SHESHU MADHAV, M.NOOR AHMED, SHAIK2022-08-232022-08-232022-08-23D6297https://krishikosh.egranth.ac.in/handle/1/5810186592IDENTIFICATION OF HOMOZYGOUS LINES HAVING BLAST AND BACTERIAL LEAF BLIGHT GENES THROUGH MARKER ASSISTED SELECTION IN BLACK RICE (Oryza sativa L.)North Eastern states of India have rich diversity in rice and black aromatic glutinous rice of Manipur is having commercial importance. Three traditional black rice varieties i.e., Chakhao poireiton, Chakhao amubi and Black chakhao are popular and Chakhao poireiton is under high acreage in North East India. This black rice is a poor yielder and susceptible to major biotic stresses like blast and bacterial leaf blight (BLB). Chakhao poireiton parent was screened phenotypically for blast and for BLB and also genotypically screened using gene specific markers for blast (Pi54, Pi2) and BLB (Xa21, xa13, xa5) genes. Both phenotyping and genotyping results have shown that Chakhao poireiton was having high susceptibility to both blast and BLB and all the five genes were found to be absent. The present investigation was attempted to pyramid BLB and blast genes in to Chakhao poireiton using marker assisted backcross breeding. SM2545 was the donor for blast resistant genes (Pi54, Pi2), while Improved Samba Mahsuri was the donor for bacterial leaf blight genes (Xa21, xa13 and xa5). The validation of parents for the target genes was done by employing RM206 (SSR marker) for Pi54 gene, AP5659-5 marker for Pi2 gene, pTA248 (STS marker) for the gene, Xa21, xa13-promo (functional marker) for xa13 gene and xa5FM marker for xa5 gene and the parents (donor and recurrent) showed polymorphism for selected target markers. Two crosses (Chakhao poireiton × ISM and Chakhao poireiton × SM2545) were attempted. From both the crosses, hybrids were confirmed and from the each cross one hybrid plant was carried forward to generate BC2F2 and BC2F3. At each backcross, foreground selection to identify the plants carrying the target genes and xiii background selection to identify lines with the highest recurrent parent genome. Out of 400 BC2F2 plants screened, eight plants showed heterozygosity for all the five target genes (Pi54, Pi2, Xa21, xa13 and, xa5). Background analysis was done using 106 polymorphic markers in eight plants BC2F2 generation to know the best plant possessing maximum introgression of recurrent parent genome (RPG). Background analysis of lines revealed that six plants had highest RPG of more than 90%. Agro-morphological evaluation was done in 8 BC2F2 plants during kharif 2019-2020 at IIRR, Hyderabad. BC2F2 plants carrying all five genes in heterozygous condition along with maximum RPG were selfed for generate BC2F3 plants. Blast screening of BC2F3 plants showed that the plants 124-1-5 and 121-1-13 were having disease score of „1‟. All the selected BC2F3 plants were screened for BLB and high level of resistance with „1‟ disease score was observed in two plants (124-1-5 and 121-1-13) of 8 plants having all the five genes whereas the remaining plants showed disease score of 2-3. In the present study genotyping in BC3 derived lines resulted that, four lines 124-1-5-1-5, 124-1-5-1-14, 124-1-5-2-4 and 124-1-5-2-5 were having all the five genes, some genes are in heterozygous condition. Among the four BC3 lines, 124-1-5 -1-14 has four genes in homozygous condition and one gene Pi2 is in heterozygous condition.EnglishThesis