Coordinated regulation of melatonin synthesis and degradation genes in rice leaves in response to cadmium treatment
Coordinated regulation of melatonin synthesis and degradation genes in rice leaves in response to cadmium treatment
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DOI：
10.1111/jpi.12232
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发表时间：
2015-05-01
影响因子：
10.3
通讯作者：
Back, Kyoungwhan
中科院分区：
文献类型：
--
作者：
Byeon, Yeong;Lee, Hyoung Yool;Back, Kyoungwhan
研究了镉胁迫下水稻叶片中褪黑素合成和降解相关基因的表达模式以及褪黑素2-羟化酶（M2H）蛋白的亚细胞定位位点。cd诱导的褪黑素合成与褪黑素生物合成基因（包括色氨酸脱羧酶（TDC）、色胺5-羟化酶（T5H）和n -乙酰5-羟色胺甲基转移酶（ASMT））的表达增加相一致。血清素n -乙酰转移酶（SNAT）是褪黑素生物合成的倒数第二基因，其表达下调，表明SNAT对褪黑素合成有拮抗作用。值得注意的是，褪黑激素生物合成基因表达的诱导与褪黑激素降解相关的四个M2H基因的诱导是耦合的，这表明褪黑激素合成和降解基因是协调调节的。诱导的M2H基因表达与M2H酶活性增强相关。其中3个M2H蛋白定位于细胞质，1个M2H蛋白定位于叶绿体，表明褪黑素降解发生在细胞质和叶绿体中。2-羟基褪黑激素诱导植物防御基因表达的生物活性比褪黑激素低50%，这表明2-羟基褪黑激素可能是褪黑激素的代谢物。总的来说，我们的数据表明，褪黑激素合成与褪黑激素降解在叶绿体和细胞质中并行发生，由此产生的褪黑激素代谢物2-羟基褪黑激素也作为防御基因诱导的信号分子。
We investigated the expression patterns of genes involved in melatonin synthesis and degradation in rice leaves upon cadmium (Cd) treatment and the subcellular localization sites of melatonin 2-hydroxylase (M2H) proteins. The Cd-induced synthesis of melatonin coincided with the increased expression of melatonin biosynthetic genes including tryptophan decarboxylase (TDC), tryptamine 5-hydroxylase (T5H), and N-acetylserotonin methyltransferase (ASMT). However, the expression of serotonin N-acetyltransferase (SNAT), the penultimate gene in melatonin biosynthesis, was downregulated, suggesting that melatonin synthesis was counter-regulated by SNAT. Notably, the induction of melatonin biosynthetic gene expression was coupled with the induction of four M2H genes involved in melatonin degradation, which suggests that genes for melatonin synthesis and degradation are coordinately regulated. The induced M2H gene expression was correlated with enhanced M2H enzyme activity. Three of the M2H proteins were localized to the cytoplasm and one M2H protein was localized to chloroplasts, indicating that melatonin degradation occurs both in the cytoplasm and in chloroplasts. The biological activity of 2-hydroxymelatonin in the induction of the plant defense gene expression was 50% less than that of melatonin, which indicates that 2-hydroxymelatonin may be a metabolite of melatonin. Overall, our data demonstrate that melatonin synthesis occurs in parallel with melatonin degradation in both chloroplasts and cytoplasm, and the resulting melatonin metabolite 2-hydroxymelatonin also acts as a signaling molecule for defense gene induction.