Construction And Screening Of A NaCl-induced CDNA Library And Function Identification Of Metallothionein-like Genes In Cotton

Cotton is one of the most important economic crops in our country. People are always interested in identifying and developing new cotton breed to make it can be widely cultivated in saline-alkali soil. Recently, a great achievement has been obtained. However, the salt tolerance ability of cotton is still very limited. So identification of the corresponding salt-tolerant cotton will have important implications for agriculture. The transgenic technology provides us with new ways to improve the plants tolerance by transferring useful genes to different plants. In this experiment, a NaCl-induced cDNA library of cotton seedlings was constructed in order to isolate more salt-tolerance genes from cotton, and 17 salt-induced clones were identified after screening the cDNA Library. Clone 5 and 17 showed high sequence similarity to each other and to some metallothein-like genes in other plants.Metallothioneins (MTs) are defined as a class of proteins with the characteristics of low molecular weight, high cysteine (Cys) residue content and metal-binding ability. They have been widely found in animals, plants, fungi and cyanobacteria. Plant MT-like proteins are divided into three major classes (MT-I, MT-II, MT-III ), which are distinguishable on the basis of the distribution of cysteine residues in their amino acid sequences. Clone 5 and 17 belong to class MT-I. In this thesis, our studies are mainly focused on the sequence and expression analysis, function identification of the two cotton...