Further Characterization of Pathogen Inducted Flavonoid Biosynthesis Genes In Sorghum Sorghum

Abstract

Sorghum, one of the top-ranked cereal crops, can be utilized as food and animal feed or for alcohol production. It is vulnerable to fungal infection, which can lead to significant economic loss. Sorghum phytoalexins, which comprise a specific group pf flavonoids called 3-deoxyanthocyanidins, may permeate cell wall and suppress fungal proliferation when produced at the right time, in the right place, and in sufficient quantities. Biosynthesis of 3-deoxyanthocyanidins requires the key flavonoid branch-point enzyme chalcone synthase encoded by a family of genes which are mostly pathogen-inducible. The next step involves the isomerization of chalcones to flavanones which is catalyzed by CHI but it may also occur spontaneously in some plants. This study investigates the involvement of CHI in the pathogen-inducible biosynthesis of 3-deoxyanthocyanidins in sorghum. After pathogen inoculation, crude protein extracts from a resistant cultivar showed earlier and higher CHI enzymatic activity compared with those prepared from a susceptible cultivar. In addition, recombinant CHI showed very high activity in vitro. We also generated sorghum CHI overexpression transgenic lines by microprojectile bombardment in callus induced from Tx430 immature embryo for further analysis.