Genetic analysis of adult-plant resistance to leaf rust in a double haploid wheat (Triticum aestivum L. em Thell) population

Abstract

A genetic analysis of adult plant resistance to leaf rust (Puccinia triticina) was performed in in vitro obtained double haploid progenies from a cross between the Brazilian wheat cultivar Trigo BR 35, which, under the high inoculum pressure of the southern region, has been resistant to leaf rust for more than 12 years, and the susceptible cultivar IAC 13-Lorena. Haplodiploidization via in vitro gimnogenesis was done by somatic elimination of the pollen donor genome after maize pollination of the F 1 plants. The advantages and usefulness of double haploids (DH) for genetic analysis of complex inherited traits like durable adult-plant resistance to wheat leaf rust were evident: it was possible to analyze inheritance patterns in this cross by using only the 35 DH homozygous segregant lines obtained by in vitro embryo culture of F 1 flowers pollinated by maize, this number being equivalent to 1,225 conventional F 2 lines because of lack of heterozygosity. After being infected with MCG and LPG races, the results indicated that Trigo BR 35 has two resistance genes. One of the genes expressed resistance only after the intermediate stage of plant development (5-6 leaves).

Leaf Rust Resistance in Selected Uruguayan Common Wheat Cultivars with Early Maturity

“…However, cultivars with only Lr34 can still have high leaf‐rust severities and suffer significant yield loss. Additional sources of APR either from South American (Barcellos et al, 2000; Brammer et al, 2004; Altieri et al, 2008; Kolmer et al, 2007) or CIMMYT (Singh et al, 2011) wheat germplasm will need to be combined with Lr34 to develop wheat cultivars with long‐lasting and highly effective leaf rust resistance. INIA Boyero and E. Benteveo have additional APR gene(s) that may be useful sources of resistance in addition to Lr34 .…”

The importance for food security of maintaining rust resistance in wheat

“…Doubled-haploid techniques not only reduce the time required to develop a new variety by about 3 to 4 years (Barnabás et al 2001) but also increases many-fold the selection efficiency of crop breeding (Choo et al 1985). In wheat rust research, double-haploids have been particularly important for the development of mapping populations used to identify markers closely associated with quantitative trait loci conferring durable resistance to stem, leaf and stripe rust (Suenaga et al 2003;Brammer et al 2004;Moldenhauer et al 2008;Chu et al 2008Chu et al , 2009Lan et al 2010;Mago et al 2011;Prins et al 2011). Faced with the disturbing outbreaks of stem rust in Africa and neighboring regions, double-haploid wheat populations have also been increasingly used as a tool for the genetic analyses, mapping and stacking of seedling and adult plant resistance genes such as Sr2, effective against race Ug99, (McNeil et al 2008) and Sr26 and SrR (Mago et al 2011) plus the gene temporarily designated SrCad (Hiebert et al 2011).…”