Use of two PGPR strains in the integrated management of blast disease in rice (Oryza sativa) in Southern Spain

Biocontrol capacity of two plant growth-promoting rhizobacteria (PGPR) strains, against blast disease in rice paddy fields in Southern Spain was studied in three cropping seasons. Both strains (Pseudomonas fluorescens Aur 6 and Chryseobacterium balustinum Aur 9) had already shown biocontrol capacity against pathogens, ability to induce systemic resistance against leaf pathogens and against salt stress in different plant species. Bacterial treatments were carried out on seeds and/or on leaves. Strains were inoculated individually and in combination. Protection against natural disease incidence was evaluated, and rice production and quality measured in 2005 and 2006 trials. In 2004, natural disease incidence was low (between 0.1% and 0.35% of damaged leaf surface) due to environmental conditions; under these conditions, both strains significantly protected plants against rice blast. In 2005, disease incidence was higher than in 2004, reaching higher values of affected leaf surface in controls. In these conditions, each strain individually protected rice against rice blast, although the combination of both strains was the most effective treatment. All three treatments (Aur 6, Aur 9 and Aur 6 + Aur 9) reached 50% protection in panicles, with Aur 9 being the most effective. In 2006, the most effective treatment was the combination of both strains on leaves in three physiological stages, suggesting a biocontrol mediated protection. On the other hand, when bacteria were applied to seeds, disease incidence decreased up to 50%, suggesting induction of systemic resistance. Finally, a direct relation between protection mediated by the PGPR and the increase in rice productivity (mT/ha) and quality (weight of 1000 seeds and number of intact grains after milling) was found.     

猪PRL基因多态性与繁殖性能的关系

试验选择野家杂交猪（大白猪和野猪杂交）F1代猪群261头,采用PCR-RFLP法进行了PRL基因的基因型和等位基因频率检测及不同基因型的仔猪初生重、30日龄体重和有效乳头数效应分析。结果表明,BB型个体仔猪的初生重、30日龄体重略高于其他基因型个体,而CC型个体的有效乳头数略高于其他基因型个体,但差异均不显著。      

Infection of horse chestnut (Aesculus hippocastanum) by Pseudomonas syringae pv. aesculi and its detection by quantitative real-time PCR

Pseudomonas syringae pv. aesculi is a pathogenic bacterium causing bleeding canker disease of horse chestnut ( Aesculus hippocastanum ). This is a serious disease which has been affecting horse chestnut in several European countries over the last five years; however, very little is known about the biology of the causal agent. One of the obstacles to studying this pathogen is the lengthy procedure associated with confirming its presence on the host. In this study, P. syringae pv. aesculi was isolated from lesions on different parts of horse chestnut and its pathogenicity confirmed on horse chestnut saplings using two inoculation techniques. Real-time PCR primers were developed based on gyrase B gene sequence data for the specific detection of P. syringae pv. aesculi . Primer specificity was tested on isolates of the target pathogen as well as on a broad range of related non-target bacteria and other bacterial spp. which inhabit horse chestnut. The real-time primers reliably amplified P. syringae pv. aesculi down to 1 pg of extracted DNA, with and without the presence of host DNA, and also amplified unextracted DNA in whole cells of the bacterium down to at least 160 colony forming units. Detection and quantification of the target pathogen in phloem and xylem of both naturally infected and inoculated horse chestnut tissues was also demonstrated. This quantitative real-time PCR assay provides the facility to study several important aspects of the biology of P. syringae pv. aesculi on horse chestnut including its potential for dissemination in different substrates.     

桃蛀螟越冬老熟幼虫过冷却点测定

通过对桃蛀螟(Dichocrocis punctiferalis Guenée)越冬老熟幼虫和蛹过冷却点的测定,初步明确了寄主植物、幼虫体重、性别等因素对其越冬幼虫和蛹抗寒性的影响。取食玉米、高粱和向日葵不同寄主植物的桃蛀螟越冬幼虫的过冷却点差异不显著;幼虫体重与其过冷却点没有显著相关性;幼虫进入越冬状态越早,过冷却点越低;雌、雄越冬幼虫的过冷却点没有显著差异;蛹与越冬幼虫的过冷却点无显著差异;采自不同地区玉米植株上的5个地理种群的越冬幼虫过冷却点差异不显著。     

阿维菌素和硫线磷对南方根结线虫的毒力

利用阿维菌素和硫线磷处理南方根结线虫离体卵与幼虫,测试其对线虫卵和卵块孵化以及对2龄幼虫的致死作用、活动能力、侵入能力的影响。结果表明阿维菌素和硫线磷均对线虫卵和卵块的孵化表现很强的抑制作用,阿维菌素5 μg/mL处理24 h对卵孵化抑制率高达82.57%,而硫线磷40 μg/mL处理24 h对卵孵化抑制率为73.05%;阿维菌素和硫线磷处理48 h对2龄幼虫的LD50分别为7.346 1、13.345 6 μg/mL;在阿维菌素2 μg/mL和硫线磷3 μg/mL处理中,2龄幼虫在沙柱中的平均移动距离仅为0.04 cm和0.05 cm,而对照处理的线虫平均移动距离为1.04 cm;在阿维菌素2 μg/mL和硫线磷50 μg/mL处理2龄幼虫48 h后,对番茄根部的侵入率为0.12%和0.45%,而空白对照处理线虫的侵入率达21.85%。     

