小麦抗茎腐病种质筛选及鉴定新方法的建立

为筛选针对我国黄淮麦区小麦茎腐病抗病新种质,建立可区分小麦其他茎基部病害的茎腐病抗性鉴定方法,本文采用室内苗期鉴定方法对主要来自黄淮麦区的108份小麦品种和高代品系进行茎腐病抗性评价,对其中45份小麦材料同时采用荧光定量PCR方法测定基部茎秆的禾谷镰刀菌DNA含量并与其茎腐病平均病级进行相关分析。共筛选到中抗茎腐病材料22份,未发现高抗和免疫品种(系);相关分析结果表明,小麦基部茎秆禾谷镰刀菌DNA含量与其茎腐病平均病级呈极显著正相关(r=0.73**),小麦基部茎秆禾谷镰刀菌DNA含量可以作为小麦茎腐病抗性的重要参考。抗病新种质的筛选和荧光定量PCR抗性评价方法的建立将为今后黄淮麦区小麦抗茎腐病品种的培育提供帮助。     

小麦禾谷镰孢菌茎基腐病抗源的筛选与评价

为了发掘我国小麦种质资源中具有禾谷镰孢菌茎基腐病(crown rot)抗性的材料,采用禾谷镰孢菌苗期接种试验的方法,研究了82份小麦种质对禾谷镰孢菌茎基腐病的抗性.结果表明,在鉴定的材料中没有发现高抗材料;中抗材料13份,占总数的15.8%,包括CI12633、红蚰子、FHB143、Tiszataj和紫秆子等;大多数材料为感病材料.值得注意的是不同小麦材料对禾谷镰孢菌赤霉病和茎基腐病具有不同的抗性水平,两种病害没有正相关性,暗示小麦茎基腐病和赤霉病的抗性机制可能不同,因此,需要广泛挖掘具有茎基腐病抗性的小麦资源.     

玉米种质和新品种对腐霉茎腐病和镰孢穗腐病的抗性分析

玉米是我国最重要的农作物之一,腐霉茎腐病和镰孢穗腐病是玉米生产上的重要病害。2006-2012年期间,对1647份玉米种质进行了抗肿囊腐霉茎腐病和拟轮枝镰孢穗腐病鉴定,筛选出高抗茎腐病和穗腐病的种质分别为564份和27份,占鉴定总材料的34.2%和1.6%,抗性材料分别为209份和352份,占比为12.7%和21.4%,表明高抗肿囊腐霉茎腐病的资源较为丰富,高抗镰孢穗腐病的种质相对匮乏。其中,13份种质对2种病害均表现高抗,207份种质对2种病害均表现抗性或对其中一种表现高抗而另一种表现抗性。自交系中对肿囊腐霉茎腐病和拟轮枝镰孢穗腐病表现抗性以上(含HR和R)的种质分别占总鉴定种质的56.5%和23.6%,在农家种中分别为21.2%和21.4%,表明玉米自交系中的抗性资源较农家种丰富。2009-2013年期间参加国家玉米区试的品种中,对腐霉茎腐病表现高抗、抗性、中抗、感病和高感的品种分别占11.5%、11.9%、40.1%、17.6%和18.9%。2009-2011年间,中抗以上的育成品种所占比例呈现明显上升趋势,但2012-2013年间,中抗以上的品种所占比例呈下降趋势。     

抗茎腐病转基因小麦新种质的筛选

为拓宽小麦茎腐病(又称茎基腐病)抗源种类,筛选抗茎腐病小麦新种质,对43份转TaPIMP1、AtNPR1和Gastrodianin基因小麦纯合株系,进行目的基因表达分析,以及茎腐病、纹枯病和赤霉病抗性鉴定。结果表明,转基因株系的目的基因均能正常表达;转基因株系间茎腐病抗性差异明显,24份转基因株系茎腐病抗性,比受体对照扬麦12显著提高;转基因株系茎腐病抗性与纹枯病抗性相关性显著,与赤霉病相关性不显著。结合农艺性状鉴定,筛选出5份抗茎腐病转基因株系,其中2份兼抗纹枯病和赤霉病,1份兼抗纹枯病,可作为长江中下游麦区茎腐病备用抗源。     

