植生生態(tài)所光合作用與環(huán)境生物學(xué)實(shí)驗(yàn)室滕勝研究組在擬南芥糖信號(hào)研究領(lǐng)域取得了重要進(jìn)展：在擬南芥中首次發(fā)現(xiàn)了一個(gè)新的果糖特異信號(hào)途徑,，這一研究成果于2月7日在線發(fā)表在國(guó)際重要學(xué)術(shù)期刊《美國(guó)科學(xué)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(zhì)代謝和能量代謝的基礎(chǔ)。目前,，糖的信號(hào)分子功能已得到廣泛認(rèn)可,，糖作為信號(hào)分子在植物生長(zhǎng)發(fā)育和對(duì)環(huán)境響應(yīng)的過(guò)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(hào)途徑已有較多的研究,，而蔗糖信號(hào)的存在也已得到證實(shí)。這些研究結(jié)果為闡明糖信號(hào)調(diào)控物質(zhì)代謝,、能量代謝,、生長(zhǎng)發(fā)育、以及響應(yīng)外界環(huán)境的分子機(jī)理打下堅(jiān)實(shí)的基礎(chǔ),。然而,，作為主要可溶性糖之一的果糖，其信號(hào)功能和相應(yīng)的信號(hào)途徑卻未明確,。
該研究利用Ler和Cvi生態(tài)型構(gòu)建的Ler X Cvi重組自交系群體進(jìn)行果糖敏感QTL的定位，通過(guò)與葡萄糖敏感QTL的比較,，發(fā)現(xiàn)了4個(gè)果糖特異的QTL,，其中的FSQ6 在近等基因系中得到證實(shí)。該研究還發(fā)現(xiàn)擬南芥的果糖敏感性獨(dú)立于葡萄糖感受體HXK1,，但仍依賴(lài)于脫落酸和乙烯信號(hào)途徑,。這些結(jié)果揭示了獨(dú)立于HXK1的果糖信號(hào)新途徑，該途徑與脫落酸和乙烯信號(hào)途徑的互作方式和HXK1介導(dǎo)的葡萄糖信號(hào)途徑相似,。通過(guò)圖位克隆和轉(zhuǎn)基因互補(bǔ),，證明了FSQ6基因是一個(gè)具有膜系留結(jié)構(gòu)域的NAC轉(zhuǎn)錄因子——ANAC089。FSQ6/ANAC089 的Cvi等位基因是一個(gè)功能獲得性等位基因,，具有抑制果糖信號(hào)的功能,，該等位基因的第三外顯子中發(fā)生了1-bp缺失，導(dǎo)致蛋白質(zhì)翻譯提前終止,，從而產(chǎn)生了膜系留結(jié)構(gòu)域缺失的ANAC089蛋白質(zhì),，該蛋白質(zhì)能直接進(jìn)入細(xì)胞核，且具有轉(zhuǎn)錄激活活性,，通過(guò)激活下游基因的表達(dá)從而抑制果糖信號(hào)途徑,。而Ler ANAC089蛋白雖然具有轉(zhuǎn)錄激活活性，但因具有膜系留結(jié)構(gòu)域,，仍滯留在細(xì)胞質(zhì)中,，不能進(jìn)入細(xì)胞核行使轉(zhuǎn)錄因子的功能。
該項(xiàng)工作得到了中科院知識(shí)創(chuàng)新工程,、國(guó)家973計(jì)劃,、轉(zhuǎn)基因重大專(zhuān)項(xiàng)、國(guó)家自然科學(xué)基金等項(xiàng)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.
