Molecular mapping of cereal cyst nematode resistance in Triticum monococcum L. and its transfer to the genetic background of cultivated wheat

Abstract

Triticum monococcum, the diploid A genome species, harbours enormous variability for resistance to biotic stresses. A spring type T. monococcum acc. 14087 was found to be resistant to Heterodera avenae (cereal cyst nematode, CCN). A recombinant inbred line population (RIL) developed by crossing this accession with a CCN susceptible T. boeoticum acc. 5088 was used for studying the inheritance and map location of the CCN resistance. Based on composite interval mapping two QTL, one each on chromosome 1AS and 2AS, were detected. The QTL on 1A, designated as Qcre.pau-1A, appeared to be a major gene with 26% contribution to the overall phenotypic variance whereas the QTL on 2A designated as Qcre.pau-2A contributed 13% to total phenotypic variation. Qcre.pau-1A is novel, being the only CCN resistance gene mapped in any 'A' genome species and none of the other known genes have been mapped on chromosome 1A. The QTL Qcre.pau-2A might be allelic to Cre5, a CCN resistance gene transferred from Ae. ventricosa and mapped on 2AS. The Qcre.pau-1A was transferred to cultivated wheat using T. durum cv. PBW114 as the bridging species. Selected CCN resistant F 8 lines showed introgression for the molecular markers identified to be linked with CCN resistance locus Qcre.pau-1A. Thus, this gene alone could impart complete resistance against CCN. These introgression lines can be used for marker-assisted transfer of Qcre.pau-1A to elite wheat cultivars.

Diploid and tetraploid progenitors of wheat are valuable sources of resistance to the root lesion nematode Pratylenchus thornei

“…Suppression of the resistance gene(s) or dilution of its products may result in a reduction of expressed disease resistance when transferred from a species of a lower level of ploidy to one of a higher level (Cox 1991;Gill et al 1986;Kerber and Green 1980;Potgieter et al 1991). However, many genes conferring resistance to diseases and pests have been transferred using direct hybridization (Cox 1991(Cox , 1998Friebe et al 1996), including CCN resistance from T. monococcum to durum and bread wheat cultivars (Singh et al 2010). Previous studies on moderately P. thornei R hexaploid wheats from the West Asia and North Africa (WANA) region have used single marker regression and QTL analysis to identify resistance loci on chromosomes 2B, 3B, 6D and 7A (Schmidt et al 2005), 1B, 2B and 6D (Toktay et al 2006) and a susceptibility locus on 1B (Schmidt et al 2005).…”

Mapping of Aegilops umbellulata‐derived leaf rust and stripe rust resistance loci in wheat

“…Wild progenitor and non‐progenitor species constitute a reservoir of genetic variability for many traits, including resistance to biotic stresses. This has led to considerable interest in interspecific hybridization for transferring resistance genes from wild species to commercial wheat cultivars (Knott & Dvorak, ; Stalker, ; Dhaliwal et al ., ; Kuraparthy et al ., ,b; Chhuneja et al ., ,b; Singh et al ., ; Riar et al ., ). Among resistance genes listed in the wheat gene catalogue, about half are derived from wild species.…”

Fine mapping of powdery mildew resistance genes PmTb7A.1 and PmTb7A.2 in Triticum boeoticum (Boiss.) using the shotgun sequence assembly of chromosome 7AL

“…Breeding cultivars with inherent resistance is the most promising approach to manage this disease. The diploid 'A' genome species, Triticum monococcum ssp monococcum (T. monococcum-A m A m ), T. monococcum ssp aegilopoides (Triticum boeoticum-A b A b ) and Triticum urartu (A u A u ), harbour useful variability for many economically important genes, including resistance to diseases (Feldman and Sears 1981;Dhaliwal et al 1993;Hussien et al 1997;Miranda et al 2007;Singh et al 2007a;Chhuneja et al 2008;Singh et al 2010). Till date, more than 73 powdery mildew resistance genes/alleles have been identified at 50 loci (Pm1-Pm54; Pm18 = Pm1c, Pm22 = Pm1e, Pm23 = Pm4c, Pm31 = Pm21) in wheat and its wild relatives (McIntosh et al 2013;Xiao et al genome and 13 on the D genome of wheat.…”