A Feedback Regulatory Loop between G3P and Lipid Transfer Proteins DIR1 and AZI1 Mediates Azelaic-Acid-Induced Systemic Immunity

Keshun Yu, Juliana Moreira Soares, Mihir Kumar Mandal, Caixia Wang, Bidisha Chanda, Andrew N. Gifford, Joanna S. Fowler, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

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151 Scopus citations


Systemic acquired resistance (SAR), a highly desirable form of plant defense, provides broad-spectrum immunity against diverse pathogens. The recent identification of seemingly unrelated chemical inducers of SAR warrants an investigation of their mutual interrelationships. We show that SAR induced by the dicarboxylic acid azelaic acid (AA) requires the phosphorylated sugar derivative glycerol-3-phosphate (G3P). Pathogen inoculation induced the release of free unsaturated fatty acids (FAs) and thereby triggered AA accumulation, because these FAs serve as precursors for AA. AA accumulation in turn increased the levels of G3P, which is required for AA-conferred SAR. The lipid transfer proteins DIR1 and AZI1, both of which are required for G3P- and AA-induced SAR, were essential for G3P accumulation. Conversely, reduced G3P resulted in decreased AZI1 and DIR1 transcription. Our results demonstrate that an intricate feedback regulatory loop among G3P, DIR1, and AZI1 regulates SAR and that AA functions upstream of G3P in this pathway.

Original languageEnglish
Pages (from-to)1266-1278
Number of pages13
JournalCell Reports
Issue number4
StatePublished - Apr 25 2013

Bibliographical note

Funding Information:
We thank Robin Guillaume for help with figures, Qing-ming Gao for help with real-time quantification, John Johnson for help with gas chromatography, and David Hildebrand for providing 14 C-18:2 and lipid standards. We thank Jean Greenberg for useful discussion and for sharing unpublished data, Tsuyoshi Nakagawa for pGWB vectors, and ABRC for SALK lines. We thank Ludmila Lapchyk for technical help and Amy Crume for managing the plant growth facility. This work was supported by a grant from the National Science Foundation (IOS#0749731 and #051909) to A.K. and P.K. K.Y. developed procedures for AA precursor analysis, TLC, and free FA estimations, and carried out these analyses. J.M.S. analyzed transgenic plants and carried out free FA analysis, G3P analysis, and real-time quantifications with contributions from M.K.M. and B.C. M.K.M. generated transgenic plants. Confocal microscopy was carried out by J.M.S. and M.K.M. SAR experiments were carried out by J.M.S., C.W., and B.C. D.N. estimated SA. A.N.G. and J.S.F. synthesized radiolabeled AA. P.K. and A.K. supervised the project and wrote the manuscript.

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology (all)


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