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1.
The production of cultivated peanut, an important agronomic crop throughout the United States and the world, is consistently threatened by various diseases and pests. Sclerotinia minor Jagger (S. minor), the causal agent of Sclerotinia blight, is a major threat to peanut production in the Southwestern US, Virginia and North Carolina. Although information on the variability of morphological traits associated with Sclerotinia blight resistance is plentiful, no molecular markers associated with resistance have been reported. The identification of markers would greatly assist peanut geneticists in selecting genotypes to be used in breeding programs. The main objective of this work was to use simple sequence repeat (SSR) primers previously reported for peanut to identify a molecular marker associated with resistance to S. minor. Out of 16 primer pairs used to examine peanut genomic DNA from 39 different genotypes, one pair produced bands at approximately 145 and 100 bp, consistent with either S. minor resistance or susceptibility, respectively. Cloning and sequencing of these bands revealed the region is well conserved among all genotypes tested with the exception of the length of the SSR region, which varies with disease resistance levels. This is the first report of a molecular marker associated with resistance to Sclerotinia blight in peanut. The identification of this marker and development of a PCR-based screening method will prove to be extremely useful to peanut breeders in screening germplasm collections and segregating populations as well as in pyramiding S. minor resistance with other desirable traits into superior peanut lines.  相似文献   

2.
Fusarium head blight (FHB) caused by Fusarium species, is among the most devastating wheat diseases, causing losses in numerous sectors of the grain industry through yield and quality reduction, and the accumulation of poisonous mycotoxins. A germplasm collection of spring and winter wheat, including nine reference cultivars, was tested for Type II FHB resistance and deoxynivalenol (DON) content. Genetic diversity was evaluated on the basis of Simple Sequence Repeat (SSR) markers linked to FHB resistance quantitative trait loci (QTLs) and Diversity Arrays Technology (DArT) markers. The allele size of the SSR markers linked to FHB resistance QTLs from known resistance sources was compared to a germplasm collection to determine the presence of these QTLs and to identify potentially novel sources of resistance. Forty-two accessions were identified as resistant or moderately resistant to Fusarium spread, and two also had very low DON concentrations. Genetic relationships among wheat accessions were generally consistent with their geographic distribution and pedigree. SSR analysis revealed that several resistant accessions carried up to four of the tested QTLs. Resistant and moderately resistant lines without any known QTLs are considered to be novel sources of resistance that could be used for further genetic studies.  相似文献   

3.
Lathyrus cicera has a high potential as fodder crop in dry areas, but can in particular environments be damaged by rust. Little is known on the availability of resistance against rust fungi and the underlying mechanisms in L. cicera germplasm. The present study assessed and characterised macro and microscopically the resistance to rust fungi Uromyces pisi and U. viciae-fabae, in a collection of L. cicera accessions. A wide range of disease reaction was found in the germplasm collection against the different rust species. L. cicera accessions were highly resistant to U. viciae-fabae being hypersensitive response the most frequent reaction. On the contrary, most accessions showed a compatible interaction with U. pisi, with varying levels of partial resistance, although cases of hypersensitivity were also identified. Differences on germination, orientated germ tube growth and appressoria differentiation were observed but were in general of marginal importance to explain the resistance to U. pisi among the L. cicera accessions. Resistance was due, to a combination of pre and post-haustorial mechanisms.  相似文献   

4.
Stem rot caused by Sclerotinia sclerotiorum is one of the most devastating diseases of rapeseed (Brassica napus L.) which causes huge loss in rapeseed production. Genetic sources with high level of resistance has not been found in rapeseed. In this study, 68 accessions in six Brassica species, including 47 accessions of B. oleracea, were evaluated for leaf and stem resistance to S. sclerotiorum. Large variation of resistance was found in Brassica, with maximum differences of 5- and 57-folds in leaf and stem resistance respectively. B. oleracea, especially its wild types such as B. rupestris, B. incana, B. insularis, and B. villosa showed high level of resistance. Our data suggest that wild types of B. oleracea possess tremendous potential for improving S. sclerotiorum resistance of rapeseed.  相似文献   

