Nuclear DNA and RNA amounts in the wild and cultivated urd and mung beans and their M1 plants.

Abstract

Recent advances on the molecular probing of the structure and organisation of complex eukaryotic genomes coupled with the cytogenetical analysis revealed the existence of bewilder ing complexity in the eukaryotic genome above one gene level (Dover et al. 1982). An un derstanding of the organisation of eukaryotic genome not only paves the way for elucidating genome evolution and speciation, but also enables us to explain how the total phenotype is influenced by the different facets of genome structure and organisation (Flavell 1982). Various reports so far indicate that chromosomal DNA amount is changeable to some extent within a species (Jones and Rees 1968, Ayonoadu 1974, Belford and Thompson 1981, Nagato et al. 1981, Yamamoto and Nagato 1984. Although enough reports are there with regard to the DNA amounts in various crops (Nagato et al. 1981, Resslar et al. 1981) not much work has been done on the mutant lines. In the present investigation, we examined the variation of DNA and RNA amounts in Vigna sublobata (Roxb.) Babu and Sharma (wild), V. radiata (L.) Wilczek and V. mungo (L.) Hepper (cultivars) along with their M1 generation plants to un derstand the mechanism of mutational action in the wild and cultivated species and its role in plant evolution and domestication. Materials and methodsSeeds of Vigna radiata cv. PS 16, V. mungo cv. T 9 (obtained from Pulse Research Labo ratory, IARI, New Delhi) and V. sublobata (harvested from the garden-grown progenies of a natural population collected from Palney Hills of Western Ghats, Tamilnadu) were used for the induction of mutations. Ethylmethane sulphonate (EMS) and gamma rays were used as mutagens. The dose of the physical mutagen was expressed as kilorads. Three mutagenic treatment-EMS alone, gamma rays alone and EMS+gamma rays combined-were employed. The dose treatments of EMS, gamma rays and EMS+gamma rays applied were: 0.1%, 0.2%, 0.3% and 0.4%, 10KR, 20KR, 30KR and 40KR, and 0.1%+10KR, 0.2%+20KR, 0.3%+30KR and 0.4%+40KR, respectively. EMS was dissolved in distilled water and the seeds were soaked in the aqueous solution of appropriate concentration for 10h, after 6h of pre-soaking in distilled water. The treated seeds were thoroughly washed in running water for 12h and the excess moisture was blotted off. The moisture content of the seed, before mutagen treatment, was adjusted to 10.5-11.0% by differential drying in an air oven. 60Co was used as the source of gamma rays for the irradiation of seeds, which was carried out at the irradiation unit of IARI, New Delhi, at a dose rate of 2500 rads min-1. For the com bined treatment, the seeds were first irradiated with gamma rays and then treated with EMS; a control was also maintained. Two replicates of 150 seeds each were sown in the field for each dose treatment in a randomized block design. Seeds from each plant of M1 generation were harvested separately and used for the analysis of DNA and RNA content.Feulgen cytophotometric method was used for the in situ localization of 2C DNA amount

Quantitative DNA variation between and within chromosome complements of Vigna species (Fabaceae)

“…The mean value differs significantly for the estimated DNA value (0.96 pg) reported by Thompson and Murray (1980). The present estimate is closer to the DNA value (3.54 pg) reported by Ignichimuthu and Babu (1988). Yet, the difference is of the order of 32 per cent.…”

Karyotype, Nuclear and Chromosomal DNA Variation in Lens culinaris Med.

“…LL-19 (Tables 2, 3). The variation in nuclear DNA content may be associated with the divergence and evolution of species (Nagato et al 1982, Narayan 1982, Seal and Rees 1982, Raina et al 1986, Ignacimuthu and Babu 1988. The factors leading to variation in nuclear DNA contents include addition or deletion of chromosome segments (Rees and Hazarika 1969) and hybridization between species with large DNA differences (Keyl 1965, Jones andRees 1968).…”