Molecular Characterization of Somatic Embryogenesis Receptor-Like Kinase-1 (ScSERK1) Gene From Sugarcane (Saccharum spp. hybrid).

Leucine-rich repeat (LRR)-containing transmembrane receptor-like kinases (RLKs) are integral components of plant signal transduction pathways. Somatic Embryogenesis Receptor-like Kinase-1 (SERK1), a member of LRR-RLK superfamily, has been proposed to output downstream signaling cascades implicated in early embryonic development, somatic embryogenesis, reproductive development and immune responses. Full-length cDNA and genomic clones (1869 and 4752 bp, GenBank acc. nos. GQ283907 and GQ457454, respectively) encoding a putative SERK1 were isolated from an embryogenic cell culture line of sugarcane (Saccharum spp. hybrid cv. CP88-1762). The ScSERK1 gene shares a highly conserved exon/intron structure with other members of the SERK gene family. The deduced ScSERK1 amino acid sequence contains 622 residues with a predicted mass of 68.53 kDa and a 25 residue signal peptide for secretory pathway targeting. The mature peptide shares all the hallmark features of LRR-RLKs, namely, a leucine zipper, five LRR regions implicated in extracellular protein-protein interactions, SPP motif, and a transmembrane domain followed by an intracellular kinase domain. Southern blot hybridization suggested that ScSERK1 is represented as a low copy number gene in the aneupolyploid sugarcane genome. Quantitative RT-PCR data confirmed spatiotemporal regulation of ScSERK1 expression during initiation, acquisition and maintenance of in vitro embryogenesis, root and shoot organogenesis and vegetative-to-reproductive phase transition. Molecular data will be presented describing protein-protein interactions within the SERK1 signaling complex during somatic embryogenesis and reproductive phase transition in sugarcane.