中文摘要：

OsEXP3基因和OsEXP5基因是GenBank上登录的从水稻中克隆的扩张蛋白基因。本研究根据其报道的mRNA序列设计引物，利用RT-PCR技术从4种旱稻根系中克隆了这2个基因的部分编码框序列，证明OsEXP3与OsEXP5基因在旱稻的根系中表达；通过Northern-blot技术对该表达特性进行了研究。结果表明，OsEXP3与OsEXP5基因在旱稻IRAT109根中的表达受到生长发育阶段的调控；受到激素ABA、干旱胁迫的正调控；且受干旱胁迫诱导表达的生长阶段不同。以上实验结果推测在干旱胁迫条件下很可能OsEXP3与OsEXP5基因在不同的生长阶段发挥各自的主要生理功能。

英文摘要：

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 ttmol/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 OsEXPS, indicating OsEXP3 and OsEXP5 function in different stages of development under drought-stress condition.