High-level overexpression of the Arabidopsis HsfA2 gene confers not only increased themotolerance but also salt/osmotic stress tolerance and enhanced callus growth
High-level overexpression of the Arabidopsis HsfA2 gene confers not only increased themotolerance but also salt/osmotic stress tolerance and enhanced callus growth
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DOI：
10.1093/jxb/erm184
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发表时间：
2007-10-01
影响因子：
6.9
通讯作者：
Nishiuchi, Takumi
中科院分区：
文献类型：
--
作者：
Ogawa, Daisuke;Yamaguchi, Kazuo;Nishiuchi, Takumi
热休克转录因子（Hsfs）是所有真核生物热休克（HS）应激反应的中心调控因子。HsfA2是拟南芥A类Hsfs之一，在所有21个拟南芥Hsfs中，HsfA2在HS胁迫下的表达诱导程度最高。本研究报道，高水平过表达HsfA2的转基因株系（El2 ohm:: HsfA2）与野生型植物相比，基础耐热性和获得性耐热性显著增强。相反，显性负突变体HsfA2 （El2 ohm::HsfA2 Delta C264）表现出较低的耐热性。这些结果表明HsfA2基因在HS应激反应中起作用。对El2 ohm::HsfA2植株进行微阵列分析，确定了可能的靶基因，包括HS胁迫诱导基因和其他胁迫应答基因。盐胁迫和渗透胁迫诱导HsfA2基因表达。事实上，El2 ohm::HsfA2植物对这些胁迫的耐受性增强，表明HsfA2参与了多重胁迫的耐受性。与野生型相比，El2 ohm::HsfA2的愈伤组织生长速度加快，而El2 ohm::HsfA2 Delta C264的愈伤组织生长速度减慢。这些观察结果表明，HsfA2除了在应激耐受性中起作用外，在细胞增殖中也起重要作用。
Heat shock transcription factors (Hsfs) are the central regulators of the heat shock (HS) stress response in all eukaryotic organisms. HsfA2 is one of the Arabidopsis class A Hsfs, and the induction of HsfA2 expression in response to HS stress is highest among all 21 Arabidopsis Hsfs. In this study, it is reported that basal and acquired thermotolerance was significantly enhanced in high-level HsfA2-overexpressed transgenic lines (El2 ohm:: HsfA2) in comparison with wild-type plants. By contrast, the dominant negative mutants of HsfA2 (El2 ohm::HsfA2 Delta C264) plants displayed reduced thermotolerance. These results indicate that the HsfA2 gene plays a role in the HS stress response. Microarray analysis of the El2 ohm::HsfA2 plants identified putative target genes, which included HS stress-inducible genes and other stress-responsive genes. Salt and osmotic stress induced HsfA2 gene expression. In fact, the El2 ohm::HsfA2 plants showed enhanced tolerance to these stresses, suggesting that HsfA2 was involved in multiple stress tolerance. El2 ohm::HsfA2 plants showed accelerated callus growth from root explants compared with the wild type, unlike the El2 ohm::HsfA2 Delta C264 plants whose growth was delayed. These observations suggest that HsfA2 plays, in addition to its role in stress tolerance, an important role in cell proliferation.