Abstract:

The OsEXP3 and OsEXP5 genes are α-expansin genes of rice reported in GenBank. In this research, according to mRNA sequence of OsEXP3 and OsEXP5 in GenBank, we designed a pair of primers each and cloned two fragments of the genes from the roots of four dryland rice cultivars using RT-PCR. It proved that expansin gene also expressed in the roots of dryland rice. The expression character of OsEXP3 and OsEXP5 genes in the roots was studied through the method of Northern-blot. The results showed the OsEXP3 gene was high expressed in 3-d-old roots and 20-d-old roots, but low expressed in 8-d-old roots and 15-d-old roots (Fig.6-a); the OsEXP5 gene was high expressed in 3-d-old roots and not expressed in 8-d-old roots of IRAT109 (Fig.6-b). And the expressions of OsEXP3 and OsEXP5 genes were enhanced in 8-d-old roots treated with 50 µmol/L ABA for three hours ( Fig.6-a and Fig.6-b). The expression of OsEXP3 was enhanced in 3-d-old seedlings with drying for 3 hours and then reduced to control level after rewatering (Fig.6-a), while that of OsEXP5 enhanced in 8-d-old seedlings with drying for 5 days (Fig.6-b). The results show the expressions of OsEXP3 and OsEXP5 genes are regulated by development stages and regulated positively by ABA and drought stress. And the expression stage of the OsEXP3 gene is different from that of OsEXP5, indicating OsEXP3 and OsEXP5 function in different stages of development under drought-stress condition.

Key words: Dryland rice root, OsEXP3, OsEXP5, RT-PCR, Northern-blot