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1.
Soybean Cyst nematode (SCN) Heterodera glycines Ichinohe is the most serious pest of soybean [Glycine max (L.) Merr.] in the world and genetic resistance in soybean cultivars have been the most effective means of control. Nematode populations, however, are variable and have adapted to reproduce on resistant cultivars over time due mainly to the narrow genetic base of SCN resistance in G. max. The majority of the resistant cultivars trace to two soybean accessions. It is hoped that new sources of resistance might provide durable resistance. Soybean plant introductions PI 467312 and PI 507354, are unique because they provide resistance to several nematode populations, i.e. SCN HG types 0, 2.7, and 1.3.6.7 (corresponding to races 3, 5, and 14) and HG types 2.5.7, 0, and 2.7 (corresponding to races 1, 3, and 5), respectively. The genetic basis of SCN resistance in these PIs is not yet known. We have investigated the inheritance of resistance to SCN HG types 0, 2.7, and 1.3.6.7 (races 3, 5, and14) in PI467312 and the SCN resistance to SCN HG types 2.5.7 and 2.7 (races 1 and 5) in PI 507354. PI 467312 was crossed to ‘Marcus’, a susceptible cultivar to generate F1 hybrids, 196 random F2 individuals, and 196 F2:3 families (designated as Pop 467). PI 507354 and the cultivar Hutcheson, susceptible to all known SCN races, were crossed to generate F1 hybrids, 225 random F2 individuals and 225 F2:3 families (designated as Pop 507). The F2:3 families from each cross were evaluated for responses to the specific SCN HG types in the greenhouse. Chi-square (χ2) analyses showed resistance from PI 467312 to HG types 2.7, and 1.3.6.7 (races 5 and 14) in Pop 467 were conditioned by one dominant and two recessive genes (Rhg rhg rhg) and resistance to HG type 0 (race 3) was controlled by three recessive genes (rhg rhg rhg). The 225 F2:3 progenies in Pop 507 showed a segregation of 2:223 (R:S) for response to both HG types 2.5.7 and 2.7 (corresponding to races 1 and 5). The Chi-square analysis showed SCN resistance from PI 507354 fit a one dominant and 3 recessive gene model (Rhg rhg rhg rhg). This information will be useful to soybean breeders who use these sources to develop SCN resistant cultivars. The complex inheritance patterns determined for the two PIs are similar to the three and four gene models for other SCN resistance sources known to date.  相似文献   

2.
Genetic analysis of resistance to soybean cyst nematode in PI 438489B   总被引：2，自引：0，他引：2  
Soybean (Glycine max L. Merr.) plant introduction PI 438489B is a unique source that has resistance to all known populations of soybean cyst nematode (Heterodera glycines Ichinohe, SCN). This PI line also has many desirable agronomic characteristics, which makes it an attractive source of SCN resistance for use in a soybean breeding program. However, characterization of SCN resistance genes in this PI line have not been fully researched. In this study, we investigated the inheritance of resistance to populations of SCN races 1, 2, 3, 5, and 14 in PI 438489B. PI 438489B was crossed to the susceptible cultivar ‘Hamilton’ to generate F1 hybrids. The random F2 plants and F3 lines were evaluated in the greenhouse for reaction to these five populations of SCN races. Resistance to SCN races 1, 3, and 5 were mostly conditioned by three genes (Rhg Rhg rhg). Resistance to race 2 was controlled by four genes (Rhg rhg rgh rgh). Three recessive genes were most likely involved in giving resistance to race 14. We further concluded that resistance to different populations of SCN races may share some common genes or pleiotropic effects may be involved. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

