外引玉米种质对两种穗腐病原镰孢菌抗性鉴定

采用双牙签接种技术,2016-2017年连续2年对从美国、加拿大、罗马尼亚、德国、法国、荷兰等国家引进的177份玉米种质资源抗玉米穗腐病原拟轮枝镰孢(F.verticillioides)和禾谷镰孢(F.graminearum)进行了鉴定。结果表明,鉴定的177份玉米种质资源中,对拟轮枝镰孢表现高抗(HR)的资源2份,占总数的1.13%;抗病(R)38份,占总数的21.47%;中抗(MR)75份,占总数的42.37%;感病(S)48份,占总数的27.12%;高感(HS)14份,占总数的7.91%。177份玉米种质资源中,对禾谷镰孢(F.graminearum)表现抗病(R)12份,占鉴定资源总数的6.78%;中抗(MR)66份,占总数的37.29%;感病(S)64份,占总数的36.16%;高感(HS)35份,占总数的19.77%,未发现对禾谷镰孢菌表现高抗的材料。在177份玉米种质资源中,兼抗两种穗腐病原镰孢菌的种质资源有12份。     

44份玉米自交系对镰孢穗腐病的抗性鉴定北大核心CSCD

在2016年和2017年分别对44份不同来源的在自然发病条件下对穗腐病表现为抗病或感病的玉米自交系,分别人工接种拟轮枝镰孢和禾谷镰孢,对其抗性进行了鉴定。结果表明,塘四平头群的自交系发病最重,旅大红骨群的自交系发病最轻,瑞德群的自交系之间抗性差异较大。玉米自交系吉V203、承351和丹598对拟轮枝镰孢和禾谷镰孢均表现为高抗,而PHTD5和掖81162对两种致病菌均表现为高感。44份自交系在不同年份的抗性评级存在一定的差异,说明玉米穗腐病的发病受环境因素影响较大,也在一定程度上说明玉米穗腐病抗性遗传的复杂性。高抗和高感的玉米自交系在不同年份发病稳定,而中等抗性水平的自交系在不同年份的发病程度存在差异,受环境因素影响较大。本研究结果将为玉米穗腐病的抗性遗传改良提供一定的参考依据。     

玉米种质抗拟轮枝镰孢与禾谷镰孢穗腐病鉴定及抗性多样性分析

穗腐病是玉米生产上最重要的病害之一,严重影响其产量和品质,威胁人畜健康.选育和利用优良的抗穗腐病品种,是防治玉米穗腐病最为经济有效的措施.利用花丝通道注射法,在北京昌平和海南三亚2个试验点,对346份玉米自交系进行了抗拟轮枝镰孢与禾谷镰孢穗腐病的鉴定与评价.综合分析2个试验点的抗性鉴定数据表明,对拟轮枝镰孢穗腐病表现高...     

我国东北地区玉米穗腐镰孢菌的种类及其分离频率

从辽宁、吉林、黑龙江三省采集的43份玉米病穗上共分离获得327株镰孢菌,根据形态特征鉴定属于7个种,其分离频率分别为半裸镰孢菌(Fusarium semitecturrt)37.77%,尖孢镰孢菌(F.oxysporum)3.51%,拟轮枝镰孢菌(F.verticillioides)3.57%,克鲁克威尔镰孢菌(F.c...     

玉米重要自交系的肿囊腐霉茎腐病抗性鉴定与评价

由肿囊腐霉菌(Pythium inflatum Matthews)引起的玉米茎腐病是影响玉米产量的一种重要病害。为进一步拓展可利用的抗源,于2010-2011年在田间采用人工接种方法对287份重要的玉米自交系种质进行了玉米茎腐病的抗性鉴定评价。结果表明,287份鉴定材料中有171份自交系对茎腐病的抗性达到中抗以上水平,占鉴定材料的59.58%,其中高抗自交系共43份,占鉴定材料总数的14.98%;感病类型自交系共116份,占鉴定材料的40.42%,其中高感自交系共95份,占鉴定材料总数的33.10%。Lancaster、Reid及P群种质中具有丰富的茎腐病抗源,而塘四平头种质群中茎腐病抗源相对缺乏,多为感病类型。该研究结果可为今后我国玉米茎腐病抗性种质的引进和改良提供重要参考。     

玉米抗禾谷镰孢菌穗粒腐病种质资源鉴定

穗粒腐病是玉米主产区普遍发生的穗部真菌性病害,发掘优异的抗性种质资源和选育优良抗病品种,是防治玉米穗粒腐病最为经济有效的措施.本研究采用针刺果穗注射接种法,在北京通州和小汤山两个试验点,对国内外324份玉米自交系种质资源进行禾谷镰孢菌抗性鉴定.综合2个试验点的抗性评价结果,鉴定到了 9份禾谷镰孢菌穗粒腐病表现高抗的自交...     

