Characterization of HHO5, a transcription factor involved in nitrogen response in A. thaliana and rice

Abstract

Nitrogen deficiencies and the use of fertilizers is a major issue for crops production having both economic and environmental consequences. In a previous work, we have demonstrated that HHO5 gene is expressed in both A. thaliana and O. sativa when the plant is supplied with a nitrogen source and that plays an important role in the nitrogen response regulatory network with a systems biology perspective (Obertello et al., 2015). Our goal is to characterize HHO5 and to understand its role in nitrogen response pathway in both species. . Our in silico analysis of HHO5 endogen promoter compared with data of genes expressed under N supply conditions in both species revealed possible associations of HHO5 and regulatory pathways other than nitrogen use. We found sites targeted by known TFs associated with stress response, such as ABI5 and OsWRKY11 with two and three target sites respectively in OsHHO5 promoter and AtWRKY28 with two sites in AtHHO5 promoter. Based on that analysis, we selected different length of endogenous pAtHHO5 promoters in order to study its regulation and expression pattern in a N context. We generated several transgenic lines in A. thaliana using YFP and GUS as reporters genes. Also, in order to analyze HHO5 localization and its effects in N use efficiency, we generated O. sativa transgenic 35Sp::OsHHO5-GFP overexpressing lines.