细胞微丝骨架在玉米抗纹枯病菌Rhizoctonia solani 侵染中的作用

为探究细胞微丝骨架在玉米抗纹枯病侵染过程中的作用,采用微丝骨架解聚剂LatB预处理玉米离体叶片后接种立枯丝核菌Rhizoctonia solani AG1-IA,显微观察病原菌的侵染过程,并检测活性氧(ROS)、细胞坏死及抗病基因(PR1、ZmDREB2A)表达等抗病反应情况。结果显示,与未经LatB预处理相比,LatB预处理加快了R.solani侵染后玉米病斑的形成,并影响了侵染结构的发育;在侵染后期,LatB促进了R.solani诱导的玉米叶片中ROS积累、细胞坏死反应和PR1基因表达;溶剂DMSO预处理与未经LatB预处理的结果类似,表明DMSO对本试验的影响较小。研究表明,细胞微丝骨架不仅参与玉米抗R.solani的侵入,而且通过调控ROS、PR1基因表达,细胞死亡等抗病信号提高玉米抗病防御能力。本研究为进一步研究细胞微丝骨架在玉米对纹枯病的抗病机理中的作用提供了重要参考。     

绿豆立枯丝核菌研究初报

本研究通过形态学、菌丝融合群和致病力测定研究,对从河北省石家庄地区绿豆种植区分离的90个立枯丝核菌进行鉴定。在90个分离物中有71个属于AG4,占供试分离物的78.89%,2个属于AG2-2,占供试分离物的2.22%,另外17个分离物与标准菌株不融合,占供试分离物的18.89%;属于AG4的71个分离物中,55个与AG4完全融合（占77.46%）,16个与AG4不完全融合（占22.54%）。在温室条件下采用人工接菌法对40个代表性分离物的致病力进行测定,发现不同分离物对同一品种的致病力存在差异,其中分离物R3、R6、R9、R35致病力最强,分离物R23、R31-1致病力最弱。属于AG 4的分离物R3、R6、R9、R35与其他供试分离物致病力差异极显著;属于未知群体的分离物R20、R29和R24之间致病力差异极显著;属于AG2-2的分离物R21、R31-1致病力较弱,且差异不显著。     

水稻纹枯病菌毒素致病机理研究

 Crude toxin of Rhizoctonia solani(RS-toxin) caused obvious damage to the cell of rice.The permeability of cell membrane changed and phosphorous permeated exterior when the sheath and leaves were treated with RS-toxin.After 12 hours treated with RS-toxin,chloroplast membrane was damaged and lamella was relaxed and swollen,with some cavities in the chloroplast.Treated with RS-toxin for 36 hours,the chloroplast was disassembled,other organelles became unclear and disappeared such as mitochondria,and some parts of the cell wall thinned and loosed.Treated with 10 times diluted RS-toxin,the chlorophyll content in the rice plants was reduced over 85%.With higher RS-toxin concentration and longer treatment time,the lower the chlorophyll content became.     

两个玉米自交系对纹枯病的抗病反应机制初探

玉米纹枯病是由立枯丝核菌(Rhizoctonia solani Kühn)引起的一种重要病害。具有优良性状的自交系是开展玉米抗病品种选育的重要种质资源。本试验以西南地区两个优良玉米自交系R08与18-599R为材料,采用人工接种R.solani菌丝融合群AG1-IA,对成株期玉米进行了抗性鉴定,并对病原菌诱导后苗期玉米叶片上的活性氧(ROS)、抗病相关基因(PR1、ZmDREB2A、ZmERF3和WIP1)表达及细胞坏死情况进行了动态检测。结果显示,R08对纹枯病表现为中抗,而18-599R为高感材料;受R.solani侵染后,玉米叶片ROS的积累在R08中较18-599R多;两个自交系中基因表达量及表达时间存在显著差异;R08叶片出现显著的细胞坏死反应,而18-599R相对较轻。本研究表明两个自交系对R.solani的抗性差异主要体现在相关抗病反应的时间和强度上,这为进一步研究玉米纹枯病抗病机理提供了依据。     

