Sponsor(s): Chinese Academy of Agricultural Sciences；Chinese Association of Agricultural Science Societies
24 issues per year
Current Issue: Issue 10, 2018
Scientia Agricultura Sinica, the 1st in Comprehensive Agricultural Science, is supervised by Ministry of Agriculture of PRC, and sponsored by Chinese Academy of Agricultural Sciences; Chinese Association of Agricultural Science Societies. Scientia Agricultura Sinica, launched in 1960, is a leading peer-reviewed and mufti-disciplinary journal and published semi-monthly in Chinese with English title, abstract, figures, tables and references. It aims to publish those papers that are influential and will significantly advance scientific understanding in agriculture fields worldwide. The scope covers Crop Genetics, Breeding, Germplasm Resources; Physiology, Biochemistry, Cultivation, Tillage Plant Protection; Soil & Fertilization, Agro-Ecology & Environment, Bio-energy; Animal Science, Veterinary Science, Agricultural Information Science; Food Science; Agricultural Economics and Management; Agricultural Sustainability. The journal is included in JST, CA and CSCD.
Editor-in-Chief Wan Jianmin Associate Editor-in-Chief Zou Ruicang Tang HuaJun Wu Kongming Guo YuYuan Geng Xu Sun Tan Executive Editor Lu Wenru
Scientia Agricultura Sinica,2018,Vol 51,No. 10
[Objective] Microorganisms play the key role of switcher in soil nutrient cycling. The aim of this study is to study the effects of soil microbial community structure under long-term fertilization of biochar and biochar-based fertilizer, and to provide a theoretical reference on reasonable administration of different organic fertilizers with traditional organic fertilizer (corn straw and piggery manure compost). [Method] This study was based on the long-term experiment of soil improvement of brown soil in Shenyang Agricultural University (began in 2009). The changes of soil physic-chemical properties, soil microbial community structure and their relationship by long-term organic fertilizer plus NPK fertilization were studied by PLFA and correlation analysis. Soil samples were collected from treatments of biochar-based compound fertilizer (BF), piggery manure compost combined with NPK fertilizer (PMC), corn straw returning (CS), and biochar (BIO), respectively. [Result] The soil values pH of PMC and BF were higher than that of BIO significantly; the total N (TN) of PMC was significantly higher than those of BF and CS, and the TN of BIO had no significant difference with that of PMC; the soil organic matter (SOM) of PMC was significantly higher than those of BF and BIO; the moisture content (MC) of PMC was the highest of all the treatments; the total K (TK) of all the treatments had no significant difference. The total PLFAs of PMC were significantly higher than those of other treatments, but there was no significant difference among other treatments; the bacterial PLFAs of PMC were the highest of all the treatments, and the bacterial PLFAs of BF were significantly lower than those of BIO and CS; the fungal, Gram-positive bacterial, Gram-negative bacterial PLFAs of PMC were significantly higher than those of BIO, and had no significant difference with those of BF; the actinomycete PLFAs of PMC were significantly higher than those of CS, and there were no significant difference in actinomycete PLFAs between BIO and BF. The Shannon-Winner index ( H) and the fungal/bacterial PLFAs ratio of BF were significantly higher than those of BIO, the Gram-positive/Gram-negative PLFAs ratios of BF and PMC were significantly lower than that of BIO. The result of redundancy analysis (RDA) showed that the microbial PLFAs were extremely and significantly influenced ( P < 0.01) by soil pH, TN, and SOM, and significantly influenced ( P < 0.05) by MC and TK. [Conclusion] The soil physic-chemical properties were obvious improved by long-term fertilization of biochar and biochar-based compound fertilizer. Compared with PMC, farmland with BIO was bad for the growth of fungi and Gram-negative bacteria, and the farmland with BIO and BF had different effects on soil microbial community structure, namely, farmland with BIO could increase the biomass of bacteria, while the farmland with BF could increase the fungi/bacteria ratio and the diversity of soil microbial community structure. Soil pH, TN, SOM, MC, and TK were the important factors influencing the soil microorganism community structure in this study.
