxygen species (ROS), partly via ROS-JNK/AMPK signaling pathways; 2) triggering mitophagy by damaging mitochondria; 3) inducing endoplasmic reticulum stress to activate autophagy via AKT1-mTOR signaling pathway.
In addition, salinomycin does not interfere with the autophagosomelysosome fusion except suppressing autophagic flux at the late stage by diminishing the lysosome activity. Poor microenvironmental conditions, such as hypoxia, elevated interstitial fluid pressure, glycolysis, low pH and inflammatory cell infiltration, are common features of solid tumors, which are closely related to tumor progression, metastasis and therapy. Salinomycin significantly reduces F4/80+ and CD11B+ inflammatory cells of the tumor microenvironment in mice with pulmonary metastasis. Hypoxia, the focus of most studies, is involved in tumor angiogenesis and the generation and maintenance of CSCs. Low pH has a great influence on drug metabolism, rendering multidrug resistant of the cancer cells. Autophagy is always upregulated in hypoxic and low pH regions of tumors for the metabolic adaptation of cancer cells. The efficiency of hydroxychloroquine, a latestage autophagy inhibitor by disrupting lysosome acidification under clinical investigation, is strongly impaired in acidic tumor environments due to drug resistance. However, according to a new study, salinomycin could effectively inhibit autophagy flux under conditions of transient and chronic acidosis. This contributed to the elimination of several cancer cell lines and enhanced cytotoxic effects o
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Comparative study on the difference of growth and nutritional quality for lettuce (Lactuca sativa L.) between aeroponic and hydroponic cultivation systems under different nitrogen levels
DING Wenya, LIN Ruoyun, ZHOU Weiwei, ZHOU Kai, LIN Xianyong
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 703-712.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.251
Soilless culture is considered to be an alternative to soilbased cultivation. It has been developed quickly because of rapid growth on biomass and high quality of crops. Hydroponics and aeroponics are both soilless culture, but with different techniques. Aeroponics is a newly soilless culture technique, in which the roots are suspended midair inside a chamber and are intermittently sprayed with a nutrient solution to supply the plants with mineral and water. Unlike hydroponics using water as a growing medium and relying on essential mineral to sustain plant growth, aeroponics is conducted without a growing medium. Thus, there are significant differences of root zone between aeroponic and hydroponic cultivation systems. However, little effort has been found in the literature evaluating the effect of the two soilless techniques on yield and quality of growing vegetable.
In this study, experiments were carried out to compare the biomass production and nutritional quality of lettuce between hydroponic and aeroponic cultivation systems under different nitrogen levels (2, 8 and 20 mmol/L NO3--N).
Results showed that under the same nitrogen level, higher biomass, root growth, relative growth rate and photosynthetic rate were observed for lettuces grown in aeroponics than in hydroponics. Nitrate and glutathione contents were lower in aeroponics, while the ferric reducing/antioxidant power (FRAP) value and 1, 1-diphenyl-2-picrydrazyl (DPPH) radical scavenging rate were comparable to those in hydroponics. There were no differences in contents of soluble protein, soluble sugar and ascorbic acid, but the accumulations of soluble protein, soluble sugar, ascorbic acid and glutathione in aeroponics were markedly higher than those in hydroponics. Furthermore, the contents of nitrate and soluble protein of lettuces increased both in hydroponics and aeroponics, while the concentrations of soluble sugar, ascorbic acid and glutathione, FRAP value and DPPH radical scavenging rate decreased with increasing nitrogen level. Highest biomass, root morphological index, photosynthetic index, accumulations of soluble protein, soluble sugar, ascorbic acid and glutathione were observed under the nitrogen level of 8 mmol/L.
In sum, aeroponics is beneficial for higher biomass, antioxidant accumulation and antioxidative activity, especially under the nitrogen level of 8 mmol/L.