花生种质资源果腐病的抗性评价

花生果腐病是一种由真菌引起的世界性的严重病害,直接影响花生的产量及品质。通过田间自然发病对引进的77份美国资源和39份国内资源进行连续2年的鉴定,筛选抗果腐病的花生种质资源,为花生抗果腐病育种提供优异材料。结果表明:供试花生材料间的受害指数差异极显著(P0.01),两年间的差异也达到显著水平(P0.05)。根据受害指数的聚类分析将供试花生材料的果腐病抗性分为高抗、抗、中抗、感病和高感病5组,该结果作为花生果腐病抗性评价标准,能够明确评价供试花生材料对果腐病的抗性。综合两年抗性表现较一致的96份种质,筛选到高抗材料2份,平均受害指数分别为16.67和21.91;抗性材料6份,平均受害指数分布在26.33~42.41之间;中抗材料32份,平均受害指数在45.19~60之间;感病材料34份,平均受害指数在60.87~74.39之间;高感材料22份,平均受害指数在75.27~83.34之间。该结果为评价花生果腐病抗性和合理利用种质资源进行花生抗病品种遗传改良提供了参考和优异材料。     

玉米抗腐霉茎腐病种质标记基因型鉴定与遗传多样性分析

腐霉茎腐病(Pythium stalk rot)是玉米生产上的重要病害。本研究利用14个与8个抗玉米茎腐病基因连锁的分子标记对196份抗腐霉茎腐病玉米种质进行抗病标记基因型鉴定,并采用42对多态性SSR标记对54份抗病自交系进行遗传多样性分析,以期阐明玉米抗腐霉茎腐病种质的标记基因型和遗传背景,并为资源的有效利用、新基因的挖掘和杂种优势模式确定提供参考信息。14个与抗病基因连锁的分子标记将196份抗性种质鉴定为128种标记基因型,表明存在多样的抗性基因组合方式。191份种质获得与齐319、X178或1145中一个或多个的相同的扩增,表明97.45%种质可能含有与3个抗玉米茎腐病材料相同的抗病基因;粤61、郑653、赤L136、白53和18--14共5份种质均未扩增出与齐319、X178和1145相同的标记基因型,可能携带其他抗茎腐病基因;遗传背景相近的抗性种质分属不同的标记基因型,表明抗病种质携带的抗病基因可能在育种选择中发生了分离。42对多态性SSR引物在54份抗病材料中共检测出119个等位基因(Na),多态位点百分率(PPB)为99.17%,平均有效等位基因数(Ne)为1.7070,平均Nei′s基因多样性(H)为0.3999,平均Shannon′s信息指数(I)为0.5844,平均多态信息含量(PIC)为0.5527,变幅为0.2061～0.7844;通过UPGMA聚类分析,54份抗病材料被划分为2个类群,共6个亚群中,分别是旅大红骨亚群、BSSS亚群、塘四平头亚群、PA亚群、PB亚群、Lan亚群,表现出较高的遗传多样性。结果表明,我国6个杂种优势群中均含有较为丰富的抗腐霉茎腐病种质资源,其中PA亚群包含的抗病种质最多。     

不结球白菜种质资源对TuMV的抗性鉴定与评价

分别利用苗期人工接种鉴定及ELISA检测方法,对127份不结球白菜种质资源进行芜菁花叶病毒(TuMV)的抗性鉴定。结果显示,苗期人工接种鉴定的病情指数(DI)分布在3.55~95.68之间,不同种质间表现出较大的抗性差异。不同抗性级别的次数分布图基本符合正态分布,略向感病区域偏离。基于病情指数的聚类分析结果与抗病性分级基本一致。通过苗期鉴定共筛选获得高抗TuMV的不结球白菜种质6份,抗病种质13份,其主要农艺性状表现出一定的多样性。其中叶面皱缩和具有刺毛的抗病材料所占比例较高,可能与TuMV抗性存在一定的相关性。ELISA检测结果显示,117份供试种质的P/N值分布在3.10~25.37之间,不同种质间表现出病毒含量的差异,但与DI值未呈现明显相关性,可作为抗病材料筛选的辅助指标。     

