Morphological and molecular characterization of mandarin (Citrus reticulata Blanco) germplasm and F1 hybrids
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Date
2016
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Punjab Agricultural University, Ludhiana
Abstract
The present study entitled “Morphological and molecular characterization of mandarin (Citrus reticulata Blanco) germplasm and F1 hybrids” was conducted during years 2013 to 2015 at Punjab Agricultural University, Ludhiana. Nineteen mandarin genotypes grafted on rough lemon (C. jambhiri Lush) rootstocks were evaluated for morphological characters based on IPGRI descriptors. The genetic diversity based on quantitative morphological characters of genotypes was assessed by using DARwin software. The dendrogram grouped all the genotypes into three major clusters irrespective of their geographical region indicating variation in morphological traits. Genetic variability and fingerprint profiles of mandarin genotypes were determined by using 60 SSR markers. Of the 57 SSR markers amplified, a total of 96 alleles were detected by 39 polymorphic SSR loci and maximum 5 alleles were observed with an average of 2.46 alleles per primer pair. The CAT01 was the highly informative marker as it revealed maximum number of alleles (5), PIC value (0.75) and genetic diversity (0.79). Twenty-six SSR markers revealed specific/unique alleles and identified nine genotypes including all the hybrids. Across the genotypes, maximum number of alleles (83) was detected in Daisy hybrid and the percentage of polymorphic marker was maximum (80.32) in Nova hybrid. The higher average expected heterozygosity (35.6%) with in a mandarin group as compared to the average observed heterozygosity (27.2%) may be explained by selfing, which reduced the proportion of heterozygotes. The dendrogram illustrating genetic relationship grouped all the indigenous genotypes (selections) in cluster-I and the exotic genotypes (hybrids) were grouped in cluster-II and cluster-III. The maximum genetic similarity coefficient ranged from 0.91 to 0.95 in cluster-I, however it ranged from 0.73 to 0.77 in cluster-II and III. CCSM170, CiBE6006, CMS31 and CiBE3397 markers were highly informative in identification of hybrid zygotic seedlings in F1 hybrids of different crosses viz., ‘Daisy x Kinnow’, ‘Kinnow x Daisy’, ‘W. Murcott x Kinnow’ and ‘Kinnow x W. Murcott’, respectively. Therefore, the set of microsatellites in the present study were successful in DNA fingerprinting, evaluating genetic diversity, and identification of genetic origin of seedlings in F1 hybrids of intra-specific crosses in mandarins.
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Keywords
Mandarin, genotype, morphological characterization, molecular characterization