QTL Mapping for Milling Quality in Elite Western U.S. Rice Germplasm

Rice (Oryza sativa L.) milling yield is a key export and domestic grain quality trait whose genetic control is poorly understood. To identify genomic regions infl uencing grain quality, quantitative trait locus (QTL) mapping was performed for quality-related traits including head-rice yield (HR) in 205 recombinant inbred lines (RILs) derived from a cross of L-204, a high-HR longgrain cultivar, with 01Y110, a low-HR advanced breeding line with high yield potential in the temperate U.S. rice-growing region. In replicated trials planted in California during 2007–2008, four QTLs carrying the HR-increasing allele from L204 and three from 01Y110 were consistently expressed. Multi-QTL models accounted for 30% of genetic variation for HR and up to 58% for other quality-related traits. Measures of kernel damage, though correlated with HR, were poor predictors of HR. Heading time, kernel dimension, apparent amylose content, and other highly heritable traits showed no correlation with HR. Stable QTLs for HR are likely to be revealed best by multienvironment experiments employing larger population sizes or more direct measurement of kernel structure and development traits involved in kernel breakage. J.C. Nelson, Dep. of Plant Pathology, Kansas State Univ., 4024 Throckmorton Plant Sciences Center, Manhattan, KS 66506; F. Jodari, A.I. Roughton, and K.M. McKenzie, California Cooperative Rice Research Foundation, P.O. Box 306, Biggs, CA 95917; A.M. McClung, USDA-ARS, Rice Research Unit, 1509 Aggie Dr., Beaumont, TX 77713; A.M. McClung and R.G. Fjellstrom, USDA-ARS, Dale Bumpers National Rice Research Center, 2890 Hwy. 130 E., Stuttgart, AR 72160; B.E. Scheffl er, USDA-ARS, Genomics and Bioinformatics Research Unit and Mid South Area Genomics Facility, Stoneville, MS 38776. Received 17 June 2011. *Corresponding author ( jcn@ksu.edu). Abbreviations: BR, brown-rice yield; CPVIS, cool paste viscosity; DTH, days to heading; HR, head-rice yield; HT, plant height; KL, kernel length; KTHK, kernel thickness; KW, kernel width; KWT, kernel weight; LOD, log10 likelihood ratio; MIM, multiple-interval mapping; MR, total milled rice; QEI, quantitative trait locus × environment interaction; QTL, quantitative trait locus; RIL, recombinant inbred line; SS, sum of squares; SSR, simple sequence repeat. Published in Crop Sci. 52:242–252 (2012). doi: 10.2135/cropsci2011.06.0324 Published online 31 Oct. 2011. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.