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Export performance and supply chain analysis of major vegetables of Kerala

By: Mohandas K.
Contributor(s): Regeena, S(Guide).
Material type: materialTypeLabelBookPublisher: Vellayani Department of Agricultural Economics, College of Agriculture 2020Description: 258p.Subject(s): Quantity and value of vegetables exported from KeralaDDC classification: 630.33 Dissertation note: PhD Abstract: ABSTRACT Bacterial leaf blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most devastating disease of rice in the world. Major rice growing countries are affected by this disease leading to losses upto 80% in susceptible cultivars. Exploitation of host plant resistance is the most suitable practical strategy for the disease management in an eco-friendly manner. Till date, about 42 BLB resistance genes, conferring resistance against various strains of Xoo, have been identified from the rice germplasm collections worldwide. So, the present study entitled “Marker assisted selection for bacterial leaf blight resistance genes in the backcross progenies of Prathyasa variety of rice (Oryza sativa L.)” was undertaken at College of Agriculture, Vellayani during 2017-2019 to identify lines in the BC2F2 progeny of Prathyasa pyramided with two/three genes (xa13, Xa21, and xa5) through marker assisted selection for resistance to bacterial leaf blight and to evaluate these lines morphologically to assess Prathyasa phenome recovery. In this study, the recurrent parent was Prathyasa (MO 21) susceptible to bacterial leaf blight and donor parent was Improved Samba Mahsuri (RPBio-226) resistant to bacterial leaf blight with xa13, Xa21 and xa5 resistance genes. BC2F2 seeds from ten BC2F1 plants selected on the basis of recurrent parent genome recovery was used for the study. The isolated DNA samples from about 289 BC2F2 plants and the parents were subjected to quality and quantity analysis. The diluted DNA was utilized for PCR amplification using gene-specific co-dominant functional markers xa13pro, pTA248 and xa5FM for the genes xa13, Xa21 and xa5 respectively, to identify the presence of genes. Among the 289 plants subjected to molecular analysis, 155 plants were found to have resistance genes in combination. Besides this, thirty-two plants with homozygous xa13, thirty-one plants with heterozygous xa13, three plants with homozygous Xa21 and two plants with heterozygous Xa21 were also identified. Among the 155 plants with gene combination, 136 BC2F2 plants with the presence of homozygous xa13 and Xa21 genes in combination and a single plant with the presence of homozygous xa13 and xa5 genes in combination were identified. Four plants with homozygous xa13 and heterozygous Xa21, seven plants with heterozygous xa13 and homozygous Xa21, six plants with heterozygous xa13 and heterozygous Xa21 and a plant with heterozygous xa13 and homozygous xa5 were also identified. Euclidean distance analysis of the segregants with two gene combination using the quantitative traits such as plant height, days to maturity, number of productive tillers plant-1, length of panicle, number of grains panicle-1, 1000 grain weight and length/breadth ratio of grain revealed the divergence of each individual from the recurrent parent Prathyasa. Plants ICDE 13-3/46/4/31, ICDE 13-3/46/4/7, ICDE 13-3/46/4/48, and ICDE 13-3/46/4/50 were having the minimum euclidean distance of 1.25, 2.35, 3.06, and 4.01 respectively from recurrent parent. These lines had the red kernels of Prathyasa. Among them, ICDE 13-3/46/4/7 and ICDE 13-3/46/4/48 had homozygous combination xa13 and Xa21, ICDE 13-3/46/4/31 had heterozygous combination of xa13 and Xa21 and ICDE 13-3/46/4/50 had heterozygous xa13 and homozygous Xa21 genes. The plants ICDE 13-3/46/4/46 with a combination of homozygous xa13 and xa5 and ICDE 13-3/46/4/41 with a combination of heterozygous xa13 and homozygous xa5 had a genetic distance of 11.46 and 8.45 respectively from the recurrent parent. Both these plants showed red kernels. The plants up to a maximum euclidean distance of 15 units from Prathyasa were selected and upon clustering using the proximity dissimilarity matrix, the plants ICDE 13-3/46/4/31, ICDE 13-3/46/4/7 and ICDE 13-3/46/4/48 were in the same cluster along with the recurrent parent Prathyasa. The plants ICDE 13-3/46/4/7 and ICDE 13-3/46/4/48 with two bacterial blight resistance genes (xa13 and Xa21) in the homozygous state were the best BC2F2 plants identified with a maximum phenotypic resemblance to Prathyasa. These plants can be either subjected to selection by forwarding to BC2F3 generation or backcrossing with the recurrent parent for maximizing recurrent parent genome in the progeny. Even though the plants with the combination of xa13 and xa5 were more divergent from Prathyasa parent, the presence of red kernels in them signifies its selection for either backcrossing or generating BC2F3 population for fixation of resistance genes. These plants can be utilized to generate triple gene pyramided essentially derived variety (EDV) of Prathyasa to provide durable resistance to bacterial leaf blight.
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Theses
Reference Book 630.33 MOH/EX PhD (Browse shelf) Not For Loan 174845

