Abstract: Hd6 gene plays an important role in photoperiod sensitive phenomenon in rice (Oryza sativa L.). In the present study, a Hd6-like gene was cloned by RT-PCR and rapid amplification of cDNA ends (RACE) using a photosensitive tropical maize (Zea mays L.) inbred line CML288. A predicated 999-bp open reading frame was detected in the cloned sequence, which encoded 332 amino acids. By BLAST analysis, we found the gene sequence shared a high similarity with a gene encoding protein kinase CK2 in maize. The amino acid sequence contained two CK2 activity domains, one ATP binding site, one basic stretch (NLS), one N terminal domain, a putative serine/thereonine protein kinase active site, and showed a high homologization with that of protein kinase CK2α in maize, wheat, rice and Arabidopsis. We established fluorescence quantitative RT-PCR system with CML288, and studied the expression of Hd6-like in shoot apical meristem (SAM) and leaf under long day and short day conditions between 5-leaf and 9-leaf stages. We found that Hd6-like gene expressed both in SAM and leaf of CML288. Under the short day treatment, it expressed higher in SAM than in leaf from 6-leaf to 8-leaf stages with the highest expression level at 7-leaf stage. Under the long day treatment, the expression level fell down suddenly at 6-leaf stage in SAM with the peak at 9-leaf stage in leaf. Our results suggest that Hd6-like gene encodes protein kinase CK2α that closely relates to photoperiod-sensitive, and may function in regulating photoperiod sensitivity in maize.

Key words: Photoperiod sensitive, Gene clone, Hd6-like gene, Real-time quantitative RT-PCR, Maize