Low genetic variability in Sclerotinia sclerotiorum populations from common bean fields in Minas Gerais State,Brazil, at regional,local and micro‐scales

Sclerotinia sclerotiorum, causal agent of white mould, is the most destructive and widely distributed soilborne pathogen of common bean during the autumn–winter season in Brazil. Nevertheless, little is known about the genetic structure of the pathogen population. Microsatellite (SSR) markers and mycelial compatibility groups (MCGs) were used to characterize 118 isolates collected from 20 bean fields located in the most important growing regions of Minas Gerais State (MG). Additionally, the genetic variability among 10 isolates obtained from a single sclerotium was investigated in 10 different sclerotia. Seventy SSR haplotypes and 14 MCGs were identified among the 118 isolates. The genetic differences within bean growing areas accounted for most of the genetic variation (72%). Despite the relatively high genotypic diversity, the SSR loci were at linkage disequilibrium. Moreover, 70% of the isolates were assigned to only two MCGs, and haplotypes of a given MCG were closely related. The discriminant analysis of principal components revealed five groups. There was strong genetic differentiation between isolates collected in one municipality in southern MG when compared to other regions. Common bean resistance to white mould should be assessed with representative isolates of the five genetic groups and, if possible, of the different MCGs detected in the present study. One to five haplotypes were detected among the 10 isolates obtained from a single sclerotium. Therefore, in order to ensure genetic identity of an isolate, hyphal tip or monoascosporic isolates should be used.     

Genotypic diversity and migration of clonal lineages of Botrytis cinerea from chickpea fields of Bangladesh inferred by microsatellite markers

An analysis of allelic diversity at nine microsatellite loci provided an insight into the population structure of Botrytis cinerea from four fields (sampled in 2003 and 2004) that represented important regional locations for chickpea production in Bangladesh. Although three populations were limited by sample size after clone‐correction, a total of 51 alleles were amplified among 146 B. cinerea isolates from Bangladesh, which revealed a high amount of within‐population and overall genetic diversity (H_S = 0·48 and H_T = 0·54, respectively). The percentage of maximal genotypic diversity (G) ranged between populations (G = 23–40), with a total of 69 haplotypes detected (G = 25). Bayesian cluster analysis depicted two major clusters distributed among the four Bangladesh populations, indicating population admixture from two origins that have spread throughout these regions. Genotype flow between regions was detected and indicated the spread of clonal lineages, consistent with relatively low differentiation among the four populations (mean G_ST = 0·1, P < 0·05). These results highlighted the potential threat of host resistance breakdown as a result of considerable genetic diversity, genotype flow and the evolutionary potential of B. cinerea.     

Host‐induced gene silencing in the necrotrophic fungal pathogen Sclerotinia sclerotiorum

Sclerotinia sclerotiorum is a necrotrophic fungus that causes a devastating disease called white mould, infecting more than 450 plant species worldwide. Control of this disease with fungicides is limited, so host plant resistance is the preferred alternative for disease management. However, due to the nature of the disease, breeding programmes have had limited success. A potential alternative to developing necrotrophic fungal resistance is the use of host‐induced gene silencing (HIGS) methods, which involves host expression of dsRNA‐generating constructs directed against genes in the pathogen. In this study, the target gene chosen was chitin synthase (chs), which commands the synthesis of chitin, the polysaccharide that is a crucial structural component of the cell walls of many fungi. Tobacco plants were transformed with an interfering intron‐containing hairpin RNA construct for silencing the fungal chs gene. Seventy‐two hours after inoculation, five transgenic lines showed a reduction in disease severity ranging from 55·5 to 86·7% compared with the non‐transgenic lines. The lesion area did not show extensive progress over this time (up to 120 h). Disease resistance and silencing of the fungal chs gene was positively correlated with the presence of detectable siRNA in the transgenic lines. It was demonstrated that expression of endogenous genes from the very aggressive necrotrophic fungus S. sclerotiorum could be prevented by host induced silencing. HIGS of the fungal chitin synthase gene can generate white mould‐tolerant plants. From a biotechnological perspective, these results open new prospects for the development of transgenic plants resistant to necrotrophic fungal pathogens.     

