Gene discovery in recombinant doubled haploid populations for breeding wheat resistance against aphids

CASTRO AM, TOCHO EF, TACALITI MS, VASICEK A, GIMÉNEZ DO, BÖRNER A, SNAPE JW

COPING WITH WHEAT IN A CHANGING ENVIRONMENT BIOTIC STRESSES

Sidney University Press

Lugar: Sidney, Australia; Año: 2008; p. 7 - 12

Russian wheat aphid (RWA) (Diuraphis noxia) and greenbug (Schizaphis graminum) are two devastating pests of wheat worldwide. In Argentina another new aphid pest, Sipha maydis, infesting wheat and barley, appeared in 2002. These aphids cause severe damage to plant growth and production at the seedling and adult plant stages. RWA and greenbug have evolved several biotypes virulent to most of the resistance genes introduced into wheat cultivars. The fast deployment of resistance genes and the continuous appearance of new biotypes and pests requires the assessment of new sources of resistance for breeding plant-defence. Resistance to aphids consists of three mechanisms: antixenosis, which prevents the insect selection of plant hosts; antibiosis, which imposes a reduced aphid longevity and fertility; tolerance, which allows the host to maintain a normal growth rate under infestation. Marker assisted genetic analysis and the use of recombinant doubled haploid (RDH) lines and RILs has allowed the mapping of novel resistance genes for Argentinean populations of aphids. Resistance QTLs against greenbug have been mapped onto several chromosomes. Antixenosis QTLs were located on chromosome 6A of a CS x Synthetic set of RDH, and on chromosome 7D of the ITMI RILs. QTLs for tolerance and antibiosis have been mapped onto chromosome 1B of the ITMI RIL population and 7D of the CS x Synthetic set of RDH.  Resistance to RWA was accounted for by QTLs on different chromosomes. QTL for antixenosis to biotype 2 were located on chromosome 6A and tolerance and antibiosis on 1D and 7D of the CS x Synthetic set of RDH. Most of the QTLs for tolerance traits to S. maydis were mapped on the homoeologous group 1 and 2 chromosomes. These novel genes could be transferred into wheat cultivars by marker-assisted selection to enlarge the genetic base of defence against the aphid pests.