丙环唑对水稻纹枯病菌的抑制作用及对纹枯病的防治效果

为明确丙环唑对水稻纹枯病的防治作用,通过离体抑菌试验,温室盆钵试验和田间试验研究了丙环唑对水稻纹枯病菌的抑制作用和对纹枯病的防治效果.离体抑菌试验表明,丙环唑能够强烈抑制水稻纹枯病菌(Rhizoctonia solani)的菌丝生长,EC50为0.045 μg/mL,并能够强烈抑制菌核产生,但不能抑制菌核萌发.温室试验表明,纹枯病菌经丙环唑处理后,致病力随药剂浓度提高而显著减弱;丙环唑可以很好地被水稻叶片和根系吸收,并输送到水稻的茎部和叶鞘;丙环唑对水稻纹枯病具有保护和治疗作用,400 μg/mL丙环唑处理水稻,抑制病斑长度分别达到82.16％和76.61％,并随药剂处理浓度的降低而降低;丙环唑对立枯丝核菌有较长的持效期,800 μg/mL处理水稻11 d后再接种的防效为40.10％.田间药效试验表明,25％的丙环唑乳油在有效剂量150 g/hm2下3次喷药后14 d的防效达到89.15％,丙环唑在本试验剂量范围内对水稻安全.表明丙环唑对水稻纹枯病有很好的防治作用,可为生产上防治水稻纹枯病和科学用药提供依据.     

Pathotypic and genetic diversity in the population of Rhizoctonia solani AG1‐IA causing rice sheath blight in China

Sheath blight, caused by Rhizoctonia solani AG1‐IA, is one of the most serious diseases of rice. In this study, a total of 175 isolates of R. solani AG1‐IA were collected from five rice‐growing regions in China. Pathogenicity tests revealed that all isolates were virulent to five cultivars with different levels of resistance at the rice seedling stage in the greenhouse. There was considerable variation in aggressiveness, and the isolates were classified into three pathotypes based on disease severity, with moderately virulent isolates prevalent in the population. Forty‐three haplotypes were identified based on ITS sequencing, and 39 haplotypes were distinct among isolates. There were high levels of haplotype diversity and nucleotide diversity within the populations of R. solani AG1‐IA. High gene flow (Nm = 1·63–5·22) was detected, consistent with relatively low differentiation between pairs of populations. Five populations were divided into two distinct clusters by the unweighted pair group method with arithmetic mean (UPGMA), and no spatial population differentiation was discernible. The majority (97·8%) of genetic diversity was distributed among isolates within populations, with only 2·2% of the genetic diversity attributed to differences among populations. The star‐like shape of the haplotype network provided evidence of signatures of population expansion in recent history. No significant relationships were found between the genetic diversity and aggressiveness or geographic origin among populations of R. solani AG1‐IA. These results highlight that the population characteristics of R. solani AG1‐IA should be taken into account in evaluating the germplasm resistance of rice cultivars to sheath blight.     

水稻纹枯病菌胞外蛋白酶特性研究

植物病原菌产生蛋白水解酶被认为是病原菌侵染寄主的一个重要策略。作者对水稻纹枯病菌(Rhizoctonia solani Kühn)产生的胞外蛋白酶的特性进行了研究。结果表明,水稻纹枯病菌产生一个分子量约为49.5ku的胞外蛋白酶。该酶对胰蛋白酶专一性底物Benz-Phe-Val-Arg-NA有较高的活性,并能从羧基端降解Arg和Lys。胰蛋白酶抑制剂对该酶活性有较强的抑制作用,表明该蛋白酶是一种类胰蛋白酶。在离体试验下,该蛋白酶可以降解水稻细胞壁蛋白并释放羟脯氨酸。SDS-PAGE电泳分析显示,至少有4个多肽被降解,分子量范围分别在14.4～20.1、20.1～31ku和31～43ku范围内。说明该胞外蛋白酶具有降解水稻细胞壁的能力,因此,该蛋白酶可能在水稻纹枯病菌的致病过程中起重要作用。     

Characterization of Rhizoctonia solani AG 2 isolates causing bare patch in field grown tulips in the Netherlands