3.
G. O. Myers  S. C. Anand 《Euphytica》1991,55(3):197-201
Summary The objectives of this study were to determine if genes for resistance to soybean cyst nematode (SCN) in soybean PI 437654 were identical or different from the genes in Peking, and PI 90763. The F2 plants and F3 families were studied from crosses between PI 437654, Peking, and PI 90763. The cross PI 437654 × susceptible Essex was included to determine inheritance of resistance to SCN. For Race 3, PI 437654 was found to have genes in common with Peking and PI 90763. The segregation in PI 437654 × Essex indicated the presence of one dominant and two recessive genes. For Race 5, PI 437654 indicated the presence of similar genes as those in PI 90763 and Peking whereas, PI 437654 × Essex indicated the action of the segregation ratios of two dominant and two recessive genes. For Race 14, the data from the cross PI 437654 × PI 90763 indicated monogenic inheritance with resistance being dominant; whereas PI 437654 × Peking showed a recessive gene controlling resistance. The segregation in PI 437654(R) × Essex(S) suggested one dominant and two recessive genes for Race 14 reaction.  相似文献   

4.
Worldwide, soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is the most destructive pathogen of soybean [Glycine max (L.) Merr.]. Crop losses are primarily mitigated by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars over time because resistance primarily traces to two soybean accessions, Plant Introduction (PI) 88788 and Peking. Soybean cultivar Hartwig, derived primarily from PI437654, was released for its comprehensive resistance to most SCN populations. A synthetic nematode population (LY1) was recently selected for its reproduction on Hartwig. The LY1 nematode population currently infects known sources of resistance except soybean PI567516C; however, the resistance to LY1 has not been characterized. The objective of this study was to identify quantitative trait loci (QTLs) underlying resistance to the LY1 SCN population in PI567516C, identify diagnostic DNA markers for the LY1 resistance, and confirm their utility for marker-assisted selection (MAS). Resistant soybean line PI567516C was crossed to susceptible cultivar Hartwig to generate 105 recombinant inbred lines (F2-derived F5 families). QTLs were mapped using simple sequence repeats (SSRs) covering 20 Linkage Groups (LGs) and three diagnostic markers, Satt592, Satt331, and Sat_274, were identified on LG O. These markers have a combined efficacy of 90% in identifying resistant lines in a second cross that has been generated by crossing a susceptible cultivar 5601T with resistant PI567516C. F2-derived F4 segregating population was used in MAS to identify resistant lines.  相似文献   

5.
黄淮大豆主产区大豆胞囊线虫生理小种分布调查   总被引：1，自引：0，他引：1  
大豆胞囊线虫(SCN)在黄淮地区普遍发生,调查小种分布情况,确定优势小种对抗病育种有重要意义。2012-2015年,取样调查黄淮地区6个省份土样,利用Riggs模式鉴定生理小种,绘制黄淮地区SCN生理小种分布图,并与文献报道结果对比,探讨黄淮地区SCN生理小种类型及其分布规律。结果表明,该病害在黄淮大豆主产区均有分布,在采集受SCN感染的322份土样中,112份被鉴定出生理小种类型,包括1号、2号、3号、4号、5号、6号和11号小种。其中,57份为2号小种,占样本总体的50.9%;26份土样为5号小种,占23.2%;11份土样为4号小种,占9.8%,1号、3号、6号和11号小种分别占总体的4.5%、5.4%、4.5%和1.8%。依据不同生理小种在各省发生频率由高到低的顺序,河南分布5号、2号、3号、11号小种;河北分布2号、5号、6号、3号、4号小种;安徽分布2号、5号、6号、3号小种;山西分布2号、4号、5号、1号、3号、11号小种;山东分布2号、3号、5号、1号、6号小种;江苏分布2号、5号、1号小种。以上结果表明,2号小种是目前黄淮海地区的优势小种,其次是5号小种,致病力最强的4号小种主要分布在山西省。在黄淮海地区,抗线虫育种目标应以抗2号生理小种为主,兼抗5号小种,部分地区应以兼抗2号和4号小种为主。在黄淮地区3号、6号和11号小种是新发现的小种。与2001-2003年调查结果比较,黄淮海地区大豆胞囊线虫生理小种组成及分布有一定的改变。  相似文献   

