Wang Hao Wen, Shi Xu Zhen, Zhong Xiao Yu, Ai Gan, Wang Yan Hui, Zhou Zhi Zhong, Lu Dan, Liu Xiao Liang, Chen Zhao Jie
Guangxi Key Laboratory of Agric-Environment and Agric-Products Safety, College of Agriculture, Guangxi University, Nanning, China.
The Key Laboratory of Plant Immunity, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
Plant Genome. 2025 Mar;18(1):e20547. doi: 10.1002/tpg2.20547.
Tryptophan decarboxylase (TDC) belongs to a family of aromatic amino acid decarboxylases and catalyzes the conversion of tryptophan to tryptamine. It is the enzyme involved in the first step of melatonin (MT) biosynthesis and mediates several key functions in abiotic stress tolerance. In Oryza sativa under pesticide-induced stress, TDC function is unclear. Three TDC differentially expressed genes (DEGs) and six TDC-coding genes were found to be expressed in fluroxypyr-meptyl (FLUME)-treated rice transcriptome datasets, which allowed researchers to explore the properties and roles of rice TDC family genes under pesticide-induced stress. By applying sequence alignment and phylogenetic analysis, two subfamilies of the TDC gene family-DUF674 and AAT_I-were found in rice, Glycine max, Zea mays, Hordeum vulgare, and Solanum lycopersicum. According to chromosomal location studies, segmental duplication aided in the expansion of the OsTDC gene family, and the three TDC DEGs in rice were irregularly distributed on two of its 12 chromosomes. In addition, nine rice TDC genes displayed a collinear relationship with those of soybean, maize, barley, and tomato. Rice TDC genes can encode a variety of biotic and abiotic stress responses because of their diverse gene architectures, cis-elements, motif compositions, and conserved domains. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis confirmed that a proportion of TDC genes (Os08g0140300, Os08g0140500, and Os10g0380800) were preferably expressed under 0.08 mg L FLUME stress, with a 5.2-, 3.2-, and 3.9-fold increase in roots and a 2.1-, 2.4-, and 2.6-fold increase in shoots, respectively. MT treatment further increased the expression of these genes, with a 2.1-fold, 3.1-fold, and fivefold increase in roots and a 1.5-, 1.1-, and 1.1-fold increase in shoots than that treated with 0.08 mg L FLUME only, respectively. When rice seedling roots and shoots were subjected to 0.08 mg L FLUME stress, TDC activity was increased by 2.7 and 1.6 times higher than in the control, respectively. MT application also further promoted TDC activity in rice tissues; TDC activity in rice roots and shoots was twofold and 1.4-fold higher, respectively, than that under 0.08 mg L FLUME alone. These findings indicate that TDC genes respond effectively to FLUME stress, and the application of MT could enhance the expression of these TDC genes, which comprise a set of candidate genes that regulate pesticide metabolism and degradation with the application of MT.
色氨酸脱羧酶（TDC）属于芳香族氨基酸脱羧酶家族，催化色氨酸转化为色胺。它是褪黑素（MT）生物合成第一步所涉及的酶，并在非生物胁迫耐受性中发挥多种关键功能。在农药诱导胁迫下的水稻中，TDC的功能尚不清楚。在氟氯吡啶酯（FLUME）处理的水稻转录组数据集中发现了3个TDC差异表达基因（DEG）和6个TDC编码基因，这使研究人员能够探索农药诱导胁迫下水稻TDC家族基因的特性和作用。通过序列比对和系统发育分析，在水稻、大豆、玉米、大麦和番茄中发现了TDC基因家族的两个亚家族——DUF674和AAT_I。根据染色体定位研究，片段重复有助于水稻OsTDC基因家族的扩张，水稻中的3个TDC DEG不规则地分布在其12条染色体中的两条上。此外，9个水稻TDC基因与大豆、玉米、大麦和番茄的TDC基因呈现共线关系。由于其多样的基因结构、顺式元件、基序组成和保守结构域，水稻TDC基因可编码多种生物和非生物胁迫反应。逆转录定量聚合酶链反应（RT-qPCR）分析证实，部分TDC基因（Os08g0140300、Os08g0140500和Os10g0380800）在0.08 mg/L氟氯吡啶酯胁迫下优先表达，根中分别增加了5.2倍、3.2倍和3.9倍，地上部分别增加了2.1倍、2.4倍和2.6倍。MT处理进一步增加了这些基因的表达，根中分别比仅用0.08 mg/L氟氯吡啶酯处理增加了2.1倍、3.1倍和5倍，地上部分别增加了1.5倍、1.1倍和1.1倍。当水稻幼苗的根和地上部分受到0.08 mg/L氟氯吡啶酯胁迫时，TDC活性分别比对照提高了2.7倍和1.6倍。施用MT也进一步促进了水稻组织中的TDC活性；水稻根和地上部分的TDC活性分别比仅用0.08 mg/L氟氯吡啶酯处理时高2倍和1.4倍。这些发现表明，TDC基因对氟氯吡啶酯胁迫有有效响应，施用MT可增强这些TDC基因的表达，这些基因是一组在施用MT时调节农药代谢和降解的候选基因。
