RICE LINES WITH HEAT TOLERANCE VIA MARKER-ASSISTED SELECTION

Abstract

                    A total of 310 lines (BC2F2) derived from the cross of OM5930/N22 have been evaluated for heat stress at flowering. Genetic map has been set up with 264 polymorphic SSR markers to detect linkage to the target traits. The map covers 2,741.63 cM with an average interval of 10.55 cM between marker loci. Markers associated with heat tolerance have been located mostly on chromosomes 3, 4, 6, 8, 10, and 11. The proportions of phenotypic variation explained by each QTL of markers RM3586, RM160 on chromosome 3 and RM3735 on chromosome 4 have been 36.2, 17.1 and 32.6 percent respectively. Four QTLs have been detected for filled grains per panicle on chromosome 4 at the interval of RM468-RM7076 and RM241-RM26212, explaining 13.1% and 31.0% of the total phenotypic variation respectively.

Two QTLs controling unfilled grain percentage have been also detected at loci RM554, RM3686 on chromosome 3, explaining only 25.0% and 11.2% of the total phenotypic variation. One QTL has been detected for 1,000-grain weight located at the locus RM103 on chromosome 6, explaining 30.6% of the total phenotypic variation. A single QTL at the locus RM5749 on chromosome 4 was identified explaining 10.8% of the total phenotypic variation of grain yield. Attentions have been paid to the interval of RM3586- RM160 on chromosome 3 at the range of 8.1 cM for heat tolerance score. Promising lines HTL1, HTL2, HTL3 and HTL4 have been selected from BC4F2 populations of 10 crosses via marker-assisted selection.