In vitro direct seed-to-seed regeneration of Lens culinaris Medik. for speed breeding

This study optimized a protocol for in vitro direct seed-to-seed regeneration of lentil (Lens culinaris Medik.) var. WBL77 (Maitree) to facilitate the rapid advancement of generations for speed breeding applications. Three lentil varieties (WBL77, BL16 and MM216) were initially evaluated on Murashige and Skoog (MS) medium for germination and early seedling growth. WBL77 outperformed BL16 and MM216 in that preliminary germination and growth evaluation, demonstrating the shortest germination time (2.8 days), highest shoot number (2.2), root number (3.4), and root length (6.8 cm), establishing it as the ideal variety for subsequent in vitro regeneration experiments using a two-phase seed-to-seed development approach. Observations on growth and developmental parameters from seed germination to harvest were recorded during both phases. In phase-1, fresh seeds of WBL77 were cultured on MS medium supplemented with 1.5 mg L^− 1 meta-Topolin, wherein a quicker germination (2.7 days), higher number (6.4) and length (14.0 cm) of shoots, and pods shoot^-1 (4.9). On the other hand, phase-2, that initiated with the seeds harvested from regenerated plantlets of phase-1, exhibited a higher root number (4.1) along with earlier flower initiation (41.3 days) and pod formation (51.4 days). Both phases showed a rapid generation advancement than the field condition, demonstrating the applicability of this protocol for speed breeding in lentil.