Molecular cloning and functional characterization of the CEP RECEPTOR 1 gene MdCEPR1 of Apple (Malus × domestica)

Leucine-rich repeat-receptor-like kinases (LRR-RLKs) are major gene families that play an important role in in many aspects of plant growth and development particularly in the process of signal transmission. RLK XYLEM INTERMIXED WITH PHLOEM 1 (XIP1)/C-TERMINALLY ENCODED PEPTIDE (CEP) RECEPTOR 1 (CEPR1) has been identified as a leucine-rich repeat (LRR) receptor kinase. In this study, the MdCEPR1 gene (GenBank ID: DQ221207) from apple (Malus × domestica), was isolated and characterized. MdCEPR1 transcripts were highly accumulated in roots and leaves, and MdCEPR1 was significantly induced under low nitrate conditions. In addition, suppressing the MdCEPR1 gene in apple calli increased anthocyanin content. Overexpression of MdCEPR1 promoted growth of apple calli and Arabidopsis thaliana under low nitrate condition by increasing nitrate assimilation and up regulating the expression of genes involved in nitrate assimilation. Ectopic expression of MdCEPR1 also promoted lateral root development in transgenic Arabidopsis. Taken together, our results indicated that MdCEPR1 acts as a positive regulator of plant nitrate utilization and lateral root development.