Department of Agronomy, Horticulture and Plant Science, South Dakota State University, Brookings, SD 57007, USA.
Department of Biology, Washington Univeristy in St. Louis, St. Louis, MO 63130, USA.
Int J Mol Sci. 2019 Feb 14;20(4):827. doi: 10.3390/ijms20040827.
Fabaceans produce two major classes of symbiotic nodules: the indeterminate type characterized by a persistent meristem, and the determinate type that lacks a persistent meristem. The class III homeodomain leucine zipper (HD-ZIP III) transcription factor family influence development of multiple lateral organs and meristem maintenance, but their role in determinate nodule development is not known. HD-ZIP III protein activity is post-translationally regulated by members of the small leucine zipper protein (ZPR) family in arabidopsis. We characterized the ZPR gene family in soybean and evaluated their ability to interact with two key members of GmHD-ZIP III family through yeast two-hybrid assays. GmZPR3d displayed the strongest interaction with GmHD-ZIP III-2 among the different pairs evaluated. GmHD-ZIP III-1, -2, and GmZPR3d showed overlapping expression patterns in the root stele and in nodule parenchyma tissues. Over-expression of GmZPR3d resulted in ectopic root secondary xylem formation, and enhanced expression of vessel-specific master switch genes in soybean. The nodules in ZPR3d over-expressing roots were larger in size, had a relatively larger central zone and displayed increased nodule vascular branching. The results from this study point to a key role for GmZPR3d in soybean root and nodule development.
不定型，其特征为持久的分生组织；定型，缺乏持久的分生组织。III 类同源域亮氨酸拉链（HD-ZIP III）转录因子家族影响多个侧生器官和分生组织的维持，但它们在定型根瘤发育中的作用尚不清楚。HD-ZIP III 蛋白活性在拟南芥中受小亮氨酸拉链蛋白（ZPR）家族成员的翻译后调控。我们对大豆中的 ZPR 基因家族进行了表征，并通过酵母双杂交试验评估了它们与两个关键的 GmHD-ZIP III 家族成员相互作用的能力。在评估的不同对中，GmZPR3d 与 GmHD-ZIP III-2 表现出最强的相互作用。GmHD-ZIP III-1、-2 和 GmZPR3d 在根中柱和根瘤薄壁组织中表现出重叠的表达模式。GmZPR3d 的过表达导致次生木质部的异位形成，并增强了大豆中脉特异性主开关基因的表达。在 ZPR3d 过表达根中的根瘤体积较大，中央区相对较大，并显示出增加的根瘤血管分枝。这项研究的结果表明 GmZPR3d 在大豆根和根瘤发育中起着关键作用。
