INTROGRESSION OF RESISTANCE TO BLAST DISEASE FROM MONOGENIC LINE IRBLta2-Re TO CIHERANG RICE VARIETY

Rice (Oryza sativa L.) cultivar Ciherang is most widely cultivated in Indonesia since it has a high yield and resistance to some pests and diseases. Nevertheless, in recent years, there has been a decline in the resistance trait of Ciherang to blast disease. Therefore, the efforts to improve the resistance trait of Ciherang to blast disease are needed. The improvement of Ciherang resistant trait can be done by introgression of a resistance gene from IRBLta2-Re monogenic line (ML) carrying Pita-2 gene. IRBLta2-Re has a broad spectrum of resistance to blast. The objective of this study was to introgress the blast-resistant trait from the IRBLta2-Re to the Ciherang cultivar. The research began with a cross between Ciherang as the female parents and IRBLta2-Re as the male parents to create an F-1 population. This F1 population was then crossed to Ciherang as recurrent parent to create a backcross population. Pyricularia oryzae race ID96 was used to select the blast-resistant trait in populations BC1F1, BC2F1, and BC3F1. Selection to 2074 plants of BC1F1 population resulted in 148 plants resistant to blast disease with a 0 score. The BC2F1 population was developed by backcrossing four selected blast-resistant BC1F1 lines viz. lines 627, 1141, 2129 and 2192. Screening to 848 plants of the BC2F1 population showed that 59 plants were blast-resistant with a 0 score. Among 59 blast resistant lines of BC2F1 population, two lines, i.e. lines 627-5 and 2192-3 were separately crossed with recurrent parent to develop BC3F1. Screening to 244 plants of the BC3F1 population resulted in 32 plants resistant to blast disease. These results indicate that introgression of the Pita-2 gene from IRBLta2-Re to Ciherang was successful and produced blast-resistant lines in the BC1F1, BC2F1 and BC3F1 populations.