000			03784nam a22001817a 4500
999			_c289756 _d289756
082			_a660.6 _bAIS/AS PG
100			_aAiswarya Mohandas
245			_aAssessment of recurrent parent genome in the two/three R genes phyramided lines of the rice variety aiswarya through genome wide marker assay
260			_aVellayani _bDepartment of Plant Biotechnology, College of Agriculture _c2022
300			_a96p.
502			_aBSc-MSc (Int.)
520			_aBacterial leaf blight (BLB) in rice caused by Xanthomonas oryzae pv. oryzae(Xoo) is one of the most destructive epidemic of rice throughout the world and widespread in Asia, especially in South East Asian countries like India. Durable and effective resistance against BLB can be attained by pyramiding resistance genes into the genetic background of BLB susceptible popular rice cultivars. In the present study entitled “Assessment of recurrent parent genome in the two/ three R genes pyramided lines of the rice variety Aiswarya through genome wide marker assay.” was undertaken at the Department of Seed Science and Technology, College of Agriculture, Vellayani, Thiruvananthapuram to estimate the recurrent parent genome recovery in BC2F4lines pyramided with BLB resistance genes, viz., Xa21, xa13 and xa5 from the donor variety Improved Samba Mahsuri (ISM) in to the genetic background of rice variety ‘Aiswarya’. DNA markers, pTA248, xa13pro and xa5FM tightly linked to the BLB resistance genes Xa21, xa13 and xa5 respectively were used for the selection of lines with two or three resistance gene combination in the BC2F4 lines in foreground screening. The comparison of allele sizes of amplicons of these markers in BC2F4 lines with that of both the parents confirmed the presence or absence of the marker associated with respective gene of resistance. Foreground selection was performed initially on 50 BC2F4 plants to identify the presence of the three R genes for BLB resistance. Xa21 gene was shown to be fixed in all the plants. A total of five plants were found to be homozygous for xa13 gene and another five was shown to be heterozygous for the gene. One BC2F4 line had the three genes xa5, xa13 and Xa21 in homozygous condition. 96 Background screening was done in four plants (Ai- 543- 7- 10- 11, Ai- 543- 7- 10- 16, Ai- 543- 7- 10- 18 and Ai- 543- 7- 10- 24) with the homozygous two gene combination of Xa21 and xa13 and the one plant (Ai- 543- 7- 10- 10) with homozygous three gene combination. 150 genome wide SSR markers specific to Aiswarya had been identified in the previous studies. In BC2F2 generation, 140 out of 150 had been fixed in homozygous condition. The remaining 10 markers (RM4B, RM110, RM190, RM214, RM271, RM277, RM313, RM447, RM502 and RM517) were used in this study. The percentage of recurrent parent genome (RPG) recovery was calculated based on the results of background screening. The highest recurrent parent genome recovery of 96% was observed in the lines Ai-543-7-10-16 and Ai-543-7-10-24. The line Ai-543-7- 10-10 with three gene combination showed 95.67% recovery of genome as in the rest of the lines screened (Ai-543-7-10-11 and Ai-543-7-10-18). The present could study identify BC2F4 lines Ai-543-7-10-16 and Ai-543-7-10-24 plants with homozygous two and three R gene combination with more than 95% recurrent parent genome recovery. These lines can be forwarded by self pollination and with stringent screening on the morphological traits of the recurrent parent to develop Essentially Derived Variety for Aiswarya with durable resistance to BLB.
650			_aPlant Biotechnology
650			_aRice
650			_aRice variety
700			_aV G Jayalekshmy (Guide)
942			_2ddc _cTH