小麦种质对茎基腐病抗性评价及优异种质筛选

小麦茎基腐病是由镰孢菌侵染引起的一种世界性土传病害,近年来已严重威胁到我国小麦的安全生产。为筛选具有茎基腐病抗性的小麦种质资源,本研究采用孢子悬浮液浸种法,分别以国外抗病材料Sunco和中国品种陕253为抗病和感病对照,对670份我国小麦品种(系)进行了茎基腐病温室苗期抗性鉴定。结果发现,我国供试品种(系)感病材料(病情指数>30)所占比例达到84%,且包含多个近年来小麦生产中的主推品种,表明我国小麦品种总体抗性水平低是导致茎基腐病近年来发病频率与程度不断增加的重要原因之一。经多轮筛选,发掘获得15份抗病表现稳定、抗性水平与抗病对照Sunco相仿的材料。15份材料平均病情指数在10.9~19.4之间,其株高、抽穗期等农艺性状表现出较为丰富的变异,为我国小麦抗茎基腐病品种选育和抗性遗传研究提供了种质资源。     

绿豆尖镰孢枯萎病抗性鉴定方法

绿豆是我国的主要食用豆类之一。由尖镰孢引起的绿豆枯萎病是一种严重的土传病害,病原菌从根部侵入,引起植株矮化,叶片黄化、枯萎,根茎部维管束变褐,严重时导致植株死亡。防治枯萎病最经济、有效的方法是培育利用抗病品种。本研究在控制条件下以具有不同抗性表型绿豆品种为材料,分别对接种方法、植株生育期、接种体浓度、接种体处理时间及接种后植株培养温度等影响绿豆抗性表型的因素进行比较研究,以期建立一个快速、准确和高效的绿豆枯萎病抗性鉴定方法,为抗病资源的筛选和抗病育种提供技术支持。结果表明,绿豆枯萎病苗期抗性鉴定最适宜的接种方法为剪根浸根法,最适宜接种体浓度为105~106孢子/m L,接种最佳植株生育期为2叶期,最短有效接种体浸根时间为2 min,最适宜发病温度为25℃,接种后14 d调查病情。     

玉米穗腐病抗性鉴定、遗传分析与分子机制*

玉米是我国主要农作物之一,其产量占全国谷物总产量三分之一左右,在国民生活中发挥了重要作用。玉米生长过程中受多种病害侵扰,其中穗腐病是一种由真菌导致的常见病害,目前已鉴定出40余种可诱发玉米穗腐病的病原菌。穗腐病不仅可造成玉米产量损失也导致籽粒品质严重下降,病原微生物所产生次生毒素更是危及人畜安全。目前穗腐病防治以化学方法为主,但是因此所造成的种植成本增加和环境污染问题日益突出,选育抗性品种成为防控玉米穗腐病最经济和安全有效的方法。玉米穗腐病抗性属于典型数量性状,国内外已有多个研究组通过建立玉米穗腐病抗性研究体系,开展玉米群体大规模穗腐病抗性鉴定工作,并筛选出一批抗病材料,这为玉米穗腐病抗性遗传改良奠定了材料基础。利用数量性状位点(quantitative trait locus, QTL)定位和全基因组关联分析(genome-wide association study, GWAS)等方法在玉米 1~10号染色体均检测到显著相关位点。尽管如此,玉米穗腐病抗性研究成果应用于生产的实例较少,生产上仍然缺乏综合性状优良且高抗穗腐病的玉米品种。这一方面是由于玉米穗腐病抗性遗传机制十分复杂、抗性基因克隆工作进展缓慢;另一方面为缺乏对玉米穗腐病抗性遗传研究进展进行系统总结,未有效开发分子标记用于分子育种所致。通过综述玉米穗腐病抗性遗传研究进展,汇总已定位QTL位点和显著关联SNP,构建一致性图谱和鉴定出定位热点区间,并进一步对比分析定位区间候选基因特征和转录组、代谢组研究进展,对促进玉米穗腐病抗性机制研究和玉米抗性育种均具有重要意义。     

