English abstract
Eight accessions of tomato were tested for in vitro regeneration responses. Two explants i.e. fully expanded true leaves and cotyledon leaf were cut into leaf discs and cultured on two distinct media. Murashige and Skoog salts were modified with 6-Benzylaminopurine (1.0 mg/l) and 1-Naphthaleneacetic acid (0.1 mg/l) and 3-Indoleacetic acid (0.1 mg/l) and zeatin (1.0 mg/l) for true leaf and cotyledon leaf explants, respectively for callus induction. For shoot regeneration, Murashige and Skoog salts modified with zeatin (2 mg/l) and 3-Indoleacetic acid (0.1 mg/l) were used for each of two explants. Data were collected for the percentage of callus induction, callus fresh weight, callus size and number of shoots. There were significant genotypic and explants effects observed for initiation and growth of callus. The highest percentage (47) for callus induction was for accession PT4719A. Shoot regeneration occurred after repeated subcultures. Again, genopytic and explant effects were significant. All accessions regenerated plantlets from true leaf explants whereas cotyledon leaf explants of accessions PT4719A, PT4664B and CLN2116B were unresponsive for callus induction and regeneration. The highest percentage of callus was 100% in the case of cotyledon explant of accession CL5915206. The highest area of callus spread for true and cotyledon explant was observed in PT4719A (2,68 cm2) and CLN2123A (2.59 cm2) respectively. Amongst true leaf and cotyledon leaf explants, the callus fresh weight was highest for CLN2123A (1.52 mg) and CLN2026D (2.53 mg), respectively. CLN2026D also produced highest number of shoots per callus (12) from cotyledon explant and 0.4 from true leaf explant. PT4719A gave highest number of shoots per callus from true leaf explant (4.6) whereas it was unresponsive for cotyledon leaf regeneration. The results showed that though some accessions like PT4719A gave highest regeneration response for true leaf explants, it was totally unresponsive for cotyledon explants. In the case of cotyledon explants, it was observed that there was no correlation between the percentage of callus induction and number of shoots per callus. There was no direct correlation between percentage of callus induction, callus weight, size and number of shoots regenerated for any of the genotype and explant combinations. Clearly, the genotype and explant effects were significant.
