Song Jong Tae, Koo Yeon Jong, Seo Hak Soo, Kim Min Chul, Choi Yang Do, Kim Jeong Hoe
School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
Phytochemistry. 2008 Mar;69(5):1128-34. doi: 10.1016/j.phytochem.2007.12.010. Epub 2008 Jan 28.
We reported previously that a recombinant salicylic acid (SA) glucosyltransferase1 (AtSGT1) from Arabidopsis thaliana catalyzes the formation of both SA 2-O-beta-D-glucoside (SAG) and the glucose ester of SA (SGE). Here, transgenic Arabidopsis plants overexpressing AtSGT1 have been constructed, and their phenotypes analyzed. Compared to wild-type plants, transgenic plants showed an increased susceptibility to Pseudomonas syringae and reduced the accumulation levels of both free SA and its glucosylated forms (SAG and SGE). On the other hand, the overexpression increased the levels of methyl salicylate (MeSA) and methyl salicylate 2-O-beta-D-glucoside (MeSAG), and also induced SA carboxyl methyltransferase1 (AtBSMT1) expression, whose products catalyze the conversion of SA to MeSA. Our data indicate that reduced resistance by AtSGT1 overexpression results from a reduction in SA content, which is at least in part caused by increases in MeSAG and MeSA levels at the expense of SA. Our study also suggests that genetic manipulation of AtSGT1 can be utilized as an important regulatory tool for pathogen control.
我们之前报道过，来自拟南芥的一种重组水杨酸（SA）糖基转移酶1（AtSGT1）催化SA 2-O-β-D-葡萄糖苷（SAG）和SA的葡萄糖酯（SGE）的形成。在此，构建了过表达AtSGT1的转基因拟南芥植株，并对其表型进行了分析。与野生型植株相比，转基因植株对丁香假单胞菌的易感性增加，游离SA及其糖基化形式（SAG和SGE）的积累水平降低。另一方面，过表达增加了水杨酸甲酯（MeSA）和水杨酸甲酯2-O-β-D-葡萄糖苷（MeSAG）的水平，还诱导了水杨酸羧基甲基转移酶1（AtBSMT1）的表达，其产物催化SA向MeSA的转化。我们的数据表明，AtSGT1过表达导致的抗性降低是由于SA含量的减少，这至少部分是由MeSAG和MeSA水平的增加以SA为代价所致。我们的研究还表明，AtSGT1的基因操作可作为病原体控制的重要调控工具。
