AUTHOR=Yu Si-in , Han Jin-Hee , Chhoeun Chanvotey , Lee Byeong-ha 

TITLE=Genetic Screening for Arabidopsis Mutants Defective in STA1 Regulation under Thermal Stress Implicates the Existence of Regulators of Its Specific Expression, and the Genetic Interactions in the Stress Signaling Pathways

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00618

DOI=10.3389/fpls.2016.00618

ISSN=1664-462X

ABSTRACT=<p>To cope with environmental stresses, plants have developed various stress tolerance mechanisms that involve the induction of many stress responsive genes through stress-specific and common signaling pathways. Stress-specific/common transcription factors, rather than general basal factors, were considered important in this stress tolerance. The <italic>Arabidopsis STABILIZED1</italic> (<italic>STA1</italic>) gene encodes a putative pre-mRNA splicing factor that is similar to the human U5 snRNP-associated 102-kDa protein and the yeast pre-mRNA splicing factors, PRP1p and Prp6p. As pre-mRNA splicing is a necessary process for proper gene expression in eukaryotes, <italic>STA1</italic> is expected to be constantly functional in all conditions. Interestingly, <italic>STA1</italic> expression is induced by temperature stresses, and <italic>STA1</italic> recessive mutation (<italic>sta1-1</italic>) resulted in temperature stress-specific hypersensitivity. This suggests <italic>STA1</italic>’s stress specific function in addition to its presumed “housekeeping” role. In order to establish the genetic system to understand the regulation of <italic>STA1</italic> expression in temperature stresses, we generated a bioluminescent <italic>Arabidopsis</italic> plant harboring the <italic>STA1</italic> promoter fused to the firefly luciferase coding sequence (<italic>STA1p-LUC</italic>). Through genetic analysis, the bioluminescent <italic>Arabidopsis</italic> homozygous for one-copy <italic>STA1p-LUC</italic> was isolated and characterized. In this <italic>STA1p-LUC</italic> line, the expression patterns of <italic>STA1p-LUC</italic> were similar to those of the endogenous <italic>STA1</italic> gene under cold and heat stresses. The <italic>STA1p-LUC</italic> line was then chemically mutagenized and screened to isolate the genetic loci of <italic>STA1</italic> regulators under cold or heat stresses. Mutants with altered <italic>STA1p-LUC</italic> luminescence were identified and further confirmed through luminescence imaging in the next generation and analysis of endogenous <italic>STA1</italic> expression. The categorization of <italic>STA1p-LUC</italic> deregulated mutants implicated the existence of cold or heat stress-specific as well as common genetic regulators for <italic>STA1</italic> expression. Interestingly, some mutants showed opposite-directional deregulation of <italic>STA1</italic> expression depending on the type of thermal stress, suggesting that the loci may represent important switch factors which determine the direction of signaling pathways for <italic>STA1</italic> expression in response to temperature.</p>