Zhao Qiong, Yu Dashi, Chang Hongping, Guo Xinhong, Yuan Congying, Hu Shuai, Zhang Cheng, Wang Ping, Wang Yu
School of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, 410082, People's Republic of China.
Mol Biol Rep. 2013 Sep 27. doi: 10.1007/s11033-013-2773-2.
AtGALK2 belongs to galactokinase of GHMP family in Arabidopsis thaliana. Two homozygous T-DNA insertion mutants (Atgalk2-1 and Atgalk2-2) of the AtGALK2 gene were identified. The AtGALK2 gene was highly expressed in flowers and roots, but less in stems, leaves and petioles. It was found that the expression of AtGALK2 gene was induced by NaCl and ABA. The two Atgalk2 mutants showed higher germination activity when treated with ABA and NaCl than wild type (Col-0). Through comparing the results of seed germination, root growth, stomatal aperture, water loss, and proline accumulation between the Atgalk2 mutants and Col-0, it was found that Atgalk2 mutants showed less sensitive to ABA than Col-0. The expression levels of ABI1, ABI2, RAB18, ABF3, RD22, RD29A, and RD29B in the Atgalk2 mutants were higher than in Col-0. However, the expression level of OST1 in the Atgalk2 mutants was lower than in Col-0. Taken together, these results suggested AtGALK2 was required for abscisic acid regulation of seed germination, root growth and gene expression, and was involved in salt and osmotic stress response in the early development stage. This study provides important clues to galactokinase activities of GHMP family in ABA signaling and plant development.
AtGALK2属于拟南芥中GHMP家族的半乳糖激酶。鉴定出了AtGALK2基因的两个纯合T-DNA插入突变体（Atgalk2-1和Atgalk2-2）。AtGALK2基因在花和根中高表达，但在茎、叶和叶柄中表达较少。发现AtGALK2基因的表达受NaCl和ABA诱导。与野生型（Col-0）相比，两个Atgalk2突变体在ABA和NaCl处理下表现出更高的萌发活性。通过比较Atgalk2突变体和Col-0之间种子萌发、根生长、气孔开度、水分损失和脯氨酸积累的结果，发现Atgalk2突变体对ABA的敏感性低于Col-0。Atgalk2突变体中ABI1、ABI2、RAB18、ABF3、RD22、RD29A和RD29B的表达水平高于Col-0。然而，Atgalk2突变体中OST1的表达水平低于Col-0。综上所述，这些结果表明AtGALK2是脱落酸调控种子萌发、根生长和基因表达所必需的，并且参与早期发育阶段的盐和渗透胁迫响应。本研究为GHMP家族半乳糖激酶在ABA信号传导和植物发育中的活性提供了重要线索。