6.
Worldwide, cyst nematode (SCN) Heterodera glycines is the most destructive pathogen on cultivated soybean (Glycine max (L.) Merr.). In the USA yield losses in 2001 were estimated to be nearly 60 million dollars. Crop losses are primarily reduced by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars overtime because resistance primarily traces to two soybean accessions. Recently cv. Hartwig was released which has comprehensive resistance to most SCN populations. A virulent nematode population LY1 was recently selected for its reproduction on Hartwig. LY1 population originated from a mass mating of Race 2 (HG Type 1.2.5-) females with Race 5 (HG Type 1.2-) males. LY1 nematode population infects currently known sources of resistance except PI 567516C. The female indices obtained on PI 567516C and Hartwig were 7% (resistant) and 155% (susceptible), respectively. However, the genetic basis of LY1 resistance in soybean PI 567516C is not known. Resistant PI line 567516C was crossed to susceptible cultivar Hartwig to generate 105 F2:5 families. These families together with parents, seven indicator lines and a susceptible control cv. Lee-74 were evaluated for response to LY1 nematode population in the greenhouse. Chi-square analysis showed resistance in PI567516C to LY1 was conditioned by one dominant and two recessive genes (Rhg, rhg, rhg). Chi-square value was 0.15 and P = 0.70. This information will be useful to soybean researchers for developing resistant cultivars to nematode population that infects Hartwig.  相似文献   

7.
大豆胞囊线虫(Heterodera glycines Ichinohe)是我国大豆的全国性主要病害之一。1号和4号生理小种是黄淮地区的优势小种。以Essex×ZDD2315、Peking×ZDD2315、PI88788×ZDD2226、Peking×ZDD2226的P1、P2、F1、BC1F2为材料,用主基因＋多基因混合遗传模型分析大豆对胞囊线虫1号和4号生理小种抗性的遗传机制。结果表明,ZDD2315、ZDD2226对1号生理小种的抗性受主效基因控制,未发现多基因效应,且与Peking存在相同的抗病基因;抗性遗传表现组合特异性,Essex×ZDD2315组合为3对加性主基因遗传模型,主基因遗传率72.02%,PI88788×ZDD2226组合为2对显性上位主基因遗传模型,主基因遗传率62.33%。对4号生理小种的抗性为主基因＋多基因混合遗传模型,Essex×ZDD2315、Peking×ZDD2315、PI88788×ZDD2226等3个组合为3对主基因+多基因遗传模型,主基因遗传率分别为67.76%、72.46%和53.25%,多基因遗传率分别为24.48%、21.31%和35.77%;Peking×ZDD2226表现为2对主基因遗传模型,主基因遗传率45.40%。抗性基因表现为隐性,育种上可以在早代选择。培育多抗品种应以抗4号生理小种为主要目标进行基因聚合。  相似文献   

8.
Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is one of the most damaging pests of soybean (Glycine max (L.) Merr.). Host plant resistance has been the most effective control method. Because of the spread of multiple SCN races in Hokkaido, the Tokachi Agricultural Experiment Station has bred soybeans for SCN resistance since 1953 by using 2 main resistance resources PI84751 (resistant to races 1 and 3) and Gedenshirazu (resistant to race 3). In this study, we investigated the genetic relationships of SCN resistance originating from major SCN resistance genes in Gedenshirazu and PI84751 by using SSR markers. We confirmed that race 1 resistance in PI84751 was independently controlled by 4 genes, 2 of which were rhg1 and Rhg4. We classified the PI84751- type allele of Rhg1 as rhg1-s and the Gedenshirazu-type allele of Rhg1 as rhg1-g. In the cross of the Gedenshirazu-derived race 3-resistant lines and the PI84751-derived races 1- and 3-resistant lines, the presence of rhg1-s and Rhg4 was responsible for race 1-resistance. These results indicated that it was possible to select race 1 resistant plants by using marker-assisted selection for the rhg1-s and Rhg4 alleles through a PI84751 origin × Gedenshirazu origin cross.  相似文献   

