Ding Qi, Zeng Jun, He Xin-Qiang
State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
J Plant Physiol. 2016 Jul 1;198:1-9. doi: 10.1016/j.jplph.2016.03.017. Epub 2016 Apr 16.
Dormancy is an effective strategy for perennial plants in temperate zones to survive the winter stress. MicroRNAs (miRNAs) have been well known as important regulators for various biological processes. In this study, we checked the expression of miR169 members in the cambium zone during dormancy and active growth in poplar and found that they had distinct expression patterns. We identified and characterized a dormancy-specific target gene of miR169, PagHAP2-6. 5' RACE assays confirmed the direct cleavage of PagHAP2-6 mRNA by miR169. The yeast functional complementation analysis showed that PagHAP2-6 was a homolog of Heme Activator Protein2 (HAP2)/Nuclear factor Y-A (NF-YA) transcription factor in poplar. qRT-PCR analysis indicated that PagHAP2-6 was highly expressed in the dormant stage, which was converse to the expression pattern of pag-miR169a, n, and r. In addition, the transcription of PagHAP2-6 was induced by exogenous abscisic acid (ABA), and both over-expression of PagHAP2-6 in Arabidopsis and transient co-expression assays in Nicotiana benthamiana indicated that PagHAP2-6 could increase the resistance to exogenous ABA. Taken together, the results suggested that miR169 and its target PagHAP2-6 regulated by ABA were involved in poplar cambium dormancy, which provided new insights into the regulatory mechanisms of tree dormancy-active growth transition.
休眠是温带多年生植物应对冬季胁迫的有效策略。微小RNA（miRNA）作为各种生物学过程的重要调节因子已广为人知。在本研究中，我们检测了杨树休眠期和生长活跃期形成层区域中miR169成员的表达，发现它们具有不同的表达模式。我们鉴定并表征了miR169的一个休眠特异性靶基因PagHAP2-6。5' RACE分析证实miR169可直接切割PagHAP2-6 mRNA。酵母功能互补分析表明，PagHAP2-6是杨树中血红素激活蛋白2（HAP2）/核因子Y-A（NF-YA）转录因子的同源物。qRT-PCR分析表明，PagHAP2-6在休眠期高表达，这与pag-miR169a、n和r的表达模式相反。此外，PagHAP2-6的转录受外源脱落酸（ABA）诱导，在拟南芥中过表达PagHAP2-6以及在本氏烟草中进行瞬时共表达分析均表明，PagHAP2-6可增强对外源ABA的抗性。综上所述，结果表明受ABA调控的miR169及其靶基因PagHAP2-6参与了杨树形成层休眠，这为树木休眠-生长活跃转变的调控机制提供了新的见解。
