Isoflavone malonyl-CoA acyltransferase GmMaT2 is involved in nodulation of soybean by modifying synthesis and secretion of isoflavones.

Muhammad Zulfiqar Ahmad, Yanrui Zhang, Xiangsheng Zeng, Penghui Li, Xiaobo Wang, Vagner A Benedito, Jian Zhao

Journal of experimental botany 2021 Feb 24

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Malonyl-CoA:flavonoid acyltransferases (MaTs) modify isoflavones, but only a few have been characterized for activity and assigned to specific physiological processes. Legume roots exude isoflavone malonates into the rhizosphere, where they are hydrolyzed into isoflavone aglycones. Soybean GmMaT2 was highly expressed in seeds, root hairs, and nodules. GmMaT2 and GmMaT4 recombinant enzymes used isoflavone 7-O-glucosides as acceptors and malonyl-CoA as an acyl donor to generate isoflavone glucoside malonates. GmMaT2 had higher activity towards isoflavone glucosides than GmMaT4. Overexpression in hairy roots of GmMaT2 and GmMaT4 produced more malonyldaidzin, malonylgenistin, and malonylglycitin, and resulted in more nodules than control. However, only GmMaT2 knockdown (KD) hairy roots showed reduced levels of malonyldaidzin, malonylgenistin, and malonylglycitin, and, likewise, reduced nodule numbers. These were consistent with the up-regulation of only GmMaT2 by rhizobial infection, and higher expression levels of early nodulation genes in GmMaT2- and GmMaT4-overexpressing roots, but lower only in GmMaT2-KD roots compared with control roots. Higher malonyl isoflavonoid levels in transgenic hairy roots were associated with higher levels of isoflavones in root exudates and more nodules, and vice versa. We suggest that GmMaT2 participates in soybean nodulation by catalyzing isoflavone malonylation and affecting malonyl isoflavone secretion for activation of Nod factor and nodulation. © The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Citation

Muhammad Zulfiqar Ahmad, Yanrui Zhang, Xiangsheng Zeng, Penghui Li, Xiaobo Wang, Vagner A Benedito, Jian Zhao. Isoflavone malonyl-CoA acyltransferase GmMaT2 is involved in nodulation of soybean by modifying synthesis and secretion of isoflavones. Journal of experimental botany. 2021 Feb 24;72(4):1349-1369