9.
Summary Cultivar Peking has been extensively used as a source of resistance to Race 3 and Race 5 of soybean cyst nematode, Heterodera glycines I., and Peking genes for resistance are present in a wide range of resistant soybean cultivars. Peking is also used as a host differential in the soybean cyst nematode race classification system. Thirteen Peking lines maintained in the USDA Soybean Germplasm Collection and in several breeding programs were surveyed using RFLP and RAPD markers for genetic characterization. Based on the molecular diversity combined with reaction to soybean cyst nematode, Peking genotypes from a common original source were identified. Peking lines PI 297543 (introduction from Hungary), and PI 438496A, PI 438496B and PI 438496C (introductions from Russia) represented unrelated germplasms. Identified molecular polymorphism can be used to validate the genetic purity of Peking lines used as host differentials for soybean cyst nematode classification system as well as utilization of an individual germplasm line in genetic-breeding programs.  相似文献   

10.
大豆是主要的油料作物,起源于中国,在我国种质资源十分丰富。大豆孢囊线虫(SCN)(HeteroderoglycinesIchinohe)是一种土传的定居性内寄生线虫,不易防治,常引起大豆黄萎病等病害,是大豆生产上危害最大的病害之一。大豆孢囊线虫病生理小种多达十几种,在我国,大豆孢囊线虫病病原主要为3、4号生理小种。大豆抗孢囊线虫的研究一直是世界上大豆抗病育种研究的热点之一。在本课题的前期研究中,根据已克隆的植物抗孢囊线虫病基因的保守序列设计引物,对经常规鉴定为抗(感)孢囊线虫3号生理小种的15个大豆品种基因组DNA进行PCR扩增,在大豆抗病品种中获得一条大豆抗孢囊线虫的特异条带。本研究在此基础上利用该对引物,对高抗孢囊线虫3号小种的北京小黑豆基因组DNA进行扩增,并克隆了特异扩增片段,命名为RSCN3,经测序及BLAST分析,发现其DNA序列与GenBank、EMBL、DDBJ、PDB中的大豆似受体激酶RHG4、水稻TMK(leucinerichprotein,receptor-likekinase)基因等均有80%以上的同源性。根据该DNA序列推测其氨基酸序列,在其序列中共找到21个亮氨酸,将该序列与蛋白质序列同源性进行比较,结果发现与植物中的受体激酶、富含亮氨酸重复的蛋白激酶有较高的同源性。因此推测RSCN3克隆片断为一个与受体激酶有类似作用的抗病相关基因的RGA,并将该序列登录到GenBank中,登录号为:AY580161。  相似文献   

11.
D. Rubiales  A. Martín 《Euphytica》1999,109(3):157-159
The inheritance of resistance to yellow mosaic virus spread by Bemisia tabaci Gen. in Glycine soja (Linn.) Seib. & Zucc. was studied following natural infection in the field condition. The resistant wild accession, Glycine soja was crossed with susceptible cultivars ‘Ankur’, ‘Bragg’, ‘PK 472’ and ‘Kalitur’ of Glycine max (Linn.) Merr. Resistance reactions of F1 and F2 plants, and individual F2 plant derived F3 families indicated that resistance was controlled by a single dominant gene. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