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Effects of different cultivation methods on stem apex yield and quality of sweetpotato for vegetable use under urban roof condition
LI Huan, BEI Jiawei, PAN Chao, ZHAO Weidong, LU Guoquan
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 713-719.
https://doi.org/10.3785/j.issn.1008-9209.2015.08.251
Sweetpotato (Ipomoea batatas) is an important upland crop in China, which plays an important role in feed and industrial raw materials. The root tuber has rich nutrition, and the aerial part of stems and leaves also has extremely high nutritive value. Recently, research on sweetpotato for vegetable use increased gradually. With the rapid development of urbanization process, the cultivated area decreased gradually, along with the decline in quantity and quality of agricultural products. However, the increased space of balcony and roof accelerated the development of balcony agriculture and urban roof agriculture. Meanwhile, new devices for planting become popular in daily life in cities. Sweetpotatoes grow faster in summer, and can solve the problem of leaf vegetables in short supply. Moreover, people can plant organic sweetpotato for vegetable use at home in a convenient and safe way.
In this paper, three cultivation methods (soil cultivation, substrate cultivation and pipeline nutrient solution culture) and three cultivars (Pushu 53, Guangcaishu 5 and Fushu 18) of sweetpotato for vegetable use were selected for urban roof agriculture, to compare the impact of different cultivation methods on yield and quality of sweetpotato. In July 2014, stem cuttings from each of the three cultivars were planted under three cultivation methods in roof of Jixian Building in Zhejiang A & F University. Experiments were conducted in a randomized complete block design with three replications. Seedlings were examined and replanted in time after cutting to ensure a full stand of seedlings. Furthermore, control and prevention for pests should be conducted during the growth period, and sweetpotato tips (15 cm) were harvested after growth. The yield, water content, pigment content, soluble sugar content, soluble protein content, vitamin C content and nitrate content were determined in the lab.
The results showed that the pipeline nutrient solution culture had significant advantages compared with soil cultivation or substrate cultivation. The stem apex yield, chlorophyll b content, total chlorophyll content, carotenoid content and soluble sugar content of Pushu 53, Guangcaishu 5 and Fushu 18 were highest under the pipeline nutrient solution culture condition among all the treatments, while the nitrate content was the lowest.
In conclusion, planting Fushu 18 using pipeline nutrient solution culture in urban roof agriculture will be a better choice, with higher biomass and guaranteed quality of sweetpotato for vegetable use.
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Alleviation role and effects of selenium on mineral nutrients in rice (Oryza sativa) seedlings under cadmium stress
DAI Zou, WANG Chunyu, LI Na, JIANG Mingjin, YAN Fengjun, XU Hui, SUN Yongjian, MA Jun
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 720-730.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.141
Substantial amounts of heavy metals including cadmium have been released to the environment by geological activities or by anthropogenic impacts and industrialization, such as mining, smelting activities, sewage sluge, and the unreasonable utility of fertilizers and pesticides. Cadmium (Cd) is a toxic heavy metal with high mobility and can be readily absorbed into rice plants and transported to human bodies through the food chain. Selenium (Se) is an essential element for animals and human beings, which usually acts as a cofactor in antioxidant enzymes in human bodies. Though Se is not considered as an essential element for plants, there are lots of evidence suggesting its beneficial effects for plant growth and resistance to heavy metal stress. However, little effort has been found about the comparative study of Se effects with respect to different grain Cd-accumulative rice seedlings. Therefore, the aim of the present study is to explore the mitigation mechanisms of Se to Cd stress in different rice cultivars.
In this research, a hydroponic experiment was conducted to study the alleviation role of Se in two hybrid rice variety (Yixiang 2115 with low grain Cd accumulation, Chuanguyou 2348 with high grain Cd accumulation) seedlings. Cd in the concentrations of 0, 0.1, 1 mmol/L with or without 3 μmol/L Se (Na2SeO3) solutions were treated on the two rice seedlings. The root and shoot biomasses, chlorophyll contents, Cd concentration and contents of mineral nutrient elements were measured.
