Yan Zongyun, Jia Jianheng, Yan Xiaoyuan, Shi Huiying, Han Yuzhen
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
Plant Mol Biol. 2017 Dec;95(6):549-565. doi: 10.1007/s11103-017-0667-8. Epub 2017 Oct 26.
The two novel CCCH zinc-finger and K-homolog (KH) proteins, KHZ1 and KHZ2, play important roles in regulating flowering and senescence redundantly in Arabidopsis. The CCCH zinc-finger proteins and K-homolog (KH) proteins play important roles in plant development and stress responses. However, the biological functions of many CCCH zinc-finger proteins and KH proteins remain uncharacterized. In Arabidopsis, KHZ1 and KHZ2 are characterized as two novel CCCH zinc-finger and KH domain proteins which belong to subfamily VII in CCCH family. We obtained khz1, khz2 mutants and khz1 khz2 double mutants, as well as overexpression (OE) lines of KHZ1 and KHZ2. Compared with the wild type (WT), the khz2 mutants displayed no defects in growth and development, and the khz1 mutants were slightly late flowering, whereas the khz1 khz2 double mutants showed a pronounced late flowering phenotype. In contrast, artificially overexpressing KHZ1 and KHZ2 led to the early flowering. Consistent with the late flowering phenotype, the expression of flowering repressor gene FLC was up-regulated, while the expression of flowering integrator and floral meristem identity (FMI) genes were down-regulated significantly in khz1 khz2. In addition, we also observed that the OE plants of KHZ1 and KHZ2 showed early leaf senescence significantly, whereas the khz1 khz2 double mutants showed delayed senescence of leaf and the whole plant. Both KHZ1 and KHZ2 were ubiquitously expressed throughout the tissues of Arabidopsis. KHZ1 and KHZ2 were localized to the nucleus, and possessed both transactivation activities and RNA-binding abilities. Taken together, we conclude that KHZ1 and KHZ2 have redundant roles in the regulation of flowering and senescence in Arabidopsis.
两种新型的含CCCH锌指结构域和K-同源结构域（KH）的蛋白质KHZ1和KHZ2，在拟南芥中对开花和衰老的调控起着冗余作用。含CCCH锌指结构域的蛋白质和K-同源结构域（KH）的蛋白质在植物发育和应激反应中发挥重要作用。然而，许多含CCCH锌指结构域的蛋白质和KH蛋白质的生物学功能仍未得到表征。在拟南芥中，KHZ1和KHZ2被鉴定为两种新型的含CCCH锌指结构域和KH结构域的蛋白质，属于CCCH家族的第七亚家族。我们获得了khz1、khz2突变体和khz1 khz2双突变体，以及KHZ1和KHZ2的过表达（OE）株系。与野生型（WT）相比，khz2突变体在生长发育上没有缺陷，khz1突变体开花稍晚，而khz1 khz2双突变体表现出明显的晚花表型。相反，人工过表达KHZ1和KHZ2导致早花。与晚花表型一致，开花抑制基因FLC的表达上调，而开花整合基因和花分生组织特性（FMI）基因在khz1 khz2中的表达显著下调。此外，我们还观察到KHZ1和KHZ2的OE植株叶片衰老明显提前，而khz1 khz2双突变体叶片和整株植物的衰老延迟。KHZ1和KHZ2在拟南芥的所有组织中均有广泛表达。KHZ1和KHZ2定位于细胞核，具有反式激活活性和RNA结合能力。综上所述，我们得出结论，KHZ1和KHZ2在拟南芥开花和衰老的调控中具有冗余作用。
