Differential Chromosome Banding and RAPD Analysis in Three Varieties of Glycine max (L.) Merr.

Abstract

Three varieties of Glycine max (L.) Merr. (soybean) released by Bangladesh Agricultural Research Institute (BARI), viz., BARI-5, BARI-6 and Shohag, were investigated cytogenetically and at the molecular level using RAPD-markers for authentic characterization. The three varieties represented variation for several phenotypic and agronomic traits. Although the varieties were all found to possess 2n=40 metacentric chromosomes, they differed in other karyotypic features such as total length of 2n chromosome complements, range of relative length, centromeric index, etc. Five to eight CMA-positive bands were found at different locations in the metaphase chromosomes of the three soybean varieties. Entirely DAPI-fluoresced chromosomes were frequent in these varieties. The number, location and distributions of GC- and AT-rich repeats are specific for each variety. Fluorescent banding revealed the occurrence of genomic alterations within these varieties. Five RAPD primers generated 36 distinct bands with 66.67% polymorphisms indicating a highly diversed nature. In addition to polymorphism, seven variety specific RAPD fragments were identified in the three soybean varieties. The dendrogram based on RAPD analysis made variety Shohag distinct from the other two varieties and placed it in a separate cluster that correlated with its phenotypic, agronomic and cytogenetical features. Therefore, each variety has been characterized authentically by cytogenetical and molecular analysis.