Production of monoclonal antibodies against AFLM (Ver-1), a middle key protein involved in aflatoxin biosynthesis

Aflatoxins are potent carcinogens, mutagens and teratogens, and are harmful to both humans and animals. As many as 30 genes are involved in aflatoxin biosynthesis. Among them, aflM (ver-1) gene was predicted to encode a 28-kDa NADPH-dependent ketoreductase (AFLM), which catalyzed middle enzymatic steps in aflatoxin biosynthetic pathway. AFLM (Ver-1) was proved to be necessary for conversion of versicolorin A (VERA) to demethylsterigmatocystin (DMST) in aflatoxin B₁ (AFB₁) biosynthesis. For these reasons, aflM gene was cloned and specific monoclonal antibodies for AFLM was developed to better define potential pathways of AFLM involved in AFB₁ biosynthesis. Monoclonal antibodies 11B2-1D7 and 3G5-4E7 were successfully screened out by immunizing mouse. Immunoblot analysis revealed that both had high sensitivity and specificity to identify native AFLM protein in A. flavus with detection limit of 11 ​ng/mL and 8 ​ng/mL respectively. These results showed that it was suitable for quantitative detection of AFLM in A. flavus isolate. Further investigation revealed that aflatoxin accumulations of various A. flavus were not dependent on AFLM biosynthesis. Overall, this is the first report for development for AFLM monoclonal antibody development and application in A. flavus quantitative detection.     

An efficient approach for obtaining plant organelle genomes

Plant organelle (plastid and mitochondrial) genomes contain substantial information for plant evolution and adaptation. Therefore, it’s important to reveal plant whole-genome sequences including plastid and mitochondrial genomes. To decode these sequences, it is required to efficiently separate organelle genomic DNA from nucleus genome, which is difficult and laborious. In this study, an efficient procedure was established to obtain plant organelle genomes without extraction of plastid and mitochondria. Organelle DNA was extracted from three materials including Sinapis arvensis var. ‘Yeyou 18’, a cytoplasmic male sterile line (Nsa CMS) and its corresponding maintainer line ‘Zhongshuang 4’. DNA was sequenced by Roche 454 FLX+ and Illumina Miseq platforms. Organelle genomes were assembled using the generated reads and public organelle genome sequences. This research presented a procedure that efficiently assembled organelle genomes and subsequent fill gaps by extending the consensus contig terminals. This method enabled us to assemble plant plastid and mitochondrial genomes simultaneously. The obtained organelle genomes could accelerate understanding of mitochondrial rearrangements and laid a foundation for further study of Sinapis arvensis evolution and sterility gene of Nsa CMS.     

Bacillus megaterium A6 suppresses Sclerotinia sclerotiorum on oilseed rape in the field and promotes oilseed rape growth

Sclerotinia sclerotiorum causes serious yield losses in oilseed rape and other crops worldwide. Field trials were conducted at two locations to evaluate two formulations of oilseed rape seed containing the plant-growth promoting bacterium Bacillus megaterium A6 for suppression of this pathogen. Treatments containing strain A6 in pellet and in wrap formulations resulted in oilseed rape seed yields that were similar to the chemical control and significantly greater than the untreated seed control at both locations. Treatments containing A6 in pellet and wrap formulations also resulted in an incidence of disease caused by S. sclerotiorum that was similar to the chemical control. Both of these treatments significantly decreased disease incidence relative to the untreated seed control and to the respective formulated seed controls (that did not contain strain A6) at both locations. Strain A6 applied to oilseed rape seed in these two formulations promoted growth in greenhouse pot studies conducted with autoclaved soil. In two experiments, these treatments resulted in significant increases in mean shoot dry weight per pot and mean % total N per plant relative to their respective controls containing formulated oilseed rape seed without strain A6 and to the untreated seed control. Both formulations provided stable B. megaterium A6 (≥10⁶ CFU) and seed germination (>85%) over a six month period at room temperature. Experiments reported here indicate the commercial potential of these formulations of B. megaterium A6 for suppression of S. sclerotiorum on oilseed rape.     

