Effect of AgNO3 and aminoethoxyvinylglycine on in vitro shoot and root organogenesis from seedling explants of recalcitrant Brassica genotypes.

The presence of 1-10 μM aminoethoxyvinylglycine (AVG) or 5-30 μM AgNO3 markedly enhanced shoot regeneration from cotyledon and hypocotyl cultures of eight recalcitrant Brassica campestris and B. juncea genotypes tested. Expiants of B. campestris ssp. chinensis and ssp. parachinensis grown with a high AVG concentration (20 μM), regenerated poorly. All cytokinins tested were equally effective in promoting shoot formation, except that kinetin was inhibitory to shoot regeneration from hypocotyls of B. campestris ssp. pekinensis (cv. Wong Bok). Both AgNO3 and AVG had no effect on percent rooting and number of roots per rooted cutting of Wong Bok, White Sun and Leaf Heading, but AgNO3 was inhibitory to rooting of India Mustard. However, root elongation of all cuttings was markedly inhibited by AVG at concentrations of 5 and 10 μM.