Underground AZA priming against pathogens
S. ROYCHOUDHRY (1), N. Cecchini (2), J. Greenberg (1) (1) University of Chicago, U.S.A.; (2) University of Chicago, U.S.A.

Local foliar infection by diverse pathogens can lead to whole plant immunity, a condition known as systemic acquired resistance (SAR). During this process, distal leaves become ‘primed’ to mount a stronger defense response after secondary infection, due to the translocation of mobile signals from the site of infection to distal tissue. One such mobile priming molecule is the dicarboxylic acid azelaic acid (AZA) that is made in plastids. The lipid transfer protein AZI1 and its paralog EARLI1 are required for normal AZA transport during SAR. Interestingly, AZI1 and EARLI1 are also expressed in roots and are necessary for induced systemic resistance (ISR) upon colonization by Pseudomonas fluorescens. This suggests that AZA signaling and/or transport may play a role in ISR. The mechanism(s) by which AZA (and other priming molecules) induce ISR remain unknown. We investigated the effects of AZA on Arabidopsis roots. Growth on AZA-containing MS plates drastically inhibited root growth in WT, but not azi1 and earli1 plants. Moreover, treatment of the roots of soil-grown Arabidopsis with AZA induced systemic resistance to P. syringae in aerial tissue in WT plants. We found that AZI1 localizes to the plasma membrane and is also present in small punctate structures across root cells. Additionally, AZI1 also partially co-localizes with root plastids, suggesting that the sites of action of AZI1 in roots may be similar to that in leaves. Taken together, our results suggest that AZA or similar molecules derived from roots may serve as a systemic priming signal through an AZI1/EARLI1-dependent pathway.

Abstract Number: C15-4, P18-700
Session Type: Concurrent