玉米种质资源对六种重要病虫害的抗性鉴定与评价

在2003－2005年间,对604份玉米种质进行了抗弯孢菌叶斑病和玉米螟鉴定,筛选出抗弯孢菌叶斑病的材料93份,抗玉米螟材料22份。2006－2009年间,对836份玉米种质进行了抗大斑病、茎腐病、穗腐病和瘤黑粉病的鉴定与评价,筛选出一批高抗和多抗的资源。在836份资源中,对大斑病1、2和N号3个生理小种具有抗性的材料均为50％左右;抗茎腐病材料为41.3％,高抗和抗性种质分别为264和81份;穗腐病高抗和抗性种质分别为5和171份,占比为21.1％;瘤黑粉病高抗和抗性种质各261和14份,占总鉴定材料的32.9％。上述结果表明抗大斑病、茎腐病和瘤黑粉病的种质资源较为丰富。通过对抗性结果进行对比分析,发现不同生态区玉米种质的抗性强弱以及抗性多样性存在明显差异,黑龙江和内蒙的种质对病虫害的抗性强弱及多样性程度明显高于四川种质。此外,玉米自交系对病虫害的抗性强弱以及多抗性程度高于农家种。     

玉米种质资源对六种重要病虫害的抗性鉴定与评价

在2003-2005年间,对604份玉米种质进行了抗弯孢菌叶斑病和玉米螟鉴定,筛选出抗弯孢菌叶斑病的材料93份,抗玉米螟材料22份。2006-2009年间,对836份玉米种质进行了抗大斑病、茎腐病、穗腐病和瘤黑粉病的鉴定与评价,筛选出一批高抗和多抗的资源。在836份资源中,对大斑病1、2和N号3个生理小种具有抗性的材料均为50%左右;抗茎腐病材料为41.3%,高抗和抗性种质分别为264和81份;穗腐病高抗和抗性种质分别为5和171份,占比为21.1%;瘤黑粉病高抗和抗性种质各261和14份,占总鉴定材料的32.9%。上述结果表明抗大斑病、茎腐病和瘤黑粉病的种质资源较为丰富。通过对抗性结果进行对比分析,发现不同生态区玉米种质的抗性强弱以及抗性多样性存在明显差异,黑龙江和内蒙古的种质对病虫害的抗性强弱及多样性程度明显高于四川种质。此外,玉米自交系对病虫害的抗性强弱以及多抗性程度高于农家种。     

抗青枯病烟草种质资源在云南省的评价

筛选出抗性稳定的种质资源是选育抗病品种的重要基础。本文采用人工接种和病田自然发病方法鉴定了48份烟草种质的青枯病抗性表现。土壤盆栽接种鉴定表现为高抗的材料有CF207、岩烟97、TI448A、DB101、G80、RG17、GTH-1等7份材料,表现抗病的有MSK149、Oxford 2028、NC95、YN108、K346、K358、Enshu FC、Oxford 207、RG11等9份材料。苗期恒温水培接种鉴定结果表明,Oxford 207和岩烟97表现为高抗,Enshu FC表现抗病,抗病材料与云烟85和K326杂交F1的抗性表现为中感至抗病。田间自然发病鉴定结果表明,我国审定的中抗青枯病的品种RG17、RG11、K358和K346,在云南省田间抗性表现为中抗,产值较高。TI448A田间表现为抗青枯病,但易感黑胫病和空茎病。Oxford 2028和Oxford 207田间表现为抗病至高抗,产值较高。G3和岩烟97田间分别表现为高抗和抗病,产值较低。根据接种鉴定和田间病圃2年抗性鉴定,筛选出育种潜力较大的青枯病抗源Oxford 207、Enshu FC,岩烟97和TI448A。     

Identification of quantitative trait loci (QTL) for resistance to Fusarium crown rot (Fusarium pseudograminearum) in multiple assay environments in the Pacific Northwestern US

