Genotypic and media effects on plant regeneration from cotyledon explant cultures of someBrassica species

Abstract

Conditions were established for efficient plant regeneration from cotyledon explant calli in different cultivars of Brassica juncea, B. campestris and B. carinata on Murashige & Skoog's (MS) medium supplemented with various combinations of cytokinins and auxins.Regeneration frequency, however, varied with genotype and the different growth hormone combinations in media. Almost in all species, MS medium with zeatin (1.0mg 1 -t) and IAA (0.1 mg 1-t ) was found to be best for shoot organogenesis followed by the ones containing high kinetin (2.0mg 1 -t) and low IAA (0.02 or 0.2mg l -t) concentrations. On these media, the cotyledonary explants invariably underwent callusing followed by multiple shoot formation, which could be separated and subcultured for further propagation. Number of shoots per cotyledon explant cultured varied from 0 to as many as 50. In B. juncea and B. campestris, the regeneration frequency declined sharply in the absence of auxin in medium. BAP in combination with NAA yielded no or a reduced number of shoots. Shoot organogenesis also declined with the reduction in photoperiod from continuous light to 16 hours. Shoots were easily rooted during prolonged incubation on the same medium and whole plants were transferred to pots in the greenhouse and grown to maturity.

A non-antibiotic selection system uses the phosphomannose-isomerase (PMI) gene forAgrobacterium-mediated transformation of Chinese cabbage

“…Compared with other Brassica members, this species is generally considered recalcitrant to in vitro shoot regeneration (Murata and Orton, 1987;Jain et al, 1988;Narashimhulu and Chopra, 1988). Although lower levels of mannose result in more transformants, but simultaneously allow for more untransformed escapes (Fry et al, 1987;Radke et al, 1988), those smaller concentrations can be successful as markers for reducing selection pressure.…”

Genetic transformation of Brassica

“…Tissue culture involves complex interactions and thus to a large extent must rely on empirical data. Almost all imaginable parameters have been investigated such as media, genotype (Jain et al 1988), variation among different explants and the amount of growth regulators applied (Khehra and Mathias 1992). The starting material must be in good physiological condition.…”

Enhancement of Naphthaleneacetic Acid-Induced Rhizogenesis in TL-DNA-Transformed Brassica napus without Significant Modification of Auxin Levels and Auxin Sensitivity

“…Until now, this has not been convincingly demonstrated (19,21). Therefore, we decided to check these two hypotheses by comparing the ability of transformed and untransformed tissues to regenerate buds and roots because it is well known that organogenesis is controlled by numerous interactions among which genotypic and hormonal factors are essential (8,15). Thus, we have undertaken a study using rape (Brassica napus L. var oleifera, cv Brutor) floral stem explants of nontransformed and pRi A4 TL-DNA-transformed genotypes, comparing their responses to several plant growth regulators.…”