The results showed that, Se increased significantly the biomass and chlorophyll a content of the two rice seedlings under the Cd stress, but decreased the chlorophyll b content in Chuanguyou 2348, which had the high Cd content in grain. The contents of ascorbic acid and glutathione in the two rice seedlings also increased with the supplement of Se, but those were higher in Chuanguyou 2348 than in Yixiang 2115, showing the differences between the two varieties. Under the 1 mmol/L Cd stress, Se promoted the synthesis of ascorbic acid and reduced glutatione to alleviate Cd stress in Chuanguyou 2348, but accelerated the synthesis of phytochelatins in Yixiang 2115 to mitigate Cd stress. Se also mitigated the injuries of the Cd stress to roots, which kept root activity in higher level than those without Se supplementation. The Cd content in shoots of the two varieties increased sharply with the Cd concentration increasing in the nutrient solution. Se could inhibit the absorption of Cd in the two varieties directly. Se could decrease the contents of calcium (Ca) and zinc (Zn) in shoots of the two varieties under the Cd stresses, but induced different reactions on cuprum (Cu) and manganese (Mn) contents. To the roots, Se increased the Ca and Cu contents, but decreased the Zn and Mn contents in the two varieties under the Cd stress conditions.
It is concluded that, Se can mitigate inhibition of Cd stress to rice seedling growth by elevating seedling biomass, chlorophyll a content, changing the contents of ascorbic acid, glutathione and non-protein thiols, keeping higher root activity compared with only Cd treatment. Besides, Se can directly suppress Cd uptake in rice seedlings and mainly affects Cu and Mn concentrations in shoots between the two rice varieties.
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Contribution of environmental and genetic variation to chemical similarity of Maca (Lepidium meyenii Walp.)
ZHOU Wenbin, CHENG Zhehong, ZHAO Yunpeng, FU Chengxin
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 731-738.
https://doi.org/10.3785/j.issn.1008-9209.2015.12.131
Maca, Lepidium meyenii Walp. (Brassicaceae), has been domesticated as a medicinal crop at high altitude of the Peruvian Andes for two millennia. Its cultivars or landraces with different chemical profiles were bred and introduced out of Peru to various countries for industrial cultivation as driven by the increasing demand. Maca, which was approved on the China Inventory of New Resource Food in 2011, was also massively cultivated in multiple regions in China. The applied Maca cultivars differed among the producers, which may result in significant inconsistency of Maca quality. Thus, it is increasingly urgent to assess the quality of Maca roots with different cultivars and cultivation localities.
We simultaneously conducted both common garden and translocation experiments to address the contribution of both genetic and environmental variation to chemical similarity of Maca. Contents of mineral elements, amino acids, total alkaloid, and macamides were determined on five replicate samples of each Maca category using inductively coupled plasma mass spectrometer (ICP-MS), L8900 amino acid analyzer, UV-2700 spectrophotometer and ProStar 210 high performance liquid chromatograph. Both the chemical component contents and overall similarity coefficient were calculated and compared for the four parameters above using analysis of variance (ANOVA), principal component analysis (PCA), hierarchical clustering analysis (HCA) and cosine coefficient. Data analyses were conducted using SPSS version 22.0.
The results showed that the same cultivar from the translocation experiment (H6, A6) demonstrated remarkably greater chemical dissimilarity than the four cultivars (H1, H2, H3, H6) from the common garden experiment. The former experimental pair significantly differed in 11 components, while the latter four cultivars differed in five components. Although different groups of components differed to different extents between either cultivars or localities, the contents of mineral elements were prominently different between localities. Specifically, the total content and the contents of five of the total eight mineral elements were significantly different between the two studied localities. Meanwhile, Maca from Hongyuan of Sichuan Province (H6) showed a significantly higher content of total alkaloids than that from Aba of Sichuan Province (A6). Macamides did not differ either between localities or cultivars. A remarkable differentiation and the greater chemical dissimilarity between localities were also supported by the comparisons of the overall chemical similarity using PCA, HCA and cosine coefficient.
In conclusion, the chemical quality of the analyzed Maca is mainly determined by the environmental difference, particularly the soils which may directly impact the contents of mineral elements in Maca roots. More attention should be laid on the selection of farm localities and the control of cultivation environments. Further investigations of genetic distances of Maca cultivars and their relationships with chemical similarity will help better understand the exact contribution of cultivars.
