Micropropagation of three genotypes of Indian mustard [{Brassica juncea} (L.) Czern.] using seedling-derived transverse thin cell layer (tTCL) explants

TL;DR

This study developed an efficient micropropagation protocol for three Indian mustard genotypes using seedling-derived tTCL explants, optimizing hormone concentrations and silver nitrate addition to maximize shoot induction and plantlet survival.

Contribution

It introduces a novel, optimized micropropagation method for Indian mustard using seedling-derived tTCL explants with specific hormone and silver nitrate treatments.

Findings

Cotyledon-derived tTCLs showed highest shoot induction.

Silver nitrate significantly increased shoot induction rates.

Rooted plantlets had 99% survival and flowered normally.

Abstract

Micropropagation of three genotypes of Indian mustard [\textit{Brassica juncea} (L.) Czern.] using 7-days old seedling-derived transverse thin cell layer (tTCL) explants was accomplished. The genotype, explant source and addition of silver nitrate to the medium significantly influenced shoot bud induction. MS medium with 26.6 $\mu$M of 6-Benzylaminopurin (BAP) and 3.22 $\mu$M of 1-naphtaleneacetic acid (NAA) was identical (in the case of cotyledon tTCLs whatever the organ) and superior for the induction of buds (in the cases of petiole tTCL explants of genotypes 1 and 2 and hypocotyl tTCL explants of genotypes 1 and 3) than 53.3 $\mu$M of BAP and 3.22 $\mu$M of NAA. However, 53.3 $\mu$M of BAP was superior for the induction of buds than 26.6 $\mu$M in the presence of the same concentration of NAA for petiole tTCL explants of genotype 3 and hypocotyl tTCL explants of genotype 2. The addition of silver nitrate significantly enhanced the rate of shoot induction in all genotypes. Cotyledon-derived tTCL explants exhibited the highest shoot bud induction potential and was followed by petiole- and hypocotyl-derived ones. Addition of 10 $\mu$M of silver nitrate to BAP and NAA supplemented medium induced higher frequency shoot bud induction (up to 100 %) with the highest means of 4.45 shoots per cotyledon-derived tTCL explants obtained with the genotype 2. Shoot regenerated were rooted on MS basal medium without PGRs which induced 99 % of roots per shoot. The plantlets established in greenhouse conditions with 99 % survival, flowered normally and set seeds.