In Vitro Organogenesis of Brassica juncea (L.) from Callus as Explant from Stem and Leaf

This study aimed to establish an optimized in vitro callus induction and proliferation protocol from different parts of Indian Brassica juncea (L.) Czern & Coss. (mustard). The leaf and stem explants were cultured on Murashige and Skoog (MS) medium supplemented with various auxins and cytokinin concentrations for optimal conditions of growth of callus formation. Indole-3-acetic acid (IAA) at 0.5, 1, and 2 mg/L, Benzyl aminopurine at 0.5, 1, and 2 mg/L, as well as 2,4-dichlorophenoxyacetic acid (2,4-D) at 0.5, 1, and 2 mg/L were the hormonal combinations tested. Callus production from leaves and stem explants, based on callus induction frequency was assessed in three replications on the set of different periods and culture conditions of light, temperatures, and humidity. The results of the leaf as an explant in MS media supplemented with BAP and 2,4 D in a 1:1 ratio showed the highest callus induction rate after 45 days of inoculations which is unique. After 45 days of inoculation of stem explant, the callus generated at hormonal concentrations BAP: IAA (0.5:1). These generated calli displayed noticeable elongation and well-formed leaves. This proliferation of undifferentiated callus tissues greening, and formation of mature shoots highlights the efficacy of the callus Habituation after subculturing, and continued passage results in no need for Cytokinin additions in media. Acquired cytokinin by callus tissues, results in shooting and vegetative organ development. In turn, these cells allowed for organogenesis where mature plants regenerated successfully. This reproducible protocol can be used in callus induction and plant regeneration, which are important tools in plant breeding or biotechnological applications including genetic transformation for crop improvement. Moreover, knowledge about interactions between phytohormones in mustard tissues has been improved by the established protocol.