Marker-assisted pseudo-backcross breeding for improvement of amylose content and aroma in Myanmar rice cultivar Sinthukha.

Breeding for consumers preferring grain qualities has become a chief goal for rice breeding programs in the world. Amylose content (AC) and aroma are important qualities for consumers' preference and market price. To introgress the alleles of waxy (Wxb) and fragrance (badh2) genes into Sinthukha, a widely adaptable high-yield rice variety in Myanmar which has intermediate AC and non-aroma, RNP20-145-1-9 line was used as a donor parent, and pseudo-backcross breeding was designed to shorten the backcross program. In this approach, only one backcross (BC1F1) and one self-pollinated (BC1F2) population was generated to select for the plants with donor alleles of waxy and fragrance genes in foreground selection, and the selected plants were screened for the highest percentage of recurrent genome content (%RGC) in background selection by amplified fragment length polymorphism (AFLP) analysis. The progenies with the highest %RGC, 84% and 92% were selected in BC1F1 and BC1F2 populations, respectively, and these selected plants possessed heterozygous alleles in fragrance and waxy genes. The agronomic and yield performance, grain size and shape of selected BC1F2 plants were most similar to those of Sinthukha. Nevertheless, amylose content of the selected plants was as low as that of RNP20-145-1-9 rice line. In this study, marker-assisted pseudo-backcross approach was useful in the introgression of low amylose and aroma genes from RNP20-145-1-9 line into Sinthukha, and it could accelerate backcross breeding program through the combination of marker-assisted foreground and background selections. AFLP analysis could save not only time consumption but also the cost of analysis and workload in background selection. [ABSTRACT FROM AUTHOR]