AtU2AF65b functions in abscisic acid mediated flowering via regulating the precursor messenger RNA splicing of ABI5 and FLC in Arabidopsis

First author: Feng Xiong; Affiliations: Shandong Agricultural University (山东农业大学): Taian, China

Corresponding author: Xiu‐Ling Wang

In mammalians and yeast, the splicing factor U2AF65/Mud2p functions in precursor messenger RNA (pre‐mRNA) processing. Arabidopsis AtU2AF65b encodes a putative U2AF65 but its specific functions in plants are unknown. This paper examines the function of AtU2AF65b as a negative regulator of flowering time in Arabidopsis. We investigated the expression and function of AtU2AF65b in abscisic acid (ABA)‐regulated flowering as well as the transcript abundance and pre‐mRNA splicing of flowering‐related genes in the knock‐out mutants of AtU2AF65b. The atu2af65b mutants show early‐flowering phenotype under both long‐day and short‐day conditions. The transcript accumulation of the flowering repressor gene FLOWERING LOCUS C (FLC) is reduced in the shoot apex of atu2af65b, due to both increased intron retention and reduced transcription activation. Reduced transcription of FLC results, at least partially, from the abnormal splicing and reduced transcript abundance of ABSCISIC ACID‐INSENSITIVE 5 (ABI5), which encodes an activator of FLC in ABA‐regulated flowering signaling. Additionally, the expression of AtU2AF65b is promoted by ABA. Transition to flowering and splicing of FLC and ABI5 in the atu2af65b mutants are compromised during ABA‐induced flowering. ABA‐responsive AtU2AF65b functions in the pre‐mRNA splicing of FLC and ABI5 in shoot apex, whereby AtU2AF65b is involved in ABA‐mediated flowering transition in Arabidopsis.

在哺乳动物和酵母中，剪切因子U2AF65/Mud2p作用于前提信使RNA，即pre‐mRNA的加工。拟南芥的AtU2AF65b基因编码一个U2AF65蛋白，但其在植物中的功能还不清楚。本文的研究显示AtU2AF65b基因作为拟南芥开花的负调控因子发挥作用。作者研究了AtU2AF65b在脱落酸调控的开花过程中的表达和功能，同时还有拟南芥AtU2AF65b功能缺失突变体中开花相关基因的表达丰度和pre‐mRNA的剪切。在atu2af65b突变体的茎尖部位，由于内含子保留的增加和转录活性的降低，开花抑制基因FLC的积累有所减少。FLC基因转录的降低至少部分是由于异常的剪切和ABI5基因表达丰度的降低所造成的，而ABI5基因是ABA调控开花信号通路上的一个基因，其编码的蛋白能够激活FLC基因。另外，ABA能够促进AtU2AF65b基因的表达。atu2af65b突变体中成花转变以及FLC和ABI5基因的剪切在ABA诱导的开花过程中受到了损害。能够响应ABA的AtU2AF65b基因作用于茎尖组织中FLC和ABI5基因的剪切，进而AtU2AF65b参与了拟南芥中ABA介导的成花转变。

通讯：王秀玲 (http://life.sdau.edu.cn/2019/0227/c2453a144962/page.htm)

个人简介：1994年，山东农业大学，学士；1997年，山东农业大学，硕士；2006年，中国农业大学，博士。

研究方向：拟南芥糖和激素ABA信号转导中相关基因响应非生物胁迫的分子机制；玉米和拟南芥中胚发育相关基因的表达调控及作用机制。

doi: https://doi.org/10.1111/nph.15756

Journal: New Phytologist

Published online: March 18, 2019