A Productive Direct Regeneration Protocol for a Wide Range of Winter Squash (Cucurbita maxima Duch.) and Pumpkin (Cucurbita moschata Duch.) Lines

Abstract

The success of Cucurbit transgenic technology depends on regeneration protocol and recovery of transformed plants. Therefore, an efficient regeneration protocol was established for in vitro shoot regeneration from cotyledon explants to optimize the regeneration of multiple adventitious shoots formation in winter squash and pumpkin lines. Proximal parts of cotyledon explants were excised from in vitro seedlings and were cultured on solid MS medium supplemented with various concentrations and combinations of BAP and TDZ. The number of shoot per regenerated explants was ranged from 2.1 (in line 14BO01) to 7.8 (in line 57SI21) in MS medium by addition of 0.5 mg/l BAP and 1 mg/l BAP + 1 mg/l TDZ, sequentially. The cultures were incubated at 25 +/- 1 degrees C and 16-h photoperiod for 4 to 5 weeks. Donors were effective on shoot formation, and 57SI21 in winter squashes and G9 in pumpkins were superior lines. Regenerated shoots were rooted and elongated on MS medium combined with 0.01 mg/l IAA. Elongated and rooted plants were acclimatized with 84% survival rate. Overall, 122 plants (91 of winter squash and 31 of pumpkin) were obtained during the regeneration process. The ploidy analyses revealed that 118 plants were diploid and 4 plants were tetraploid.