Introgresi gen tahan blas dari oryzica llanos-5 pada populasi silang balik lanjut way rarem x oryzica Llanos-5

Abstract

Upland rice is an alternative resource for enhancing rice productivity in Indonesia. However upland rice cultivation technology is still not optimum, particularly in controlling blast pathogen (Pyricularia oryzae). The development of cultivar multiline using NIL (Near isogenic lines) population is one of the important efforts to prevent the breaking down of blast resistance in field. The advanced backcross lines were developed using the recurrent parent Way Rarem, which is high yielding but recently was destroyed by blast, and the durable blast resistant Oryzica Llanos-5, as a donor parent. The study was aimed 1) to develop NIL Way Rarem x Oryzica Llanos-5 having a higher blast resistance compared to Way Rarem; 2) to obtain molecular markers which could detect the introgression segment of blast resistance-carrying donor on the advanced backcross lines; and 3) to get information about the blast resistance inheritance of Oryzica Llanos-5. The evaluation of blast resistance demonstrated that the percentage of the blast resistant plant on BC4F1 and BC5F1 were higher than that on BC3F1 and BC4F1, respectively. The blast test using each 133 and 173 blast races on BC5F1 showed that there were several BC5F1 plants having a higher blast resistance to each both blast races compared to Way Rarem. This high blast resistance character might be derived from the introgression segments of Oryzica Llanos-5. The detection of blast resistance introgression from Oryzica Llanos-5 using SSR primers on BC3F1 population demonstrated that three markers (RM411, RM7 and RM251) on chromosome 3 and three markers (RM276, RM549 and RM585) on chromosome 6 were polymorphic markers and could identify the donor introgression based on the appearance of heterozygous allele on PCR amplification. The six SSR markers and the evaluation of blast resistance were used to select the plant on each BC4F1, BC5F1 and BC6F1 generation which was backcrossed to Way Rarem. Based on the genome wide scan in the blast resistant BC6F1 plant we found several SSR markers which could detect the donor introgression on chromosome 2, 3, 6 and 8. RM207 and RM266 were on chromosome 2, also RM404 was on chromosome 8. This is interesting information because the introgression segment on both chromosomes could not detect in earlier research by Lestari et al. (2011). Both introgression segments were located quite close to blast resistance QTL derived from Oryzica Llanos-5 alleles in RIL population Fanny x Oryzica Llanos-5 that the introgression segment on chromosome 2 was located close to Pib gene and on chromosome 8 was located close to Pi33 gene. In addition there were also introgressions segment of Oryzica Llanos-5 on chromosome 3 that could be detected by RM565 and RM514 which were similar position with blast resistance QTLs on population of cross between Fanny x Oryzica Llanos-5 varieties.