Thidiazuron Induces High-Frequency Shoot Regeneration in Intact Seedlings of Pea (Pisum sativum), Chickpea (Cicer arietinum) and Lentil (Lens culinaris)

Abstract

Axenic seedling cultures of chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.) and garden pea (Pisum sativum L.) were established by culturing mature seeds on Murashige and Skoog medium (MS) supplemented with thidiazuron (TDZ). Of various cytokinins or compounds with cytokinin-like activity (Kinetin, TDZ, Zeatin) tested for inducing shoot formation in pea seeds cultures, TDZ was found to be most effective. Pea seedlings exhibited a unique pattern of shoot formation which was accomplished in two distinct phases. Multiple shoots developed within a week, from the nodal and basal regions of the primary epicotyl in a medium that contained 5-50 μM TDZ. When these seedlings were exposed for a prolonged time period (3-4 weeks), to the same medium, numerous shoot buds emerged de novo from the base and/or from the upper part of multiple shoots. These shoots had no apparent vascular connection with parent tissues. The inductive capability of TDZ was then tested in several other genotypes of Pisum sativum and two other large-seeded grain legumes, Cicer arietinum, and Lens culinaris. In Cicer arietinum, and Lens culinaris, multiple shoots developed after 1 week of seed culture on media that contained 1-50 μM TDZ. However, de novo differentiation of shoot buds occurred in cultures exposed to TDZ for 4-6 weeks, only from nodal and subjacent areas. Secondary shoot formation occurred frequently in all of the species tested. Developing shoots were able to form roots and eventually whole plants on a modified MS medium containing 2.5 μM NAA. No genotypic difference for morphogenesis was observed.