Over Expression of Chitinase and Chitosanase Genes from <i>Trichoderma harzianum</i> under Constitutive and Inducible Promoters in order to Increase Disease Resistance in Wheat (<i>Triticum aestivum</i> L)

Abstract

Powdery mildew of wheat, caused by Erysiphe graminis f.sp. tritici is a serious threat to wheat grain production in many parts of the world. Efforts have been made to engineer resistance into wheat using single gene technology which culminated in the improved resistance efficiency but never a complete control. Some efforts of expressing genes for disease resistance under the control of constitutive promoter resulted in the production of abnormal plants. We used double gene technology and over expressed a couple of antifungal genes i.e., chitinase and chitosanase from Trichoderma harzianum simultaneously into winter wheat genotype Florida . They were expressed separately under the constitutive promoter ( Ubiquitin- 1) from Maize and stress cum disease inducible promoter ( Vst -1) from Vitis vinefera . Six lines achieved under constitutive promoter and five lines under inducible promoter showed the co-integration and expression of chitinase and chitosanase genes. All these lines showed multiple copy integration of both these genes except one line which showed single copy integration of chitinase under ubiquitin promoter. The copy number varied for Chitinase (1-3) and Chitosanase (2-10). Different promoters did not seem to have any impact on transformation efficiency. Pathological analysis done with E.graminis showed a decrease in the susceptibility for both types of transgenic plants. A decrease in susceptibility was seen upto 75% when the transgenics were under inducible promoter. While in transgenics under constitutive promoter the decrease in susceptibility of upto 60% was seen. All the primary transforments with the exception of a couple showed normal growth.