The Arabidopsis Transcription Factor CDF3 Is Involved in Nitrogen Responses and Improves Nitrogen Use Efficiency in Tomato

Abstract

Nitrate is an essential macronutrient and a signal molecule that regulates the expression of multiple genes involved in plant growth and development. Here, we describe the participation of <i>Arabidopsis</i> DNA binding with one finger (DOF) transcription factor CDF3 in nitrate responses and shows that <i>CDF3</i> gene is induced under nitrate starvation. Moreover, knockout <i>cdf3</i> mutant plants exhibit nitrate-dependent lateral and primary root modifications, whereas <i>CDF3</i> overexpression plants show increased biomass and enhanced root development under both nitrogen poor and rich conditions. Expression analyses of <i>35S::CDF3</i> lines reveled that CDF3 regulates the expression of an important set of nitrate responsive genes including, <i>glutamine synthetase-1</i>, <i>glutamate synthase-2</i>, <i>nitrate reductase-1</i>, and nitrate transporters <i>NRT2.1</i>, <i>NRT2.4</i>, and <i>NRT2.5</i> as well as carbon assimilation genes like <i>PK1</i> and <i>PEPC1</i> in response to N availability. Consistently, metabolite profiling disclosed that the total amount of key N metabolites like glutamate, glutamine, and asparagine were higher in <i>CDF3</i>-overexpressing plants, but lower in <i>cdf3-1</i> in N limiting conditions. Moreover, overexpression of <i>CDF3</i> in tomato increased N accumulation and yield efficiency under both optimum and limiting N supply. These results highlight CDF3 as an important regulatory factor for the nitrate response, and its potential for improving N use efficiency in crops.