Genetic divergence among melon (Cucumis melo L.) groups for growth, yield and quality traits
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Date
2016
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation entitled, “Genetic divergence among melon (Cucumis melo L.) groups for growth, yield and quality traits” was conducted at Department of Vegetable Science and School of Agricultural Biotechnology, PAU, Ludhiana during the spring-summer seasons of 2015 and 2016. Seventy melon accessions belonging to five horticultural groups, cantalupensis, reticulatus, inodorus, momordica and callosus collected from diverse geographical locations such as, India, USA, Israel and Afghanistan were characterized for thirty-three morphological traits based on IPGRI descriptors. The genetic diversity based on quantitative morphological characters of genotypes was assessed by principle component analysis. The biplot of first two components grouped all the genotypes into four major clusters irrespective of their geographical region. Accessions belonging to momordica and callosus groups were grouped in Cluster I and Cluster II, respectively. The accessions having large fruits, particularly from inodorus group were clustered in cluster III. While, the remaining genotypes, mostly from reticulatus and cantalupensis groups were clustered in cluster IV. Genetic variability of muskmelon genotypes was determined by using 30 SSR markers. All of the 30 SSR markers amplified. A total of 67 alleles were detected by 24 polymorphic SSR loci and maximum 4 alleles were observed with an average of 2.8 alleles per primer pair. The markers CMAG59, CMTCN38, CMMS3-1 and EMS178 were highly informative as these revealed maximum number of alleles (4), PIC values (0.550, 0.600, 0.442) and genetic diversity (0.56, 0.61, 0.45, 0.54), respectively. Seven SSR markers revealed specific/unique alleles and identified twenty-three genotypes. Across the genotypes, maximum number of alleles (58) was detected in IC-274034 and the percentage of polymorphic marker was maximum (86.96) in PAUS-19. In present study, average observed heterozygosity (53%) with in a melon germplasm was higher as compared to the average expected heterozygosity (48%).The dendrogram illustrating genetic relationship, grouped the accessions belonging to reticulatus group in cluster-I and accessions belonging to cantalupensis, callosus, momordica and inodorus were grouped in cluster-II and cluster-III. The maximum genetic similarity coefficient was 0.83 in cluster-I. Similarly, it ranged from 0.88 to 0.91 in cluster-II and III. Intermixing of accessions of five horticultural groups within clusters indicates that classification of muskmelon groups on morphological does not necessarily correspond to the genetic relationship shown by molecular analysis. Hence, out crossing behavior may be the cause of genetic introgression in melons.
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