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Genetic relationship identification on germplasm resources of two white-flesh loquats from two different producing areas of Zhejiang Province
CHEN Fangyong, WANG Yin, NI Haizhi, ZHANG Qi, YAN Bangguo
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 739-746.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.211
Loquat, Eriobotrya japonica (Thunb.) Lindl., is indigenous in southeast of China, which belongs to the family Rosaceae and subfamily Maloideae. Based on the color of fruit flesh, loquat can be sorted into red- and white-flesh cultivars. Zhejiang Province is the major producing area of loquat in China, with an area of about 1.2×104 hm2; the annual production of loquat is about 6.5×104 t, with a value of about 2.5 billion Chinese Yuan. Therefore, germplasm resources of loquat are abundant in Zhejiang Province. However, there are two whiteflesh loquat germplasms (Ruantiao white-flesh loquat from Huangyan, white-flesh loquat from Lanxi) which are different in leaf morphology and fruit shape from two producing areas of Zhejiang Province. Controversy on whether the two varieties are synonyms has existed for a long time, and no conclusive evidence was presented yet.
In this paper, morphological characteristics of the two varieties were examined, and their ploidy and stomata were analyzed, and their genetic relationships were identified using simple sequence repeat (SSR) marker.
Results showed that the single fruit mass of Ruantiao white-flesh loquat from Huangyan area was 1.38 times heavier than that of whiteflesh loquat from Lanxi area. However, the number of seeds, pericarp thickness, fruit hardness of whiteflesh fruit from Lanxi were 1.36, 1.096 and 1.22 times higher than those of Ruantiao white-flesh loquat from Huangyan, respectively. Flow cytometry analysis indicated that the two varieties were both diploid. Stomatal density of whiteflesh loquat from Lanxi was significantly higher than Ruantiao white-flesh loquat from Huangyan, while conversely, the stomatal area from Lanxi was significantly smaller than that from Huangyan. The cluster analysis using SSR marker showed that the genetic similarity coefficient (GS) of the loquat from Huangyan was 0.40, and 0.45 from Lanxi, indicating these two kinds of white-flesh loquats had a distant genetic relationship. The difference of the two varieties in maturation periods was mainly affected by variety characteristics and different geographical regions.
In conclusion, the two experimental materials have a distant genetic relationship and belong to different germplasms. The creation of the novel germplasm has positive significance in enriching market supply and industrial development of white-flesh loquat.
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Response of community distribution and biodiversity of grassland plants to environmental factors based on a “3circles” paradigm
WANG Xing, SONG Naiping, YANG Xinguo
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 747-759.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.181
To obtain the relationship between the pattern of plant community biodiversity and distribution and environmental factors, we conducted a study in a “3-circles” paradigm, which included grassland, sand, and beach land. Based on the “3-circles” paradigm, a 11.7 km land belt was selected, including three land types of girder land, slope land and beach land, which represented grassland, sandy land and wet land, respectively, and located in the ecotone area of grassland and sandy land in Wanjigou and Shabianzi villages of Yanchi County, Ningxia, China. Vegetation characteristics, soil water content at different layers, litter biomass and faeces counts on the ground and elevation were surveyed in August 2012. We conducted a clustering analysis by the important value of dominate species and then analyzed the relationship among the spatial distribution of community and biodiversity and different environmental factors (soil water content, litter biomass, faeces counts and elevation) by redundancy analysis (RDA).
Results showed that: 1) A total of 56 plant species were recorded, including 14 families and 38 genera. The grasses, legumes and weeds were shown as the main species. The average coverage of plant showed a good restoration effect in comparison with that before enclosure and grazing prohibition, but the community structure did not change significantly, and psammophytic species were still the dominant species. The value (0.2-2) of plant diversity was lower, and the interferential factors (litter biomass and faeces counts on the ground) had significant effects, which were primary factors for the changes of plant biodiversity along the belt. 2) The plant communities were classified into 12 groups at the fifth level of division by twoway indicator species analysis (TWINSPAN) and were classified into five groups by detrended correspondence analysis (DCA). The results of TWINSPAN and DCA were similar in the level of vegetation type in the desert steppe. The soil water content (60-80 cm) had a significant influence and it controlled the spatial distribution patterns of the plant community.
