1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Introgression of mosaic resistance in popular short duration cassava varieties of Kerala through marker assisted selection(Deparment of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Darshan, S; Arya, KThe present study entitled “Introgression of mosaic disease resistance in to popular short duration cassava varieties of Kerala through marker assisted breeding”was conducted in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Kerala Agricultural University and Division of Crop Improvement, ICAR- Central Tuber Crops research Institute, Sreekariyam, Thiruvananthapuram, Kerala during the period 2014 - 2017 with the core objective of introgression of cassava mosaic disease (CMD) resistance to short duration varieties of cassava through marker assisted selection (MAS) and to study the inheritance of early bulking nature. The research work was carried out as four experiments. In the first experiment, Five early bulking high yielding lines viz, Sree Jaya, Sree Vijaya, Vellayani Hraswa, CI 889 and 9S 75 and three testers viz, CR 54A3, IMS2-5 and CI 273 with resistance to cassava mosaic disease were selected and planted in a pollination block and crossed in Line x Tester (LxT) design to produce hybrid seeds of 15 F1 combinations. Experiment II was conducted in two parts. Screening of F1 seedlings for CMD resistance and early bulking nature was carried out in the first part of experiment II, where hybrids along with the parents were evaluated. Analysis of variance revealed significant differences among the genotypes for all the traits studied. All the agronomic traits were recorded and inheritance of early bulking and its correlation with other traits were studied. The CMD incidence expressed significant and negative correlation with tuber yield per plant where as significant and positive correlation for all other traits with tuber yield per plant was observed among the F1’s. As a part of experiment II (b), seedlings without the CMD visual symptoms were subjected to multiplex PCR and the results revealed that among the parents Sree Jaya, Sree Vijaya, Vellayani Hraswa expressed presence of Srilankan Cassava mosaic Virus (SLCMV) and Vellayani Hraswa expressed the presence of both SLCMV and Indian Cassava mosaic Virus (ICMV). Among the crosses, Sree Jaya x CR54 A3 (L1x T1), Sree Jaya x IMS2-5 (L1xT2), Vellayani Hraswa x IMS2-5 (L3xT2), CI 889 x CI 273 (L4xT3) expressed the presence of SLCMV. Real time PCR (qPCR) assay for seedlings identified CI 889 (L4), 9S 75(L5), CR 54A3 (T1), IMS2-5 (T2) and CI 273(T3) among the parents and Sree Jaya x CR54 A3 (L1x T1), Sree Jaya x IMS2-5 (L1xT2), Sree Jaya x CI 273(L1x T3) and 9S 75 x CR54 A3 (L5x T1), 9S 75 x IMS2-5 (L5xT2) and 9S 75 x CI 273 (L5x T3) among the crosses as highly resistant, based on viral load present in the DNA sample. Based on the previous report ten CMD resistance linked markers were screened through BSA and five of which SSRY 28, SSRY 44 SSRY 40, SSRY 106 and SSRY 235 were selected. Among the CMD linked SSR markers studied, the maximum polymorphism was elucidated by SSRY 28, SSRY 44 and followed by SSRY 235. SSRY 28 is a strongly linked marker to CMD2 which is a dominant gene conferring resistance among the clones of combinations (L1xT1, L2xT2, L3xT1 and L3xT3) three of five markers revealed alleles associated with CMD2 gene In the third experiment to evaluate the early bulking clones, field was laid out in randomized block design (RBD) with three replications consisting of CMD resistant clones along with parental clones using miniset technique. Analysis of variance revealed significant differences among the genotypes for all the traits. Measurement of heterosis was carried out considering parent Vellayani Hraswa (L3) as check and results revealed that standard heterosis was positive and significant in the combinations Sree Jaya x CR 54A3 (L1xT1) and Sree Jaya x CI 273 (L1xT3) for all the yield contributing traits. The crosses Sree Jaya x CR54 A3 (L1x T1) and Sree Jaya x CI 273 (L1xT3) exhibited negative standard heterosis for CMD. Combining ability analysis showed significant gca, sca variances and gca, sca effects for all the traits. Moreover gca/sca variance ratio indicated preponderance of dominance / non-additive gene action for the inheritance of all traits. Among the lines, Sree Jaya (L1) exhibited positive and significant gcaeffect for tuber yield and yield contributing traits. Among the testers, IMS2-5 (T2) exhibited negative and significant gca effect for CMD. Among the crosses Sree Jaya x CR54 A3 (L1x T1) exhibited positive and significant scaeffect for girth of tuber and stem girth, 9S 75 x CI 273 (L5xT3) exhibited positive and significant scaeffect for tuber yield per plant, CI 889 x CR 54A3 (L4xT1) exhibited negative and significant scaeffect for CMD. In the last experiment, through bulk segregants analysis using 5 SSR markers linked to early bulking in cassava were selected out of 9 SSR markers selected. Among 5 SSR markers of CMD and early bulking nature two SSR markers (SSRY 28 and SSRY 106) associated with resistance to CMD and One SSR marker, ESTs (SSRY) 292 associated to early bulking nature has been identified. Among the crosses, clones from Sree Jaya x CR54 A3 (L1xT1), Sree Jaya x CI 273 (L1x T3) and 9S 75 x CR 54A3 (L5xT1) are being confirmed with CMD resistance as well as early bulking nature.Item Morphological and molecular characterisation of variability in vitro derived seedlings of vanilla (Vanilla planifolia Andrews)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2005) Hena, K K; Nazeem, P AThe research project “Morphological and molecular characterization of variability in in vitro derived seedlings of vanilla (Vanilla planifolia Andrews)” was carried out at the College of Horticulture, Vellanikkara, Thrissur during the period 2001-2003. The major objectives of the study was to characterize the existing variability in field established vanilla plants, derived from in vitro seed culture, using morphological and molecular markers. The study revealed that among the 10 morphological characters selected i.e., leaf length, leaf width, leaf area, number of leaves, total growth, leaf shape, phyllotaxy, root origin and number of roots, except leaf shape, phyllotaxy, root origin and number of roots, all other characters showed significant variation. Twenty different accessions which were highly variable could be selected from the 360 accessions studied. In biochemical studies, the protocol for isozyme analysis could be standardised. The study was done based on esterase and peroxidase patterns. Based on the dendrogram constructed, the 20 different accessions studied could be grouped into different clusters. Based on esterase pattern they were grouped into 9 clusters and based on peroxidase pattern they were grouped into 15 clusters. The accessions a82, a481, a58, a370 and a425 showed high level of polymorphism in both the isozyme patterns. Accessions a82, a396, a370 and a425 showed high level of polymorphism in esterase pattern and accessions a555, a136, a46, a428, a47 a159and a425 showed polymorphism in peroxidase pattern. Molecular studies involved RAPD analysis using 10 primers which gave 16 amplification products. Dendrogram constructed based on the study grouped the 20 accessions into 3 major clusters. The 20 different accessions studied were varying from each other in both the morphological and molecular studies. Hence, it can be said that there is considerable variability in the in vitro derived seedlings of vanilla. The study revealed a similar trend for morphological and molecular markers in assessing variability. Morphological markers need more refinement so as to get precise information on the yield characters too which is more important in case of vanilla. Molecular studies based on AFLP, RFLP etc. can be attempted to get exact picture on variability in vanilla.