铵类化合物对南方根结线虫2龄幼虫存活的影响

在实验室内寄主体外测定了铵类化合物对南方根结线虫2龄幼虫（Meloidogyne incognita J2）存活的影响。结果表明：供试的8种化合物在不同浓度下对南方根结线虫J2有不同程度的致死作用,并且随着浓度的升高致死效果均显著增加。其中NH4HCO3对J2作用最为敏感,浓度为0.025 mol/L（25 ℃,pH 7.95）时校正死亡率达53.5%,浓度达到0.05 mol/L（25 ℃,pH 8.20）时校正死亡率可达100%,而其他化合物只有在高浓度时致死效果才显现出来。致死浓度由低到高的顺序为：NH4HCO3＜(NH4)2SO4＜NH4CNS＜NH4NO3 ＜NH4H2PO4＜NH4Cl＜(NH4)3PO4•3H2O＜(NH4)2HPO4。同时测定了南方根结线虫J2的酸度适应范围是pH4.1~11.0。     

白粉寄生孢寄生黄瓜白粉菌的特性研究

采用白粉寄生孢（Ampelomyces quisqualis Ces.AQ）接种离体条件下赛璐酚上黄瓜白粉菌［Sphaerotheca fuliginea (Schlecht)Poll.］和活体条件下黄瓜白粉菌后,通过棉兰染色和显微观察分析,初步明确了白粉寄生孢的侵染寄生过程。白粉寄生孢分生孢子产生芽管可入侵黄瓜白粉菌的分生孢子、菌丝、分生孢子梗;有时黄瓜白粉菌串生的分生孢子、分生孢子梗可被2~3条白粉寄生孢的菌丝寄生,随着寄生过程的进一步发展,黄瓜白粉菌的分生孢子梗基部膨大成无色的椭圆形或球形,其上逐渐产生由黄色至褐色的白粉寄生孢的分生孢子器,器内含有大量的分生孢子。     

福寿螺18S rRNA和28S rRNA基因片段的克隆与进化分析

为从分子水平上明确入侵我国的福寿螺在分类学上的地位,采用分子克隆和序列比对的方法,对来自菲律宾及我国广东、广西、浙江等不同地理种群福寿螺的18S rRNA基因和28S rRNA基因片段进行扩增、克隆和序列测定,并同瓶螺科、田螺科和环口螺科相关物种进行系统发育分析。结果表明,获得的福寿螺18S rRNA基因和28S rRNA基因片段长度分别为602 bp、325 bp,且不同地理种群间碱基序列无差异。通过邻接法（NJ）和最大简约法（MP）构建的系统树基本一致,证实福寿螺隶属于瓶螺科,与田螺科物种亲缘关系较近,而与环口螺科亲缘关系较远。     

小核盘菌保藏过程中活力和致病力影响因素研究

研究了小核盘菌保藏过程中活力和致病力影响因素,结果表明：接种后培养6 d的小核盘菌活力（以该菌在PDA平板上培养形成的菌落直径表示）和致病力（以该菌在蒲公英叶片上形成的菌斑直径表示）最大,分别为66.2 mm和52.9 mm。保藏期间小核盘菌的活力和致病力均随时间呈下降趋势。保藏90 d后,培养8 d的小核盘菌的活力和致病力最大,分别为31.7 mm和17.9 mm;培养4 d的小核盘菌的活力和致病力最小,分别为6.3 mm和2.6 mm。保藏期间低水活度有利于小核盘菌活力和致病力的保持,活力和致病力均随水活度的降低而增加。当水活度低于0.432时,活力和致病力不再增加,趋于稳定。低温有利于小核盘菌活力和致病力的保持, 25 ℃下保藏90 d的小核盘菌失去了全部活力和致病力,而-16 ℃下小核盘菌的活力和致病力仅分别下降25.8 %和 13.7%。     

翦股颖上腥黑粉菌近似种多重分子检测

匍匐翦股颖(Agrostis stolonifera)和细弱翦股颖(A. tenuis)是优良的牧草和草坪草。寄生于翦股颖上的腥黑粉菌共有3种,即小麦网腥黑穗菌(Tilletia caries,TCT)、翦股颖腥黑穗菌(T. sphaerococca)和苍白腥黑粉菌（T. pallida）。在形态、自发荧光和萌发生理3方面比较研究的基础上,选取冬孢子形态非常相似的2种腥黑粉菌TCT和T. sphaerococca为研究对象,依据序列特点设计4套引物,成功建立了TCT和T. sphaerococca菌丝基因组DNA的特异双重PCR检测方法和冬孢子的特异套式双重PCR检测方法。