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Authors: Asish, I Edakkalathur
Advisor: Minimol, J S
Title: Characterization and taxonomic evaluation of landraces of capsicum spp. in Kerala
Publisher: Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara
Language: en
Type: Thesis
Pages: 172
Agrotags: null
Abstract: Capsicum is a unique genus coming under the family Solanaceae. This genus includes nearly 40 species among which five viz. C. annuum, C.chinense, C. frutescens, C. baccatum and C. pubescens are cultivated. Large number of types, the transitory nature of these types, introgressive hybridization and environmental influence make species arrangement in Capsicum a confusing task. Even though Kerala is rich in the diversity of Capsicum, a comprehensive study of landraces available has not yet been carried out. In this background, the present project was carried out with the objective of characterizing the landraces of Capsicum species in Kerala using morphological markers and validating the key for the identification of different taxa using molecular and biochemical markers. Ripened fruit samples of 262 accessions were collected from the different districts of Kerala during December, 2013 to August, 2014. These accessions were planted in augmented block design along with released varieties from Kerala Agricultural University as checks at National Bureau of Plant Genetic Resources, Regional Station, Thrissur. Morphological characterization was done by considering both qualitative and quantitative characters. Numerical Taxonomy and Multivariate Analysis System (NTSYS) software version 2.10 z was used for construction of phenogram based on forty four qualitative characters available in the Capsicum descriptor (IPGRI, 1995). Accessions belonging to three species viz., C. annuum, C.chinense and C. frutescens formed species specific clusters. C. baccatum accessions clustered with C. frutescens. C. chinense accessions were clearly separated and distantly placed from C. annuum accessions revealing genetic dissimilarity between the above two species.. Out of 42 clusters formed at 70 per cent similarity level, 39 are mono-specific clusters. Morphological characterization based on qualitative unit characters aligned 95 per cent of the accessions into species specific clusters. Diversity relationship accessed on the basis of 32 quantitative characters grouped the accessions into 14 clusters. C. annuum accessions formed mono- specific clusters where as C. chinense and C. frutescens accessions grouped together in three different clusters revealing that C. frutescens and C. chinense are inseparably related. C. annuum accessions were found standing as a separated group. C. baccatum accessions clustered along with C. frutescens - C. chinense group. Representative accessions selected from each qualitative cluster along with eight released varieties were analysed using 17 RAPD primers. Dendrogram consisted of eleven mono-specific clusters indicating the ability of RAPD markers to align the genotypes into correct taxa. Clustering of C. annuum accession with C. frutescens (two clusters) and C. chinense (two clusters) as well as clustering between C. frutescens and C. chinense (three clusters) accessions points to the genetic similarity within the annuum complex. C. baccatum accession expressed more similarity with C. frutescens. The genetic background of the annuum complex was further scrutinized with 18 SSR primers among 19 genotypes comprising of eight C. annuum, seven C. chinense and four of C. frutescens accessions. Out of five clusters formed, two were mono-specific C. annuum clusters. Other three clusters composed of both C. frutescens and C. chinense accessions in each clusters. Thus SSR characterization clearly revealed the close genetic similarity between C. frutescens and C. chinense species and this group is distantly placed from C. annuum species. Clustering pattern based on RAPD primers for the above 19 genotypes strongly supported the result of SSR analysis with formation of two major clusters viz., one composed of C. annuum type only and the other major cluster comprising both species viz., C. frutescens and C. chinense. Dendrogram constructed based on RAPD and SSR banding pattern also substantiated above result by forming mono-specific C. annuum clusters and clusters comprising accessions from both species viz., C. frutescens and C. chinese. Both RAPD and SSR analysis points to the close similarity among the released varieties. All the released varieties of C. annuum type are grouped in to the same cluster. Combined analysis based on RAPD and SSR data resulted in the formation of two major clusters viz., first cluster comprising of only released varieties and second of landraces. Compared to separate RAPD or SSR characterization, combined analysis based on RAPD and SSR data more precisely assigned accessions into corresponding species specific clusters and formed mono-specific clusters. At 70 per cent similarity level, combined RAPD-SSR analysis expressed 79 per cent accuracy for allotting accessions to species specific clusters. More number of molecular markers improve the accuracy of species alignment and molecular markers serve a complementary role to assist phenetics. Quantity of ascorbic acid ranges from 81.40 to 327.58 mg per 100g of ripe chilly. The upper limit of capsaicin and oleoresin were 0.87 and 23.5 per cent, respectively. Accessions superior in performance to the check varieties for economic and biochemical characters were identified through the agronomic characterization. Majority of the yield contributing characters exhibited high GCV coupled with moderate to high heritability and high genetic gain revealing wide variability contributed by genetic factors and indicating scope for selection. DNA fingerprinting profile of released varieties and elite accessions were developed using SSR primers. Species specific fingerprinting of C. annuum, C. chinense and C. frutescens species were also made for differentiation of species with SSR primers. Validation of taxonomic key carried out integrating characters viz., spot colour at the throat of corolla, annular constriction at calyx, number of flowers per axil, corolla colour, position of flower at anthesis, leaf shape, margin of calyx at fruiting, fruit to pedicel length ratio and level of main stem bifurcation. SSR primers viz., CAMS-101, CAMS-806 and CAMS-864 as well as RAPD primers viz., OPB-10,OPG-02, OPG-03, OPB-08 and OPA-03 identified as promising in identification and differentiation of cultivated species of Capsicum.
Description: Ph.D
Subject: Plant Breeding
Theme: Characterization and taxonomic evaluation
These Type: Ph.D
Issue Date: 2018
Appears in Collections:Theses

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