Microsatellite marker dependent genetic divergence assessment within and among heterotic groups of tropical maize inbred lines

Sharma, P.V.K.; Kumar, P.

Maydica 63(3): M23


ISSN/ISBN: 0025-6153
Accession: 070899061

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Use of microsatellite markers can be helpful in assessing the nature and extent of genetic diversity among inbred lines, assigning inbred lines efficiently to heterotic groups and making the choice of heterotic parents to develop new hybrids. A study was conducted to determine the heterotic groups of 18 inbred lines of maize including three inbred testers and to examine the nature and extent of divergence within and between heterotic groups of inbred lines based on the analysis of targeted microsatellite sites. Using hybrid index and hybrid mean values obtained from the results of experimental trials conducted over the two seasons as the indices, inbred lines were classified into three heterotic groups. Microsatellite profiling with a panel of 28 primer pairs covering all chromosomes revealed ample genetic polymorphism, which allowed unique genotyping and unambiguous classification of inbred lines. Basically, the inbred lines and testers were differentiated into four genotypic groups. Principal coordinate analysis based on similarity indices and spatial ordination of the genetic profiles showed four well defined genotypic groups of 18 inbreds. The distribution pattern of the entries into different heterotic groups formed on the basis of hybrid index value and hybrid mean value corresponded with the microsatellite markers based groups to the extent of 75% and 67% in the first heterotic group, 40% and 29% in the second heterotic group and 33% and 40% in the third heterotic group, respectively. Overall coincidences of inbred lines in heterotic groups based on microsatellite markers with the hybrid index value and hybrid mean value based heterotic groups (47% and 40%, respectively) indicated that microsatellite markers may be effectively and efficiently utilized to assign the inbred lines to heterotic groups for the purpose of reducing the number of single crosses to be generated and evaluated. Average genetic divergence revealed within and between heterotic groups by the microsatellite markers may be utilized as the criterion for parental line selection during development of experimental hybrids