不同杀菌剂对采后柑橘绿霉病的防治效果比较

本文报道先刺伤接种柑橘绿霉病菌（Penicillium digitatum）孢子悬浮液,再进行不同类型、不同浓度药剂对抗苯并咪唑类和咪唑类杀菌剂（双抗）或双敏感菌系的防治效果。结果表明：500 、1000mg/L甲基硫菌灵、咪鲜胺和抑霉唑（500mg/L）单剂,或500mg/L甲基硫菌灵和咪鲜胺混剂对双抗菌系防治作用均低于50%。而1000mg/L百可得,500、1000mg/L百可得与相同浓度咪鲜胺均可控制双抗菌系引起的腐烂。1000mg/L咯菌腈防效为83.33%,500、1000mg/L嘧霉胺防效分别为91.11%、98.89%。500mg/L百可得、抑霉唑和嘧霉胺单剂,500mg/L百可得和相同浓度咪鲜胺混配,500mg/L甲基硫菌灵和相同浓度咪鲜胺混配对敏感菌系均有89%以上防效。基于研究结果,建议不再使用苯并咪唑类和咪唑类杀菌剂单剂,或这两类杀菌剂混剂防治柑橘采后病害,可选择1000mg /L百可得单剂,500mg /L百可得和相同浓度咪唑类混剂,同时建议将嘧霉胺登记用于柑橘采后处理。     

Genetic analysis and molecular characterisation of laboratory and field mutants of Botryotinia fuckeliana (Botrytis cinerea) resistant to QoI fungicides

BACKGROUND: QoI fungicides, inhibitors of mitochondrial respiration, are considered to be at high risk of resistance development. In several phytopathogenic fungi, resistance is caused by mutations (most frequently G143A) in the mitochondrial cytochrome b (cytb) gene. The genetic and molecular basis of QoI resistance were investigated in laboratory and field mutants of Botryotinia fuckeliana (de Bary) Whetz. exhibiting in vitro reduced sensitivity to trifloxystrobin. RESULTS: B. fuckeliana mutants highly resistant to trifloxystrobin were obtained in the laboratory by spontaneous mutations in wild‐type strains, or from naturally infected plants on a medium amended with 1–3 mg L^?1 trifloxystrobin and 2 mM salicylhydroxamic acid, an inhibitor of alternative oxidase. No point mutations were detected, either in the complete nucleotide sequences of the cytb gene or in those of the aox and Rieske protein genes of laboratory mutants, whereas all field mutants carried the G143A mutation in the mitochondrial cytb gene. QoI resistance was always maternally inherited in ascospore progeny of sexual crosses of field mutants with sensitive reference strains. CONCLUSIONS: The G143A mutation in cytb gene is confirmed to be responsible for field resistance to QoIs in B. fuckeliana. Maternal inheritance of resistance to QoIs in progeny of sexual crosses confirmed that it is caused by extranuclear genetic determinants. In laboratory mutants the heteroplasmic state of mutated mitochondria could likely hamper the G143A detection, otherwise other gene(s) underlying different mechanisms of resistance could be involved. Copyright © 2012 Society of Chemical Industry     

实验室制粒机

实验室制粒机主要为大专院校、科研单位,在实验室内压制各种规格的颗粒饲料,作饲养试验用。制粒机的研制试验结果表明,各项性能指标和制造质量均已达到设计要求,而在其使用的方便性和配套性方面超出了进口样机。     

立式双层孔环模生物质压块机设计与试验

针对目前环模压块机存在生产率低、能耗高等问题,该文采用立式环模原理和双层孔环模结构,创新设计了双层孔模块及对应的压辊,双层环模模块两边线夹角8°,模孔偏心角4.3°,双模孔中心线夹角10°。样机完成后进行了生产性试验,结果表明:压块机生产率为2.39 t/h,吨料能耗55.86 k W·h/t,成型率为96%以上,成型密度为1.1 g/cm3以上,各项指标均达到设计及标准要求;对比于单层环模的立式环模生物质成型机生产参数,该创新设计的设备性能有所提高;设备自身下层环模与上层环模相比,成型率、生产率均有提高,差异不大。该立式双层环模压块机提高了生产率和产品质量,为中国生物质成型燃料产业化的发展提供装备保障。     

砀山梨、苹果烟煤病防治研究

 采用以植物保护剂为主体,调节果树内部营养生理增加抗性为基础,结合农药复配等技术,进行烟煤病的综合防治。     

ZMCJ型系列纸浆模快餐具生产线可行性分析

分析了纸浆模快餐具的生产成本，对产品市场前景和生产线投资规模进行了预测，介绍了产品工艺流程及生产设备。     

Failure of UV irradiation to reduce blue mould infections beneficially in an experimental water handling system for pome fruit

A reduction in the number of wounds of pears and apples which developed blue mould (Penicillium expansum) infection was associated with reduced spore concentration. An experimental ultraviolet irradiation treatment of water in a fruit-handling system reduced both spore numbers and fruit rots, but not to a level which would suggest that the technique is worth pursuing to a commercial application stage.