12.
The resistance of soybean (Glycine max L. Merr.) cultivars varies with the different races of the soybean cyst nematode (SCN), Heterodera glycines, referred to as HG types (biotypes). Resistant cultivars with durable resistance are emphasized in recent years. The aim here was to identify quantitative trait loci (QTLs) for resistance to two SCN HG types (HG type 2.5.7, race 1; and HG type 1.2.3.5.7, race 4) in resistant cultivar ‘L‐10’ and to analyse the additive and epistatic effects of the identified QTLs. A total of 140 F5‐derived F10 recombinant inbred lines (F5:10 RILs) were advanced via single‐seed‐descent from the cross between ‘L‐10’ (broadly resistant to SCN) and “Heinong 37” (SCN‐susceptible). For SCN HG type 2.5.7 and HG type 1.2.3.5.7 resistance, three and six QTLs for resistance to SCN HG type 2.5.7 and HG type 1.2.3.5.7 were identified, respectively, most of which could explain <10% of the phenotypic variation. Among these QTLs, five were identified over 2 years, while the other QTLs were detected in either 2009 or 2010. QSCN1‐2, located near the SSR marker Sat_069 of linkage group D1b (Chromosome, 2), was responsible for the largest proportion of phenotypic variation (16.01% in 2009 and 18.94% in 2010), suggested that it could effectively be used as a candidate QTL for the marker‐assisted selection (MAS) of soybean lines resistant to SCN. Additionally, for SCN HG type 2.5.7 and HG type 1.2.3.5.7 resistance, two and four QTLs showed an additive effect (a), respectively. One epistatic pair of QTLs (QSCN1‐1‐QSCN1‐3) for SCN HG type 2.5.7 resistance and eight epistatic pairs of QTLs for SCN HG type 1.2.3.5.7 resistance were found to have significant aa effects, among which one pair of QTLs (QSCN4‐4 and QSCN4‐5) contributed a large proportion of aa effects (3%). The results indicated that additive and epistatic effects could significantly affect SCN resistance. Therefore, both of a and aa effects should be considered in MAS programmes.  相似文献   

13.
大豆胞囊线虫病是严重危害大豆生产的重要病害之一,根据抗病候选基因发掘标记可以为分子标记辅助选择抗病材料提供标记资源。本研究通过对大豆胞囊线虫抗病候选基因rhg1的序列比对分析,发现4个插入/删除位点,针对其中3个多碱基插入/缺失位点开发了InDel标记。应用开发的3个InDel标记对33份栽培大豆进行基因型鉴定,共检测到等位变异11个,平均每个位点3.67个。其中rhg1-I1位点有等位变异5个,rhg1-I2位点有等位变异2个;rhg1-I4位点有等位变异4个。各等位变异发生频率范围为0.8%~77.3%。InDel标记与大豆胞囊线虫抗性间的关联分析表明,rhg1-I4为抗性相关标记,对抗病资源的检出效率为88.2%,对感病资源的检出效率为100%。该标记的288 bp等位变异和294 bp等位变异为抗病相关等位变异,269 bp等位变异和272 bp等位变异为感病相关等位变异。此标记与常用于标记辅助选择的Satt309配合鉴定可以提高SCN抗病资源的检测效率。  相似文献   

14.
Genetic analysis of resistance of plant introduction (PI) 438489B to soybean cyst nematode (SCN) have shown that this PI is highly resistant to many SCN HG types. However, validation of the previously detected quantitative trait loci (QTL) has not been done. In this study, 250 F2:3 progeny of a Magellan (susceptible) × PI 438489B (resistant) cross were used for primary genetic mapping to detect putative QTL for resistance to five SCN HG types. QTL confirmation study was subsequently conducted using F6:7 recombinant inbred lines (RILs) derived from the same cross. Simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers were employed for molecular genotyping. Interval mapping (IM), permutation tests, cofactor selection, and composite interval mapping (CIM) were performed to identify and map QTL. Results showed that five QTL intervals were associated with resistance to either multiple- or single-HG types of SCN. Among these, two major QTL for resistance to multiple-SCN HG types were mapped to chromosomes (Chr.) 8 and 18, consistent with the known rhg1 and Rhg4 locations. The other QTL were mapped to Chr. 4. The results of our study confirmed earlier reported SCN resistance QTL in this PI. Moreover, SSR and SNP molecular markers tightly linked to these QTL can be useful for the near-isogenic lines (NILs) development aiming to fine-mapping of these QTL regions and map-based cloning of SCN resistance candidate genes.  相似文献   

