MAPPING OF QTL CONTROLLING NIR PREDICTED HOT-WATER EXTRACT AND GRAIN NITROGEN-CONTENT IN A SPRING BARLEY CROSS USING MARKER-REGRESSION

A restriction fragment length polymorphism (RFLP) map constructed from 99 doubled haploid lines of a cross between two spring barley varieti es ('Blenheim' x 'Kym') was used to map QTL controlling hot water extr act and grain nitrogen content (predicted by analysis with near-infrar ed reflectance spectroscopy). Eight QTL affecting predicted hot water extract were identified by a marker-regression approach. The largest e ffects were found on chromosomes 3HL, associated with the denso dwarfi ng gene which is present in 'Blenheim' and conferred poorer predicted hot water extract quality, and 4HL. Other QTL were detected on chromos omes 1HS, 1HL, 2HS, 2HL, 5HL and 6HS. Analysis of single markers by an alysis of variance detected an additional effect on chromosome 1H. Eig ht QTL affecting predicted grain nitrogen content were identified by m arker-regression, on chromosomes 1HS, 1HL, 2HL, 5HS, 6H, 7HS and 7HL. There was also evidence for an additional QTL on chromosome 5HL. The p ositions of the grain nitrogen content QTL on 5HS and 5HL are comparab le to QTL on wheal chromosomes 5A and 5D that affect grain protein con tent. The denso gene had no detectable effect on grain nitrogen conten t.