During a spring survey in 1991, 130 isolates of R. solani were collected in 25 commercial flower bulb fields from diseased plants occurring in bare patches. On the basis of hyphal fusion frequency and pathogenicity to flower bulbs, tulip isolates were provisionally assigned to AG 2-t to distinguish these isolates from AG 2-1 isolates which were non-pathogenic to bulbs. Hyphal fusion frequency of a subgroup of 7 AG 2-t isolates was highly variable when paired with 7 AG 2-1 isolates (2-75%), thus making assignment of AG 2-t isolates to AG 2-1 inconclusive. The mean hyphal fusion frequency among AG 2-t isolates was 65% (±6%) indicating AG 2-t to be a relatively homogeneous group. Hyphal fusion frequency among AG 2-1 isolates was highly variable with a mean 51% (±25%) indicating AG 2-1 to be a heterogeneous group. The optimum growth temperature for AG 2-t and AG 2-1 isolates on malt peptone agar was 20-25 °C. The host range of AG 2-t and two AG 2-1 isolates comprised tulip, iris, hyacinth and lily at both 9 and 18 °C, and cruciferous, sugarbeet and lettuce seedlings at 18 °C. Six other AG 2-1 isolates were pathogenic to cruciferous seedlings, but not to any of the bulbous crops. The tested narcissus, Tagetes patula, tomato, potato, wheat, leek and maize cultivars were not susceptible to AG 2-t and AG 2-1 isolates. Statistical analysis using a proportional-odds model revealed significant differences in aggressiveness between R. solani AG 2-t isolates and differences in susceptibility between tulip and iris cultivars. At 18 °C, but not at 9 °C, isolates representing AG 2-2, AG 4, AG 5 and AG BI were pathogenic to bulbous crops. In addition to bare patch causing AG 2-t isolates, other anastomosis groups may cause disease in field grown tulips. For the development of optimal crop rotation schedules, the impact of bulb rot causing isolates under field conditions needs further study.     

中国东北地区水稻纹枯病病原菌种类及融合群的分子鉴定

为明确中国东北地区水稻纹枯病病原菌种类及融合群的归属情况, 2015－2017年从黑龙江省、吉林省和辽宁省的17个水稻主产区采集水稻纹枯病标样, 分离获得水稻纹枯病菌214株, 运用水稻纹枯病菌的不同病原菌及融合群的特异性引物对214株水稻纹枯病菌进行病原菌种类和融合群鉴定, 并利用rDNA内转录间隔区(ITS)序列, 对供试水稻丝核菌的融合群归属进行了分析。结果表明:供试214株水稻纹枯病菌分属于茄丝核菌Rhizoctonia solani和水稻丝核菌Rhizoctonia oryzae-sativae, 菌株数分别为198株和16株, 占比分别为92.52%和7.48%。茄丝核菌菌株分属于2个融合群, 分别为AG1-IA和AG4, 菌株数分别为191株和7株, 占比分别为96.46%和3.54%。水稻丝核菌菌株均属于AG-Bb融合群, 菌株数为16株。不同年份水稻纹枯病的病原菌种类及融合群出现的频率和地域分布无明显变化, 而不同地域间水稻纹枯病病原菌的种类及融合群具有明显的分化特征, AG1-IA融合群在中国东北三省各个水稻产区均有分布且均为优势融合群, AG4融合群在辽宁省盘锦市出现频率最高, 水稻丝核菌AG-Bb融合群在吉林省吉林市、通化市和梅河口市出现频率最高。     

水稻纹枯病菌PG的分离纯化及其理化性质研究

水稻纹枯病菌产生的多聚半乳糖醛酸酶(Polygalacturonase,PG)是其重要的致病因子之一。用丙酮法提取PG粗蛋白,分别经DEAE-Sepharose Fast Flow离子交换柱、Phenyl-Sepharose 6 Fast Flow疏水柱、Sephadex G-75凝胶柱和DE52离子交换柱层析纯化得到一种具有较高活性的PG纯蛋白。该蛋白分子量为39.81 kD;等电点为4.58;含有糖基,含糖量为1.48%;含有α氨基酸,但不含芳香族氨基酸;不含脂基。这种蛋白在pH4~12范围内均具有活性,pH5时活性最大;对热不稳定,100℃下水浴20 min,活性完全丧失;对胰蛋白酶和蛋白酶K敏感,酶处理后其活性只有对照的35.0%和35.2%;对紫外线和氯仿亦敏感,处理后活性仅为对照的40.0%和51.7%。     

