QTL mapping of genes controlling ear emergence time and plant height on chromosome 5A of wheat

Chromosome 5A of wheat carries major gene loci for agronomic traits including the vernalization requirement Vrn-A1) and ear morphology (Q). To determine whether the genetic variation for ear emergence time and plant height is attributable to either of these major genes as pleiotropic effects or independent QTL, we combined a RFLP map constructed from 120 recombinant substitution lines derived from a cross between 'Chinese Spring' (Cappelle-Desprez 5A) and CS(Triticum spelta 5A) with data collected from held trials over 3 years. For ear emergence time the main effects on flowering time were by Vrn-A1 and QEet.ocs5A.1, the latter a QTL in the 28.6-cM Xcdo584/Q interval linked to Q by less than 10 cM. The CS(T. spelta 5A) allele at QEet.ocs-5A.1 contributed to an earlier ear emergence time by 2.7-6.0 days, which was approximately equal to the effects of Vrn-A1. For plant height, three QTLs were identified on the long ann and linked in repulsion. The CS(T. spelta 5A) allele at Vrn-A1 or closely linked to Xfba068 contributed to a height reduction of 3.5-6.1 cm, whereas both the Q allele and Qt.ocs-5A.1 allele within the Xcdo1088/Xbcd9 interval from CS(Cappelle-Desprez 5A) produced a shorter plant. When plant height was partitioned into culm length and ear length, the Vrn-A1 allele and CS(Cappelle-Desprez 5A) allele at QCl.ocs-5A.1 within the Xcd1088/Xbcd9 interval were found to contribute to a shorter culm. CS(T. spelta 5A) allele at q was a major determinant of a long ear, together with minor effects at QEl.ocs-5A1. within the Xcdo1088/Xbcd9 interval.