Assorted response of mutated variants of vanilla planifolia Andr. towards drought

The mutated variants of Vanilla planifolia Andr. exhibited much variability in their morphology as well as their growth rate. While all the variants and control recorded a decrease in the leaf chlorophyll content and O-2 evolution rate on being subjected to drought stress, in V-3 alone, the decrease in the O-2 evolution rate did not vary much from its unstressed genotypes. The limited distribution of stomata in V-3 (1.65) as compared to other variants and control plants ensured sufficient gas exchange for an efficient photosynthesis, at the same time helps to counter the water loss effectively. The high level of lipid peroxidation in V-4 and V-5 points out towards its inefficiency in utilizing the incident light when exposed to drought, which was otherwise found to be optimal under normal conditions, whereas, the MDA level was lesser in V-3 (only 22% more than watered) as compared to other variants. Proline and carotenoids were found to have a significant role in the detoxification of the free radicals in V-3 as compared to the role of peroxidase, whereas in other variants and control plants, peroxidase was found to have a prominent role in free radical scavenging. The enhanced synthesis of proteins observed in stressed plants of C-1, V-2 and V-3 might help to alleviate the stress-related damage to the system. The enhanced pool of free amino acids in these plants supplements the enhanced rate of protein synthesis observed in them. Total carbohydrates were found to increase in plants subjected to water stress, which contributes towards the osmotic adjustment. The results of this study denote the different level of drought tolerance of mutated variants of Vanilla planifolia Andr.