首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Net blotch, caused by Pyrenophora teres f. teres, is a damaging foliar disease of barley worldwide. It is important to identify resistance germplasm and study their genetics. 'Chevron', a six-rowed barley used as a parent for the production of a doubled haploid (DH) population for mapping of Fusarium head blight (FHB) resistance, was also found to be resistant to net blotch. To map the resistance genes, the population was evaluated for resistance at the seedling stage in a greenhouse. The resistance data showed a two-peak distribution. Through linkage mapping, one resistance gene, tentatively called Rpt, was located on chromosome 6HS flanked by Xksua3b-Xwg719d, which was also detected by QTL mapping. This QTL explained 64% of the phenotypic variance for the resistance in this DH population. In addition, a minor QTL was found on chromosome 2HS defined by Xcdo786-Xabc156a. 'Chevron' and 'Stander' contributed the resistant alleles of Rpt and the 2HS QTL, respectively. Both QTLs together explained nearly 70% of the phenotypic variance. The markers for these QTLs are useful for marker-assisted selection of net blotch resistance in barley breeding.  相似文献   

2.
A doubled haploid barley (Hordeum vulgare L.) population from a cross between the cultivar `Ingrid' and the Ethiopian landrace `Abyssinian' was mapped by AFLP, RFLP, SSR and STS markers and tested for resistance to isolates`4004', `2', `16-6', `17', `22' and `WRS 1872' of Rhynchosporium secalis (Oudem.) J.J. Davis, the causal agent of leaf scald. Resistance tests were conducted on parents, DH-lines, a near-isogenic line of `Abyssinian' (NIL) into `Ingrid', and an F2 population descended from the same F1 plants as the DHs. The DH population segregated for at least two major R. secalis resistance QTL. All isolates tested identified a major QTL on chromosome 3 (3H) associated with R. secalis resistance, in a 4 cM support interval between the co-segregating markers Bmac0209/Falc666 and MWG680. The QTL was linked with the markers Falc666 (2.3 cM), YLM/ylp (0.3 cM), MWG680 (1.7 cM), cttaca2 (2.5 cM) and agtc17 (9.8 cM). The second QTL was located on chromosome 1 (7H).However, this QTL was only detected by one isolate and was located in an interval of 16 cM in the distal part of the chromosome. At this QTL the allele for improved scald resistance originated from the parent `Ingrid'. There were a number of minor QTL on chromosomes 2 (2H), 4 (4H) and 6 (6H) that were not repeatable either across replications or analysis methods. The importance of checking QTL-models by cross-validation is stressed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

3.
Stagonospora nodorum blotch (SNB) is an important foliar disease of durum wheat (Triticum turgidum var. durum) worldwide. The combined effects of SNB and tan spot, considered as components of the leaf spotting disease complex, result in significant damage to wheat production in the northern Great Plains of North America. The main objective of this study was the genetic analysis of resistance to SNB caused by Phaeosphaeria nodorum in tetraploid wheat, and its association with tan spot caused by Pyrenophora tritici-repentis race 2. The 133 recombinant inbred chromosome lines (RICL) developed from the cross LDN/LDN(Dic-5B) were evaluated for SNB reaction at the seedling stage under greenhouse conditions. Molecular markers were used to map a quantitative trait locus (QTL) on chromosome 5B, explaining 37.6% of the phenotypic variation in SNB reaction. The location of the QTL was 8.8 cM distal to the tsn1 locus coding for resistance to P. tritici-repentis race 2. The presence of genes for resistance to both SNB and tan spot in close proximity in tetraploid wheat and the identification of molecular markers linked to these genes or QTLs will be useful for incorporating resistance to these diseases in wheat breeding programs.  相似文献   

