Karyomorphological and Phylogenetic Studies in Different Species of Sorghum L. Moench

Abstract

Summary Karyotypes of six species of Sorghum were analysed in detail. The karyomorphological features of S. intrans, S. propinquum, S. bicolor, S. purpureo-sericeum, S. halepense and S. sudanense showed close similarities at interspecific levels among species with 2nϭ20 and between species with 2nϭ40 chromosomes. The extent of chromosome morphology was critically evaluated on the basis of combination of karyotypic parameters like relative length, arm ratio, chromosome index and nucleolar organizers. The results brought out the existence of close similarities among the species notwithstanding the minor structural differences that existed within the species but within limits. The present study confirmed the validity and importance of karyotype analysis with different parameters in distinguishing even the lowest hierarchial level in the genus Sorghum. Key words Sorghum, Karyotypes, Diploid, Tetraploid.Sorghum (L) Moench assumes specific importance in India as a major food grain and fodder crop. It is a staple food crop in India and Africa extensively grown in wide range of agricultural situations. It is assigned to the family Poaceae and shows immense morphological variability, genetic diversity and adaptations to varying habitats has differentiated in to numerous species. Cytological investigations yield a wealth of information about the homology and composition of the genomes in crop plants and wild relatives, which form the basis for the breeder and researchers to understand the cytogenetic manipulations and scientific methods in gene transfer. During the past, appreciable extent of cytogenetical research on gene homology and chromosome pairing has been reported in the genus Sorghum. However, not much is known about the detailed and precise karyomorphology of this genus due to technical difficulties encountered in the cytological manipulation of somatic cells and chromosomes, which are invariably smaller. Keeping the recent approaches in view, studies were taken up in the present investigation in 6 different species of Sorghum to enhance the basic understanding of inter and intra specific variation in the genus. Materials and methodsExperiments were carried out at School of Genetics, Tamil Nadu Agricultural College, Coimbatore. Different species of Sorghum seeds were procured from the Genetic Resources Unit, International Crop Research Institute for Semi Arid Tropics (ICRISAT), Hyderabad, India and Millet Research Station, TNAU, Coimbatore, Tamil Nadu. Seed materials of wild species were raised in pots to get root tips for the cytological studies. Actively growing root tips were excised and pretreated with saturated solution of a-bromonaphthalene in dark at 4°C for 2 h. The pretreated roots were washed with distilled water and fixed in OH fixative (1% picric acid, methyl alcohol and chloroform mixture) at 4°C for 18 h. The root tips were hydrolyzed in 1 N HCl at 60°C for 6 min and washed thoroughly with distilled water till it becomes free of acid. The roots were subjected to enzymatic treatment with a mixture o...

Karyomorphology in Nine Species of Jute (Corchorus L., Tiliaceae)

“…Karyotype analysis from root tip mitosis yields a wealth of information about the homology and composition of the genomes, and it has been revealed as the basis of cytogenetic manipulations in gene transfer and crop improvement (Saha and Datta 2002, Parvatham and Sree Rangasamy 2004, Carvalho et al 2008. Karyomorphological studies in Jute (Corchorus, Tiliaceae) species, including the cultivated members C. capsularis L. and C. olitorius L. (extensively used for fibre production with commercial purposes), are scarce (Banerjee 1932, Rao and Datta 1953, Sharma and Roy 1958, Datta et al 1966, Paria and Basak 1973.…”