Fine genetic mapping of greenbug aphid-resistance gene Gb3 in Aegilops tauschii.
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 D(t)D(t)) 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 F(2:3) 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.
Texas AgriLife Research, 6500 Amarillo Blvd W, Amarillo, TX 79106, USA. aperumal@noble.org
Perumal
P
Azhaguvel
Jackie C
JC
Rudd
Yaqin
Y
Ma
Ming-Cheng
MC
Luo
Yiqun
Y
Weng
D054458:Amplified Fragment Length Polymorphism Analysis; D000818:Animals; D001042:Aphids; D001947:Breeding / Q000379:methods*; D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D020224:Expressed Sequence Tags; D017343:Genes, Plant / Q000235:genetics*; D005819:Genetic Markers / Q000235:genetics; D010935:Plant Diseases / Q000469:parasitology*; D006109:Poaceae / Q000235:genetics* / Q000469:parasitology; D016324:Sequence Tagged Sites
D005819:Genetic Markers