4.
J. Jensen    G. Backes    H. Skinnes  H. Giese 《Plant Breeding》2002,121(2):124-128
Three quantitative trait loci (QTL) for scald resistance in barley were identified and mapped in relation to molecular markers using a population of chromosome doubled‐haploid lines produced from the F1 generation of a cross between the spring barley varieties ‘Alexis’ and ‘Regatta’. Two field experiments were conducted in Denmark and two in Norway to assess disease resistance. The percentage leaf area covered with scald (Rhynchosporium secalis) ranged from 0 to 40% in the 189 doubled‐haploid (DH) lines analysed. One quantitative trait locus was localized in the centromeric region of chromosome 3H, Qryn3, using the MAPQTL program. MAPQTL was unable to provide proper localization of the other two resistance genes and so a non‐interval QTL mapping method was used. One was found to be located distally to markers on chromosome 4H (Qryn4) and the other, Qryn6, was located distally to markers on chromosome 6H. The effects of differences between the Qryn3, Qryn4 and Qryn6 alleles in two barley genotypes for the QTL were estimated to be 8.8%, 7.3% and 7.0%, respectively, of leaf covered by scald. No interactions between the QTLs were found.  相似文献   

5.
D. Rubiales  A. Moral  A. Martín 《Euphytica》2001,122(2):369-372
Septoria leaf blotch and common bunt are important diseases of wheat to which Hordeum vulgare is resistant. Addition lines of H. vulgare in wheat were utilized to determine which H. vulgare chromosomes carry resistance genes. Resistance to septoria leaf blotch was conferred by gene(s) present all over the barley genome, but more strongly by those located on chromosomes 7 and 4. Almost complete resistance to common bunt was conferred by gene(s) present in chromosomes 6 and a slight but significant level of resistance was conferred by chromosome 7. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

6.
One thousand four hundred and seven spring wheat germplasm lines belonging to Indian and CIMMYT wheat programs were evaluated for stay green (SG) trait and resistance to spot blotch caused by Bipolaris sorokiniana during three consecutive crop seasons, 1999–2000, 2000–2001 and 2001–2002. Disease severity was recorded at six different growth stages beginning from tillering to late milk stage. SG trait was measured by following two approaches: difference for 0–9 scoring of green coloration (chlorophyll) of flag leaf and spike at the late dough stage (GS 87) and a new approach of leaf area under greenness (LAUG). Germplasm lines showed a wide range (7–89) for LAUG and were grouped into four viz., SG, moderately stay green, moderately non-stay green and non-stay green (NSG). However, very few (2.2%) lines showed high expression of SG trait, i.e., LAUG >60. LAUG appeared to be a better measure of SG trait than a 0–9 scale. Mean spot blotch ratings of SG genotypes were significantly lower than those of NSG genotypes at all growth stages. Two spot blotch resistant genotypes (Chirya 3 and Chirya 7) having strong expressions of SG trait were crossed with NSG, spot blotch susceptible cv. Sonalika. Individually threshed F2 plants were used to advance the generations. SG trait and spot blotch severity were recorded in the parents and F1, F3, F4, F5, F6 and F6–7 generations under disease-protected and inoculated conditions. SG trait in the F1 generation was intermediate and showed absence of dominance. Evaluation of progenies (202–207) in the segregating generations revealed that SG trait was under the control of around four additive genes. Lines homozygous for SG trait in F4, F5, F6 and F6–7 generations showed significantly lower mean area under disease progress curve (AUDPC) for spot blotch than those with NSG expression. A positive correlation (0.73) between SG trait and AUDPC further indicated a positive influence of SG on severity of spot blotch. The study established that variation for SG trait exists in spring wheat; around four additive genes control its inheritance in the crosses studied and there is positive association between SG trait and resistance to spot blotch.  相似文献   

