转录因子ABI4调控草莓果实成熟的分子机理

Fruit ripening regulation mechanisms has been an important issue of fruit trees disciplines. In our previous study, strawberry fruit as material, we confirmed ABA (abscisic acid) is one of the core signal in regulation of fruit ripening, However, there are still many signal components need to be identified in ABA signal transduction pathways. It has been confirmed in the model plant Arabidopsis thaliana that the transcription factor ABA-insensitive4 (ABI4) is an important downstream component in ABA signal transduction pathway, but its role in fruit development is still unclear. In order to reveal the molecular mechanisms of ABI4 gene in the regulation of strawberry fruit ripening, Sweet Charlie strawberry varieties as test materials, on the basis of strawberry FaABI4 homologous gene cloning, firstly FaABI4 gene bioinformatics, temporal expression and copy number will be analyzed, secondly after the molecule manipulation of FaABI4 gene expression level in strawberry fruit, the changes of physiological indicators such as phenotypic, sugar, ABA, pigments content, and ripening-related gene expression levels such as genes involved in ABA signaling components, sugar metabolism, pigment, softening will be analyzed. This study further reveals the molecular mechanisms of information transmission in fruit development, and thus also lays an important foundation for future molecular improvement of strawberries breeding.

果实成熟调控机制的研究一直是果树学科的一个重点问题。我们前期以草莓果实为研究对象，证实了脱落酸ABA（abscisic acid）是调控草莓果实成熟的核心信号之一，然而，ABA信号转导路径中还有很多信号组分有待鉴定。在模式植物拟南芥中证实，转录因子ABA-insensitive4（ABI4）是ABA信号转导路径重要的下游组分，但其在果实发育中的作用目前还不清楚。本项目拟以草莓品种甜查理为试材，在克隆草莓FaABI4同源基因的基础上，首先对FaABI4基因进行生物信息学、时空表达和拷贝数分析，其次通过分子操纵草莓中FaABI4基因表达水平，分析草莓果实的表型变化、糖、ABA、色素等生理指标和与ABA信号组分、糖代谢、色素、软化等成熟相关基因的表达水平，揭示ABI4调控草莓果实成熟的分子理。该研究有助于深入揭示果实发育信息传递的分子机制，也为今后草莓的分子改良育种奠定重要的基础。

果实发育及品质调控一直是果树学科的核心问题，但其发育成熟调控机理还未清晰。以八倍体草莓品种甜查理为试验试材，通过分析脱落酸信号路径下游重要调控因子ABI4在果实发育过程中的作用，组织表达模式和拷贝数，以及ABI4信号网络的构建，综合分析ABI4对草莓品质的影响。结果表明ABI4随着果实的发育表达量不断提高，在花中表达量最高，其次是果中；ABI4在草莓中为单拷贝，可通过调控果实花色苷代谢、细胞壁代谢、糖代谢进而参与果实的发育进程；ABI4在草莓果实中超表达能促进果实的着色成熟进程，相反，ABI4在草莓果实中表达瞬时沉默会延迟果实的着色成熟进程；ASR也是果实成熟的正向调控因子，能影响果实的生理和分子水平来调控果实的发育进程，但ABI4与ASR在果实发育过程中是拮抗关系；通过酵母双杂交技术分离出ABI4蛋白的互作蛋白bHLH类基因MYCA蛋白，而且通过BiFC和pull down技术确定了两者是互作关系。ABI4能调控MYCA基因进而影响果实着色成熟进程。构建了以ABI4为核心的受脱落酸调控的参与果实着色的信号调控网络。为有效利用功能基因指导育种工作提供理论基础。

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