2016年9月23日，国际植物学顶级期刊《plant Physiology》杂志上在线发表了华中农业大学园艺林学学院园艺植物教育部重点实验室刘继红教授果树逆境团队关于多胺合成转录调控的最新科研进展。研究成果题为"A NAC transcription factor represses putrescine biosynthesis and affects drought tolerance"。博士研究生吴昊为论文第一作者，刘继红教授为论文通讯作者。
课题组在前期鉴定了枳(柑橘砧木)精氨酸脱羧酶(ADC)基因功能基础上，通过酵母单杂交技术获得调控ADC基因的转录因子PtrNAC72，并发现其负调控ADC基因表达和胁迫应答。
多胺普遍存在于植物中，主要包括腐胺，亚精胺和精胺三种，在非生物胁迫应答中起重要的作用。ADC是腐胺合成的关键酶，植物ADC基因受胁迫诱导的研究报道较多，但其转录调控方面的研究尚不多。该课题组近年来围绕ADC基因功能及其转录调控机制开展了大量的研究，2015年在J Exp Bot和Plant Cell Environ等期刊相继报道能够正调控ADC基因表达和腐胺合成的转录因子ABF和WRKY70，而此次报道的NAC72是第一个负调控ADC基因表达和腐胺合成的转录因子，这些调控因子的鉴定有利于阐明非生物胁迫下多胺生物合成的转录调控机制，为利用转录因子调控多胺合成以改良非生物胁迫抗性奠定了理论基础。
原文链接：
A NAC transcription factor represses putrescine biosynthesis and affects drought tolerance
原文摘要：
Arginine decarboxylase (ADC)-mediated putrescine biosynthesis plays an important role in plant stress responses, but the transcriptional regulation of ADC in response to abiotic stress is not well understood. We isolated a NAM, ATAF1/2 and CUC (NAC) domain-containing transcription factor PtrNAC72 from trifoliate orange (Poncirus trifoliata (L.) Raf.) by yeast one-hybrid screening. PtrNAC72, localized to the nucleus, specifically binds to the promoter of PtADC and acts as a transcriptional repressor. PtrNAC72 expression was induced by cold, drought, and abscisic acid. ADC mRNA abundance and putrescine levels were decreased in transgenic tobacco plants overexpressing PtrNAC72, but increased, compared to wild type, in an Arabidopsis thaliana T-DNA insertion mutant, nac72. While tobacco lines overexpressing PtrNAC72 were more sensitive to drought, plants of the Arabidopsis nac72 mutant exhibited enhanced drought tolerance, consistent with the accumulation of reactive oxygen species (ROS) in the tested genotypes. In addition, exogenous application of putrescine to the overexpression lines restored drought tolerance, while treatment with D-arginine, an ADC inhibitor, compromised the drought tolerance of nac72. Taken together, these results demonstrate that PtrNAC72 is a repressor of putrescine biosynthesis and may negatively regulate drought stress response, at least in part, via modulation of putrescine-associated ROS homeostasis.
