Transgenic Chili PossessingBaculovirus Chitinase GeneExhibitsin vitroFungal Inhibition

Abstract

Cultivation of chili ( Capsicum annuum L.) is limited by several fungal diseases, the serious among them being anthracnose.In the absence of a source of resistance for anthracnose in C. annuum background, the transgenic approach, i.e., introduction of a gene encoding pathogen cell wall-degrading enzyme, viz., chitinase, into the host plant against the test fungus Alternaria alternata as well as anthracnose ( Colletotrichum capsici) was explored. Chili being recalcitrant to in vitro regeneration, the regeneration protocol was optimized in cotyledonary explants using different cytokinins, viz., 6-benzyl amino purine (BAP), thidiazuron (TDZ), or zeatin, in combination with gibberellic acid (GA 3 ) and/or auxins, viz., indole-3-acetic acid (IAA) or phenyl acetic acid (PAA). Agrobacterium-mediated transformation of cotyledonary explants with Autographa californica baculovirus chitinase gene under the control of 35S promoter resulted in seven putative transformants under kanamycin selection. The Color versions of one or more of the figures in the article can be found online at www. tandfonline.com/wcim. 159 160 J. B. Mythili et al.presence of transgene was confirmed in two of the seven primary transformants. One of the transformants exhibited enhanced inhibition of the fungus Alternaria alternata in in vitro bio-assays at T0 (primary transformant) stage. The two transgenic plants were then advanced to T1 generation (progenies of T0) and their fruits were examined for resistance to anthracnose. A few lines among the progenies of each of the primary transformants exhibited higher tolerance to anthracnose than the rest of the lines and untransformed control. Higher endochitinase activity in one of the primary transformants was correlated to better expression of anthracnose tolerance in its progenies, suggesting the possibility of chitinase gene being used for developing transgenic lines tolerant to anthracnose.