Transcriptional and Promoter Analysis of CaDUR3, a Coffea arabica Urea Transporter Gene

Nitrogen is one of the most expensive nutrients to supply and commercial fertilizers represent one of the major costs in coffee production. Urea is the major nitrogen form supplied as fertilizer in agriculture. Despite the importance of efficient use of urea-containing nitrogen fertilizers by crops, membrane transporters that might contribute to the uptake and transport of urea in plants were characterized only in model systems. Coffee is one of the most important agricultural commodities in the world, but molecular responses to environmental factors that may affect coffee production are still poorly understood. In this work, we evaluated the transcriptional pattern of Coffea arabica DUR3 (CaDUR3), a membrane transporter that plays an effective role in improvement of urea acquisition in rice and Arabidopsis. CaDUR3 was mostly expressed in leaves and secondary roots, while little to no expression were observed in flower buds, flowers, plagiotropic shoots and pericarp of mature fruits. Transcriptional analysis by qPCR indicated that this gene was upregulated under nitrogen starvation, water deficit, high salt and heat stress. To determine the molecular mechanisms underpinning the differential expression of this gene, the upstream region of the gene was analysed in silico and putative binding sites for Dof, MYB and WRKY transcription factors were identified in Arabidopsis and Coffea orthologs. Further studies in gene structure and functional analysis in heterologous systems may confirm if CaDUR3 is an active urea transporter that plays a significant role in urea acquisition and utilization in coffee plants. Finnancial support: Cnpq, FINEP and Consorcio Pesquisa Café.