Over-Expression of Endogenous SUGARWIN Genes Exalted Tolerance against Colletotrichum Infection in Sugarcane

Abstract

Sugarcane being the major contributor of sugar and potential source of biofuel around the globe, occupies significant commercial importance. Red rot is the most devastating disease of sugarcane, severely affecting its quality as well as yield. Here we report the overexpression of SUGARWIN1 and SUGARWIN2 genes in any field crop for the first time. For this purpose, SUGAWIN1 and SUGARWIN2 were cloned downstream of maize ubiquitin (Ubi-1) promoter to construct two independent expression cassettes. The bar gene conferring resistance against phosphinothricin was used as selectable marker. Embryogenic calli of sugarcane were bombarded with both expression cassettes and selected on regeneration medium supplemented with phosphinothricin. The phosphinothricin-resistant shoots were rooted and then, analyzed using molecular tools at the genomic as well as transcriptomic levels. The transcriptomic analysis, using real time qPCR, showed that expression of SUGARWIN1 (SWO) and SUGARWIN2 (SWT) was higher in transgenic plants as compared to untransformed plants. Our results further demonstrated that over expression of these genes under maize ubiquitin (Ubi-1) promoter causes significant restriction in proliferation of red rot causal agent, Colletotrichum falcatum in sugarcane transgenic plants, under in vitro conditions. This report may open up exciting possibilities to extend this technology to other monocots for the development of crops with better ability to withstand fungal pathogens.