Pyramiding bacterial leaf blight resistance genes into popular rice varieties of Kerala through marker assisted selection
| dc.contributor.advisor | Jayalekshmy, V G | |
| dc.contributor.author | Ramaling Hundekar | |
| dc.date.accessioned | 2020-01-15T11:11:12Z | |
| dc.date.available | 2020-01-15T11:11:12Z | |
| dc.date.issued | 2017 | |
| dc.description | Ph.D | en_US |
| dc.description.abstract | Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a devastating disease of rice in Asia and Africa . Major rice growing areas of Kerala are highly prone to this disease which results in damage upto 35%. Exploitation of host plant resistance is the only practical strategy for managing the disease in an ecofriendly manner. Till date, more than 40 resistance genes for BB have been identified from diverse sources and pyramiding of these resistance genes will impart durable resistance. So, present study entitled “Pyramiding Bacterial Leaf Blight resistance genes into popular rice varieties of Kerala through marker assisted selection” was undertaken at the College of Agriculture Vellayani Thiruvananthapuram, to pyramid the genes for resistance to bacterial blight (xa13, Xa21, Xa33, Xa38) into the popular rice varieties, Prathyasa and Aiswarya through foreground selection for the genes using molecular markers, to obtain lines with the two/three resistance genes combination in the background of above cultivars. DNA markers closely linked to the BB resistance genes, such as pTA248 (Xa21 gene), xa13 pro (xa13 gene), RMWR7.1 (Xa33 gene) and Oso4g53050- 1(Xa38 gene) were used for validation of the marker polymorphism in the donors of the genes for resistance to BB viz. Improved Samba Mahsuri with xa13 and Xa21, Improved Samba Mahsuri with Xa33, and PR-114 with Xa38 and susceptible recipient parents Aiswarya and Prathyasa . This validation confirmed the absence of the genes in the recurrent parents chosen for the study. These polymorphic markers were also used for foreground selection in F1 plants and backcross generations. Initial hybridization was performed between two recipient parents and three donor parents to transfer the genes for resistance. Foreground selection was carried out in 193 F1 plants from these six crosses using molecular markers specific to the genes. F1 plants (163) with heterozygous loci for trait specific marker were backcrossed with respective recurrent parent and obtained 776 BC 1F1 plants in six cross combinations. These plants were screened with four trait specific foreground markers and 279 plants were identified with genes of interest. From among these forty two plants in the 2 crosses Aiswarya x ISM (xa13 and Xa21) and Prathyasa x ISM (xa13 and Xa21) had both genes (xa13 and Xa21) in heterozygous condition. χ2 test was done with the genotypic data of BC1F1 plants with single gene viz. Xa33 and Xa38. Segregation ratios in BC1F1 population from the crosses viz. Prathyasa x ISM (Xa33), Aiswarya x PR-114(Xa38) and Prathyasa x PR-114(Xa38) did not show significant deviation from the expected 1:1 ratio. But BC1F1 plants with Xa33 gene of the cross Aiswarya x ISM showed significant deviation from 1:1 segregation ratio. This suggests the presence of segregation distortion in these segregants. For the background selection four varieties were genotyped with 270 microsatellite loci and 180 discrete, unambiguous amplicons specific for the four varieties were identified. The background selection was carried out on altogether 279 plants from six BC1F1 populations using 143 loci polymorphic in the parents. The BC1F1 plants with highest percentage of recurrent parent genome recovery in the six populations were selected based on the background markers. These plants were used for intermating programme to pyramid the genes. The disease screening of donors, Improved Samba Mahsuri(xa13 and Xa21), Improved Samba Mahsuri (Xa33), and PR-114 (Xa38) against local isolate of Xanthomonas oryzae pv.oryzae conducted at RRS, Moncompu showed resistant disease reaction in the donors ISM (xa13 and Xa21) and ISM (Xa33). PR- 114(Xa38) exhibited moderate susceptible disease reaction and so this donor was excluded from further breeding programme. BC1F1 plants having xa13 and Xa21 genes were used as female parent and BC1F1 plants with Xa33 used as male parent in intermating programme for pyramiding. Foreground selection was performed in the intermated plants using trait specific markers. Among Aiswarya derived BC1F1 intermated plants, seven plants showed three resistance gene combination (Xa21+ xa13 +Xa33) and forty four plants showed two resistance gene combinations. Among the forty four plants with two resistance gene combination, seventeen had xa13+Xa33, 18 had Xa21 + xa13 and 9 had Xa21 + Xa33. In Prathyasa derived BC1F1 intermated plants 12 plants had Xa21+xa13 gene combinations and nine had xa13 + Xa33 resistance gene combination. Based on the four quantitative traits (plant height, number of productive tillers, grain L/B ratio and days to maturity) Euclidean coefficient of dissimilarity was assessed in comparison with the respective recurrent parents, in plants pyramided with resistance genes. In Aiswarya derived pyramided plants coefficient of dissimilarity with Aiswarya for the four quantitative traits varied from 2.24 to 27.25. Coefficient of dissimilarity with Prathyasa in the Prathyasa derived pyramided lines based on the four quantitative traits ranged from 3.00 to 17.47. The morphological traits of the two / three gene pyramided BC 1F1 genotypes were found to be either superior or on par with the recurrent parents Aiswarya and Prathyasa. Majority of pyramided lines showed red kernel colour of the recurrent parents. This research lead to development of plants pyramided with two /three genes for resistance to BB in the background of Aiswarya and plants with two resistance genes in the background of Prathyasa. These pyramided lines can be used for further breeding programme to develop Essentially Derived Varieties (EDVs) to tackle the Bacterial Leaf Blight (BB) disease. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810140488 | |
| dc.keywords | Plant breeding, Varieties of rice, Marker-assisted selection, Gene, Resistence | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 176 | en_US |
| dc.publisher | Department of Plant Breeding and Genetics, College of Agriculture, Vellayani | en_US |
| dc.sub | Plant Breeding | en_US |
| dc.subject | null | en_US |
| dc.theme | bacterial leaf blight resistance genes into popular rice varieties | en_US |
| dc.these.type | Ph.D | en_US |
| dc.title | Pyramiding bacterial leaf blight resistance genes into popular rice varieties of Kerala through marker assisted selection | en_US |
| dc.type | Thesis | en_US |