Genetic divergence evaluation in tomato using morpho-biochemical characters and microsatellite markers
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Date
2019
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DRPCAU, Pusa, Samastipur
Abstract
A study was conducted to determine the genetic variation and divergence among 24 genotypes of tomato using three different parameters namely morphological, biochemical and molecular. The morphological observations were recorded on randomly selected five plants for plant height at maturity, number of Primary branches per plant, number days to 50% flower initiation, number of days to 50% fruit initiation, number of flowers per cluster, number of fruits per cluster, number of fruits per plant, number of locules per fruit, polar diameter of fruit, equilateral diameter of fruit, number of days to fruit maturity, fruit yield per plant, total soluble solid and ascorbic acid content of fruit and shape and size of fruit. Among 24 genotypes of tomato 16 best performing genotypes were selected for molecular characterization.
Analysis of variance revealed highly significant differences among the genotypes evaluated in respect of all the characters under investigation. Invariably, a narrow magnitude of difference between phenotypic and genotypic coefficient of variation was noticed for all the characters with the exception of number of primary branches per plant, number of fruits per plant and yield per plant. A narrow magnitude of difference indicate comparatively less environmental influence on these characters. Exploitable amount of genetic variability among the genotypes for various characters was observed number of fruits per plant, yield per plant, plant height at maturity, number of fruits per cluster, polar diameter and equilateral diameter of fruit, TSS and ascorbic acid content of fruit.Among the other characters studied, number of flowers per cluster, number of locules per fruit, number of primary branches per plant, had moderate value of genotypic coefficient and high to moderate estimates for heritability in broad sense and/or genetic advance as percent of mean. Using
hierarchical cluster analysis, twenty four genotypes were classified into four separate and well characterized groups on the basis of taxonomic distance.
Numerical taxonomic approach for classification of entries made it possible to discern subtle differences between entries at different phenon level. Thus the numerical taxonomy appeared to be more potent to distinctly discriminate the entries for their use in recombination breeding programme.
Hierarchical cluster analysis, numerical taxonomic approach were supported by principal component analysis.
Genetic polymorphism was observed in sixteen genotypes of tomato at the molecular level by implication patterns generated by twenty two microsatellite primers.
All 22 primer pairs were found to be polymorphic revealing 87 allelic variants including 18 unique and 69 shared alleles with an average of 3.95 alleles per primer, showing the polymorphic nature of the primer pairs. Polymorphic information content of these primers ranged from 0.218 to 0.835 with an average of 0.613. The primer pairs SSR42, SSRSSR111, SSR276 and SSR80 generated considerably greater number of allelic variants per primer and high discriminating ability in the pair-wise combinations of genotypes making them highly polymorphic and comparatively more informative primers for the purpose of molecular evaluation of entries.
The results revealed ample diversity at the molecular level amongst the sixteen tomato entries under evaluation. The value of similarity coefficient between JT-3 and K.Amrit was found to be the maximum amongst the pair-wise combinations of all the entries.
Analysis of divergence pattern allowed differentiation of all the genotypes. The dendrogram based on UPGMA divided the tomato entries into a mono-genotypic group (B), a multi-genotypic group (A), two di-genotypic group (C) and tri-genotypi (D). Clustering pattern of the entries based on similarity coefficient and principal co-ordinate analyses showed almost complete correspondence.
The appreciable diversity on the basis of morphological, biochemical and molecular characterization was identified on the sixteen genotypes of tomato used in the present study. The study identified a panel of twenty two highly polymorphic SSR primer pairs which can be used to discriminate between different genotypes of tomato.
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