Key Laboratory of Tropical Fruit Biology (Ministry of Agriculture), South Subtropical Crops Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang 524091, China.
State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.
Gene. 2020 May 15;738:144455. doi: 10.1016/j.gene.2020.144455. Epub 2020 Feb 13.
DELLA proteins are members of the plant-specific GRAS family, acting as negative regulators of plant growth. In this study, we identified two DELLA protein-coding genes in litchi, denoted as LcGAI and LcRGL1. Motif analysis showed that LcGAI and LcRGL1 proteins both contain a conserved DELLA and TVHYNP motif at the N-terminus as well as LHR1, VHIID, LHR2, PFYRE, and SAW motifs at the C terminus. The fused proteins of LcGAI-GFP and LcRGL1-GFP were both localized in the nucleus. Overexpression of LcGAI and LcRGL1 in Arabidopsis substantially inhibits leaf growth. Expression analysis showed that HLH factors, PRE1 and PRE5, were restrained, whereas gibberellin (GA) receptors GID1a and LcGID1b were enhanced in LcGAI and LcRGL1 overexpression lines. Results of the yeast two-hybrid assay showed that LcGAI and LcRGL1 interact with LcGID1b/LcGID1c in a GA dose-dependent manner, whereas LcGAI and LcRGL1 had a greater binding capacity to LcGID1b than LcGID1c. These observations suggested that LcGAI and LcRGL1 proteins are nuclear growth repressors.
DELLA 蛋白是植物特异性 GRAS 家族的成员，作为植物生长的负调控因子。在本研究中，我们在荔枝中鉴定了两个 DELLA 蛋白编码基因，分别命名为 LcGAI 和 LcRGL1。基序分析表明，LcGAI 和 LcRGL1 蛋白的 N 端都含有一个保守的 DELLA 和 TVHYNP 基序，C 端都含有 LHR1、VHIID、LHR2、PFYRE 和 SAW 基序。LcGAI-GFP 和 LcRGL1-GFP 的融合蛋白都定位于细胞核中。LcGAI 和 LcRGL1 在拟南芥中的过表达显著抑制了叶片的生长。表达分析表明，HLH 因子 PRE1 和 PRE5 受到抑制，而赤霉素（GA）受体 GID1a 和 LcGID1b 在 LcGAI 和 LcRGL1 过表达系中增强。酵母双杂交试验结果表明，LcGAI 和 LcRGL1 与 LcGID1b/LcGID1c 以 GA 剂量依赖性的方式相互作用，而 LcGAI 和 LcRGL1 与 LcGID1b 的结合能力大于 LcGID1c。这些观察结果表明，LcGAI 和 LcRGL1 蛋白是核生长抑制剂。