PhD

ABSTRACT

Bacterial leaf blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most devastating disease of rice in the world. Major rice growing countries are affected by this disease leading to losses upto 80% in susceptible cultivars. Exploitation of host plant resistance is the most suitable practical strategy for the disease management in an eco-friendly manner. Till date, about 42 BLB resistance genes, conferring resistance against various strains of Xoo, have been identified from the rice germplasm collections worldwide. So, the present study entitled “Marker assisted selection for bacterial leaf blight resistance genes in the backcross progenies of Prathyasa variety of rice (Oryza sativa L.)” was undertaken at College of Agriculture, Vellayani during 2017-2019 to identify lines in the BC2F2 progeny of Prathyasa pyramided with two/three genes (xa13, Xa21, and xa5) through marker assisted selection for resistance to bacterial leaf blight and to evaluate these lines morphologically to assess Prathyasa phenome recovery.
In this study, the recurrent parent was Prathyasa (MO 21) susceptible to bacterial leaf blight and donor parent was Improved Samba Mahsuri (RPBio-226) resistant to bacterial leaf blight with xa13, Xa21 and xa5 resistance genes. BC2F2 seeds from ten BC2F1 plants selected on the basis of recurrent parent genome recovery was used for the study. The isolated DNA samples from about 289 BC2F2 plants and the parents were subjected to quality and quantity analysis. The diluted DNA was utilized for PCR amplification using gene-specific co-dominant functional markers xa13pro, pTA248 and xa5FM for the genes xa13, Xa21 and xa5 respectively, to identify the presence of genes.
Among the 289 plants subjected to molecular analysis, 155 plants were found to have resistance genes in combination. Besides this, thirty-two plants with homozygous xa13, thirty-one plants with heterozygous xa13, three plants with homozygous Xa21 and two plants with heterozygous Xa21 were also identified.
Among the 155 plants with gene combination, 136 BC2F2 plants with the presence of homozygous xa13 and Xa21 genes in combination and a single plant with the presence of homozygous xa13 and xa5 genes in combination were identified. Four plants with homozygous xa13 and heterozygous Xa21, seven plants with heterozygous xa13 and homozygous Xa21, six plants with heterozygous xa13 and heterozygous Xa21 and a plant with heterozygous xa13 and homozygous xa5 were also identified.
Euclidean distance analysis of the segregants with two gene combination using the quantitative traits such as plant height, days to maturity, number of productive tillers plant-1, length of panicle, number of grains panicle-1, 1000 grain weight and length/breadth ratio of grain revealed the divergence of each individual from the recurrent parent Prathyasa. Plants ICDE 13-3/46/4/31, ICDE 13-3/46/4/7, ICDE 13-3/46/4/48, and ICDE 13-3/46/4/50 were having the minimum euclidean distance of 1.25, 2.35, 3.06, and 4.01 respectively from recurrent parent. These lines had the red kernels of Prathyasa. Among them, ICDE 13-3/46/4/7 and ICDE 13-3/46/4/48 had homozygous combination xa13 and Xa21, ICDE 13-3/46/4/31 had heterozygous combination of xa13 and Xa21 and ICDE 13-3/46/4/50 had heterozygous xa13 and homozygous Xa21 genes. The plants ICDE 13-3/46/4/46 with a combination of homozygous xa13 and xa5 and ICDE 13-3/46/4/41 with a combination of heterozygous xa13 and homozygous xa5 had a genetic distance of 11.46 and 8.45 respectively from the recurrent parent. Both these plants showed red kernels.
The plants up to a maximum euclidean distance of 15 units from Prathyasa were selected and upon clustering using the proximity dissimilarity matrix, the plants ICDE 13-3/46/4/31, ICDE 13-3/46/4/7 and ICDE 13-3/46/4/48 were in the same cluster along with the recurrent parent Prathyasa.
The plants ICDE 13-3/46/4/7 and ICDE 13-3/46/4/48 with two bacterial blight resistance genes (xa13 and Xa21) in the homozygous state were the best BC2F2 plants identified with a maximum phenotypic resemblance to Prathyasa. These plants can be either subjected to selection by forwarding to BC2F3 generation or backcrossing with the recurrent parent for maximizing recurrent parent genome in the progeny. Even though the plants with the combination of xa13 and xa5 were more divergent from Prathyasa parent, the presence of red kernels in them signifies its selection for either backcrossing or generating BC2F3 population for fixation of resistance genes. These plants can be utilized to generate triple gene pyramided essentially derived variety (EDV) of Prathyasa to provide durable resistance to bacterial leaf blight.

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