Molecular cloning of two maize (<italic>Zea mays</italic>) <italic>ZmCOP1</italic> genes and their transcription abundances in response to different light treatments

Abstract

<p id="C3">As an E3 ubiquitin ligase, CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) mediates ubiquitination and degradation of positive regulatory factors such as HY5, LAF1, HFR1, and CO of the light signal transduction in <italic>Arabidopsis thaliana</italic>, thus mediating seedling photomorphogenesis, anthocyanin synthesis, and flowering time. To explore functional differentiation of <italic>ZmCOP1</italic> genes, we cloned two <italic>ZmCOP1</italic> genes, designated as <italic>ZmCOP1a</italic> and <italic>ZmCOP1b</italic>, from maize inbred line B73 by reverse transcription PCR (RT-PCR). The physicochemical properties, domain prediction and phylogenetic tree of ZmCOP1 were analyzed by bioinformatics software and website. The transcription abundances of two <italic>ZmCOP1</italic> genes in different tissues and their responses to different light treatments at seedling stage were further analyzed by quantitative RT-PCR (qRT-PCR). We found that the open reading frames (ORFs) of <italic>ZmCOP1a</italic> and <italic>ZmCOP1b</italic> possessed 2082 and 2061 nucleotides, encoding 693 and 686 amino acids, respectively. The COP1 proteins of maize, rice, sorghum, millet, and <italic>Arabidopsis</italic> shared the same structural domains and high amino acid sequence identity, indicating that they may have similar functions. The two <italic>ZmCOP1</italic> genes were mainly expressed in the above-ground tissues. Both of them could rapidly respond to different light treatments, while the transcription abundances of <italic>ZmCOP1a</italic> were generally higher than those of <italic>ZmCOP1b</italic>. It might suggest that <italic>ZmCOP1a</italic> may play more important roles under different light conditions. Under long-day or short-day condition, the transcription abundances of both <italic>ZmCOP1a</italic> and <italic>ZmCOP1b</italic> during the dark phase were higher than those during the light phase. Another interesting case is that both genes kept similar expression patterns during the light phase, while, transcription abundances of <italic>ZmCOP1b</italic> were higher than those of <italic>ZmCOP1a</italic> during the dark phase. It might imply that <italic>ZmCOP1b</italic> may be more important than <italic>ZmCOP1a</italic> in response to long-day or short-day treatment. In conclusion, both <italic>ZmCOP1a</italic> and <italic>ZmCOP1b</italic> had got functional redundancy and differentiation. Both genes could participate in different light signal pathways, and regulate maize photomorphogenesis and flowering period. Our results also provide a research foundation for further exploration of two <italic>ZmCOP1</italic> genes and application in molecular breeding in maize.