Abstract:

Significant difference in adventitous root number（ARNs）was found between waterlogging tolerant line Zaoer-N and waterlogging sensitive line Pepino after 72 hours of waterlogging treatment，the average number of ARNs generated in Zaoer-N was 24.6，but only 1.5 in Pepino. Cucumis sativus calcium-dependent protein kinase 5（CsCDPK5）was cloned from the two lines，which shared a sequence identity of 100%，the length of CsCDPK5 was 1 887 bp，and encoded 629 amino acids. It was predicted that the molecular mass of this protein was 59.17 kD，and pI was 5.65. CsCDPK5 protein was predicted to be localized in cytoplasm. The two lines shared a sequence identity of 99% in promoter sequence，and include 14 single nucleotide polymorphisms. Both of the two lines contained cis-acting regulatory elements essential for phytohormone and anaerobic induction，whereas AT-rich sequence and F-box were special in Zaoer-N. The results of quantitative real-time PCR showed that：(1) CsCDPK5 was predominantly expressed in hypocotyls；(2) CsCDPK5 transcripts were upregulated at the beginning followed a slight down regulated in both hypocotyls of Zaoer-N and Pepino during waterlogging treatment，but higher in the former than latter；(3) CsCDPK5 transcripts were irregular in roots and leaves of both lines；(4) compared with controls，no significant changes were observed in CsCDPK5 transcripts when pretreatment with 1-MCP. In conclusion，CsCDPK5 is a waterlogging responsive gene and significant difference in transcripts were observed in hypocotyls of Zaoer-N and Pepino during waterlogging，and might play an important role in waterlogging-induced adventitious root formation.

Key words: cucumber, waterlogging stress, adventitious root, CDPK