7.
Spot blotch of wheat (Triticum aestivum L.), caused by Bipolaris sorokiniana (Sacc. in Sorok.) Shoem., is a major disease in South Asia. Popular commercial cultivars have low levels of resistance to spot blotch. Information on the inheritance of spot blotch resistance in wheat is lacking. Field studies were conducted in four wheat crosses, each involving a Chinese hexaploid parent with high levels of resistance and a commercial cultivar with low to intermediate levels of resistance to spot blotch. Data were recorded in the F2, F3 and F4 generations to estimate heritability. Field studies were conducted in three years (1992–94) at Rampur. Nepal, involving 150 lines in each cross. The spot blotch score was recorded as the percentage necrosis and associated chlorosis of the two upper most leaf surface. In the F2 generation three spot blotch readings on the flag leaf were taken whereas in the F3 and F4 generations four readings were recorded at 5-day intervals on the flag and the penultimate leaves. The highest disease score (HDS) and the area under disease progress curve (AUDPC) were analysed. Heritability (h2) estimates for spot blotch resistance were intermediate to high measured in terms of HDS (0.47 < h2 < 0.67) and also AUDPC (0.58 < h2 < 0.77) both in F3 and F4 generations in each of the four crosses. Heritability values were somewhat higher for AUDPC than HDS. There were significant negative correlations (r) of days to heading with HDS (-0.186 < r < -0.515) and AUDPC (-0.218 < r < -0.623). One-hundred kernel weight was significantly negatively correlated to AUDPC (-0.245 < r < -0.454) in all crosses in each generation. The results suggest that selection for resistance to spot blotch could be effective in the segregating populations generated from hexaploid wheat parents having different levels of resistance. Although AUDPC appeared to be a better measure to determine genetic differences for spot blotch in wheat, HDS would be adequate in screening trials for resistance to spot blotch.  相似文献   

8.
QTL analysis of Cercospora leaf spot resistance in sugar beet   总被引：3，自引：0，他引：3  
The inheritance of Cercospora leaf spot resistance in sugar beet was investigated by means of quantitative trait loci (QTL) analysis of a segregating population of 193 individuals, using 110 AFLP and 35 restriction fragment length polymorphism (RFLP) markers. Five QTL were found through composite interval mapping on linkage groups 1, 2, 3, and 9, respectively, two of which were linked on linkage group 3. The significance of these QTL was tested by permutation analysis The QTL had mostly additive, but also certain negative dominance effects; all the resistance alleles came from the Cercospora-resistant parent. Each quantitative trait locus accounted for 7-18% of the phenotypic variation, leaving 37% of the variation unexplained. The results are discussed in relation to the potential use of marker-assisted breeding for Cercospora leaf spot resistance in sugar beet.  相似文献   

9.
Sugarcane (Saccharum Spp.) produces 80% of the world's sugar along with other by‐products. The production of sugarcane is vulnerable to infestation of sugarcane yellow leaf virus (SCYLV) worldwide. A study was conducted using an F1 segregating population derived from CP95‐1039 × CP88‐1762 to identify the genetic factors underlying SCYLV resistance. The disease infection data were measured using tissue blot immunoassay after 6 years of exposure to the virus under natural field conditions. Genetic maps were created using genotyping by sequencing‐based markers for each parent separately following a pseudo‐testcross approach. Two quantitative trait loci (QTL) were detected for SCYLV resistance accounting for 28% of the phenotypic variation. A major QTL qSCYLR79 located on linkage group 79 and linked with marker 3PAV3154 appears to be unique for SCYLV resistance in sugarcane. Progeny having a combination of two major alleles had 31% less SCYLV incidence than progeny with a combination of major and minor alleles in the genomic region of qSCYLR79. Thus, selection against the minor allele may decrease the SCYLV incidence in sugarcane.  相似文献   

