The plant galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) have been linked to the anti-inflammatory and cancer benefits of a green leafy vegetable diet in humans due to their ability to regulate the levels of free radicals like nitric oxide (NO). Here, we show that DGDG contributes to plant NO as well as salicylic acid biosynthesis and is required for the induction of systemic acquired resistance (SAR). In contrast, MGDG regulates the biosynthesis of the SAR signals azelaic acid (AzA) and glycerol-3-phosphate (G3P) that function downstream of NO. Interestingly, DGDG is also required for AzA-induced SAR, but MGDG is not. Notably, transgenic expression of a bacterial glucosyltransferase is unable to restore SAR in dgd1 plants even though it does rescue their morphological and fatty acid phenotypes. These results suggest that MGDG and DGDG are required at distinct steps and function exclusively in their individual roles during the induction of SAR.

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Notes/Citation Information

Published in Cell Reports, v. 9, no. 5, p. 1681-1691.

©2014 The Authors

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

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Funding Information

This work was supported by grants from National Science Foundation (IOS#0749731, MCB#0421914) and Kentucky Science and Engineering Foundation (2930-RDE-016).

mmc1.pdf (3585 kB)
Document S1. Supplemental Experimental Procedures and Figures S1–S5.

mmc2.pdf (6762 kB)
Document S2. Article plus Supplemental Information.