15.
Arthur T. Trese 《Euphytica》1995,81(3):279-282
Summary Rhizobium fredii USDA257 will effectively nodulate Asiatic and unimproved soybean cultivars, such as Peking, but most of the highly selected North American cultivars, such as McCall, produce at most rudimentary, ineffective nodules. In R. fredii USDA 257, a locus containing 6 open reading frames is responsible for this cultivar specific incompatibility. To examine the genetic control of incompatability on the part of the host, the soybean cultivars Peking and McCall were crossed to produce five F1 progeny. These plants and their selfed progeny were tested for nodulation with USDA257. Resistance to nodulation was found to be conditioned by a single dominant gene. These results indicate that, in soybean, strain specific resistance to nodulation can result from gene(s)-for-gene interactions.  相似文献   

16.
The objective of this work was to check the possible allelism between two sources of resistance to the root-knot nematode Meloidogyne incognita race 1 in lettuce (‘Grand Rapids’ and ‘Salinas-88’). The experiments were carried out in greenhouses, in expanded 128-cell polystyrene trays filled with commercial substrate. Lettuce cultivars ‘Salinas 88’ and ‘Grand Rapids’ were tested along with the populations F1 (‘Grand Rapids’ × ‘Salinas-88’), F2 (‘Grand Rapids’ × ‘Salinas-88’), F3 (‘Grand Rapids’ × ‘Salinas-88’), and with F4 families derived from the latter population. Seedlings were inoculated 15 days after sowing with a nematode egg suspension equivalent to 30 eggs ml−1 of substrate. Plants were evaluated for apparent gall incidence, gall scores, egg mass scores and extracted egg numbers 45 days after the inoculation date. There was evidence that two different genes are involved in control of resistance to M. incognita race 1 in lettuce cultivars Grand Rapids and Salinas-88. Lines with higher levels of nematode resistance than either Grand Rapids or Salinas-88 could be selected in the F4 generation of the cross between these resistant parental lines.  相似文献   

17.
Asian rust, caused by the fungus Phakopsora pachyrhizi, is the most severe disease currently threatening soybean crops in Brazil. The development of resistant cultivars is a top priority. Genetic characterization of resistance genes is important for estimating the improvement when these genes are introduced into soybean plants and for planning breeding strategies against this disease. Here, we infected an F2 population of 140 plants derived from a cross between ‘An-76’, a line carrying two resistance genes (Rpp2 and Rpp4), and ‘Kinoshita’, a cultivar carrying Rpp5, with a Brazilian rust population. We scored six characters of rust resistance (lesion color [LC], frequency of lesions having uredinia [%LU], number of uredinia per lesion [NoU], frequency of open uredinia [%OU], sporulation level [SL], and incubation period [IP]) to identify the genetic contributions of the three genes to these characters. Furthermore, we selected genotypes carrying these three loci in homozygosis by marker-assisted selection and evaluated their genetic effect in comparison with their ancestors, An-76, PI230970, PI459025, Kinoshita and BRS184. All three genes contributed to the phenotypes of these characters in F2 population and when pyramided, they significantly contributed to increase the resistance in comparison to their ancestors. Rpp2, previously reported as being defeated by the same rust population, showed a large contribution to resistance, and its resistance allele seemed to be recessive. Rpp5 had the largest contribution among the three genes, especially to SL and NoU. Only Rpp5 showed a significant contribution to LC. No QTLs for IP were detected in the regions of the three genes. We consider that these genes could contribute differently to resistance to soybean rust, and that genetic background plays an important role in Rpp2 activity. All three loci together worked additively to increase resistance when they were pyramided in a single genotype indicating that the pyramiding strategy is one good breeding strategy to increase soybean rust resistance.  相似文献   

