Posts Tagged ‘Microsatellites’

QTL Mapping for Adult-Plant Resistance to Stripe Rust in a Common Wheat RIL Population Derived from Chuanmai 32/Chuanyu 12

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Integrative Agriculture 11 (11) : 1775-1782, 2012

Wu Ling, Xia Xian-Chun, Zheng You-liang, Zhang Zheng-yu, Zhu Hua-zhong, Liu Yong-jian, Yang En-nian, Li Shi-zhao and He Zhonghu

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. The Chinese wheat cultivar Chuanmai 32 has shown stable resistance to stripe rust for 10 yr in Sichuan Province, a hotspot for stripe rust epidemics. The objective of the present study was to map quantitative trait loci (QTL) for adult-plant resistance (APR) to stripe rust in a population of 140 recombinant inbred lines (RILs) derived from Chuanmai 32/Chuanyu 12. Field trials were conducted in Chengdu and Yaan, Sichuan, from 2005 to 2008, providing stripe rust reaction data for 6 environments. 797 simple sequence repeat (SSR) markers were screened for association with stripe rust reaction, initially through bulked segregant analysis (BSA). Based on the mean disease values averaged across environments, the broad-sense heritability of maximum disease severity (MDS) was 0.75. Two QTLs for stripe rust resistance were detected by composite interval mapping (CIM). They were designated QYr.caas-3BL and QYr.caas-3BS and explained from 6.6 to 20.1%, respectively, of the phenotypic variance across environments. QYr.caas-3BL came from Chuanmai 32; QYr.caas-3BS with lower effect was from the susceptible parent Chuanyu 12. Both QTLs appear to be new.

QTL mapping of adult-plant resistance to stripe rust in Chinese wheat cultivar Chuanyu 16

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Agricultural Science 4 (3): 57-70, 2012

Ling Wu, Youliang Zheng, Xianchun Xia, Yunliang Peng, Huazhong Zhu, Yongjian Liu, Yu Wu, Shizhao Li, Zhonghu He

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a serious wheat fungal disease, causing significant annual yield losses worldwide. The Chinese wheat cultivar Chuanyu 16 has shown good adult-plant resistance (APR) to stripe rust in Sichuan province, a hotspot for stripe rust epidemics. Chuanyu 16 was crossed with Chuanyu 12 and Chuanmai 32. Two populations, each with 140 recombinant inbred lines (RILs), were developed by single-seed descent, and used for quantitative trait locus (QTL) mapping. Field trials were conducted in Chengdu and Yaan from 2005 to 2008, providing stripe rust reaction data for six environments. Seven hundred and thirty one simple sequence repeat (SSR) markers were screened for association with stripe rust reaction, initially through bulked segregant analysis (BSA). Three QTLs for stripe rust resistance derived from Chuanyu 16 were detected in the first cross. They were detected by inclusive composite interval mapping (ICIM) and designated QYr.caas-1BL.1, QYr.caas-1BL.2 and QYr.caas-2AS. They explained 6.0 – 12.8%, 4.5 – 5.8% and 14.9 – 43.0%, respectively, of the phenotypic variance across environments. One digenic epistatic QTL between QYr.caas-1BL.2 and QYr.caas-2AS explained 4.3 – 10.4% of the phenotypic variance. QYr.caas-2AS was also detected in Chuanmai 32/Chuanyu 16, explaining 27.9 – 57.2% of the phenotypic variance across six environments. This QTL showed a major effect against stripe rust in Chuanyu 16, and was located in a similar position to Yr17. Specific markers indicated the presence of a segment from chromosome 2N of Triticum ventricosum that carries Yr17. Despite the lack of evidence for Yr17 in Chuanyu 16 based on pedigree, and inconsistencies in stripe rust response relative to a near-isogenic reference stock with the gene, we concluded that QYr.caas-2AS is Yr17. QYr.caas-1BL.1 and QYr.caas-1BL.2 showed minor effects for APR against stripe rust. QYr.caas-1BL.1 is probably a new gene for APR to stripe rust.

Genetics of angular leaf spot resistance in the Andean common bean accession G5686 and identification of markers linked to the resistance genes

Posted by on , in Journal Articles

Published in Euphytica 167:381-396

Genetics of angular leaf spot resistance in the Andean common bean accession G5686 and identification of markers linked to the resistance genes

George S. Mahuku, Ángela Maria Iglesias and Carlos Jara

Angular leaf spot (ALS), caused by the fungus Phaeoisariopsis griseola is an economically important and widely distributed disease of common bean. Due to the co-evolution of P. griseola with the large and small seeded bean gene pools, stacking Andean and Mesoamerican resistance genes is a strategy most likely to provide lasting resistance to ALS disease. This strategy requires identification and characterization of effective Andean and Mesoamerican resistance genes, and the development of molecular markers linked to these genes. This study was conducted to elucidate the genetics of ALS resistance in the Andean accession G5686 using an F2 population derived from a G5686 × Sprite cross. Segregation analysis revealed that three dominant and complementary genes conditioned resistance of G5686 to P. griseola pathotype 31-0. Three microsatellite markers, Pv-ag004, Pv-at007 and Pv-ctt001 segregated in coupling phase with the resistance genes in G5686. Microsatellites Pv-ag004 and Pv-ctt001, located on opposite ends of linkage group B04 segregated with resistance genes Phg G5686A , Phg G5686B at 0.0 and 17.1 cM, respectively, while marker Pv-at007, localized on linkage group B09 segregated with resistance gene Phg G5686C at 12.1 cM. Parental surveys showed that these markers were polymorphic in Andean and Mesoamerican backgrounds. The usefulness of G5686 ALS resistance genes in managing the ALS disease, and the potential utility of identified molecular markers for marker assisted breeding are discussed.