Fusarium crown rot (FCR), caused by Fusarium pseudograminearum and F. culmorum, reduces wheat (Triticum aestivum L.) yields in the Pacific Northwest (PNW) of the US by as much as 35%. Resistance to FCR has not yet been discovered in currently grown PNW wheat cultivars. Several significant quantitative trait loci (QTL) for FCR resistance have been documented on chromosomes 1A, 1D, 2B, 3B, and 4B in resistant Australian cultivars. Our objective was to identify QTL and tightly linked SSR markers for FCR resistance in the partially resistant Australian spring wheat cultivar Sunco using PNW isolates of F. pseudograminerarum in greenhouse and field based screening nurseries. A second objective was to compare heritabilities of FCR resistance in multiple types of disease assaying environments (seedling, terrace, and field) using multiple disease rating methods. Two recombinant inbred line (RIL) mapping populations were derived from crosses between Sunco and PNW spring wheat cultivars Macon and Otis. The Sunco/Macon population comprised 219 F(6):F(7) lines and the Sunco/Otis population comprised 151 F(5):F(6) lines. Plants were inoculated with a single PNW F. pseudograminearum isolate (006-13) in growth room (seedling), outdoor terrace (adult) and field (adult) assays conducted from 2008 through 2010. Crown and lower stem tissues of seedling and adult plants were rated for disease severity on several different scales, but mainly on a numeric scale from 0 to 10 where 0?=?no discoloration and 10?=?severe disease. Significant QTL were identified on chromosomes 2B, 3B, 4B, 4D, and 7A with LOD scores ranging from 3 to 22. The most significant and consistent QTL across screening environments was located on chromosome 3BL, inherited from the PNW cultivars Macon and Otis, with maximum LOD scores of 22 and 9 explaining 36 and 23% of the variation, respectively for the Sunco/Macon and Sunco/Otis populations. The SSR markers Xgwm247 and Xgwm299 flank these QTL and are being validated for use in marker-assisted selection for FCR resistance. This is the first report of QTL associated with FCR resistance in the US.     

Pyramiding QTL increases seedling resistance to crown rot (Fusarium pseudograminearum) of wheat (Triticum aestivum)

Crown rot of wheat (Triticum aestivum), predominantly caused by the fungus Fusarium pseudograminearum, has become an increasingly important disease constraint in many winter cereal production regions in Australia. Our group has previously identified a range of quantitative trait loci (QTL) for partial resistance to crown rot in various bread wheat sources. Here, we report on work that has assessed the effectiveness of pyramiding QTL to improve resistance to crown rot. Two doubled haploid populations were analysed—one from a cross between two previously characterised sources of partial seedling resistance (2-49 and W21MMT70; n = 208) and one from a cross between 2-49 and the commercial variety Sunco, a source of adult field resistance (n = 134). Both populations were phenotyped for seedling resistance to crown rot. Microsatellite and DArT markers were used to construct whole genome linkage maps for use in composite interval mapping (CIM) to identify QTL. Three QTL were detected in both trials conducted on the 2-49/W21MMT70 population. These were located on chromosomes 1D (QCr.usq-1D.1), 3B (QCr.usq-3B.1) and 7A. QCr.usq-1D.1 and the previously undetected 7A QTL were inherited from 2-49. QCr.usq-3B.1, inherited from W21MMT70, was the most significant of the QTL, explaining up to 40.5% of the phenotypic variance. Three QTL were identified in multiple trials of the Sunco/2-49 population. These were located on chromosomes 1D (QCr.usq-1D.1), 2B (QCr.usq-2B.2) and 4B (QCr.usq-4B.1). Only QCr.usq-2B.2 was inherited from Sunco. QCr.usq-4B.1 was the most significant of these QTL, explaining up to 19.1% of the phenotypic variance. In the 2-49/W21MMT70 population, several DH lines performed significantly better than either parent, with the best recording an average disease severity rating of only 3.8% of that scored by the susceptible check cultivar Puseas. These lines represent a new level of seedling crown rot resistance in wheat.     

Microsatellite DNA polymorphism divergence in Chinese wheat (Triticum aestivum L.) landraces highly resistant to Fusarium head blight

Genetic differences between 20 Chinese wheat (Triticum aestivum L.) landraces highly resistant to Fusarium head blight (FHB) and 4 wheat lines highly susceptible to FHB were evaluated by means of microsatellite markers, in order to select suitable parents for gene mapping studies. Thirty-nine out of 40 microsatellite markers (97.5%) were polymorphic among the 24 wheat genotypes. A total of 276 alleles were detected at the 40 microsatellite loci. The number of alleles per locus ranged from 1 to 16, with an average of 6.9 alleles. Among these microsatellite loci, the largest polymorphism information content (PIC) value was 0.914 (GWM484), while the lowest PIC value was 0 (GWM24). The mean genetic similarity index among the 24 genotypes was 0.419, ranging from 0.103 to 0.673. Clustering analysis indicated that the highly susceptible synthetic wheat line RSP was less genetically related to and more divergent from the Chinese highly resistant landraces. These results were useful in the identification of suitable parents for the development of mapping populations for tagging the FHB resistance genes among these Chinese wheat landraces.     