In summary, under the “3-circles” belt condition, the spatial distribution of water resource in deep soil layer and interferential factors on the ground lead to the distinguished patch features of grassland. In the landscape level, the spatial distribution of soil water resource influenced the spatial distribution of plant community, and the interferential factors drived the change of plant diversity. There existed arduousness and feasibility in the restoration process of desert steppe, and the integration of geography and biology provide a new way for the restoration of desert steppe. Based on the redistribution of soil water resource in the zone of “3-circles”, future studies would focus on the spatial relationship between the soil water resource and community type, which will help make sure a reasonable and scientific program in ecological restoration and reconstruction in the desert steppe.
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Effects of carbon-to-nitrogen ratios and nitrogen sources on composting of mushroom residue
BAI Yongjuan, XU Weinan, CHANG Xiaoxiao, HU Xiaohui
Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(6): 760-768.
https://doi.org/10.3785/j.issn.1008-9209.2016.01.061
With the increase production of agricultural products by years, large quantitative accumulations of agricultural waste have brought severe environmental problems and wasting of resources. Therefore, recycling and reusing the agricultural waste become urgent. Recently, composting of agricultural waste has become the research focus of soilless culture substrate. With the advantages such as stable physiochemical property, adequate supply of fat, wide variety of sources and low cost, soilless culture substrates have been accepted by majority of farmers, and the demand for substrates increased quickly. Mushroom waste contains large amounts of mycoprotein, a variety of metabolites and underutilized nutrients, which is a good substrate material. In this study, mushroom residue was selected as the main material for composting, the effects of different carbon-to-nitrogen ratios and nitrogen sources on physiochemical properties of composting were investigated, to find the optimal condition for transformation of mushroom residue to soilless culture substrate, to provide optimized composting parameters for the practical production, to offer scientific basis for the widespread application of the mushroom substrates.
The carbon-to-nitrogen (C/N) ratio was set at three levels of 25∶1, 30∶1, and 35∶1. Five different combinations of nitrogen sources were selected, including cow manure, chicken manure, urea, a mixture of cow manure and urea, and a mixture of chicken manure and urea. Actually, the C/N ratio of mushroom was 40∶1, and the dry cow manure, dry chicken manure and urea were used to adjust the C/N ratio. Each treatment contained 100 kg mushroom residue and 3% effective microorganism (EM) agents, and the water content was adjusted to 60%. Static composting at high temperature was applied and the experimental containers were covered by plastic sheeting. The piles were turned over every 10 days, and were sampled every 15 days for a study period of 80 days. Composting temperature, total porosity, air-filled porosity, water holding capacity, air-water ratio, electrical conductivity (EC), pH and bulk density were measured for each sample. The temperature in center of each pile was recorded using a temperature meter every day.
The results showed that during the composting period, the C/N ratios had significant influence on all parameters, while the nitrogen sources had significant influence on all parameters except total porosity. The optimal condition to keep high temperature (>50 ℃, and last for 8, 8 and 9 days, respectively), and to shorten the composting period of mushroom residue was C/N ratio of 30∶1, and adding the mixture of cow manure or chicken manure and urea as an additive nitrogen source. Under the C/N ratio of 30∶1, bulk density and porosity tend to be stable after 70-day fermentation, beneficial to composting of mushroom residue. When the mixture of cow manure or chicken manure and urea was added as nitrogen source, bulk density, water holding capacity, pH and EC values tended to be stable after 70-day composting.
In conclusion, the optimal condition for composting of mushroom residue is the initial C/N ratio of 30∶1 and the mixture of cow manure or chicken manure and urea as the nitrogen source.
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15 articles
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