QTL mapping of grain arabinoxylan contents in common wheat using a recombinant inbred line population

Arabinoxylans (AX) are major polymers of wheat grain cell walls and affect the end-use properties and nutritional quality. Total (TOT-AX), water-unextractable (WU-AX), and water-extractable (WE-AX) AX contents were determined in grain of 240 recombinant inbred wheat lines (RILs), derived from the cross PH82-2/Neixiang 188. A total of 195 SSR and STS markers were used to construct a genetic map and to detect quantitative trait loci (QTL). Wide ranges of variation in TOT-AX, WU-AX, and WE-AX contents were observed among the RILs, with line effects contributing the largest phenotypic variation. Broad sense heritabilities (h(2)) were 0.50, 0.38 and 0.71, respectively. Inclusive composite interval mapping (ICIM) identified four additive QTL for TOT-AX content on chromosomes 1B, 1D, 3B and 5B, explaining 3.7-14.6 % of the phenotypic variance (PV), among which two were involved in significant additive 9 season interactions, contributing 0.5-2.4 % of the PV. Two additive QTL for WU-AX content were identified on chromosomes 1B and 1D, accounting for 6.4 and 8.6 % of the PV, respectively; both were involved in significant additive 9 season interactions, contributing 0.6-1.4 % of the PV. Nine additive QTL for WE-AX content were identified on chromosomes 1A, 1B, 2B, 3B, 5A, 5B, 6B, 7A and 7B, explaining 3.8-15.2 % of the PV, and three of them were involved in significant additive 9 season interactions, contributing 0.5-2.1 % of the PV. Two pairs of epistatic QTL, with significant epistatic 9 season interactions, were identified for TOT-AX and WU-AX contents, contributing 16.6 and 18.6 % of the PV, respectively. The QTL identified on chromosomes 1B (associated with rye secalin marker sec1), 5A, 5B and 7A showed stable effects on WE-AX content across seasons.