RBB1 negatively regulates rice disease resistance by modulating protein glycosylation

Area of Science:

• Plant molecular biology
• Biochemistry
• Plant pathology

Background:

• Glycosylation is a key post-translational modification in eukaryotes, crucial for protein function in physiological and pathological processes.
• UDP-N-acetylglucosamine (UDP-GlcNAc) is vital for glycosylation, but its role in plant defense and senescence is not fully understood.

Purpose of the Study:

• To investigate the role of glycosylation in rice defense responses.
• To identify novel genetic factors influencing plant disease resistance.

Main Methods:

• Identification and characterization of a novel rice mutant (rbb1) with broad-spectrum disease resistance.
• Analysis of biochemical markers, gene expression, and proteome modifications related to defense and glycosylation.
• Gene knockout experiments for specific proteins (Prx4, Prx13).

Main Results:

• The rbb1 mutant, a loss-of-function mutant in glucosamine-6-phosphate acetyltransferase, exhibits enhanced resistance to rice blast and bacterial blight.
• rbb1 shows activated defense responses, including increased reactive oxygen species and malondialdehyde, and reduced UDP-GlcNAc content.
• Alterations in N-glycosylation of disease-resistance proteins, particularly reduced Prx4 and Prx13, were observed in rbb1.
• Knockout of Prx4 or Prx13 also confers enhanced resistance to bacterial and fungal pathogens.

Conclusions:

• Loss of glucosamine-6-phosphate acetyltransferase activity impacts glycosylation and enhances plant defense.
• Altered N-glycosylation of specific proteins like Prx4 and Prx13 is a novel mechanism contributing to broad-spectrum disease resistance in rice.
• These findings suggest potential targets for developing disease-resistant rice varieties.