5.
Summary Lentil is a self-pollinating diploid (2n = 14 chromosomes) annual cool season legume crop that is produced throughout the world and is highly valued as a high protein food. Several abiotic stresses are important to lentil yields world wide and include drought, heat, salt susceptibility and iron deficiency. The biotic stresses are numerous and include: susceptibility to Ascochyta blight, caused by Ascochyta lentis; Anthracnose, caused by Colletotrichum truncatum; Fusarium wilt, caused by Fusarium oxysporum; Sclerotinia white mold, caused by Sclerotinia sclerotiorum; rust, caused by Uromyces fabae; and numerous aphid transmitted viruses. Lentil is also highly susceptible to several species of Orabanche prevalent in the Mediterranean region, for which there does not appear to be much resistance in the germplasm. Plant breeders and geneticists have addressed these stresses by identifying resistant/tolerant germplasm, determining the genetics involved and the genetic map positions of the resistant genes. To this end progress has been made in mapping the lentil genome and several genetic maps are available that eventually will lead to the development of a consensus map for lentil. Marker density has been limited in the published genetic maps and there is a distinct lack of co-dominant markers that would facilitate comparisons of the available genetic maps and efficient identification of markers closely linked to genes of interest. Molecular breeding of lentil for disease resistance genes using marker assisted selection, particularly for resistance to Ascochyta blight and Anthracnose, is underway in Australia and Canada and promising results have been obtained. Comparative genomics and synteny analyses with closely related legumes promises to further advance the knowledge of the lentil genome and provide lentil breeders with additional genes and selectable markers for use in marker assisted selection. Genomic tools such as macro and micro arrays, reverse genetics and genetic transformation are emerging technologies that may eventually be available for use in lentil crop improvement.  相似文献   

6.
S. Nadal    J. I. Cubero    M. T. Moreno 《Plant Breeding》2007,126(1):110-112
Little is known about the levels of resistance to Orobanche crenata available in narbon vetch. A germplasm collection of 200 accessions of narbon vetch (Vicia narbonensis L.) originating from different countries was screened for resistance to crenate broomrape under field conditions. Thirteen accessions were selected for more detailed screening under controlled conditions and for additional field testing. Resistance to O. crenata was manifested by lower germination of broomrape seeds, reduced emergence of Orobanche shoots and fewer root attachments per narbon vetch plant. Differences in pod yield among narbon vetch accessions were also found in response to Orobanche infestation. Finally, eight accessions were selected and identified as new sources of narbon vetch resistant to broomrape.  相似文献   

7.
明确花生种质资源的遗传多样性和分布规律,对于发掘优良种质资源,选配优良亲本,拓宽育成品种的遗传基础具有重要意义。核心种质为种质资源的研究、评价和鉴定带来了方便。本研究从206对SSR引物中筛选26对引物对我国花生小核心种质和ICRISAT微核心种质共466份资源进行了遗传多样性分析,相似系数为0.49～0.99,鉴定出遗传差异最大的种质L2刚果(中国花生资源)与ICG12625(ICRISAT资源),相似系数为0.49。分析结果表明,多粒型花生的多态性信息量(0.761)和遗传多样性指数(0.97～1.11)均最大(平均相似系数最小,0.73～0.76),其次是普通型花生。中国花生种质资源与ICRISAT资源存在较大差异,尤其是ICRISAT的赤道型材料ICG12625,与中国花生资源的差异最大。相似系数和遗传多样性指数的分析结果均表明,我国花生种质资源的遗传多样性比ICRISAT资源丰富。  相似文献   