A comparison of the lipid and fatty acid profiles from the kernels of the fruit (nuts) of Ximenia caffra and Ricinodendron rautanenii from Zimbabwe

The lipid profile of nuts from Ximenia caffra and Ricinodendron rautanenii was determined and compared. Although the total oil content of X. caffra and R. rautanenii nuts was similar (47.6 ± 7.5% versus 53.3 ± 13.7%), the fatty acid profiles differed significantly. X. caffra had a higher content (p < 0.05) of saturated fatty acids than R. rautanenii (20.19 ± 1.07% versus 13.87 ± 3.68%) and contained C22:0 and C24:0 which were lacking in R. rautanenii. Total monounsaturated fatty acids were higher in X. caffra than R. rautanenii (71.48 ± 0.99% versus 36.66 ± 1.95%). Oleic acid (C18:1n9) was the major monounsaturated fatty acid (MUFA) in X. caffra whereas erucic acid (C22:1n9), the major MUFA in R. rautanenii, was undetectable in X. caffra. R. rautanenii had a greater polyunsaturated fatty acid content than X. caffra which contained C18:3n3 (α-linolenic acid) and nervonic acid (24:1n9). X. caffra is potentially an important source of essential fatty acids.     

花生籽仁大小相关性状QTL定位

花生籽仁大小相关性状是决定花生产量的直接因素。为发掘与花生籽仁大小相关的QTL,本研究以中花16×J11构建的RIL群体为材料,得到了一张包含289个SSR标记、21个连锁群、覆盖长度为947.3cM的遗传连锁图谱。连续2年对籽仁大小相关性状鉴定表明,各性状在群体中变异广泛,呈典型正态分布,且大部分性状间显著相关。结合本研究构建的遗传图谱,利用WinCart2.5进行QTL定位分析,2年共检测到66个QTL,贡献率为3.23%～33.01%。与籽仁长(SL)、籽仁宽(SW)、籽仁长宽比(LWR)和百仁重(HSW)相关的QTL分别有18、16、18和14个。在这些QTL中,A05染色体上的区间A05A1500-A05A1530同时存在控制籽仁长(qSLA05.1和qSLA05.2)和百仁重的相关的QTL(qHSWA05.1);B06染色体上的区间A06B135-A06B113同时存在控制籽仁宽(qSWB06.2和qSWB06.4)和百仁重相关的QTL (qHSWB06.4),这些稳定存在的主效QTL将为花生产量相关性状的精细定位和分子育种奠定基础。     

马铃薯耐盐性研究进展

从马铃薯耐盐资源的评价、盐胁迫对马铃薯的生理影响、马铃薯盐胁迫应答分子机制和基因工程提高马铃薯耐盐性等4个方面综述马铃薯耐盐性研究现状,并做出讨论和展望,以期为揭示马铃薯耐盐机理、耐盐种质资源鉴定和培育耐盐马铃薯品种提供理论参考。     

添加水稻秸秆对油菜(Brassican apus L.)幼苗生长的影响

近几年,水稻秸秆直接还田对油菜幼苗生长的负效应受到关注。有许多研究在水稻残体或腐解物中检测出了酚酸等被广泛证实具有化感作用的物质,因此在水稻秸秆产生的负效应中,化感抑制作用不容忽视。本研究以酚酸为目标化感物质,以湖北省油菜主栽品种"中双11号"为受体,采用4种采自典型稻油轮作系统中的土壤进行盆栽试验,研究水稻秸秆对油菜幼苗生长的影响。结果表明:(1)整体看来,添加秸秆对油菜幼苗总生物量的主效应在进贤土为正,在汉川土为负,在阳逻和麻城土为无明显影响;(2)功能叶片光合色素含量在全部土壤下的显著降低均出现在播种后33d之内,与水稻秸秆腐解速率最大值的出现与存在时间上的重叠。秸秆处理对油菜幼苗的负效应在早期强于后期;(3)土壤水溶态酚酸含量为3.3~49.0μg·g^-1soil。添加秸秆虽导致土壤中水溶态酚酸浓度增加,但其明显增加主要发生在试验后期,且增量与幼苗生物量化感效应指数呈正相关关系。因此酚酸含量的变化不能解释水稻秸秆的负效应,为揭示秸秆处理的负效应机制,需要转换目标化感物质。