Suekawa Marina, Fujikawa Yukichi, Inada Shuhei, Murano Asako, Esaka Muneharu
Graduate School of Biosphere Sciences, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
Graduate School of Biosphere Sciences, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
J Plant Physiol. 2016 Aug 1;200:35-44. doi: 10.1016/j.jplph.2016.05.015. Epub 2016 Jun 2.
The functional role of an uncharacterized tomato (Solanum lycopersicum) aldo-keto reductase 4B, denoted as SlAKR4B, was investigated. The gene expression of tomato SlAKR4B was detected at a high level in the senescent leaves and the ripening fruits of tomato. Although d-galacturonic acid reductase activities tended to be higher in tomato SlAKR4B-overexpressing transgenic tobacco BY-2 cell lines than those in control cell lines, SlAKR4B gene expression was not well correlated with l-ascorbic acid content among the cell lines. The analysis of the transgenic cell lines showed that tomato SlAKR4B has enzyme activities toward d-galacturonic acid as well as glyceraldehyde and glyoxal, suggesting that the SlAKR4B gene encodes a functional enzyme in tomato. Gene expression of SlAKR4B was induced by NaCl, H2O2, and plant hormones such as salicylic acid and jasmonic acid, suggesting that SlAKR4B is involved in the stress response. The transient expression assay using protoplasts showed the promoter activity of the SlAKR4B gene was as high as that of the cauliflower mosaic virus 35S promoter. Also, the promoter region of the SlAKR4B gene was suggested to contain cis-element(s) for abiotic stress-inducible expression.
对一个未鉴定的番茄（茄属番茄）醛酮还原酶4B（记为SlAKR4B）的功能作用进行了研究。在番茄的衰老叶片和成熟果实中检测到番茄SlAKR4B的基因表达水平很高。尽管在过表达番茄SlAKR4B的转基因烟草BY-2细胞系中，d-半乳糖醛酸还原酶活性往往高于对照细胞系，但在这些细胞系中，SlAKR4B基因表达与l-抗坏血酸含量并没有很好的相关性。对转基因细胞系的分析表明，番茄SlAKR4B对d-半乳糖醛酸以及甘油醛和乙二醛具有酶活性，这表明SlAKR4B基因在番茄中编码一种功能性酶。SlAKR4B的基因表达受到NaCl、H2O2以及水杨酸和茉莉酸等植物激素的诱导，这表明SlAKR4B参与了应激反应。使用原生质体的瞬时表达试验表明，SlAKR4B基因的启动子活性与花椰菜花叶病毒35S启动子的活性一样高。此外，SlAKR4B基因的启动子区域被认为含有用于非生物胁迫诱导表达的顺式元件。