10.
A.K. Joshi  R. Chand 《Euphytica》2002,124(3):283-291
One thousand four hundred and seven spring wheat germplasm lines belonging to Indian and CIMMYT wheat programs were evaluated for their leaf angle and resistance to spot blotch caused by Bipolaris sorokiniana during three consecutive crop seasons, 1994–95, 1995–96 and 1996–97.Disease severity was recorded at six different growth stages beginning from tillering to late milk stage. Three crosses (M 3109 × Sonalika, HP 1808 × K 9006 and HD 2662 × K 9006) were made between genotypes with erect and drooping leaves. M 3109 was resistant, Sonalika susceptible while the other three lines possessed moderate resistance to spot blotch. Individually threshed F2 plants were used to advance the generations. Leaf angle and spot blotch resistance were recorded in parents, F1, F3, F4and F5 generations. Leaf erectness in F1 generation showed partial dominance. Evaluation of F3, F4 and F5 progenies(120–150) revealed that leaf angle was under the control of few genes that appeared to be close to three. Germplasm lines with erect and semi-erect leaves displayed lower spot blotch severity than those having drooping and semi-drooping leaves. Lines homozygous for erect leaf posture in F3,F4 and F5 generations showed significantly lower mean AUDPC than those with drooping leaves. A positive correlation (0.58) between leaf angle and AUDPC further indicated a positive influence of leaf erectness on severity to spot blotch disease. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
Spot blotch, caused by Cochliobolus sativus (Ito and Kurib.) Drechsler ex Dastur, and heat stress are two important stresses of bread wheat (Triticum aestivum L.) causing substantial yield reduction in the warm areas of South Asia. These two stresses put pressure on at least 25 million hectares of wheat areas worldwide. This study was conducted to examine variation in physiological traits and its association with heat and spot blotch. Eleven diverse bread wheat genotypes were evaluated in replicated field trials under spot blotch epidemics and heat stress conditions in 2006 and 2007 at Rampur, Nepal. Canopy temperature depression (CTD), chlorophyll fluorescence (CF), chlorophyll content, percent disease leaf area, yield and yield components were recorded. Heat and spot blotch individually reduced CTD, CF, chlorophyll content, grain yield (GRY), and thousand kernel weight (TKW), with greater reductions recorded under combined stress. Genotypes showing lower GRY or TKW loss due to spot blotch also exhibited lower yield loss due to heat stress or combined heat and disease stress, suggesting an association between tolerance mechanisms to the stresses. The physiological traits chlorophyll content, CF and CTD showed higher correlations with GRY and TKW than with area under disease progress curve (AUDPC) suggesting their potential application in screening for heat and spot blotch tolerant genotypes. Genotypes with lower disease showed the highest values for chlorophyll content, CF and CTD. Our findings provide new information on the relationship of these physiological traits with spot blotch resistance and heat tolerance when examined in the same study. The physiological traits studied have potential application in integrative indirect selection criteria for improving spot botch and heat tolerance in wheat.  相似文献   

12.
Fusarium crown rot (FCR) is becoming a major disease in many parts of the cereal‐growing regions worldwide. Significant QTL conferring FCR resistance have been reported on 13 of the 21 possible hexaploid wheat chromosomes in wheat and on three of the seven chromosomes in barley. Available results show that host resistance to FCR is not pathogen species‐specific, that resistance QTL have strong additive effect and that both plant height and growth rate affect FCR severity. Further, different loci seem to be responsible for resistances to FCR and Fusarium head blight although both diseases can be caused by the same Fusarium pathogens. Although marker‐assisted selection for FCR resistance has been initiated, the available markers are all derived from QTL mapping, which provides only limited resolution. Further work has to be conducted in developing diagnostic markers before significant progress can be made in deploying marker‐assisted selection as a routine tool to accelerate and improve FCR in breeding programmes.  相似文献   

13.
Brown spot (BS) is a destructive foliar disease in tobacco (Nicotiana tabacum L.) and is caused by Alternaria alternata. BS poses a serious threat to tobacco production worldwide. To develop molecular markers that are tightly linked to BS resistance for marker-assisted selection (MAS), F2, F2:3 and BC3F2:3 populations were developed from a cross between a source of BS resistance Jingyehuang (JYH) and a BS susceptible flue-cured variety NC82. One hundred eighty-one F2 individuals, 180 F2:3 lines and 256 BC3F2:3 lines were evaluated for field resistance under different environments and quantitative trait loci (QTL) were identified by linkage mapping. A major QTL was mapped on chromosome15; this QTL explained 8.6–18.0% of the phenotypic variation under different conditions. Furthermore, 219 accessions were evaluated for their responses to BS at two sites, and association mapping (AM) was used to verify the chromosomal region harboring the major QTL. The AM results showed that six significant marker-trait associations were detected at two sites. Among these markers, the marker Indel53 within the specific chromosomal region exhibited the most significant association with resistance to BS and explained 20.0 and 21.5% of the phenotypic variation at the two sites, respectively. An approximately 2-Mb physical interval at the locus of marker Indel53 contained 31 predicted genes; quantitative real-time PCR results suggested that two of these genes (Nitab 4.5_0000264g0050.1 and Nitab 4.5_0000264g0130.1) were probable candidate genes for resistance to BS. In summary, our results suggested that the novel major QTL from tobacco variety JYH for resistance to BS provided partial effective resistance against A. alternata and was useful for MAS of resistance to BS in tobacco breeding.  相似文献   