玉米茎基腐病生防菌的筛选及应用

【目的】拟针对禾谷镰孢进行生防菌的筛选和应用研究,以期为玉米茎基腐病生防菌剂的研制奠定基础。【方法】通过对峙培养法对玉米茎基腐病的主要致病菌禾谷镰孢进行玉米内生生防细菌的筛选,从玉米主栽品种九单48幼苗内部获得一株具有较强抑菌效果的内生生防细菌(简称48SJ7-1);基于传统鉴定、16S rRNA基因序列测定及系统发育分析,对48SJ7-1进行鉴定;并通过盆栽试验测定该生防菌株的防效。【结果】菌株48SJ7-1经鉴定为甲基营养型芽孢杆菌,GenBank登录号为KU377993,48SJ7-1盆栽防效为68.47%,与对照药剂2%戊唑醇悬浮种衣剂差异不显著。【结论】48SJ7-1对玉米茎基腐病的主要致病菌禾谷镰孢有较好防效,对玉米生长还有明显的促进作用,而且表观上无药害发生。     

QTL mapping of resistance to Fusarium ear rot using a RIL population in maize

Fusarium ear rot is a prevalent disease in maize, reducing grain yields and quality. Resistance breeding is an efficient way to minimize losses caused by the disease. In this study, 187 lines from a RIL population along with the resistant (87-1) and susceptible (Zong 3) parents were planted in Zhengzhou and Beijing with three replications in years 2004 and 2006. Each line was artificially inoculated using the nail-punch method. Significant genotypic variation in response to Fusarium ear rot was detected in both years. Based on a genetic map containing 246 polymorphic SSR markers with average genetic distances of 9.1 cM, the ear-rot resistance QTL were firstly analyzed by composite interval mapping (CIM). Three QTL were detected in both Zhengzhou and Beijing in 2004; and three and four QTL, respectively, were identified in 2006. The resistant parent contributed all resistance QTL. By using composite interval mapping and a mixed model (MCIM), significant epistatic effects on Fusarium ear rot as well as interactions between mapped loci and environments were observed across environments. Two QTL on chromosome 3 (3.04 bin) were consistently identified across all environments by the two methods. The major resistant QTL with the largest effect was flanked by markers umc1025 and umc1742 on chromosome 3 (3.04 bin), explaining 13–22% of the phenotypic variation. The SSR markers closely flanking the major resistance QTL will facilitate marker-assisted selection (MAS) of resistance to Fusarium ear rot in maize breeding programs.     

Variation in pathogenicity of Fusarium verticillioides and resistance of maize genotypes to Fusarium ear rot

Abstract

The ineffective control measures of pathogens is due to variability among their populations. Hence, the study of pathogenic variation of Fusarium verticillioides strains on maize genotypes. Six F. verticillioides infected maize ear were randomly obtained from three agro-ecological zones in Southwest Nigeria. Pathogenicity of F. verticillioides strains at 1.0?×?10⁶ spores/mL were examined in vivo based on the rating scale of 1–7 on maize genotypes T2L COMP.1.STR SYN-W-1, PVA SYN 8F2, and T2L COMP.4. The pathogens were inoculated to the maize genotypes on 8th week for disease severity and were all moderately susceptible, however, genotype T2L COMP.4 was the most susceptible. It was observed that, 9.4% were classified as highly virulent, 12.5% as virulent, 37.5% as moderately virulent, 21.8% as slightly virulent, and 18.8% as non-virulent. In all, Fusarium verticillioides strains displayed different degrees of virulence, however, maize genotype T2L COMP.4 was the most susceptible to ear rot.     