18.
The purpose of this work was to identifymicrosatellite markers linked to a gene forresistance to Heterodera glycinesIchinohe (Soybean Cyst Nematode – SCN) insoybean cultivar Hartwig. ABC1F2 mapping population derivedfrom a cross between Hartwig (resistant)and the Brazilian soybean line Y23(susceptible) was used. About 200microsatellite or simple sequence repeat(SSR) primer pairs were tested in a bulkedsegregant analysis (BSA). Those thatshowed clear polymorphisms were amplifiedin the BC1F2 population, whichhad been previously inoculated andevaluated for resistance/susceptibility toSCN Race 3. Three SSR markers linked toSCN resistance were detected in thepopulation. Two of them, Satt 038 and Satt163, flanking a dominant resistant gene(d/a = –0.90), explained 37% of thephenotypic variance. This gene was mappedat the edge of molecular linkage group G. Broad and narrow sense heritabilities wereestimated to be 50.54% and 37.73%,respectively. A selection efficiency of91.18% was obtained with the simultaneoususe of the two markers. The identified SSRmarkers will be useful tools for assistingthe selection of homozygous genotypes andfor expediting the introgression of the SCNresistance locus from cv. Hartwig tosoybean elite cultivars.  相似文献   

19.
The use of resistant cultivars is one of the best methods for nematode control and reduction of economic losses caused by these pathogens. Studies of inheritance of nematode resistance in common bean (Phaseolus vulgaris L.) are nonetheless scarce. The present paper reports on the estimation of genetic parameters associated with resistance to the root nematode Meloidogyne incognita race 1 in common beans. Two contrasting bean lines, ‘Aporé’ (P1 = nematode resistant) e ‘Macarr?o Rasteiro Conquista’ (P2 = susceptible), and the generations F1 (P1 × P2), F2 (P1 × P2), BC1(P1) = (F1 × P1) and BC1(P2) = (F1 × P2), were assessed 45 days after nematode inoculation, through a scale related to the number of eggs per gram of root tissue. Dominant genetic effects were inferior in magnitude to additive effects, indicating incomplete dominance of nematode resistance. Dominance was in the direction of increased nematode resistance (i.e., lower number of eggs per g root). Resistance to Meloidogyne incognita race 1 in common bean is under control of a single gene locus, with incomplete dominance of the resistance allele present in ‘Aporé’, but modifier genes affecting its expression appear to be present in the susceptible parent ‘Macarr?o Rasteiro Conquista’.  相似文献   

20.
Inheritance of resistance to Soybean mosaic virus in FT-10 soybean   总被引：1，自引：0，他引：1  
The occurrence of a new isolate from the G5 strain of Soybean mosaic virus (SMV), which broke the resistance of soybean cultivar FT-10, was first reported in Brazil in 1995. Cultivar Davis is an ancestor of ‘FT-10’ and the likely source of resistance to the virus. Diallel crosses among resistant cultivars Epps (PI 96983), Ogden and FT-10, and susceptible cultivar Hill were made to investigate the inheritance of SMV resistance in FT-10. The experiments for genetic studies were performed undergreen house conditions. Plants of the F2 population and F3 families from each cross and the parents were inoculated with SMV G1 and G5 strains. Plants were classified as: symptom less (R), susceptible with typical symptoms of mosaic (S), and systemic necrosis (N). Plants showing necrosis or no symptoms were classified as resistant. Each F3 family was classified as resistant (homozygous),susceptible (homozygous), or segregating (heterozygous). The results of both F2 and F3 were analyzed by Chi-square tests. The results suggested that FT-10 carries an allele at the Rsv 1 locus for resistance to SMV. However, the allele is different from those in Epps and Ogden. The symbol Rsv 1 d is a tentatively named for the newly detected allele in FT-10. This allele probably originated from Davis cultivar. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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