Jump to Main Content
Fine genetic mapping of greenbug aphid-resistance gene Gb3 in Aegilops tauschii
- Azhaguvel, Perumal, Rudd, Jackie C., Ma, Yaqin, Luo, Ming-Cheng, Weng, Yiqun
- Theoretical and applied genetics 2012 v.124 no.3 pp. 555-564
- germplasm, restriction fragment length polymorphism, microsatellite repeats, Aegilops tauschii, grain crops, bacterial artificial chromosomes, loci, marker-assisted selection, Schizaphis graminum, telomeres, expressed sequence tags, wheat, biotypes, chromosome mapping, Triticum aestivum, pests, hexaploidy, genetic markers
- The greenbug, Schizaphis graminum (Rondani), is an important aphid pest of small grain crops especially wheat (Triticum aestivum L., 2n = 6x = 42, genomes AABBDD) in many parts of the world. The greenbug-resistance gene Gb3 originated from Aegilops tauschii Coss. (2n = 2x = 14, genome DᵗDᵗ) has shown consistent and durable resistance against prevailing greenbug biotypes in wheat fields. We previously mapped Gb3 in a recombination-rich, telomeric bin of wheat chromosome arm 7DL. In this study, high-resolution genetic mapping was carried out using an F₂:₃ segregating population derived from two Ae. tauschii accessions, the resistant PI 268210 (original donor of Gb3 in the hexaploid wheat germplasm line ‘Largo’) and susceptible AL8/78. Molecular markers were developed by exploring bin-mapped wheat RFLPs, SSRs, ESTs and the Ae. tauschii physical map (BAC contigs). Wheat EST and Ae. tauschii BAC end sequences located in the deletion bin 7DL3-0.82–1.00 were used to design STS (sequence tagged site) or CAPS (Cleaved Amplified Polymorphic Sequence) markers. Forty-five PCR-based markers were developed and mapped to the chromosomal region spanning the Gb3 locus. The greenbug-resistance gene Gb3 now was delimited in an interval of 1.1 cM by two molecular markers (HI067J6-R and HI009B3-R). This localized high-resolution genetic map with markers closely linked to Gb3 lays a solid foundation for map based cloning of Gb3 and marker-assisted selection of this gene in wheat breeding.