Influence of High Concentrations of Copper Sulfate on In Vitro Adventitious Organogenesis of Cucumis sativus L.

Abstract

The effects of different concentrations of copper sulfate (0.2 to 5 mg L-1) on in vitro callus and shoot formation of cucumber was investigated. Four-day-old cotyledon explants from the inbred line Wisconsin 2843 and the commercial cultivars Marketer and Negrito were used. The results on callus-derived shoots showed that the optimal concentration of CuSO4 added to Murashige & Skoog (MS)-derived shoot induction medium containing 0.5 mg L-1 IAA and 2.5 mg L-1 BAP was 8-200 fold greater than in standard MS medium, and was genotype dependent. The highest genotypes response on shoot frequency and shoot number was achieved in this order by Marketer, Negrito and Wisconsin 2843 with 1, 0.2 y 5 mg L-1 CuSO4, respectively. The genotype with the lowest control performance demanded the highest concentration of CuSO4 for its optimal morphogenic response - 6- and 10-fold more in shoot frequency and shoot number, respectively. The other cultivars registered a 2-fold increase in both variables. All explants formed callus and the response on callus extension varied among cultivars. The regression analysis showed a statistically significant relationship between shoot number and concentrations of CuSO4 and absence of association with callus extension. The present results indicate that application of specific concentrations of CuSO4 higher than in standard MS medium, increases adventitious cucumber shoot organogenesis.