Transformation of Indian citrus for overexpression of a pea Heat Stress Transcription Factor gene (PsHsfA2a)

Abstract

The genus Citrus is one of the most widely grown fruits. The fruits are rich in vitamin C and hence are important part of the world fruit crops. However being sessile they are prone to abiotic as well as biotic stress. Due to climate change, heat stress is the major abiotic stresses. Heat shock proteins are molecular chaperons that are abundant in plants and play an important role in their survival when they are exposed to heat. The heat stress factors (Hsf) are transcriptional regulators of these Hsps. This study aimed at improving heat tolerance of citrus plant by incorporating a novel heat shock factor, HsfA2a, isolated from Pisum sativum (Garden pea). PsHsfA2a, cloned in binary vector pCAMBIA2301 was introduced using Agrobacterium mediated transformation approach. Agrobacterium tumefaciens bacterial strain EHA105 harbouring binary plasmid was used for transformation. This plasmid contains gusA (ß glucuronidase enzyme) reporter gene and NPTII gene conferring kanamycin resistance. Epicotyl explants of Citrus sinensis and Citrus aurantifolia were used to obtain the transgenic plants. An efficient regeneration protocol in presence of BAP (6-Benzylaminopurine) and NAA (1 Naphthaleneacetic acid) hormones were used to develop successful transgenic plants. MS media is used as a basal media for the plant tissue culture. The explants were histochemically assayed for gusA reporter gene expression to confirm the presence of PsHsfA2a transgene.