J Exp Bot:中科院遗传所谢旗实验室发表ABA介导植物开花新机制
2015年10月27日《JouRNAl of Experimental Botany》杂志在线发表于发表中国科学院遗传与发育生物学研究所谢旗研究组最新的研究结果，研究揭示了ABA介导植物开花的新机制。舒凯博士和博士研究生陈倩为论文的共同第一作者，谢旗研究员为论文通讯作者。
植物的开花时间是农业生产上一个重要农艺性状，适宜的开花时间有利于作物灌浆成熟，保证产量和质量，具有重要的经济学意义;同时，开花时间调控本身极为复杂，也是植物学基础研究领域一个热点。大量研究表明，开花时间受到包括赤霉素(GA)途径在内的四大途径协同调控。脱落酸(ABA)与GA是一对经典的植物激素，它们在许多生物学过程中都表现出拮抗效应，诸如种子休眠与萌发和根的发育等。虽然GA调控开花时间已有大量深入研究，但ABA如何调控开花?植物学界还值得进一步深入研究。
中国科学院遗传与发育生物学研究所谢旗研究组早前发现，ABA信号途径中一个正调控因子ABI4通过介导ABA与GA的合成及信号转导，进而精确调控种子休眠(Shu et al., 2013,PLoS genetics)，同时发现abi4突变体表现出早花的表型;随后，谢旗研究组以ABI4为切入点，详细研究了ABA通过ABI4调控开花时间的分子机理。结合遗传学、分子生物学、生物化学和植物生理学等研究方法，证实ABI4通过正调控开花关键基因FLC的转录，进而负调控开花时间。有趣的是，FLC同时也是ABA信号途径上另一个重要因子ABI5的靶标基因(Wang et al., 2013, JXB);因此ABI4也是继ABI5之后，在ABA途径上一个新鉴定到的调控开花的关键基因。
原文链接：
ABsciSIC ACID-INSENSITIVE 4 negatively regulates flowering through directly promotingArabidopsis FLOWERING LOCUS C transcription
原文摘要：
During the life cycle of a plant, one of the major biological processes is the transition from the vegetative to the reproductive stage. InArabidopsis, flowering time is precisely controlled by extensive environmental and internal cues. Gibberellins (GAs) promote flowering, while abscisic acid (ABA) is considered as a flowering suppressor. However, the detailed mechanism through which ABA inhibits the floral transition is poorly understood. Here, we report that ABSCISIC ACID-INSENSITIVE 4 (ABI4), a key component in the ABA signalling pathway, negatively regulates floral transition by directly promoting FLOWERING LOCUS C (FLC) transcription. The abi4 mutant showed the early flowering phenotype whereas ABI4-overexpressing (OE-ABI4) plants had delayed floral transition. Consistently, quantitative reverse transcription–PCR (qRT–PCR) assay revealed that the FLC transcription level was down-regulated inabi4, but up-regulated in OE-ABI4. The change in FT level was consistent with the pattern of FLC expression. Chromatin immunoprecipitation-qPCR (ChIP-qPCR), electrophoretic mobility shift assay (EMSA), and tobacco transient expression analysis showed that ABI4 promotes FLC expression by directly binding to its promoter. Genetic analysis demonstrated thatOE-ABI4::flc-3 could not alter the flc-3 phenotype. OE-FLC::abi4 showed a markedly delayed flowering phenotype, which mimicked OE-FLC::WT, and suggested that ABI4 acts upstream of FLC in the same genetic pathway. Taken together, these findings suggest that ABA inhibits the floral transition by activating FLC transcription through ABI4.
作者：谢旗
