Identification of PEPC genes from foxtail millet and its response to abiotic stress

Abstract

<p indent=0mm>Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme in photosynthesis of C₄ plants and plays an important role in a variety of metabolic and stress pathways. In this study, we identified six candidate PEPC genes from foxtail millet genome via sequence alignment. The characteristic parameters of all <italic>SiPEPC</italic> protein were very similar and the sequences were very conservative. All <italic>SiPEPC</italic> genes contained the PEPcase motif, which is the characteristic domain of <italic>PEPC</italic> gene. <italic>SiPEPCs</italic> were localized in cytoplasm, nucleus and mitochondrion. Promoter analysis identified a variety of light, hormonal, stress, and other growth-related cis-elements in the promoter sequences of <italic>SiPEPC</italic> members. The qRT-PCR expression profiles showed that the five <italic>SiPEPC</italic> genes (<italic>SiPEPC1</italic>,<italic> SiPEPC2</italic>,<italic> SiPEPC3</italic>,<italic> SiPEPC5</italic>,<italic> SiPEPC6</italic>) were induced by ABA, PEG, high salt and low temperature at seedling stage, indicating that five <italic>SiPEPC</italic> genes ate involved in abiotic signaling pathway at the seedling stage. The expression of five<italic> SiPEPC</italic> genes increased with the growth of foxtail millet under normal growth conditions, and increased significantly under drought stress at different growth stages, indicating that five<italic> SiPEPCs</italic> are involved in drought stress response at jointing, heading and filling stages. The weak light at jointing stage could induce the expression of five <italic>SiPEPC</italic> genes, while the expression level decreased sharply under moderate light intensity at jointing stage, moderate and weak light intensity at heading and filling stages, showing that light intensity seriously affects the expression of <italic>SiPEPC</italic> genes.