14.
Wheat (Triticum aestivum L.) cultivars for the warm regions of South Asia must produce high yields and possess resistance to spot blotch (Cochliobolus sativus), early maturity and high kernel weight. A study was conducted to determine the effectiveness of selecting for high grain yield based on a selection index for spot blotch resistance, maturity and kernel weight in four wheat crosses involving a susceptible cultivar and resistant genotypes. Initial selection of 40 progeny lines in each cross had been made using a selection index based on disease severity, days to heading and kernel weight as reported by Sharma and Duveiller [{Crop Sci 43 (2003) 2031}]. The five highest grain-yielding progeny lines from among the 40 lines in each cross, their parents and five popular commercial cultivars were evaluated in field trials at two sites in Nepal in the 2002 and 2003 wheat seasons. Multiple spot blotch assessments were made to determine the area under disease progress curve (AUDPC). Grain yield, thousand-kernel weight (TKW), days to heading and plant height were examined. The wheat genotypes in the farmer's field were also ranked on the basis of cultivar preference criteria by the local farmers. The 20 progeny lines always showed a higher (+11 to +125%) grain yield and heavier (+10 to +44%) kernels than their parents and a lower (−83 to −89%) AUDPC than the susceptible parent. The progeny lines showed 98–100% grain yield, 97–100% TKW and 66–78% AUDPC compared to the highest grain-yielding commercial cultivar. Based on the farmers' preference criteria for a desirable wheat genotype, the best progeny lines ranked from 3rd to 5th, whereas the two commercial cultivars ranked 1st (Gautam) and 2nd (BL 1473). Results indicated that selection was effective in combining adaptation genes present in a local cultivar with some level of tolerance to spot blotch and resistance genes from exotic genotypes, which translated into improved agronomic performance and disease resistance. The selection index and farmer participatory approach used in this study could serve as a guideline in breeding efforts targeted for high yielding genotypes for wheat-growing conditions in South Asia where spot blotch is a serious biotic constraint to yield.  相似文献   

15.
Two major genes (eam8 and eam10) and two quantitative trait loci (QTL) determining flowering time in barley were associated with restriction fragment length polymorphism markers. The loci eam8 and eam10 were found to map in regions of chromosomes 1HL and 3HL, respectively, already estimated from previous classical linkage analyses. While investigating doubled haploid lines of a spring habit barley mapping population, two QTL for flowering time were detected on chromosomes 1HL and 7HS, respectively, when the material was grown under long photoperiod conditions. When growing the same lines under short photoperiod, no QTL were discernible. Allelic and homoeologous relationships with flowering time loci described earlier in barley and other Triticeae species are discussed.  相似文献   

16.
Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is a worldwide rice disease. QTL providing BB resistance were identified using a set of introgression lines (ILs) derived from a cross between Teqing and Lemont, and 3924 evenly distributed SNP markers developed from the two parents. After inoculating three Xoo pathotypes, CII, CIV and CV, seven major BB resistance‐associated QTL were detected. The alleles at all loci with improved BB resistance were from the Teqing background. Four QTL resistance to CII and CIV were identified in the reciprocal backgrounds across 2 years. Six QTL conferring resistance to CV identified in Teqing background were not detected in Lemont background, indicating that genetic background had a strong effect on the BB resistance‐associated QTL. Based on the interactions of 27 significant digenic QTL pairs among the seven main‐effect QTL, the QTL were divided into three strain‐specific groups. Genotype analyses of resistant ILs suggest that rice lines with a high level of resistance to BB can be achieved by pyramiding R gene(s) and QTL that interact with R gene(s).  相似文献   