8.
Sheath blight (ShB) disease caused by Rhizoctonia solani is one of the major threats to rice crop world-wide. Progress in breeding for resistant rice varieties is limited due to lack of highly resistant germplasm against sheath blight. In present study, diverse rice landrace were phenotyped against R. solani and resistant and moderately resistant sources were identified from the panel of 134 germplasm pool. Landrace Nizam shait showed resistance, where as Bidar local-2, Jigguvaratiga, NavaliSali, Jaddu and Tetep exhibited moderate resistance. Population structure was analysed by genotyping the accessions using 63 genome wide Rice Microsatellite markers which divided the mapping panel into two groups. Association mapping using GLM?+?Q model of TASSEL indicated significant association between twenty-one marker loci on nine chromosomes with ShB resistance with phenotypic variation (R2) ranging 3.02–22.71 per cent. We identified 13 new markers to be associated with ShB resistance. The present work validates previously identified eight markers flanking different shB QTLs. None of the allele from the tested markers was unique and common among resistant and moderately resistant landraces identified in this work except allele 420 bp of RM337 and allele 310 bp of RM5556 noticed only in Tetep. Our findings predict the possible presence of unreported QTL region in marker interval of RM337 and RM5556 on chromosome 8 for ShB resistance in Tetep which invites further investigation.  相似文献   

9.
中国花生核心种质的建立及与ICRISAT花生微核心种质的比较   总被引：13，自引：3，他引：10  
以中国花生种质资源数据库中记录的6 390份花生资源为材料, 以其基本数据、特征数据和评价数据为信息, 采用分层分组聚类以及随机取样与必选资源相结合的方法, 构建了由576份资源组成的花生核心种质, 占基础收集品的9.01%。除出仁率外, 核心种质与基础收集品种间的其他14个性状平均值和多样性指数差异均不明显, 表明本研究建立的核心种质是有效的。与ICRISAT花生微核心种质的比较, 中国花生资源在龙生型和珍珠豆型方面具有优势, 叶片长、叶片宽、种子长、种子宽的遗传多样性丰富; 而ICRISAT花生资源在多粒型和普通型方面具有优势, 且植株高度和总分枝数的遗传多样性比中国花生资源丰富。  相似文献   

10.
Portugal has a diverse common bean germplasm, which is still grown in farmers' fields. In this work, we searched for resistance to rust (Uromyces appendiculatus) and powdery mildew (Erysiphe diffusa) in a representative collection of the Portuguese common bean germplasm. Despite many accessions depicting intermediate levels of resistance when compared to the susceptible check, 24 and 13 accessions showed low levels of infection, in spite of a compatible interaction (disease severity (DS) values lower than 5% and infection type (IT) of 4), to rust and powdery mildew, respectively, indicative of partial resistance. Moreover, a resistant reaction was observed in 11 accessions when inoculated with powdery mildew (IT = 0–1) and in additional 11 accessions (one in common) when inoculated with rust (IT = 0–2). The levels of resistance found in this report anticipate great potential of the Portuguese national germplasm, recently reported as genetically closer to the Andean common bean gene pool, for disease resistance breeding of this important crop.  相似文献   

11.
The Pi-z gene in rice confers resistance to a wide range of races of the rice blast fungus, Magnaporthe oryzae. The objective of this study was to characterize Pi-z in 111 rice germplasm accessions using DNA markers and pathogenicity assays. The existence of Pi-z in rice germplasm was detected by using four simple sequence repeat (SSR) markers (RM527, AP4791, AP5659-1, AP5659-5) closely linked to Pi-z, and was verified using pathogenicity assays with an avirulent strain (IE1k) and two virulent races (IB33 and IB49). Among 111 germplasm accessions evaluated, 73 were found to contain the Pi-z gene using both SSR markers and pathogenicity assays. The remaining 38 germplasm accessions were found to be inconsistent in their responses to the blast races IB33, IEIk and IB49 with expected SSR marker alleles, suggesting the presence of unexpected SSR alleles and additional R gene(s). These characterized germplasm can be used for genetic studies and marker-assisted breeding for improving blast resistance in rice.  相似文献   

12.
Molecular marker analysis can be an effective tool when searching for new fire blight resistance donors. It can speed up the breeding process as well, even though many of the available markers linked to fire blight resistance QTLs have not yet been tested by screening a large number of cultivars. The aim of this study was to search for alternate sources of the three major QTLs of fire blight resistance; FBF7, FB_MR5 and FB_E, as well as to test the efficiency of some markers linked to minor QTLs. Altogether, nine primer pairs were used on 77 genotypes including new Hungarian cultivars and old apple cultivars from the Carpathian basin. Several marker alleles of FB resistance QTLs have been detected in the screened genotypes, most importantly the alleles coupling with FB_MR5 in the old cultivars ‘Kéresi muskotály’, ‘Szabadkai szercsika’ and ‘Batul’. We propose these cultivars as the first available resistance donors of FB_MR5 instead of the crabapple Malus × robusta 5. The results also bring new information regarding the resistance alleles of new Hungarian cultivars and selections.  相似文献   

