Heat shock transcription factor A6b, AtHSFA6b, is induced through ABA-dependent signaling and mediates several abiotic stress responses in Arabidopsis thaliana

• Main Authors: Chen-Ru Yang, 楊承儒
• Other Authors: Tsung-Luo Jinn
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/43150060478212318575

碩士 === 國立臺灣大學 === 植物科學研究所 === 100 === Plants face various environmental stresses, such as drought, salinity, heat and cold directly. In response to heat stress (HS), heat shock response (HSR) is a conserved mechanism of increasing heat shock protein (HSP) genes expression through a heat shock factors (HSFs)-dependent mechanism. According to microarray databases, AtHSFA6a is induced by salt and osmotic stress, while AtHSFA6b expression is responsive to cold, salt, osmotic and drought treatment; in addition both genes are upregulated by ABA treatment suggesting the AtHSFA6s may involve in ABA-mediated responses. This report describes our investigation of the role of AtHSFA6s in response to abiotic stress in Arabidopsis by genetic and molecular approaches. Both AtHSFA6s were induced by abscisic acid (ABA), salt and osmotic stress. Downregulated AtHSFA6b expression in ABA-deficient and ABA-insensitive mutants indicates that ABA signaling is required for AtHSFA6b expression. Notably, ABRE acts as the functional cis-element in the promoter region of AtHSFA6b, suggests AtHSFA6b is a member involved in ABA-dependent pathway. Analysis of cotyledon greening, root growth and salt tolerance in mutant lines and transgenic plants indicated that AtHSFA6b participates in ABA-mediated stress responses and acts as a positive regulator. In addition, thermotolerance tests also showed AtHSFA6b is involved in basal- and acquired-thermotolerance. These studies reveal AtHSFA6b is a positive regulator in ABA-mediated stresses, and add a new signaling pathway into the complex HSF network.