Global transcriptome analysis reveals distinct expression among duplicated genes during sorghum-interaction

Area of Science:

• Plant pathology
• Molecular biology
• Biochemistry

Background:

• Sorghum (Sorghum bicolor L. Moench) is a valuable source of natural phytochemicals.
• Target leaf spot, caused by the necrotrophic fungus Bipolaris sorghicola, is a significant sorghum disease.

Purpose of the Study:

• To identify differentially expressed genes in sorghum BTx623 upon infection with Bipolaris sorghicola.
• To understand the molecular mechanisms underlying sorghum's response to fungal pathogens.

Main Methods:

• Massive parallel mRNA sequencing of infected and mock-inoculated sorghum leaves.
• Bioinformatic analysis to predict unannotated transcripts and identify differentially expressed genes.
• Statistical analysis to determine gene significance and upregulation patterns.

Main Results:

• Identified statistically significant differentially expressed genes, with notable upregulation in tandemly duplicated paralogs.
• Observed activation of the glyoxylate shunt in the TCA cycle, shifting its role to synthesis.
• Detected activation of phytoalexin synthesis and sulfur-dependent detoxification pathways via upregulated amino acid metabolizing enzymes.
• Demonstrated coordinated gene expression potentially directing the accumulation of sorghum-specific phytochemicals like 3-deoxyanthocyanidin and dhurrin.
• Noted the absence of key enzymes for these phytochemicals in the rice genome, highlighting sorghum specificity.

Conclusions:

• Pathogen infection profoundly alters the expression of specific paralogs involved in sorghum's unique metabolic network.
• The study reveals a complex molecular response in sorghum to fungal attack, involving metabolic reprogramming and phytochemical synthesis.