【Objective】Calcium dependent proteinkinases( CPKs),a kind of serine/threonine protein kinases,are only found in plants and lower animals. Ca2 +,as a second messenger,plays important roles in various aspects of plant physiology and is involved in many cellular processes. The purpose of this paper is to study the dynamic expression of Zm CPK9 gene in seedling stage under different stress conditions and to lay the foundation for further analysis of the function and mechanism of this gene in maize adverse stres...