Identification And Research Of Salinity-tolerance On Cotton By SSR Markers

Soil salinization has become a serious global problem affecting the agricultural development and the ecological environment. Cotton, the major cash crop in China, is playing a crucial role in national economic development. China, with less cultivated lands and more people, faces the contradiction between food and cotton, which seriously affects the cultivation and production of cotton. Therefore, it is an effective way to farm saline land and to enhance the sustainable agricultural development by develop the salinity-tolerant varieties of cotton. Identification of salinity-tolerance also plays a vital role on cotton breeding. The salinity-tolerant identification methods used before, mainly based on morphological characters, were usually restricted for time-wasting, labor-costing, environment influence, and seasonal cultivation. 25 salinity- tolerant and 23 salinity-sensitive cotton accessions were used in this study to identify salinity-tolerance of cotton by SSR markers. A SSR molecular marker method was initially established to identify salinity-tolerance of cotton.1. The genetic diversity of cotton germlasm was analyzed among 48 cotton salinity-tolerance relevant accessions using 95 SSR molecular markers, which showed that most of germplasm had close genetic relationship, the cotton germplasm were of close relationship with narrow background of the intra-specific genetic diversity and broad hereditary gap between inter-specific cotton accessions. 48 cotton accessions could be classified into 3 groups by cluster analysis by UPGMA, which revealed that there was similar background among the dividing group in territorial background.2. 26 pairs of SSR core primers were screened from 5053 pairs of primers. The fingerprints of 48 salinity-tolerance relevant cotton accessions were constructed by 26 pairs of core SSR primers, which enhenced the researches of the genetic diversity, purity test, identification and evaluation of cotton germplasm.3. A new SSR molecular marker identification method was suggested for the complex of the salinity-tolerance of cotton, for the difficulty to screen dominant markers related to the salinity-tolerant genes, and for the difficulty to identify salinity-tolerance by single marker. To analyze the identification efficiency between single marker and multi-markers, the most economical and effective way to identify the salinity tolerance was the combination of 3 markers Y190, Y159 and Y258.4. A new preliminary methods, called SSR multi-markers salinity-identification method, was initially established to identify salinity-tolerance of cotton by the standardization of the whole process of DNA extraction, PCR amplification, amplification products detecting, and marker-combination. Another 11 materials were used to testify this method, which showed the coincidence of 90.91% in consistence with the identification result of 0.4%NaCl identification method. This study showed that the multi-markers identification method was proved to be used to assist identify the salinity-tolerance of cotton germplasm.The multi-markers identification method lays the foundation for molecular identification of salinity-tolerance on cotton, and provided theoretical basis for screening and breeding of salinity-tolerant cotton varieties. This method might be restricted only to be used to distinguish salinity-tolerant accessions from salinity sensitive accessions, which suggests that it need further in-depth studying to research how to grading salinity-tolerance of cotton germplasm.