Hakozaki Hirokazu, Park Jong-In, Endo Makoto, Takada Yoshinobu, Kazama Tomohiko, Takeda Yoshimitsu, Suzuki Go, Kawagishi-Kobayashi Makiko, Watanabe Masao
Laboratory of Plant Reproductive Genetics, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
Genes Genet Syst. 2008 Apr;83(2):143-52. doi: 10.1266/ggs.83.143.
The 3-ketoacyl-ACP synthase (KAS) II is a fatty-acid-related enzyme which catalyzes the elongation of 16:0-acyl carrier protein (ACP) to 18:0-ACP in plastids. The fatty acid biosynthesis 1-1 (fab1-1) mutant of Arabidopsis thaliana is partially deficient in its activity of Arabidopsis thaliana 3-ketoacyl-ACP synthase 2 (AtKAS2), and its phenotype has been intensively studied in connection with the chilling resistance and fatty acid composition. In this study, we used the T-DNA insertion mutant of AtKAS2 to examine its possible role in plant development. Reverse transcription (RT)-PCR showed that the AtKAS2 gene was expressed in various plant organs, except for roots, and was highly expressed in siliques. The fusion of beta-glucuronidase (GUS) to the AtKAS2 promoter demonstrated that the promoter was active in various tissues such as embryos, stomatal guard cells, inflorescences and pollen grains. We were not able to identify atkas2 homozygous mutant adult plants in heterozygous mutant progeny. Phenotypic and genetic analyses showed that disruption of the AtKAS2 by T-DNA insertion caused embryo lethality, and the development of the embryos was arrested at the globular stage. Taken together, our results suggest that AtKAS2 is required for embryo development in Arabidopsis during the transition from the globular to the heart stage.
3-酮脂酰-ACP合酶（KAS）II是一种与脂肪酸相关的酶，它催化质体中16:0-酰基载体蛋白（ACP）延伸为18:0-ACP。拟南芥脂肪酸生物合成1-1（fab1-1）突变体在拟南芥3-酮脂酰-ACP合酶2（AtKAS2）的活性上存在部分缺陷，并且其表型已在抗冷性和脂肪酸组成方面进行了深入研究。在本研究中，我们使用AtKAS2的T-DNA插入突变体来研究其在植物发育中的可能作用。逆转录（RT）-PCR表明，AtKAS2基因在除根以外的各种植物器官中表达，并且在角果中高度表达。β-葡萄糖醛酸酶（GUS）与AtKAS2启动子的融合表明该启动子在胚胎、气孔保卫细胞、花序和花粉粒等各种组织中具有活性。我们无法在杂合突变体后代中鉴定出atkas2纯合突变成年植株。表型和遗传分析表明，T-DNA插入导致AtKAS2破坏会引起胚胎致死，并且胚胎发育在球形期停滞。综上所述，我们的结果表明AtKAS2是拟南芥胚胎从球形期向心形期转变过程中胚胎发育所必需的。
