A plant‐specific HUA2‐LIKE (HULK) gene family in Arabidopsis thaliana is essential for development. (28th August 2014)

• Record Type: Journal Article
• Authors: Jali, Sathya S.; Rosloski, Sarah M.; Janakirama, Preetam; Steffen, Joshua G.; Zhurov, Vladimir; Berleth, Thomas; Clark, Richard M.; Grbic, Vojislava
• Is Part Of: Plant journal. Volume 80:Number 2(2014:Oct.)
• Page Start: 242
• Page End: 254
• Publication Date: 2014-08-28
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12629
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12629-abs-0001"> <title>Summary</title> <p>In <italic>Arabidopsis thaliana</italic>, the <italic>HUA2</italic> gene is required for proper expression of <italic>FLOWERING LOCUS C</italic> (<italic>FLC</italic>) and <italic>AGAMOUS</italic>, key regulators of flowering time and reproductive development, respectively. Although <italic>HUA2</italic> is broadly expressed, plants lacking <italic>HUA2</italic> function have only moderately reduced plant stature, leaf initiation rate and flowering time. To better understand <italic>HUA2</italic> activity, and to test whether redundancy with similar genes underlies the absence of strong phenotypes in <italic>HUA2</italic> mutant plants, we identified and subsequently characterized three additional <italic>HUA2‐LIKE</italic> (<italic>HULK</italic>) genes in Arabidopsis. These genes form two clades (<italic>HUA2</italic>/<italic>HULK1</italic> and <italic>HULK2</italic>/<italic>HULK3</italic>), with members broadly conserved in both vascular and non‐vascular plants, but not present outside the plant kingdom. Plants with progressively reduced <italic>HULK</italic> activity had increasingly severe developmental defects, and plants homozygous for loss‐of‐function mutations in all four <italic>HULK</italic> genes were not recovered. Multiple mutants displayed reproductive, embryonic and post‐embryonic abnormalities, and provide detailed insights into the overlapping and unique functions of individual <italic>HULK</italic> genes. With regard to flowering time, opposing influences were apparent: <italic>hua2 hulk1</italic> plants were early‐flowering, while <italic>hulk2 hulk3</italic> mutants were late‐flowering, and <italic>hua2</italic> acted epistatically to cause early flowering in all combinations. Genome‐wide expression profiling of mutant combinations using RNA‐Seq revealed complex transcriptional changes in seedlings, with <italic>FLC</italic>, a known target of <italic>HUA2</italic>, among the most affected. Our studies, which include characterization of <italic>HULK</italic> expression patterns and subcellular localization, suggest that the <italic>HULK</italic> genes encode conserved nuclear factors with partially redundant but essential functions associated with diverse genetic pathways in plants.</p> </abstract>