Identification of white campion (Silene latifolia) guaiacol O-methyltransferase involved in the biosynthesis of veratrole, a key volatile for pollinator attraction
Identification of white campion (Silene latifolia) guaiacol O-methyltransferase involved in the biosynthesis of veratrole, a key volatile for pollinator attraction
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DOI：
10.1186/1471-2229-12-158
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发表时间：
2012-08-31
影响因子：
5.3
通讯作者：
Schiestl, Florian P.
中科院分区：
文献类型：
--
作者：
Gupta, Alok K.;Akhtar, Tariq A.;Schiestl, Florian P.
背景资料：宽叶蝇子草及其传粉昆虫--双头Hadena bicruris是一种开放的苗圃传粉系统，其中花挥发物，特别是丁香酚（1，2-二甲氧基苯）、丁香醛和苯乙醛对花信号传导具有重要作用。尽管花香在保证S.结果：从宽叶香茶菜中克隆到两个全长cDNA，分别为：1、2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、显示与玫瑰苔黑酚O-甲基转移酶相似性。生化分析表明，S. Latifolia愈创木酚O-甲基转移酶1（SlGOMT 1）和S.阔叶树愈创木酚O-甲基转移酶2（SlGOMT 2）编码催化愈创木酚甲基化形成藜芦醇的蛋白质。SlGOMT 1（类似于10 μ M）和SlGOMT 2（类似于501 μ M）之间的大Km值差异导致SlGOMT 1比SlGOMT 2催化效率高31倍。qRT-PCR表达分析表明，SlGOMT基因在花和雄株中特异表达。阔叶花组织中GOMT基因的转录水平是雌花组织的3 ~ 4倍。两个相关的cDNA序列，S. dioica O-甲基转移酶1（SdOMT 1）和S. dioica O-甲基转移酶2（SdOMT 2）也从姊妹种dioica蝇子草获得，但它们编码的蛋白质不甲基化愈创木酚，这与该物种的花中缺乏藜芦醇释放一致。我们的进化分析发现SlGOMT 1和SlGOMT 2基因在正选择下进化，而SdOMT 1和SdOMT 2基因没有显示出选择的证据。总而言之，我们报告了基因SlGOMT 1的鉴定和功能特征，该基因有效地催化了β-内酰胺形成，而该基因的另一个拷贝只有一个氨基酸差异，发现SlGOMT 2在S.宽叶。
Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated.Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (similar to 10 mu M) and SlGOMT2(similar to 501 mu M) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection.Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.