诱导小麦抗叶锈病生防细菌的筛选、鉴定及其防效评价

小麦叶锈病是小麦生产上的重要病害,防治该病害主要采用抗病品种和喷施化学农药,而探索生物防治是防治该病的一种新方法。本研究使用3株细菌菌悬液对小麦种子进行处理,于小麦一叶期接种叶锈病菌10d后调查其发病率和严重度。结果表明,在盆栽试验中,Sneb1462菌株菌悬液诱导小麦抗叶锈病的效果最好,可使发病率和严重度比对照分别降低27.54%和49.90%;Sneb1462还可促进小麦根部生长,施用后小麦根长和地下部鲜重分别比对照提高30.19%和29.03%。在大田试验中,用Sneb1462菌悬液处理小麦种子后叶锈病的严重度降低38.60%,小麦株高和穗重分别提高16.44%和34.98%,表明该菌株是一株优良的抗病促生菌。经透射电镜观察、16SrDNA序列分析及生理生化的检测,鉴定该菌株为多黏类芽胞杆菌Paenibacillus polymyxa。利用生防细菌Sneb1462进行种子处理防控小麦叶锈病将是一种新型的植保措施,具有重要的研究意义。     

RNAi as an emerging approach to control Fusarium head blight disease and mycotoxin contamination in cereals

Fusarium graminearum is a major fungal pathogen of cereals worldwide, causing seedling, stem base and floral diseases, including Fusarium head blight (FHB). In addition to yield and quality losses, FHB contaminates cereal grain with mycotoxins, including deoxynivalenol, which are harmful to human, animal and ecosystem health. Currently, FHB control is only partially effective due to several intractable problems. RNA interference (RNAi) is a natural mechanism that regulates gene expression. RNAi has been exploited in the development of new genomic tools that allow the targeted silencing of genes of interest in many eukaryotes. Host‐induced gene silencing (HIGS) is a transgenic technology used to silence fungal genes in planta during attempted infection and thereby reduces disease levels. HIGS relies on the host plant's ability to produce mobile small interfering RNA molecules, generated from long double‐stranded RNA, which are complementary to targeted fungal genes. These molecules are transferred from the plant to invading fungi via an uncharacterised mechanism, to cause gene silencing. Here, we describe recent advances in RNAi‐mediated control of plant pathogenic fungi, highlighting the key advantages and disadvantages. We then discuss the developments and implications of combining HIGS with other methods of disease control. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Plant training for induced defense against insect pests: a promising tool for integrated pest management in cotton

Enhancing cotton pest management using plant natural defenses has been described as a promising way to improve the management of crop pests. We here reviewed various studies on cotton growing systems to illustrate how an ancient technique called plant training, which includes plant topping and pruning, may contribute to this goal. Using examples from cotton crops, we show how trained plants can be brought to a state of enhanced defense that causes faster and more robust activation of their defense responses. We revisit the agricultural benefits associated with this technique in cotton crops, with a focus on its potential as a supplementary tool for integrated pest management (IPM). In particular, we examine its role in mediating plant interactions with conspecific neighboring plants, pests and associated natural enemies. We propose a new IPM tool, plant training for induced defense, which involves inducing plant defense through artificial injury. Experimental evidence from various studies shows that cotton training is a promising technique, particularly for smallholders, which can be used as part of an IPM program to significantly reduce insecticide use and to improve productivity in cotton farming. © 2018 Society of Chemical Industry     

多元混菌培养对棉花黄萎菌拮抗效果的研究

特基拉芽胞杆菌C-9和鞘氨醇杆菌A1是分离得到的2株对棉花黄萎菌具有较好生防效果的菌株,平板对峙试验测定菌株C-9与A1的抑菌率分别为77.8%和83.3%,根据脂肽类抗生素相关合成基因序列进行PCR扩增,2株生防菌都能检测到surfactin、fengycin和mycosubtilins相关基因片段。通过单因素试验对液体混菌培养体系进行初步筛选,得到对棉花黄萎菌具有较好防效的最佳混菌比例A1：C-9=1：9,在此比例下的混菌培养物对棉花黄萎菌的抑制能力较单菌株A1和C-9提高了131%和36.7%。镜检发现混菌培养物抑制可致黄萎菌菌丝发生膨大畸形。盆栽试验表明,混菌培养物对棉花黄萎病的防治效果可达66.7%,混菌培养物处理的棉花在挑战接种棉花黄萎菌后,棉花体内防御酶系CAT酶活快速响应,在达到峰值时比同时期的CK组增加了135.3%。POD和SOD的基础酶活较CK分别提高22.5%和39.8%,且MDA含量始终低于CK。综合分析表明,混菌发酵可提高菌株对黄萎菌的抑制效果,可通过直接抑制黄萎菌生长和诱导植物产生防御反应来提高对棉花黄萎菌的抗性。     

热水处理诱导香蕉采后抗病性及其对相关酶活性的影响

该文探讨了热处理对采后香蕉果实软化、褪绿转黄、炭疽病病斑大小及相关防御酶活性变化的影响.香蕉果实用52℃热水处理10 min后在25℃下贮藏,在12 d内果实软化和褪绿转黄不明显,而未经热处理的对照果实在12d内明显软化和转黄.接种外源炭疽菌孢子可促进果实的软化和褪绿,但热处理果实的软化和褪绿速度仍然慢于对照果实.接种炭疽菌孢子后,对照果实病斑扩展迅速,而热处理果实病斑扩展缓慢.热处理导致果皮多酚氧化酶(PPO),过氧化物酶(POD)和超氧化歧化酶(SOD)活性的下降,诱导了酯氧合酶(LOX)活性大幅度提高,对苯丙氨酸解氨酶(PAL)活性影响不显著.这些结果表明,热处理可诱导采后香蕉的抗病性并具有一定延缓果实后熟的作用.该文还对香蕉果实抗病性的提高与相关防御酶活性的关系进行了讨论.     

