Abstract
Our earlier studies reported development of transgenic strawberry for salinity stress and standardization of transformation protocol. In view of the projections of global climate change and their implications on the ability of strawberry to adapt to such changes, we extended our studies to know the possible role of such transgenic plants in contributing to sustainable strawberry production and also made some basic studies to analyse the behaviour of osmotin (transgene)/in vitro-regenerated transgenic strawberry plants. Ten different lines of transgenic strawberry plants, with osmotin transgene were developed using Agrobacterium-mediated method. Expression of osmotin gene was observed in three transgenic lines and drought tolerance was confirmed. RAPD analysis, within its limits of sensitivity and accuracy, failed to detect any appreciable polymorphism in the genomic DNA of wild and tissue culture-raised (transgenic and control) plants. No morphological abnormalities were detected in the transgenic lines overexpressing osmotin, although their rate of growth was lesser under in vitro as well as ex vitro conditions, possibly due to diversion of energy towards constitutive expression of osmotin. These plants resumed normal growth and overcame the growth penalty when inoculated with Piriformospora indica. Surprisingly, the overexpression of osmotin, a PR-5c protein with antifungal activity, had no adverse impact on the colonization or symbiotic association of P. indica and Sebacina vermifera with these transgenic plants. We report here on the association of symbiotic fungi with transgenic strawberry and their usefulness in overcoming growth penalty in such transgenic plants.