Identification of resistance source in wheat germplasm against spot blotch disease caused by Bipolaris sorokiniana

Four hundred and twenty-two spring wheat germplasm (Triticum aestivum L.) lines belonging to Indian, CIMMYT and Chinese wheat programme were evaluated for their tolerance against natural epiphytotic conditions of spot blotch caused by Bipolaris sorokiniana at the hot spot location, Pusa, Bihar, India. Of the 422 entries screened, none of the genotype showed immunity to the disease, whereas 52 were resistant, 180 moderately susceptible, 171 susceptible and 19 highly susceptible. Indian germplasm lines tended to be more susceptible than lines originated from CIMMYT and China. Chirya 3, Chirya 7 and Mayoor from CIMMYT showed high degree of resistance to the disease both under field and polyhouse conditions. On the basis of the disease severity under field conditions, 20 promising resistant genotypes and 10 highly susceptible lines were isolated for further testing under artificial epiphytotic conditions in polyhouse for genetic analysis and their potential for spot blotch resistance breeding.     

Economic impact of Hessian fly (Diptera: Cecidomyiidae) on spring wheat in Oregon and additive yield losses with Fusarium crown rot and lesion nematode

Damage caused by Hessian fly, Mayetiola destructor (Say), was quantified in spring wheat, Triticum aestivum L., trials near Pendleton and Moro, OR, during 2001 and 2002. Five field experiments were established to examine genetic resistance to Fusarium crown rot, Fusarium pseudograminearum (O'Donnell & Aoki), and economic damage by lesion nematode, Pratylenchus neglectus (Rensch, 1924) (Filipjev Schuurmanns & Stekhoven, 1941) and Pratylenchus thornei (Sher & Allen, 1941). Hessian fly became the dominant factor affecting grain yield in four experiments. Genotypes carrying the H3-resistance gene had grain yields 66 and 68% higher than susceptible genotypes in cultivar trials during 2001 and 2002, respectively. Yield reductions were detected when Hessian fly infestation rates exceeded 50% plants during 2001 and 15% plants (8% tillers) during 2002. In two trials during 2001, in-furrow application of aldicarb (Temik) at planting improved yields of four Hessian fly-susceptible cultivars by 72 and 144% (up to 1,959 kg/ha) and yields of one Hessian fly-resistant cultivar by 2 and 3%. Resistant cultivars and aldicarb improved grain quality as much as two market grades during 2001. The value of increased grain production with Hessian fly-resistant cultivars in four field experiments ranged from dollar 112 to dollar 252/ha, excluding price incentives for improved market quality. Yield reduction due to combined damage from Hessian fly and either Fusarium crown rot or lesion nematode was additive. This report seems to be the first quantitative yield loss estimate for Hessian fly in spring wheat in the semiarid environment of the inland Pacific Northwest.     

Role of hydroxycinnamic acids in the infection of maize silks by Fusarium graminearum Schwabe

In the current study, the hydroxycinnamic acids in silks of diverse maize inbred lines differing in Fusarium resistance were determined at several times after inoculation with Fusarium graminearum or sterile water as control. The main objective was to determine the possible relationship between the hydroxycinnamic acid changes in silks and ear rot resistance. Several changes in the cell-wall-bound hydroxycinnamic acid concentrations were observed after inoculation with F. graminearum, although these changes were not directly correlated with genotypic resistance to this fungus. Ester-bound ferulic acid decreased, probably due to degradation of hemicellulose by hydrolytic enzymes produced by Fusarium spp., while p-coumaric acid and diferulates showed slight increases that, in conjunction, did not result in delayed F. graminearum progression through the silks. It is important to note that the decrease of ferulic acid in the F. graminearum treatment was faster in susceptible than in resistant genotypes, suggesting a differential hemicellulose degradation in silk tissues. Therefore, the ability of the maize genotypes to slow down that process through hemicellulose structural features or xylanase inhibitors needs to be addressed in future studies.