Scientia Agricultura Sinica,2018,Vol 51,No. 10
[Objective] This study was performed to enhance carotenoid yield, to improve nutritional value of fermentation product, and to reduce the production cost of carotenoids through optimizing solid-state fermentation substrate and fermentation conditions of Rhodotorula mucilaginosa. [Method] In this study, R. mucilaginosa TZR 2014 was used as an inoculant. First, the Mixture-Design of Design-Expert software was used to design the fermentation substrate, and the content of ingredients was as follows: 50%–80% wheat bran, 6%–20% soybean meal, 3%–15% maize flour, 2%–14% rice bran, 2%–10% maize syrup, 0.4%–2.5% ammonium sulfate, 0.05%–0.5% monopotassium phosphate, and 0.03%–0.3% magnesium sulfate. Then, the optimal ratio of ingredients in substrate was determined according to the carotenoid yield. Based on this result, an L 16(4 5) orthogonal design was used to optimize the fermentation conditions, including inoculum amount (5.0%–12.5%), fermentation time (60.0–96.0 h), fermentation temperature (26 °C–32 °C), and fermentation pH (60.0%–75.0%). Finally, the number of R. mucilaginosa and contents of carotenoids, crude fiber, crude protein, water, crude fat, ash, calcium, phosphorus, and amino acids in fermentation product were determined to evaluate the effect of the optimized fermentation process on the nutritional values of fermentation product. [Result] The results showed that there was a positive correlation between maize starch content in substrate and carotenoid content in fermentation product ( r = 0.344, P = 0.040) or between rice bran content in fermentation substrate and carotenoid content in fermentation product ( r = 0.329, P = 0.050). There was a significantly negative correlation between carotenoid yield and the content of wheat bran in solid-state fermentation substrate ( r = −0.336, P = 0.045). There was a positive correlation between the number of viable bacteria of R. mucilaginosa in fermentation product and the content of soybean meal in fermentation substrate ( r = 0.510, P = 0.001). Inoculum amount, fermentation temperature, pH, and moisture had extremely significant impacts on the number of R. mucilaginosa ( P < 0.01), thereinto, fermentation temperature had the greatest effect on the number of R. mucilaginosa, followed by moisture, inoculum amount, and pH. Fermentation time, fermentation temperature, and pH had extremely significant influence on the carotenoid content in the fermentention product ( P < 0.01); fermentation temperature had the greatest influence on the carotenoid content in the fermentation product, followed by pH and fermentation time. After the optimization of the fermentation process, the carotenoid yield by R. mucilaginosa TZR 2014 was increased to 4 535 μg·kg −1; the bacteria number was increased to 3.79 × 10 9 CFU/kg; the contents of crude fiber, crude protein, ash, threonine, glutamate, and proline in fermentation product were significantly increased ( P < 0.05); meanwhile, the contents of histidine, water and crude fat were significantly decreased ( P < 0.05). [Conclusion] The optimal ratio of solid-state fermentation substrate for R. mucilaginosa was as follows: 52.5% wheat bran, 20.0% soybean meal, 3.0% maize flour, 14.0% rice bran, 10.0% maize syrup, 0.4% ammonium sulfate, 0.05% monopotassium phosphate, and 0.04% magnesium sulfate. The optimal fermentation conditions were as follows: inoculum amount 5.0%, fermentation time 72 h, fermentation temperature 28.0 °C, pH 6.0, and moisture content 60.0%. The results suggested that the optimized fermentation process of R. mucilaginosa enhanced the yield of carotenoids and improved the nutritional value of fermentation product.
