Regeneration of the tropical legume Aeschynomene sensitiva Sw. from root explants

Abstract

Regeneration of Aeschynomene sensitiva Sw. after callogenesis was obtained from small (2–5 mm long) root explants of 30-day-old seedlings aseptically cultivated on Murashige and Skoog medium supplemented with various concentrations of growth regulators. After 4 weeks, the best results were observed with 0.54 μM α-naphthaleneacetic acid and 2.22 μM benzyladenine. On this medium, the rate of regeneration depended on seedling age and agar concentration. The highest number of shoots per explant was obtained with small cuttings from 30-day-old seedlings grown on a medium containing 8 g l⁻¹ of agar. Regeneration success was also dependent on explant size. When longer explants (7–20 mm) were cut from the main root, direct regeneration was obtained in two weeks. These cuttings also generated shoots through callogenesis in four weeks but always in lower quantities than with direct regeneration, whatever the seedling age. here also, the best regeneration was obtained with cuttings from 30-day-old seedlings maintained on a medium with 8 g l⁻¹ of agar. Regenerants were rooted on growth-regulator-free Murashige and Skoog medium and then acclimatized in a greenhouse. A better survival to transplantation was observed when plantlets were inoculated with the photosynthetic Bradyrhizobium strain ORS 278. Stem and root nodules developed on the inoculated plantlets and were able to fix nitrogen.