13.
The USDA‐ARS National Plant Germplasm System maintains a Zimbabwe sorghum collection of 1235 accessions from different provinces. This germplasm has not been extensively employed in US breeding programmes due to the lack of phenotypic and genetic characterization. Therefore, 68 accessions from Zimbabwe were phenotyped, and evaluated for their anthracnose response for two consecutive years, and genetically characterized with 21 simple sequence repeat markers. Phenotypic analysis showed significant differences among accessions with plant height and panicle length being the most variable traits. Likewise, 25 accessions were anthracnose resistant, nine showed variable responses and 34 were susceptible. Genetic analysis identified 174 alleles with an average of 8.3 alleles and 11.8 genotypes per locus and a polymorphic information content of 0.60. These results reflect a moderate genetically diverse germplasm. Neighbour‐joining clustering analysis revealed that the majority of anthracnose‐resistant accessions showed high genetic relatedness; therefore, this germplasm might represent one to six new sources of resistances. Results presented herein show that the Zimbabwe collection contains valuable germplasm for breeding programmes and is an important source of anthracnose resistance.  相似文献   

14.
There is no information in the literature about the variability of resistance of Chinese Brassica vegetables, pak choi and Chinese cabbage, to the white blister disease caused by Albugo candida (Pers.) Kuntze. A collection of 43 accessions of pak choi and 19 accessions of Chinese cabbage was screened for resistance to the Portuguese A. candida isolate Ac 506 at the cotyledon stage. Different levels of resistance were found among the germplasm tested, ranging from complete resistance to full susceptibility. Most of the accessions were highly susceptible with less than 10% of resistant seedlings, and only four accessions of pak choi, presenting more than 50% resistant seedlings, were considered as new sources or resistance to white blister. Inheritance of resistance at the cotyledon stage was studied in two crosses between the most resistant pak choi accession, BRA 117, and the highly susceptible rapid cycling Brassica rapa line CrGC 1.19. It was proposed that resistance to white blister in pak choi BRA 117 is controlled by two nuclear genes with dominant recessive epistatic gene action.  相似文献   

15.
Solanum commersonii is a wild tuber-bearing species native to Uruguay with high potential for use in potato breeding programs. Little is known about the genetic diversity within this wild species and the relationship with the resistance to the bacterial pathogen Ralstonia solanacearum. We studied 30 S. commersonii clonal accessions, 20 of which were collected from geographically different areas across the country, while the other ten were grown from seeds from a single plant. Resistance against R. solanacearum was tested and different levels of resistance were found, ranging from delayed wilting to asymptomatic reactions. The genetic variation and the relationships among individuals in this germplasm collection were studied by different molecular markers: Random Amplified Polymorphic DNA (RAPD), Amplified Fragment Length Polymorphism (AFLP) and Microsatellites or Simple Sequence Repeats (SSR). AFLP markers generated the largest number of total and polymorphic fragments per assay unit while SSR revealed the highest frequency of polymorphic bands (100%), followed by AFLP (96.2%) and RAPD (89.4%). In contrast, when comparing the number of different genetic profiles generated, the SSR markers exhibited the lowest discriminatory power. The clustering pattern obtained with the three marker systems showed a similar distribution of the S. commersonii germplasm revealing a high correlation between the three methods employed. All three dendrograms grouped most of the accessions into two main clusters, containing the same accessions regardless of the marker type. Bacterial wilt resistant accessions were present in both clusters. Accessions originated from different seeds of the same plant were grouped within one of the major clusters, and differed in the response to R. solanacearum revealing segregation of resistance. Furthermore, the distribution in two main clusters showed high correspondence with the geographical origin of the accessions, from the north and south of the country, and with the subspecies malmeanum and commersonii morphologically identified.  相似文献   

