Elevated salicylic acid levels conferred by increased expression of ISOCHORISMATE SYNTHASE 1 contribute to hyperaccumulation of SUMO1 conjugates in the Arabidopsis mutant early in short days 4. (23rd June 2014)

• Record Type: Journal Article
• Authors: Villajuana‐Bonequi, Mitzi; Elrouby, Nabil; Nordström, Karl; Griebel, Thomas; Bachmair, Andreas; Coupland, George
• Is Part Of: Plant journal. Volume 79:Number 2(2014:Jul.)
• Page Start: 206
• Page End: 219
• Publication Date: 2014-06-23
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12549
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12549-abs-0001"> <title>Summary</title> <p>Post‐translational modification of proteins by attachment of small ubiquitin‐like modifier (SUMO) is essential for plant growth and development. Mutations in the SUMO protease early in short days 4 (ESD4) cause hyperaccumulation of conjugates formed between SUMO and its substrates, and phenotypically are associated with extreme early flowering and impaired growth. We performed a suppressor mutagenesis screen of <italic>esd4</italic> and identified a series of mutants called <italic>suppressor of esd4</italic> (<italic>sed</italic>), which delay flowering, enhance growth and reduce hyperaccumulation of SUMO conjugates. Genetic mapping and genome sequencing indicated that one of these mutations (<italic>sed111</italic>) is in the gene salicylic acid induction‐deficient 2 (<italic>SID2</italic>), which encodes ISOCHORISMATE SYNTHASE I, an enzyme required for biosynthesis of salicylic acid (SA). Analyses showed that compared with wild‐type plants, <italic>esd4</italic> contains higher levels of <italic>SID2 </italic>mRNA and about threefold more SA, whereas <italic>sed111</italic> contains lower SA levels. Other <italic>sed</italic> mutants also contain lower SA levels but are not mutant for <italic>SID2</italic>, although most reduce <italic>SID2 </italic>mRNA levels. Therefore, higher SA levels contribute to the small size, early flowering and elevated SUMO conjugate levels of <italic>esd4</italic>. Our results support previous data indicating that SUMO homeostasis influences SA biosynthesis in wild‐type plants, and also demonstrate that elevated levels of SA strongly increase the abundance of SUMO conjugates.</p> </abstract>