Wen Binbin, Gong Xingyao, Deng Wenpeng, Chen Xiude, Li Dongmei, Fu Xiling, Li Ling, Tan Qiuping
College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China.
State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China.
Front Plant Sci. 2022 Aug 9;13:932767. doi: 10.3389/fpls.2022.932767. eCollection 2022.
The regulation of plant gene expression by nitrate is a complex regulatory process. Here, we identified 90 GARP family genes in apples by genome-wide analysis. As a member of the GARP gene family, the expression of ( H) is upregulated under N (nitrogen) supply. The results of DNA-binding site analysis and electrophoretic mobility shift assays (EMSA) showed that MdHHO3 binds to the motif-containing GAATC. Furthermore, MdHHO3 binds to its promoter sequence and inhibits its activity. In addition, the overexpression of in apple calli resulted in less accumulation of nitrate in 35S:MdHHO3-GFP calli and downregulated the expression of the nitrate transport-related genes but upregulated the expression of the nitrate assimilation-related genes. Similarly, the expression of the nitrate transport-related genes was downregulated and the expression of the nitrate assimilation-related genes was upregulated in overexpression and tobacco plants. Interaction experiments showed that MdHHO3 could bind to the promoter () and negatively regulate its expression. Moreover, the exposure of MdHHO3-overexpressing and tobacco to nitrate deficiency resulted in an early senescence phenotype as compared to the WT plants. These results show that MdHHO3 can not only negatively regulate nitrate accumulation in response to nitrate but also promote early leaf senescence under nitrate deficiency. This information may be useful to further reveal the mechanism of the nitrate response and demonstrates that nitrate deficiency induces leaf senescence in apples.
硝酸盐对植物基因表达的调控是一个复杂的调控过程。在此，我们通过全基因组分析在苹果中鉴定出90个GARP家族基因。作为GARP基因家族的一员，（H）的表达在氮供应下上调。DNA结合位点分析和电泳迁移率变动分析（EMSA）结果表明，MdHHO3与含GAATC的基序结合。此外，MdHHO3与其启动子序列结合并抑制其活性。另外，在苹果愈伤组织中过表达导致35S:MdHHO3-GFP愈伤组织中硝酸盐积累减少，下调了硝酸盐转运相关基因的表达，但上调了硝酸盐同化相关基因的表达。同样，在过表达和烟草植株中，硝酸盐转运相关基因的表达下调，硝酸盐同化相关基因的表达上调。相互作用实验表明，MdHHO3可与启动子（）结合并负调控其表达。此外，与野生型植株相比，过表达MdHHO3的和烟草在硝酸盐缺乏条件下表现出早期衰老表型。这些结果表明，MdHHO3不仅能响应硝酸盐负调控硝酸盐积累，还能在硝酸盐缺乏时促进叶片早期衰老。该信息可能有助于进一步揭示硝酸盐响应机制，并证明硝酸盐缺乏诱导苹果叶片衰老。