16.
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17.
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18.
A species level germplasm collection representing 76% of known taxa in the genus Vigna subgenus Ceratotropis was evaluated for resistance to two species of bruchid beetles, Callosobruchus chinensis and C. maculatus. Seven taxa consisting of 29 accessions were found to be resistant to C. chinensis and 4 taxa consisting of 24 accessions were found to be resistant to C. maculatus. This compared with no resistant accessions being found in several hundred landrace accessions of mungbean, V. radiata var. radiata, in the same subgenus. Sometimes resistance was found in all accessions of a particular taxon, such as complete resistance to both C. chinensis and C. macualtus in V. umbellata. Other taxa showed intra taxon variation for resistance such as V. reflexo-pilosa andV. minima. The levels and patterns of resistance among taxa were diverse. The results suggest that various factors cause resistance to bruchid in the subgenus Ceratotropis. While the number of eggs laid on seeds generally reflected seed size, one small seeded cultivar of V. mungo var. mungo, black gram, had an unusually high number of eggs laid per seed. No correlation was found between seed size and levels of resistance. The species level germplasm collection, which reflects the core collection concept in trying to maximize genetic diversity in a limited number of accessions, has enabled a large number of potentially useful sources of resistance to bruchid beetles to be found efficiently. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

19.
玉米种质资源大规模多年多点多病害的自然发病抗性鉴定   总被引：2，自引：0，他引：2  
病害是影响玉米生产的重要因素。利用品种的抗性是控制玉米病害的经济、安全和有效措施。2016—2019年间,在黄淮海和东华北地区,首次对2000份来源广泛且遗传背景丰富的玉米种质资源进行了多年多点多病害的田间自然发生条件下抗病性鉴定,部分材料在西北地区也进行了田间鉴定,重点调查了小斑病、茎腐病、瘤黑粉病、弯孢叶斑病、南方锈病、粗缩病、大斑病、灰斑病和丝黑穗病的抗病性。综合4年共10个不同环境的自然发病下抗性鉴定数据表明,自然发病鉴定的结果受环境因素影响较大,表现为年度间和地域间的差异。在所有鉴定的病害中,小斑病在多个年份和多个鉴定点的发病均比较充分, 11份种质对该病害表现出稳定抗性;茎腐病、大斑病和灰斑病,在不同年份的部分鉴定点发病较为充分,对这3种病害表现抗病的种质分别为440、356和423份,综合抗性鉴定结果具有较大的参考价值;弯孢叶斑病、瘤黑粉病和粗缩病仅在1个鉴定点发病较为充分,南方锈病和丝黑穗病在所有鉴定点均发生较轻,鉴定结果有待进一步验证。本研究筛选出一批在不同环境条件下对多种病害均具有稳定抗性的材料,其中JN15、953、沈977、68122、K21、SC24-1、17MC7211、17MC7223、郑591、161191等种质的综合抗性突出,对种质的利用及后续人工接种精准鉴定的种质选择具重要参考价值。  相似文献   

20.
基于表型性状构建中国花生地方品种骨干种质   总被引：1，自引：0，他引：1  
中国花生地方品种遗传多样性丰富,是花生新品种选育的重要亲本来源。本研究以种质库保存的2741份地方种质为材料,基于种植区划和植物学类型分组,平方根法确定取样量,组内按13个表型数据进行UPGMA聚类分析,类内随机取样,构建骨干种质。利用t检验、F测验、卡方测验、极差、表型保留比例、表型相关性等对骨干种质代表性进行检验和评价;并利用主成分分析和直方图对骨干种质进行确认。结果表明,构建了包含259份种质的中国花生地方品种骨干种质,占全部种质的9.4%,包括多粒型14份、珍珠豆型85份、龙生型42份、普通型103份、中间型15份。在P 0.05概率条件下,骨干种质13个性状的均值、方差、变异系数、香农指数与全部种质无显著差异,且保留了全部种质的分布范围、表型保留比例和表型相关性;二者的植物学类型组成和生态分布是一致的,具有相似的遗传结构和分布频率。建立的骨干种质很好地代表了全部种质的遗传变异和群体结构,可为花生种质创新和优异等位基因发掘奠定良好的基础。  相似文献   

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