中国中部5省(市)草坪禾草立枯丝核菌的菌丝融合群研究

 2003~2005年,从我国冷季型草坪与暖季型草坪过渡地区的上海市、浙江省、山东省、河南省和陕西省草坪褐斑病的病株样本中,分离得到了43个立枯丝核菌分离物,其寄主包括多年生黑麦草(Lolium perenne)、高羊茅(Festuca arundina-cea)、草地早熟禾(Poa pratensis)、匍匐翦股颍(Agrostis palustris)、结缕草(Zoysia japonica)和狗牙根(Cynodon dactylon)。按照Parmeter等的方法对该过渡带的草坪禾草立枯丝核菌分离物进行了菌丝融合群的测定,结果表明,上述5省(市)草坪禾草立枯丝核菌的菌丝融合群包括AG1-1A、AG1-1B、AG2-1、AG2-2ⅢB、AG2-2Ⅳ、AG-4和AG-5。不同省份、不同寄主草坪禾草的菌丝融合群类型略有不同,主要融合群类型为AG-1和AG-2。AG1-1B和AG2-1是草坪上首次报道的立枯丝核菌融合(亚)群。     

新疆11种豆科作物立枯丝核菌菌丝融合群及营养亲和群研究

从新疆11种豆科作物病株上或病株根围土样中分离纯化出250个立枯丝核菌（Rhizoctonia DC）,番红O KOH染色后观察细胞核数目,经测试全部菌株均为多核,用标准菌株测定融合群, 250个菌株分属为AG 1、AG 2、AG 3、AG 4和AG 5共5个融合群,出现频率分别为16.4%、33.2%、0.4%、32.4%和17.6%,营养亲合群判别结果表明,AG 1、AG 2、AG 4和AG 5下各有2个VCG,说明新疆豆科作物立枯丝核菌各主要菌丝融合群内均有不同程度的分化。     

云南香石竹立枯病病原的鉴定及致病性研究

 27 Rhizoctonia solani isolates from carnation with damping-off symptoms were identified as anastomosis group AG-4 based on cultural characteristics and anastomosis in Yunnan.Sequence analysis of 5.8S rDNA-ITS of yx and tx presented 99% sequence similarity with AG-4 HGⅠtester isolate.Pathogenicity tests showed that isolates of AG-4 HG Ⅰ were pathogenic to carnation.This is the first record of damping-off of carnation caused by AG-4 HG Ⅰ in China.     

Characterization of Rhizoctonia solani Associated with Soybean in Brazil

Rhizoctonia solani causes pre- and post-emergence damping-off, root and hypocotyl rot and foliar blight in soybean. Foliar blight has resulted in yield losses of 31–60% in north and northeast Brazil. The aim of this study was to characterize isolates of R. solani associated with soybean in Brazil. Among 73 Rhizoctonia isolates examined, six were binucleate and 67 were multinucleate. The multinucleate iso1ates were characterized according to hyphal anastomosis reaction, mycelial growth rate, thiamine requirement, sclerotia production, and RAPD molecular markers. Four isolates that caused hypocotyl rot belonged to AG-4 and using RAPD analysis they grouped together with the HGI subgroup. Another isolate that caused root and hypocotyl rots was thiamine auxotrophic, grew at 35°C, and belonged to AG-2-2 IIIB. All 62 isolates that caused foliar blight belonged to AG-1 IA. RAPD analysis of R. solani AG-1 IA soybean isolates showed high genetic similarity to a tester strain of AG-1 IA, confirming their classification. The teleomorph of R. solani, Thanatephorus cucumeris was produced in vitro by one AG-1 IA isolate from soybean. The AG-4 and AG-2-2 IIIB isolates caused damping-off and root and hypocotyl rots of soybean seedlings cv. FT-Cristalina, under greenhouse conditions. The AG-2-2 IIIB isolate caused large lesions on the cortex tissue, that was distinct from the symptoms caused by AG-4 isolates. The AG-1 IA isolates caused foliar blight in adult soybean plants cv. Xingu under the greenhouse and also in a detached-leaf assay.     

