2016年9月23日，國際植物學(xué)頂級期刊《plant Physiology》雜志上在線發(fā)表了華中農(nóng)業(yè)大學(xué)園藝林學(xué)學(xué)院園藝植物教育部重點(diǎn)實(shí)驗(yàn)室劉繼紅教授果樹逆境團(tuán)隊(duì)關(guān)于多胺合成轉(zhuǎn)錄調(diào)控的最新科研進(jìn)展。研究成果題為"A NAC transcription factor represses putrescine biosynthesis and affects drought tolerance"。博士研究生吳昊為論文第一作者，劉繼紅教授為論文通訊作者。
課題組在前期鑒定了枳(柑橘砧木)精氨酸脫羧酶(ADC)基因功能基礎(chǔ)上，通過酵母單雜交技術(shù)獲得調(diào)控ADC基因的轉(zhuǎn)錄因子PtrNAC72，并發(fā)現(xiàn)其負(fù)調(diào)控ADC基因表達(dá)和脅迫應(yīng)答。
多胺普遍存在于植物中，主要包括腐胺，亞精胺和精胺三種，在非生物脅迫應(yīng)答中起重要的作用。ADC是腐胺合成的關(guān)鍵酶，植物ADC基因受脅迫誘導(dǎo)的研究報道較多，但其轉(zhuǎn)錄調(diào)控方面的研究尚不多。該課題組近年來圍繞ADC基因功能及其轉(zhuǎn)錄調(diào)控機(jī)制開展了大量的研究，2015年在J Exp Bot和Plant Cell Environ等期刊相繼報道能夠正調(diào)控ADC基因表達(dá)和腐胺合成的轉(zhuǎn)錄因子ABF和WRKY70，而此次報道的NAC72是第一個負(fù)調(diào)控ADC基因表達(dá)和腐胺合成的轉(zhuǎn)錄因子，這些調(diào)控因子的鑒定有利于闡明非生物脅迫下多胺生物合成的轉(zhuǎn)錄調(diào)控機(jī)制，為利用轉(zhuǎn)錄因子調(diào)控多胺合成以改良非生物脅迫抗性奠定了理論基礎(chǔ)。
原文鏈接：
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.
