Marker assisted backcross breeding to improve cooking quality traits in Myanmar rice cultivar Manawthukha

Several components contribute to rice grain quality, and among these, fragrance and taste qualities are the most important to consumers. Manawthukha, an elite non-fragrant cultivar with high amylose content (AC), intermediate gel consistency (GC) and gelatinisation temperature (GT), occupies the largest number of acres in Myanmar. To improve fragrance and intermediate AC in Manawthukha, Basmati370 was used as a donor parent to introgress the Basmati alleles of genes conferring fragrance and intermediate AC into Manawthukha by Marker Assisted Backcrossing (MAB). Four backcrosses and one selfing were conducted to transfer positive alleles of badh2 and Wx from Basmati into Manawthukha. Twelve BC₄F₂ selected lines that carried the homozygous Basmati alleles were planted in multi-location trials (four in Myanmar and one in Thailand) and examined for their agronomic performance and cooking quality. The seeds of the improved lines and their parents, harvested from Kamphaeng Saen, Kuaukse, Kyauktada and Latpatan, were investigated for fragrance and AC. All improved lines had fragrance and intermediate AC similar to the donor parent Basmati, whereas their agronomic performances were the same as the original Manawthukha. All improved lines had medium plant heights, high tiller numbers, dense panicles, non-lodging phenotypes and high yielding potentials. Simultaneous improvement of fragrance and intermediate AC indicated that badh2 and Wx genes had major effects on the fragrance and AC, respectively. We show here the success of improving fragrance and intermediate AC by MAB and the high efficiency of selection in early generations. In the present study, MAB accelerated the development of superior qualities in the genetic background of Manawthukha. The improved Manawthukha should be immediately useful for Myanmar farmers and will help farmers to increase their incomes.