Marker-assisted introgression of the major bacterial blight resistance genes, Xa21 and xa13, and blast resistance gene, Pi54, into the popular rice variety, JGL1798

Abstract

JGL1798 (Jagtial Sannalu) is a high yielding fine grain variety released for Telangana state, India, and highly susceptible to two major rice diseases, bacterial blight (BB) and blast. To improve JGL1798 for BB and blast resistance, two bacterial blight resistance genes (xa13 and Xa21) derived from improved Samba Mahsuri (B95-1) and one blast resistance gene (Pi54) from NLR145 have been introgressed using marker-assisted backcross breeding (MABB) method. Foreground selection was carried out in two independent backcross-derived progenies JGL1798 X B95-1(C5) and JGL1798 X NLR145 (C6) using three gene linked markers viz., xa13 promoter, PTA248, and Pi54MAS. To achieve maximum genome recovery of recurrent parent, background selection was carried out among the gene positive plants at each backcross generation and identified backcross lines having high genome recovery of recurrent parent. Pyramiding three genes into one background, marker-assisted backcrossing was continued until BC2 generation and an intercross was made between highest genome recovery plants, i.e., C5-BC2F1-23and C6-BC2F1-4. The six triple heterozygous positive ICF1 plants confirmed for the presence of xa13, Xa21, and Pi54 genes in heterozygous condition. These plants were screened with polymorphic SSR markers and the ICF124 plant possessing maximum percentage (90%) of recurrent parent genome was selected, selfed and 2216 ICF2 plants were obtained and evaluated during kharif, 2013. A total of 862 plants were genotyped possessing the target resistance genes in homozygous condition. Among those, 11 homozygous plants, the ICF2-4-12 lines possessing the highest genome recovery (92.3%). The identified 11 introgressed lines displayed higher level of resistance to bacterial blight and blast with good agro-morphological traits, grain yield, physical, and cooking quality characters similar to that of JGL1798.