Abstract:

In order to study the function of polyamine uptake transporters (PUT) in rice, the members of OsPUT family in rice were identified by bioinformatics methods, and the structure of OsPUT5 protein was analyzed. The expression of OsPUT5 gene in different tissues of rice was detected by qRT-PCR, and the function of OsPUT5 gene was preliminarily studied by using rice overexpress (OE) lines, Nipponbare (Nip) lines and RNAi lines. The results showed that there were 6 OsPUTs in rice, among which, OsPUT5 was a membrane protein with 10 transmembrane domains and with the unique domain of putrescine ornithine antiporter PotE, it’s N-terminal and C-terminal were located outside the membrane. The gene expression pattern showed that OsPUT5 gene had the highest expression in leaves, but there was no significant(P>0.05) difference among roots, stems and flowers. In the life cycle, under normal conditions, there was no obvious phenotypic difference among RNAi lines, Nip lines and OE lines. At the seedling stage of rice, the relative conductivity, malondialdehyde content and proline content of RNAi lines, Nip lines and OE lines were significantly (P<0.05) increased after treatment at 4 ℃ for 30 h. Moreover, phenotypes were affected, compared with Nip lines and OE lines, RNAi lines were most affected, with withered leaves, serious water lost, significantly (P<0.05) reduced plant fresh weight and proline content, and significantly (P<0.05) increased relative conductivity and malondialdehyde content. Normal culture for 10 days after cold stress treatment, the survival rate of RNAi lines was significantly (P<0.05) lower than that of Nip lines and OE lines. It showed that overexpression or inhibition of OsPUT5 gene expression had no significant effect on the normal growth and development of rice, but inhibition of OsPUT5 gene expression reduced the resistance of rice to cold stress.

Key words: rice, polyamine transporter, polyamines