MicroRNA is a kind of small non-coding RNA, involved in plant growth and development, stress response and other physiological processes. In our previous study, we found a series of microRNA that changed expression in the stress response on the basis of gene microarray. Among them, miR 446 is particularly significant. To further explore the change and function of miRNA446 in the stress response,, we study the expression pattern of its target gene APP1 under drought and cold stress by overexpression and inhibition of miR446 in rice. The results showed that in the overexpression rice, the expression of miR446 rose after the first drop while wild-type miR446 continued to rise, and APP1 gene continue to reduce due to the splicing action of high levels miR446. In the knockout rice, the expression of miR446 was completely inhibited in the whole process, remained close to zero, and APP1 rose after the first drop in a weak trend in the stress.