稻纹枯病菌菌株与水稻品种的致病互作分析

 用离体叶接种方法进行稻纹枯病菌群体致病力和水稻抗病力测定,将结果进行统计学分析及图解分析发现,病菌群体的致病力呈现连续变异的数量性状特征,服从正态分布;菌株与品种的致病互作中,菌株间的差异、品种间的差异、以及菌株-品种互作间的差异均达到极显著水平,但互作效应对致病反应的变异所起的作用很小,致病反应的变异主要由菌株效应的差异或者品种效应的差异造成;大多数菌株在品种“中浙优1号”上的致病力排序与在“特优524”上的排序趋势是一致的;大多数品种对菌株2008-126-2的抗病力排序与对菌株2008-88-1的排序趋势是一致的。依结果认为寄主水稻的抗病力也服从正态分布。基于这些分布特征和致病互作特征,可以认为,一般要体现病害差异的试验,水稻寄主应选用中等抗病力的品种,病菌应选用中等致病力的菌株。抗病育种实践中,进行品种资源抗病性评价时,可采用二步行策略,第一步先用一个中等致病力菌株对所有品种先行鉴定,第二步用一个强致病力（或弱致病力）菌株对高抗病力（或低抗病力）的品种再行鉴定。同理,病菌材料的致病性评价也可采用二步行策略,第一步先用一个中等抗病力品种对所有菌株先行鉴定,第二步用一个高抗病力（或低抗病力）品种对强致病力（或弱致病力）的菌株再行鉴定。品种抗病性（或菌株的致病性）的鉴定结果可以采用正态分布函数计算法进行分组归类。     

苹果3种常见潜叶蛾的识别与防治

本文描述了苹果上常见的3种潜叶蛾金纹细蛾（Phyllonorycter ringoniella)、旋纹潜蛾（Leucoptera malifoliella）和银纹潜叶蛾（Lyonetia prunifoliella）的鉴别特征,附有识别特征图,并依据生物学特性提出防治措施。     

玉米纹枯病研究进展

玉米纹枯病已成为我国玉米生产上一种重要病害,且有逐年加重的趋势。本文系统介绍了玉米纹枯病症状、病原菌、致病机理、发病规律、防治措施以及玉米纹枯病抗性遗传等方面的研究进展,并从实际出发,提出了抗玉米纹枯病育种的分子标记辅助选择策略。     

Morphological and molecular variability among Indian isolates of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> causing banded leaf and sheath blight in maize

Rhizoctonia solani, a devastating soil borne fungus inciting banded leaf and sheath blight (BLSB) disease is a constraint in maize production and improvement program. Rhizoctonia isolates collected from seven diverse maize cropping zones of India were examined for morphological and molecular variability. All the tested isolates caused symptoms of BLSB on maize and were also cross infective on rice and sugarcane hosts, but showed significant variability in hyphal diameter, mean hyphal cell size, weight, size and distribution of scleorotia, culture pigmentation, incubation period, pathogenicity and expression of symptoms. Neighbour joining cluster analysis placed the 62 isolates of R. solani into four major groups, A, B, C and D. Group A was more diverse and included isolates of diverse agro-ecological zones. The cluster analysis corresponded well with principle component analysis. Pathogenicity testing of R. solani isolates on maize genotype (CM 501) revealed highly variable virulence pattern of the pathogen population suggesting its high evolutionary potential, and hence adaptability to diverse geographical regions. The study reveals a strong evidence of inherent potential of the R. solani isolates to survive in diverse ecological zones and its probable spread to other maize cultivars across India. Sequence comparisons of the internal transcribed sequence-ribosomal DNA region of 62 isolates did not reveal much diversity among the isolates. Majority of the isolates (n?=?61) clustered together with anastomosis group (AG) AG1-IA used as reference strain in the phylogram, distinct from AG1-IB, AG2–2IIIB and Waitea circinata used as reference strains. BLSB isolates representing distinct geographical locations shared identical sequences indicating long-distance dispersal of the pathogen. The study confirms that the genetic flexibility of the pathogen allows for its adaptation to variable ecological niches and long-distance introduction of new genotypes into the region. The study emphasizes that epidemiological studies may complement the molecular studies.     

Distribution of Vegetatively Compatible Populations of Rhizoctonia solani AG1-IA in a Field Planted with Different Host Species

To understand the distribution pattern and divergence of Rhizoctonia solani in a field over a 4-year period, R. solani AG1-IA isolates were collected from diseased tissues of several crops. Pairing tests between isolates to detect hyphal anastomosis and vegetatively compatible population (VCP) groupings were done on 2% water agar and potato dextrose agar. A single VCP of R. solani AG1-IA dominated a large upland crop field at the Institute of Plant Breeding, University of the Philippines at Los Ba?os. The VCP changed more slowly and at a lower frequency as compared to other reports. Received 27 September 1999/ Accepted in revised form 3 February 2000