Overexpression of β-carotene hydroxylase1 (BCH1) in Indian mulberry, Morus indica cv. K2, confers tolerance against UV, high temperature and high irradiance stress induced oxidative damage

In general, stress caused by high light, high temperature and UV irradiation is unified and leads to the production of reactive oxygen species (ROS) having detrimental consequences for plants. Carotenoids are present in all photosynthetic plants as accessory pigments and have been implicated in protection against photooxidative damage. One major enzyme in the carotenoid biosynthetic pathway, beta-carotene hydroxylase has been maneuvered for increasing stress tolerance of plants. Overexpression of beta-carotene hydroxylase1 (BCH1) in Morus indica cv. K2 under the influence of CaMV 35S promoter was undertaken by Agrobacterium-mediated transformation. This gene when over expressed shows higher levels of carotenoids and improved oxidative stress tolerance as compared with the untransformed wild type under non-stressed and stressed conditions. The carotenoid and chlorophyll content was found to be enhanced in the overexpression lines under different stresses. The amount of ROS was found to be significantly lower in the overexpression line. Also, a corresponding increase in membrane stability suggests a positive role of the over expression of BCH1 on maintaining membrane integrity under induced oxidative stress conditions. Enhanced tolerance to high light, heat and UV irradiation was achieved in M. indica cv. K2 indicating the potential of this gene to suit the changing climatic conditions.