17.
Forage sorghum cultivars grown in India are susceptible to various foliar diseases, of which anthracnose, rust, zonate leaf spot, drechslera leaf blight and target leaf spot cause severe damage. We report here the quantitative trait loci (QTLs) conferring resistance to these foliar diseases. QTL analysis was undertaken using 168 F7 recombinant inbred lines (RILs) of a cross between a female parental line 296B (resistant) and a germplasm accession IS18551 (susceptible). RILs and parents were evaluated in replicated field trials in two environments. A total of twelve QTLs for five foliar diseases on three sorghum linkage groups (SBI-03, SBI-04 and SBI-06) were detected, accounting for 6.9–44.9% phenotypic variance. The morphological marker Plant color (Plcor) was associated with most of the QTL across years and locations. The QTL information generated in this study will aid in the transfer of foliar disease resistance into elite susceptible sorghum breeding lines through marker-assisted selection.  相似文献   

18.
Quantitative trait loci (QTLs) for resistance against non-parasitic leaf spots (NPLS) were first characterized in a spring barley double haploid population derived from the cross IPZ 24727/Barke (Behn et al., 2004). The aim of the present study was to identify QTLs for NPLS resistance in the half-sibling DH population IPZ 24727/Krona and to compare them with the QTLs of the population IPZ 24727/Barke. An anther culture-derived doubled haploid population of 536 DH lines was developed from the cross IPZ 24727 (resistant)/Krona (susceptible). Field trials were performed over two years in two replications, scoring NPLS and agronomic traits that might interact with NPLS. A molecular linkage map of 1035 cM was constructed based on AFLPs, SSRs and the mlo marker. QTL analyses for NPLS identified three QTLs that accounted for 30% of the phenotypic variation. For comparison of the QTLs from each DH population, a consensus map was generated comprising 277 markers with a length of 1199 cM. In both populations, the QTLs for NPLS mapped to chromosomes 1H, 4H and 7H. A common QTL with a great effect in both populations and over all environments was localized at the mlo locus on chromosome 4H, indicating that the mlo powdery mildew resistance locus has a considerable effect on NPLS susceptibility. The steps necessary to validate the QTLs and to improve the NPLS resistance by breeding were discussed.  相似文献   

19.
Barley (Hordeum vulgare) is a major feed source for the intensive livestock industry. Competitiveness against other cereal grains depends largely on the price per unit of expressed feed quality. The traits which contribute to feed quality in barley are largely quantitative in nature but little is known about their genetic control. A study to identify the quantitative trait loci (QTLs) associated with feed quality was performed using a F6-derived recombinant inbred barley population. Samples from each line were incubated in the rumen of fistulated cattle, recovered, washed and dried for determination of in situ dry matter digestibility. Additionally, both pre- and post-digestion samples were analysed to quantify the content of key quality components relating to acid detergent fibre, total starch and protein. The data was used to identify trait-associated QTLs. Genetic analysis identified significant QTLs on chromosomes 2H, 5H and 7H. Genetic markers linked to these QTL should provide an effective tool for the selection and improvement of feed barley in the future.  相似文献   

20.
Six Swedish and one Canadian single spore isolate of Drechslera teres f. teres were used to screen 109 barley lines for disease resistance and to select a differential set of barley lines for use in assessing pathogen virulence. A large variation for net blotch resistance was found among the 109 barley lines which were classified into four groups, those showing: 1) only resistant reactions; 2) differential reactions; 3) only intermediate reactions and 4) only susceptible reactions. The European commercial varieties included, showed susceptibility to all Swedish isolates, but a few were resistant to the Canadian isolate. The 18- member differential set separated 25 Swedish and two Canadian isolates of D. teres into 14 pathotypes, three of which made up 59% of the isolates. Only one barley differential (CI 9776) was resistant to all net form isolates. Host selection on the pathogen seems to be present as all six isolates obtained from cv. Golf belonged to the same pathotype and 4 of 5 isolates from cv. Karin shared the same virulence pattern. The net form of net blotch (D. teres f. teres) predominated in the sampled regions and only one of 26 Swedish isolates was of the spot form (D. teres f. maculata). This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号