北京鸭肝上皮样干细胞生物学特性研究

为了研究北京鸭肝上皮样干细胞(liver epithelioid stem cells,LESCs)生物学特性,对其进行分离、体外培养、鉴定,多向分化潜能等实验。取孵化17日龄健康鸭胚分离北京鸭LESCs,通过免疫荧光、RT-PCR以及流式细胞术等技术对北京鸭LESCs进行鉴定,同时诱导北京鸭LESCs分化,检测多向分化潜能。结果表明:从鸭胚中分离培养的细胞为北京鸭LESCs,并成功向成脂肪细胞和成软骨细胞分化,证明具有干细胞多向分化潜能的共性。北京鸭LESCs在体外具有较强的增殖与自我更新能力,并具有一定的可塑性,可以作为种质细胞进行保存,使这一品种遗传资源以干细胞的形式长期保存下来,同时也可以为北京鸭基因的改良提供参考。     

川硬皮肿腿蜂学习经历对花椒与虎天牛虫粪挥发物的行为反应测定

采用Y型嗅觉仪和触角电位仪,研究羽化初期川硬皮肿腿蜂对花椒挥发物、花椒虎天牛虫粪木屑混合物诱导的学习效应,比较有无学习经历的川硬皮肿腿蜂对不同浓度花椒挥发物的行为反应,以探索利用学习行为提高川硬皮肿腿蜂防治花椒虎天牛效果的途径。结果表明:羽化期经历10g·mL-1花椒枝条挥发物诱导的川硬皮肿腿蜂对味源的行为反应率最高,达到66.67%,与其余9种处理间存在显著差异(P<0.05),其次是羽化期经历10g·mL-1虫粪木屑挥发物诱导的肿腿蜂,其对味源的行为反应率为64.44%,而经历0.01g·mL-1花椒枝条与虫粪木屑挥发物诱导的肿腿蜂反应率最低,表明经花椒挥发物和花椒虎天牛虫粪学习处理的川硬皮肿腿蜂对防治花椒虎天牛有正面影响,且花椒枝条挥发物在同类因素中对川硬皮肿腿蜂防治花椒虎天牛有最突出影响的结论。     

The past,present and future of bovine pluripotent stem cells: a brief overview

Although the pursuit of bovine embryonic stem cells started more than 26 years ago for the purpose of gene-targeting, true pluripotent stem cells in this economically important species are still elusive. With the rapid advances in genome-editing and cloning using homologously recombined somatic cells, the need for pluripotent stem cells for precise genetic modification in any species became questionable. With the pig being the better model for human regenerative biology, the identification of the commonalities and uniqueness of the pluripotency circuitry across mammalian species may be the main objective for studying pluripotent stem cells in the bovine.     

滔罗定对大肠杆菌和沙门氏菌混合感染鸡的药效学试验

摘要：研究了滔罗定的体外抑菌效果及对人工混合感染雏鸡大肠杆菌和沙门氏菌病的治疗效果。采用试管两倍稀释法测定滔罗定对大肠杆菌和沙门氏菌的最小抑菌浓度。选择180只4日龄罗曼雏鸡随机分为健康组（Ⅰ）,感染对照组（Ⅱ),氟苯尼考治疗对照组（Ⅲ）和滔罗定高、中、低剂量组（Ⅳ、Ⅴ、Ⅵ）等6个不同处理组,进行人工致病治疗试验。试验结果：与感染对照组相比,滔罗定高、中剂量组的死亡率分别降低了20.0%、16.7%,治愈率分别提高了23.3%、16.6%,差异均极显著(P<0.01);滔罗定高、中剂量组的有效率和治愈率均高于氟苯尼考组,但差异不显著(P>0.05);滔罗定对大肠杆菌和沙门氏菌的最小抑菌浓度大于或等于256 μg/mL。结果表明,滔罗定对人工混合感染雏鸡大肠杆菌和沙门氏菌病具有一定的治疗效果。     

寡糖诱导向日葵抗锈病超微结构

 【目的】利用电子显微镜技术研究寡糖处理向日葵植株后对锈菌侵染的抑制作用,以揭示寡糖诱发子在细胞学水平的作用机理。【方法】通过寡糖喷雾处理向日葵叶片,2 d后接种锈菌,利用扫描和透射电镜对寄主及病原菌超微结构进行了研究。【结果】诱导处理后有部分夏胞子向内凹陷,萌发受到抑制。寄主细胞对于病原菌的侵入产生了防卫反应结构和物质。表现为寄主细胞壁加厚,染色加深,寄主细胞壁下产生黑色物质沉积;吸器壁加厚,吸器外间质变宽,部分吸器畸形坏死;细胞器变形、空泡化,最终寄主细胞解体、坏死。【结论】寡糖处理对病原菌有一定的抑制作用并可诱导向日葵产生对锈病的抗病性。