The ABI4-induced Arabidopsis ANAC060 transcription factor attenuates ABA signaling and renders seedlings sugar insensitive when present in the nucleus.
The ABI4-induced Arabidopsis ANAC060 transcription factor attenuates ABA signaling and renders seedlings sugar insensitive when present in the nucleus.
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ABI4 诱导的拟南芥 ANAC060 转录因子在细胞核中存在时会减弱 ABA 信号传导并使幼苗对糖不敏感
DOI：
10.1371/journal.pgen.1004213
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发表时间：
2014-03
期刊：
影响因子：
4.5
通讯作者：
Teng S
中科院分区：
文献类型：
--
作者：
Li P;Zhou H;Shi X;Yu B;Zhou Y;Chen S;Wang Y;Peng Y;Meyer RC;Smeekens SC;Teng S
在含有高水平（约6%）葡萄糖或果糖的培养基上，幼苗的建立受到抑制。利用自然变异分析和突变体选择，已经确定了克服高糖对幼苗生长抑制的遗传位点，为糖信号通路提供了深入了解。本研究以拟南芥Col/C24 F2群体为材料，对幼苗高糖敏感性进行了QTL分析。一个葡萄糖和果糖敏感的QTL，GSQ 11，通过选择性基因分型定位，并在Col和C24背景下的近等基因系中得到证实。等位性测试和转基因互补表明GSQ 11位于ANAC 060基因内。Col ANAC 060等位基因赋予糖不敏感性，并且相对于糖敏感性C24等位基因是显性的。基因组和mRNA分析表明，Col ANAC 060中的单核苷酸多态性（SNP）影响ANAC 060的剪接模式，使得mRNA中存在20个额外的核苷酸。插入产生了一个终止密码子，导致截短的ANAC 60蛋白缺乏C24 ANAC 060蛋白中存在的跨膜结构域（TMD）。TMD的缺失导致ANAC 060的核定位。短形式的ANAC 060蛋白质存在于约12%的天然拟南芥种质中。葡萄糖诱导GSQ 11/ANAC 060表达的过程需要脱落酸（阿坝）信号。染色质免疫沉淀-qPCR和瞬时表达分析表明ABI 4直接结合GSQ 11/ANAC 060启动子以激活转录。有趣的是，Col ANAC 060降低了阿坝敏感性和葡萄糖诱导的阿坝积累，并且ABI 4表达也在Col ANAC 060系中降低。因此，糖-ABA信号级联诱导ANAC 060表达，但截短的Col ANAC 060蛋白减弱阿坝诱导和阿坝信号传导。这种来自核ANAC 060对阿坝信号传导的负反馈导致糖不敏感性。在植物中，糖起着信号分子的作用，控制着重要的过程，如光合作用、生长、碳在不同器官中的分布以及储存化合物的产生。糖信号需要植物激素脱落酸（阿坝）和ABA诱导的调节转录因子ABI 4。在这项研究中，遗传分析确定了转录因子ANAC 060作为建立糖敏感性的重要组成部分。结果发现，在天然拟南芥种群中，由于单核苷酸多态性（SNP）引起的ANAC 060 mRNA差异剪接，ANAC 060蛋白可能以长或短形式存在。具有完整跨膜结构域（TMD）的长ANAC 060蛋白被排除在细胞核之外，而缺乏TMD的短版本始终存在于细胞核中，在那里它调节基因表达。功能分析表明，Col ANAC 060参与了糖-ABA信号通路中的一个新的负反馈环。在该反馈环模型中，ABI 4激活ANAC 060表达，但Col ANAC 060的核存在抑制了Glc诱导的阿坝积累和ABI 4表达，从而降低了对糖信号的响应性。
Seedling establishment is inhibited on media containing high levels (∼6%) of glucose or fructose. Genetic loci that overcome the inhibition of seedling growth on high sugar have been identified using natural variation analysis and mutant selection, providing insight into sugar signaling pathways. In this study, a quantitative trait locus (QTL) analysis was performed for seedling sensitivity to high sugar in a Col/C24 F2 population of Arabidopsis thaliana. A glucose and fructose-sensing QTL, GSQ11, was mapped through selective genotyping and confirmed in near-isogenic lines in both Col and C24 backgrounds. Allelism tests and transgenic complementation showed that GSQ11 lies within the ANAC060 gene. The Col ANAC060 allele confers sugar insensitivity and was dominant over the sugar-sensitive C24 allele. Genomic and mRNA analyses showed that a single-nucleotide polymorphism (SNP) in Col ANAC060 affects the splicing patterns of ANAC060 such that 20 additional nucleotides are present in the mRNA. The insertion created a stop codon, resulting in a truncated ANAC60 protein lacking the transmembrane domain (TMD) that is present in the C24 ANAC060 protein. The absence of the TMD results in the nuclear localization of ANAC060. The short version of the ANAC060 protein is found in ∼12% of natural Arabidopsis accessions. Glucose induces GSQ11/ANAC060 expression in a process that requires abscisic acid (ABA) signaling. Chromatin immunoprecipitation-qPCR and transient expression analysis showed that ABI4 directly binds to the GSQ11/ANAC060 promoter to activate transcription. Interestingly, Col ANAC060 reduced ABA sensitivity and Glc-induced ABA accumulation, and ABI4 expression was also reduced in Col ANAC060 lines. Thus, the sugar-ABA signaling cascade induces ANAC060 expression, but the truncated Col ANAC060 protein attenuates ABA induction and ABA signaling. This negative feedback from nuclear ANAC060 on ABA signaling results in sugar insensitivity. In plants, sugars function as signaling molecules that control important processes such as photosynthesis, growth, carbon distribution over different organs and the production of storage compounds. Sugar signaling requires the phytohormone abscisic acid (ABA) and the ABA-induced regulatory transcription factor ABI4. In this study, a genetic analysis identified the transcription factor ANAC060 as an important component in establishing sugar sensitivity. It was found that, in natural Arabidopsis thaliana populations, the ANAC060 protein may occur as a long or a short version due to differential ANAC060 mRNA splicing caused by a single-nucleotide polymorphism (SNP). The long ANAC060 protein with an intact transmembrane domain (TMD) is excluded from the nucleus, whereas the short version lacking the TMD is always present in the nucleus, where it regulates gene expression. Functional analyses indicated that Col ANAC060 is involved in a novel negative feedback loop in the sugar-ABA signaling pathway. In this feedback loop model, ABI4 activates ANAC060 expression, but the nuclear presence of Col ANAC060 suppresses Glc-induced ABA accumulation and ABI4 expression, thereby reducing responsiveness to sugar signals.
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影响因子：
5.1
作者：
Dekkers, Bas J. W.;Schuurmans, Jolanda A. M. J.;Smeekens, Sjef C. M.
通讯作者：
Smeekens, Sjef C. M.
影响因子：
5.6
作者：
Bolouri Moghaddam MR;Van den Ende W
通讯作者：
Van den Ende W
影响因子：
4.4
作者：
Kim, Sang-Gyu;Lee, Sangmin;Park, Chung-Mo
通讯作者：
Park, Chung-Mo
影响因子：
7.2
作者：
Acevedo-Hernández, GJ;León, P;Herrera-Estrella, LR
通讯作者：
Herrera-Estrella, LR
影响因子：
5.3
作者：
Huang Y;Li CY;Biddle KD;Gibson SI
通讯作者：
Gibson SI