会议号：腾讯会议 353 381 727
Mechanism of strawberry fruit initiation induced by the fertilization-induced signal in seeds
摘要：草莓果实发育自花托，是研究果实发育启动的模式植物之一。之前的研究发现，位于果实表面的瘦果可以产生促进果实发育的激素信号，生长素和赤霉素。这些激素信号随后被运输到花托中，启动果实发育。但是，受精后种子启动生长素合成的分子机制并不清楚。利用二倍体野生草莓（Fragaria vesca），我们研究了MADS box转录因子AGL62和AGL80在启动种子和果实发育过程中的功能。CRISPR敲除AGL62突变体的种子和果实发育失败。同时，突变体种子中生长素合成基因表达下调以及生长素报告基因信号下降。但是，种子和果实的发育表型可以被体外喷洒的生长素恢复。这些实验数据表明，AGL62作为转录因子可以在受精后的种子中启动生长素合成。另外，我们发现，数个ATHB基因作用于AGL62下游，并直接调控生长素合成。我们的研究工作发现了一个调控种子受精后启动生长素合成的包含AGL62和ATHB转录因子的调控途径。
Strawberry is an accessary fruit derived from receptacle and has been serving as a model to investigate mechanisms of fruit initiation. Previous studies suggest that the seed-containing ovaries called achenes embedded on the surface of receptacle are responsible for fertilization-induced auxin and GA production. The phytohormones are subsequently transported to the receptacle to promote fruit initiation. However, how fertilization initiates auxin biosynthesis in the seed is not known. Using Fragaria vesca, the diploid wild strawberry, we investigated the function of MADS box transcription factors (TFs) AGL62 and AGL80 in initiating seed and fruit development. CRISPR/Cas9-knockout of F. vesca AGL62 led to defective seeds and no fruit formation. agl62 mutant seeds exhibited reduced auxin biosynthesis gene expression and reduced auxin activity by auxin-reporters. Consequently, the seed defect of agl62 could be rescued by exogenous auxin application. The data establishes AGL62 as a key transcription factor (TF) that activates auxin synthesis in seeds upon successful fertilization. Further, several ATHB TFs were found to act downstream of AGL62 to directly regulate auxin biosynthesis. Our data suggest a genetic pathway consisting of AGL62 and ATHB genes in mediating fertilization-induced auxin biosynthesis in seeds. The work lays the foundation for future engineering of strawberry to induce virgin (parthenocarpic) fruits.
Discovery, processing, and potential role of noncanonical 5’ end modification in RNA
摘要：RNA化学修饰是目前生命科学研究的重点方向之一。在生物的mRNA中，核酸序列中间及5’末端均可发生转录后化学修饰，其中，5’端加帽修饰对RNA的生物功能有着重要的影响。长期以来，m7G被认为是真核生物唯一的5’端加帽修饰。近几年研究发现，生物体内参与氧化还原反应的关键代谢中间物质NAD同样可形成RNA 5’端修饰结构，然而，NAD加帽修饰的研究尚处于起步阶段，其在生物中具体的生物学功能，还未可知。我们结合代谢检测及高通量测序手段，鉴定了植物中NAD RNA修饰，并挖掘可催化NAD修饰及去修饰的蛋白酶，以期探索其对植物体潜在的分子功能与生物学意义。
The modification of RNA species has been well documented for decades. In mRNA, both internal and 5’ end modifications can occur. Specifically, modification of the 5’ end is known as capping. The 5’-5’ triphosphate linked N7-methyl guanosine (m7G) structure is involved in a myriad of RNA processes and was long presumed to be the only functional cap. In recent years, this view was overturned by reports that nicotinamide adenine dinucleotide (NAD+), a critical redox cofactor, can serve as an RNA cap in bacteria. Subsequently, yeast, mammalian, and plant RNA species were also found to harbor the NAD+cap. However, the functions of noncanonical capping remain mostly unknown. Here, we describe the detection methods for noncanonical RNA caps, their mode of capping and decapping, and their potential molecular and biological functions. The discovery of noncanonical caps represents a revolution in research on RNA modifications and prompts future efforts to delve into novel epitranscriptomic processes, which may link cellular metabolism with gene expression.