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In vitro plant regeneration of 'Ramsi' tomato landrace (Solanum lycopersicum L.) from cotyledonary explant

Al-Khayri, J. M., Naik, P. M., Alwael, H. A.
Acta horticulturae 2017 no.1187 pp. 43-50
Solanum lycopersicum, benzyladenine, callus, cotyledons, cultivars, explants, genetic improvement, in vitro regeneration, indole acetic acid, indole butyric acid, landraces, naphthaleneacetic acid, oases, plantlets, potting mix, rooting, roots, shoots, tomatoes, zeatin, Saudi Arabia
The 'Ramsi' tomato (Solanum lycopersicum L.) is a landrace cultivar adapted to Qatif oasis in the Eastern Province of Saudi Arabia along the Arabian Gulf. The objective of this study was to develop an efficient in vitro plant regeneration protocol for the 'Ramsi' tomato cultivar. Cotyledonary explants were cultured for 8 weeks on Murashige and Skoog (MS) semisolid medium containing 0.5, 1, 2 and 5 mg L-1 of either 6-benzylaminopurine (BAP) or 6-(4-hydroxy-3-methylbut-2-enylamino) purine (Zeatin, ZN) in combination with 0.1, 0.5, 1 and 2 mg L-1 of either α-naphthaleneacetic acid (NAA) or indole-3-acetic acid (IAA). The highest callus growth (4.9 g) was observed in response to 1 mg L-1 BAP+0.5 mg L-1 NAA. The highest number of shoots (3 shoots explants-1) formed in 75% of the explants in response to 0.5 mg L-1 ZN+2 mg L-1 IAA. For rooting, regenerated shoots were transferred to either full- or half-strength MS medium supplemented with IAA, indole-3-butyric acid (IBA) or NAA at 0.1, 0.25, 0.5 and 1 mg L-1. After 3 weeks of culture, the highest number of roots occurred in MS full strength medium supplemented with 0.5 mg L-1 NAA (17 roots explants-1) but mean root length was only 1 cm. In contrast, 1 mg L-1 IAA induced 14.7 roots shoot-1 with the root length of 5.9 cm. Plantlets were successfully acclimatized in potting soil with 90% survival. This is the first report of in vitro regeneration of this important landrace cultivar; thus satisfying the perquisite for further application of biotechnological approaches for potential genetic improvement.