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Title: Defense-related reprogramming in Sorghum bicolor against infection by Burkholderia andropogonis : a metabolomics study

Ian Dubery

University of Johannesburg, South Africa

Biography

Prof. Ian Dubery received his PhD in 1982 and has since published more than 140 research papers in ISI-listed international journals. His interest are plant-microbe interactions, plant defense responses and plant metabolomics.

He is a council member of the South African Society for Biochemistry and Molecular Biology (SASBMB) and the director of the Research Centre for Plant Metabolomics at the University of Johannesburg, South Africa.

Abstract

Background: Burkholderia andropogonis is the causal agent of bacterial leaf stripe, one of the three major bacterial diseases affecting Sorghum bicolor. However, the biochemical aspects of the pathophysiological host responses are not well understood. An untargeted metabolomics approach was designed to understand molecular mechanisms underlying S. bicolorB. andropogonis interactions. At the 4-leaf stage two sorghum cultivars (NS 5511 and NS 5655), differing in disease susceptibility/resistance, were infected with B. andropogonis, and the metabolic changes monitored over time.

Results: The NS 5511 cultivar displayed delayed signs of wilting and lesion progression compared to the NS 5655 cultivar, indicative of enhanced resistance. The metabolomics results identified statistically significant metabolites as biomarkers associated with the sorghum defence. These include the phytohormones salicylic acid, jasmonic acid and zeatin. Moreover, metabolic reprogramming in an array of chemically diverse metabolites that span a wide range of metabolic pathways was associated with the defense response. Signatory biomarkers included aromatic amino acids, shikimic acid, metabolites from the phenylpropanoid and flavonoid pathways, as well as fatty acids. Enhanced synthesis and accumulation of apigenin and derivatives thereof, was a prominent feature of the altered metabolomes.

Conclusions: The analyses revealed an intricate and dynamic network metabolic pathways and metabolites comprisingthe sorghum defence arsenal towards B. andropogonis in establishing an enhanced defensive capacity in support of resistance and disease suppression.