DEVELOPMENT OF RICE LINES (Oryza sativa L.) TOLERANT TO SUBMERGENCE VIA Sub1 GENE INTRODUCTION INTO LANDRACES AND ELITE BREEDING LINES

Abstract

       Development of rice genotypes tolerant to complete submergence in the Mekong Delta was carried out for three continuous years by CLUES Project fund. Eighty five high-yielding cultivars and eighty four progenies from backcrossing population (BC3F3) of OM1490/IR64 Sub1 were used to study the yield components and submergence tolerance. Phenotyping was implemented at three stages: seedling, tillering and heading. Different segregation ratio and phenotypical variation indicated the complex genetic background. All genotypes have been evaluated under both submergence and non-submergence treatments. Correlation coefficient between the survival rate (%) and tiller number /10 hills was positively significant of 0.8880**. Marker-assisted backcrossing (MAB) was exploited on chromosomes 9 to address ten molecular markers (SSRs). Of them, only three polymorphic SSRs really linked to the target QTLs. Markerassisted selection helped identify elite lines, which would be breeding materials via three molecular markers on the target region viz. RM3269, RM5304 and RM1367 on chromosome 9. Three selected offspring lines from BC3F3 population of OM1490/IR64 Sub1 as 26, 38 and 50 exhibited good adaptation to submergence.