Quantitative trait loci for resistance to pre-harvest sprouting in US hard white winter wheat Rio Blanco

Abstract

Pre-harvest sprouting (PHS) of wheat is a major problem that severely limits the end-use quality of Xour in many wheat-growing areas worldwide. To identify quantitative trait loci (QTLs) for PHS resistance, a population of 171 recombinant inbred lines (RILs) was developed from the cross between PHS-resistant white wheat cultivar Rio Blanco and PHS-susceptible white wheat breeding line NW97S186. The population was evaluated for PHS in three greenhouse experiments and one Weld experiment. After 1,430 pairs of simple sequence repeat (SSR) primers were screened between the two parents and two bulks, 112 polymorphic markers between two bulks were used to screen the RILs. One major QTL, QPhs.pseru-3AS, was identiWed in the distal region of chromosome 3AS and explained up to 41.0% of the total phenotypic variation in three greenhouse experiments. One minor QTL, QPhs.pseru-2B.1, was detected in the 2005 and 2006 experiments and for the means over the greenhouse experiments, and explained 5.0-6.4% of phenotypic variation. Another minor QTL, QPhs.pseru-2B.2, was detected in only one greenhouse experiment and explained 4.5% of phenotypic variation for PHS resistance. In another RIL population developed from the cross of Rio Blanco/NW97S078, QPhs.pseru-3AS was signiWcant for all three greenhouse experiments and the means over all greenhouse experiments and explained up to 58.0% of phenotypic variation. Because Rio Blanco is a popular parent used in many hard winter wheat breeding programs, SSR markers linked to the QTLs have potential for use in high-throughput marker-assisted selection of wheat cultivars with improved PHS resistance as well as Wne mapping and map-based cloning of the major QTL QPhs.pseru-3AS.

Maximizing the identification of QTL for pre-harvest sprouting resistance using seed dormancy measures in a white-grained hexaploid wheat population

“…Alternatively, the dormancy genes are only linked to the seed coat colour genes. The 3A chromosome was previously associated with a pre-harvest sprouting resistance QTL ), Qphs.pseru-3AS, reported by Liu et al (2008) and Liu and Bai (2010), although maps could not be cross-referenced. Liu et al (2013) cloned a gene from white-seeded wheat which they designated TaPHS1.…”

Cloning and Characterization of a Critical Regulator for Preharvest Sprouting in Wheat

“…The major QTL for PHS resistance, Qphs.pseru-3AS, was previously mapped using two F 6 recombinant inbred line (RIL) populations developed from the crosses of Rio Blanco/ NW97S186 and Rio Blanco/NW97S078, where Rio Blanco carries Qphs.pseru-3AS, whereas NW97S186 and NW97S078 do not (Liu et al 2008). To fine map and clone this QTL, RIL#25, a F 6 RIL that segregated at Qphs.pseru-3AS locus, was selected from the Rio Blanco/NW97S186 population to develop recombinant near-isogenic lines (NILs) of Qphs.…”

“…However, wheat PHS usually occurs before harvest in a field at much higher temperatures, so it is not known if this gene is responsible for PHS resistance in wheat under natural conditions and whether the SNP causes the change in PHS resistance. We previously mapped a major QTL (Qphs.pseru-3AS) for PHS resistance to the distal end of the short arm of chromosome 3A of a PHS-resistant white wheat cultivar Rio Blanco (Liu et al 2008;Liu and Bai 2010). In this study, we used comparative fine mapping and map-based cloning to (1) determine the candidate gene underlining the QTL, (2) identify the causal variations in the candidate gene responsible for the change in PHS resistance in wheat, and (3) develop a diagnostic gene assay for marker-assisted selection to improve PHS resistance in wheat.…”

“…The harvested spikes were air dried for 5 days in the greenhouse at 25°6 5°and then stored in a freezer at -20°t o maintain dormancy. Sprouting assays were conducted in a moist chamber for 7 days at 23°6 2°with 100% humidity (Liu et al 2008). For association mapping, phenotyping experiments were repeated twice with two replications per experiment and five spikes from different plants per accession in each replication.…”

“…DELAY OF GERMINATION 1 (DOG1) in Arabidopsis and seed dormancy 4 (Sdr4) in rice (Bentsink et al 2006;Sugimotoa et al 2010) were cloned. In wheat, quantitative trait loci (QTL) for PHS resistance have been reported on most wheat chromosomes (Groos et al 2002;Mori et al 2005;Imtiaz et al 2008;Kulwal et al 2012), and QTL on chromosomes 2B (Munkvold et al 2009), 3A (Liu et al 2008), and 4A (Mares et al 2005;Liu et al 2011) have demonstrated major effects on PHS resistance. Recently, a MOTHER OF FT AND TFL1 was identified to be involved in seed dormancy under low temperature (13°) through a microarray study (Nakamura et al 2011).…”