Influence of Temperature and Polyamines on Occurrence of Citrus Canker Disease and Underlying Mechanisms
Scientia Agricultura Sinica,2018,Vol 51,No. 10
[Objective] Canker disease is one of the most devastating diseases that cause serious damages to citrus. It is more likely to occur under high temperature. The objective of this study is to elucidate the mechanism underlying the disease incidence at high temperature, reveal its metabolic changes, and to provide important theoretical guidance for controlling the disease using certain chemicals. [Method] Sweet orange ( Citrus sinensis), which was sensitive to canker disease, was used as the experimental material. The sweet orange plants were pre-cultured for 3 days at either 21 °C or 30 °C prior to inoculation with Xanthomonas citri subsp. citri ( Xcc), followed by evaluation of disease incidence. Expression of four defense-related genes, including AOS (allene oxide synthase), CHI (chitinase), GPX (glutathione peroxidase) and PR4A (pathogenesis-related protein 4A), in the plants pre-cultured at the two temperatures by semi-quantitative RT-PCR. Meanwhile, the endogenous polyamines (putrescine, spermidine, and spermine) in the plants pre-cultured at the two temperatures were also analyzed by HPLC. In addition, sweet orange plants were treated with exogenous spermidine (0.4 mmol·L −1), using water treatment as a control, before Xcc inoculation. The disease incidence and index of plants treated with either spermidine or water were compared, while the endogenous polyamine content and expression levels of defense-related genes ( AOS, CHI, GPX, and PR4A) in response to spermidine or water treatment were assessed. [Result] After inoculation with Xcc, it was found that the plants pre-cultured at 21 °C exhibited a lower canker disease incidence at the early stage when compared with the plants pre-cultured at 30 °C. On the 10th day, the incidence of the two treatments was similar. The HPLC analysis showed that contents of the three free polyamines (putrescine, spermidine, and spermine) in plants pre-cultured at 21 °C were significantly higher than those in the plants pre-cultured at 30 °C. In addition, the RT-PCR analysis indicated that the transcript levels of three defense-related genes, CHI, GPX, and PR4A, in plants kept at 21 °C were higher than those from 30 °C, while there was no significant difference in AOS expression between the two groups. Exogenous application of spermidine remarkably enhanced the levels of endogenous putresicne and spermidine, reduced the disease incidence and index in comparison with water treatment. Spermidine treatment reduced the disease incidence by 45% and in comparison with the control after 14 days of inoculation. In addition, the disease index of the spermidine-treated samples was 4.8 lower than that of the control. Meanwhile, the phenotype indicated that the control displayed more serious symptom than that of spermidine treatment. Moreover, spermidine treatment could up-regulate the mRNA abundance of all four defense-related genes, including AOS, CHI, GPX and PR4A. [Conclusion] Sweet orange displayed susceptibility to citrus canker at high temperature, and the potential mechanisms underlying this phenomenon may be ascribed to inhibition of defense-related genes and suppression of polyamine biosynthesis. Exogenous polyamine treatment conferred enhanced tolerance to citrus canker by up-regulating defense-related genes and triggering disease resistance response. Taken together, high temperature is one of the environmental factors accounting for outbreak of citrus canker disease, and polyamines are conducive for improving tolerance to citrus canker disease.
Scientia Agricultura Sinica,2018,Vol 51,No. 10
[Objective] It has been shown that the entry of classical swine fever virus (CSFV) into host cells is mediated by clathrin-mediated endocytosis. However, the viral protein involved in entry stage remains to be elucidated. This study aimed to clarify the role of the E2 protein in the entry of CSFV. [Method] Lentivirus carrying the E2 gene was packaged by transient transfection of HEK-293T cells. A cell line stably expressing the E2 protein was established through transducing the suspension 293 cell with the lentiviruses. The expression of the recombinant E2 (rE2) protein was optimized to achieve higher production, and the rE2 protein was purified by affinity chromatography. The expression level and reactivity of the rE2 protein was identified by SDS-PAGE and Western blotting. The effects of the E2 protein on CSFV infection, attachment and internalization were determined by respective assays. Polyclonal anti-E2 antibodies were prepared by immunizing BALB/c mice with the rE2 protein, and its blocking rate was determined by blocking ELISA. Attachment and internalization assays were performed using the prepared polyclonal antibodies to demonstrate the role of the E2 protein in virus attachment and internalization. [Result] The cell line 293 was successfully transduced with the lentivirus vector. The SDS-PAGE produced the anticipated band size of rE2 no matter the sample was treated with the reducing agent or not. The Western blotting results showed that the rE2 protein could be recognized by the anti-E2 monoclonal antibody WH303. The results indicated that suspension 293 cell line could stably express the rE2 protein. Under the optimized expression condition, the concentration of the rE2 protein in the supernatants of the established suspension 293 cell line was up to 5.84 μg·mL −1. The soluble protein blocking assay results showed that the expressed rE2 protein exerted antiviral activity during the process of CSFV infection. CSFV infection was significantly inhibited by the rE2 protein treated in the entry step; the blocking ELISA and serum neutralization test showed that the anti-E2 polyclonal antibodies could neutralize CSFV infection; at the same time, the attachment and internalization assays demonstrated that CSFV internalization could be inhibited by the rE2 protein and viral attachment was blocked by the polyclonal antibodies. [Conclusion] The E2 protein was involved in attachment and internalization of CSFV.