Tight repulsion linkage between Sr36 and Sr39 was revealed by genetic, cytogenetic and molecular analyses

• Published in: Theoretical and applied genetics 2017-03, Vol.130 (3), p.587-595
• Main Authors: Chemayek, Bosco, Bansal, Urmil K., Qureshi, Naeela, Zhang, Peng, Wagoire, William W., Bariana, Harbans S.
• Format: Article
• Language: English
• Subjects: Agriculture; Alleles; Basidiomycota; Biochemistry; Biomedical and Life Sciences; Biotechnology; Chromatin; Chromosomes; Chromosomes, Plant; Crosses, Genetic; Cultivars; Disease Resistance - genetics; Genes; Genes, Plant; Genetic Linkage; Genetic Markers; Genotype; Goat grass; Life Sciences; Microclimate; Original Article; Pathogens; Phenotype; Planning; Plant Biochemistry; Plant Breeding; Plant Breeding/Biotechnology; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Genetics and Genomics; Plants, Genetically Modified - genetics; Plants, Genetically Modified - microbiology; Poaceae - genetics; Telomeres; Translocation, Genetic; Triticum - genetics; Triticum - microbiology; Virulence; Wheat
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-016-2837-5

Key message The shortening of Aegilops speltoides segment did not facilitate recombination between stem rust resistance genes Sr36 and Sr39 . Robustness of marker rwgs28 for marker-assisted selection of Sr39 was demonstrated. Stem rust resistance genes Sr39 and Sr36 were transferred from Aegilops speltoides and Triticum timopheevii , respectively, to chromosome 2B of wheat. Genetic stocks RL6082 and RWG1 carrying Sr39 on a large and a shortened Ae. speltoides segments, respectively, and the Sr36 -carrying Australian wheat cultivar Cook were used in this study. This investigation was planned to determine the genetic relationship between these genes. Stem rust tests on F 3 populations derived from RL6082/Cook and RWG1/Cook crosses showed tight repulsion linkage between Sr39 and Sr36 . The genomic in situ hybridization analysis of heterozygous F 3 family from the RWG1/Cook population showed that the translocated segments do not overlap. Meiotic analysis on the F 1 plant from RWG1/Cook showed two univalents at the metaphase and anaphase stages in a majority of the cells indicating absence of pairing. Since meiotic pairing has been reported to initiate at the telomere, pairing and recombination may be inhibited due to very little wheat chromatin in the distal end of the chromosome arm 2BS in RWG1. The Sr39 -carrying large Ae. speltoides segment transmitted preferentially in the RL6082/Cook F 3 population, whereas the Sr36 -carrying T . timopheevii segment over-transmitted in the RWG1/Cook cross. Genotyping with the co-dominant Sr39 - and Sr36 -linked markers rwgs28 and stm773 - 2 , respectively, matched the phenotypic classification of F 3 families. The RWG1 allele amplified by rwgs28 was diagnostic for the shortened Ae. speltoides segment and alternate alleles were amplified in 29 Australian cultivars. Marker rwgs28 will be useful in marker-assisted pyramiding of Sr39 with other genes.