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Title: Glycerol-3-Phosphate Levels Are Associated with Basal Resistance to the Hemibiotrophic Fungus Colletotrichum higginsianum in Arabidopsis

Author
item CHANDA, B - UNIV OF KENTUCKY
item VENUGOPAL, S - UNIV OF KENTUCKY
item KULSHRESTHA, S - UNIV OF KENTUCKY
item Navarre, Duroy - Roy
item DOWNIE, B - UNIV OF KENTUCKY
item VAILLANCOURT, L - UNIV OF KENTUCKY
item KACHROO, A - UNIV OF KENTUCKY
item KACHROO, P - UNIV OF KENTUCKY

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2008
Publication Date: 8/1/2008
Citation: Chanda, B., Venugopal, S.C., Kulshrestha, S., Navarre, D.A., Downie, B., Vaillancourt, L., Kachroo, A., Kachroo, P. 2008. Glycerol-3-Phosphate Levels Are Associated with Basal Resistance to the Hemibiotrophic Fungus Colletotrichum higginsianum in Arabidopsis. Plant Physiology. 147(4): 2017–2029.

Interpretive Summary: This work shows that glycerol-3-phosphate (G3P) plays an important role in plant resistance to the fungal pathogen Colletotrichum higginsianum. The ability of the plant to accumulate increased levels of G3P upon encountering this fungal pathogen is important to achieve high levels of resistance. Mutant plants unable to accumulate normal levels of G3P were hypersusceptible to infection but were able to accumulate normal levels of the defense hormone salicylic acid. This work further clarifies mechanisms involved in improving plant disease resistance.

Technical Abstract: Glycerol-3-phosphate (G3P) is an important component of carbohydrate and lipid metabolic processes. In this article, we provide evidence that G3P levels in plants are associated with defense to a hemibiotrophic fungal pathogen Colletotrichum higginsianum. Inoculation of Arabidopsis (Arabidopsis thaliana) with C. higginsianum was correlated with an increase in G3P levels and a concomitant decrease in glycerol levels in the host. Plants impaired in utilization of plastidial G3P (act1) accumulated elevated levels of pathogen-induced G3P and displayed enhanced resistance. Furthermore, overexpression of the host GLY1 gene, which encodes a G3P dehydrogenase (G3Pdh), conferred enhanced resistance. In contrast, the gly1 mutant accumulated reduced levels of G3P after pathogen inoculation and showed enhanced susceptibility to C. higginsianum. Unlike gly1, a mutation in a cytosolic isoform of G3Pdh did not alter basal resistance to C. higginsianum. Furthermore, act1 gly1 double-mutant plants were as susceptible as the gly1 plants. Increased resistance or susceptibility of act1 and gly1 plants to C. higginsianum, respectively, was not due to effects of these mutations on salicylic acid- or ethylene-mediated defense pathways. The act1 mutation restored a wild-type-like response in camalexin-deficient pad3 plants, which were hypersusceptible to C. higginsianum. These data suggest that G3P-associated resistance to C. higginsianum occurs independently or downstream of the camalexin pathway. Together, these results suggest a novel and specific link between G3P metabolism and plant defense.