Characterization and mapping of <Emphasis Type="Italic">Rpi1</Emphasis>, a gene that confers dominant resistance to stalk rot in maize

The maize inbred lines 1145 (resistant) and Y331 (susceptible), and the F₁, F₂ and BC₁F₁ populations derived from them were inoculated with the pathogen Pythium inflatum Matthews, which causes stalk rot in Zea mays. Field data revealed that the ratio of resistant to susceptible plants was 3:1 in the F₂ population, and 1:1 in the BC₁F₁population, indicating that the resistance to P. inflatum Matthews was controlled by a single dominant gene in the 1145×Y331 cross. The gene that confers resistance to P. inflatum Matthews was designated Rpi1 for resistance to P. inflatum) according to the standard nomenclature for plant disease resistance genes. Fifty SSR markers from 10 chromosomes were first screened in the F₂ population to find markers linked to the Rpi1 gene. The results indicated that umc1702 and mmc0371 were both linked to Rpi1, placing the resistance gene on chromosome 4. RAPD (randomly amplified polymorphic DNA) markers were then tested in the F₂population using bulked segregant analysis (BSA). Four RAPD products were found to show linkage to the Rpi1 gene. Then 27 SSR markers and 8 RFLP markers in the region encompassing Rpi1 were used for fine-scale mapping of the resistance gene. Two SSR markers and four RFLP markers were linked to the Rpi1 gene. Finally, the Rpi1 gene was mapped between the SSR markers bnlg1937 and agrr286 on chromosome 4, 1.6 cM away from the former and 4.1 cM distant from the latter. This is the first time that a dominant gene for resistance to maize stalk rot caused by P. inflatum Matthews has been mapped with molecular marker techniques.     

蓝莓腐霉根腐病的病原菌

在山东青岛新发现一种蓝莓根腐病害,症状最初出现在根部,病根腐烂坏死,根状茎维管束和皮层变黑,导致根数量减少,叶片变黄、变红,植株生长不良,严重时叶片全部脱落,植株死亡。通过组织分离法和菌丝段分离法获得纯化菌株HMQAU 180018,经柯赫氏法则验证,综合形态学特征及ITS区和cox I基因序列分析,菌株HMQAU 180018被鉴定为畸雌腐霉Pythium irregulare。这是国内首次描述畸雌腐霉引起蓝莓根腐病的报道。     

Identification of a biocontrol agent Bacillus vallismortis BV23 and assessment of effects of its metabolites on Fusarium graminearum causing corn stalk rot

Corn stalk rot, caused by Fusarium graminearum, is one of the most destructive diseases of maize in many regions of the world. A bacterial strain BV23 was isolated from corn rhizosphere that reduced corn stalk rot significantly in greenhouse studies in 2016 and 2017. BV23 was identified as Bacillus vallismortis, which showed antagonistic effects against a number of fungal pathogens, including F. graminearum, Rhizoctonia solani, Athelia rolfsii, and Thanatephorus cucumeris. BV23 had the greatest fungistatic effect on F. graminearum, inhibiting mycelial growth by 66.2%, conidial germination by 90.1%, and conidial production by 86.7%. The probable antifungal mechanism was assessed by examining the morphology and ultrastructure of F. graminearum hyphae. Treatment by BV23 culture supernatant resulted in coarser hyphae, induced cytoplasmic granulation, and increased cell membrane permeability of F. graminearum, causing cytoplasm leakage. These effects became increasingly obvious with increasing concentration (1%, 5% and 10%). Furthermore, the antifungal active substances were sensitive to heat.     

Biochemical responses associated with resistance to bacterial stalk rot caused by Dickeya zeae in maize

Bacterial stalk rot (BSR) of maize caused by Dickeya zeae is an important disease in northwest region of India. In the current study, eighty maize lines were evaluated for resistance against this disease. Of these, 20 were moderately resistant, 25 were moderately susceptible and the rest were highly susceptible to BSR. Six lines from each set were randomly selected. Activities of three antioxidant enzymes, viz. phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO) were analysed from these three sets of maize lines representing different levels of resistance. A trend of elevated activity of PAL, POX and PPO was observed in all the three sets of maize lines. The results showed significantly more activity of these three enzymes in moderately resistant than highly susceptible maize lines. The activity of PAL and PPO peaked after 48 hr and of POX after 72 hr of challenge inoculation by D. zeae in all the maize lines. The activity of these enzymes further correlated negatively with disease development. Our results show that PAL, POX and PPO play an important role in contributing towards resistance in maize against BSR.     

Isolation and evaluation of a Bacillus methylotrophicus strain for control of corn stalk rot

Bacteria were isolated from corn plants and efficacy of a selected isolate for control of corn stalk rot caused by Fusarium graminearum was evaluated. The bacterial isolate provided the greatest suppression of F. graminearum in lab studies and reduced corn stalk rot significantly in 2013 and 2014 field experiments.