植生生態(tài)所光合作用與環(huán)境生物學實驗室滕勝研究組在擬南芥糖信號研究領域取得了重要進展：在擬南芥中首次發(fā)現了一個新的果糖特異信號途徑，這一研究成果于2月7日在線發(fā)表在國際重要學術期刊《美國科學院院刊》PNAS 上,。
在植物中,，糖作為碳骨架和能量的提供者，是一切物質代謝和能量代謝的基礎,。目前,，糖的信號分子功能已得到廣泛認可，糖作為信號分子在植物生長發(fā)育和對環(huán)境響應的過程中具有極其重要的作用,。植物中的可溶性糖主要有蔗糖、葡萄糖和果糖,。以己糖激酶HXK1為受體的葡萄糖信號途徑已有較多的研究,，而蔗糖信號的存在也已得到證實。這些研究結果為闡明糖信號調控物質代謝,、能量代謝,、生長發(fā)育、以及響應外界環(huán)境的分子機理打下堅實的基礎,。然而,，作為主要可溶性糖之一的果糖，其信號功能和相應的信號途徑卻未明確,。
該研究利用Ler和Cvi生態(tài)型構建的Ler X Cvi重組自交系群體進行果糖敏感QTL的定位,，通過與葡萄糖敏感QTL的比較，發(fā)現了4個果糖特異的QTL,，其中的FSQ6 在近等基因系中得到證實,。該研究還發(fā)現擬南芥的果糖敏感性獨立于葡萄糖感受體HXK1，但仍依賴于脫落酸和乙烯信號途徑,。這些結果揭示了獨立于HXK1的果糖信號新途徑,，該途徑與脫落酸和乙烯信號途徑的互作方式和HXK1介導的葡萄糖信號途徑相似。通過圖位克隆和轉基因互補,，證明了FSQ6基因是一個具有膜系留結構域的NAC轉錄因子——ANAC089,。FSQ6/ANAC089 的Cvi等位基因是一個功能獲得性等位基因，具有抑制果糖信號的功能,，該等位基因的第三外顯子中發(fā)生了1-bp缺失,，導致蛋白質翻譯提前終止,，從而產生了膜系留結構域缺失的ANAC089蛋白質，該蛋白質能直接進入細胞核,，且具有轉錄激活活性,，通過激活下游基因的表達從而抑制果糖信號途徑。而Ler ANAC089蛋白雖然具有轉錄激活活性,，但因具有膜系留結構域,，仍滯留在細胞質中，不能進入細胞核行使轉錄因子的功能,。
該項工作得到了中科院知識創(chuàng)新工程,、國家973計劃、轉基因重大專項,、國家自然科學基金等項目的支持,。（生物谷Bioon.com）
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.1018665108
Fructose sensitivity is suppressed in Arabidopsis by the transcription factor ANAC089 lacking the membrane-bound domain
Ping Lia,1, Julia J. Windb,1, Xiaoliang Shia, Honglei Zhanga, Johannes Hansonb,c,d, Sjef C. Smeekensb,c, and Sheng Tenga,b,c,2
Abstract
In living organisms sugars not only provide energy and carbon skeletons but also act as evolutionarily conserved signaling molecules. The three major soluble sugars in plants are sucrose, glucose, and fructose. Information on plant glucose and sucrose signaling is available, but to date no fructose-specific signaling pathway has been reported. In this study, sugar repression of seedling development was used to study fructose sensitivity in the Landsberg erecta (Ler)/Cape Verde Islands (Cvi) recombinant inbred line population, and eight fructose-sensing quantitative trait loci (QTLs) (FSQ1–8) were mapped. Among them, FSQ6 was confirmed to be a fructose-specific QTL by analyzing near-isogenic lines in which Cvi genomic fragments were introgressed in the Ler background. These results indicate the existence of a fructose-specific signaling pathway in Arabidopsis. Further analysis demonstrated that the FSQ6-associated fructose-signaling pathway functions independently of the hexokinase1 (HXK1) glucose sensor. Remarkably, fructose-specific FSQ6 downstream signaling interacts with abscisic acid (ABA)- and ethylene-signaling pathways, similar to HXK1-dependent glucose signaling. The Cvi allele of FSQ6 acts as a suppressor of fructose signaling. The FSQ6 gene was identified using map-based cloning approach, and FSQ6 was shown to encode the transcription factor gene Arabidopsis NAC (petunia No apical meristem and Arabidopsis transcription activation factor 1, 2 and Cup-shaped cotyledon 2) domain containing protein 89 (ANAC089). The Cvi allele of FSQ6/ANAC089 is a gain-of-function allele caused by a premature stop in the third exon of the gene. The truncated Cvi FSQ6/ANAC089 protein lacks a membrane association domain that is present in ANAC089 proteins from other Arabidopsis accessions. As a result, Cvi FSQ6/ANAC089 is constitutively active as a transcription factor in the nucleus.
