Comparative Proteomics Of Manihot Esculenta Leaves And Chloroplasts Under Salt Stress

Soil salinity is one of the major stresses which inhibits the growth and development of many plants. As a famous stress-resistance tropical crop, cassava can grow well in barren, drought, hot and other harsh environments. Uncovering the detail mechanism of growth regulation of cassava under salt stress can make the salt resistance mechanism of plants know and it can be improved the utilization of soil salinization.Protein is a direct participant in the activities of physiological and biochemical, by researching on proteins, we can directly reveal the level of the whole plant’s response to sanility. Protein phosphorylation is the most important one of post-translational modifications, which can regulate the activity and function of substrate proteins, thus playing an important role in the regulation of plants under stress. Chloroplast is a place for photosynthesis, and this organ contains many phosphorylated proteins that involved in the regulation of a variety of reactions. Therefore, the research of phosphoproteomics of chloroplast and leaf proteomics will help us better understanding the mechanism of cassava under salt stress.In this experiment, cassava varity South China No.8(SC8) was used as a research material. This experiment builds a control group (without salt stress) and a treatment group (300mM NaCl as the saline condition for5,10and15days, respectively). Experiments observed the morphological and determinate the physiological and biochemical indexes of cassava in different periods. With the compared of phosphoproteomics of chloroplast and the study of leaf proteomics, looking for proteins associated with salt resistance of cassava. These results can provide the basis for the study of regulatory mechanisms of cassava under tolerant environment. The main results are listed as the following:1. We observed the morphological and determinated the physiological and biochemical indexes of cassava in different periods. According to the observation of cassava under salt stress, the leaves are wilting sagging and the bottom leaves are being yellow and fall off. Soluble sugars and proline are deepening with increasing salt stress. It can be seen, cassava according by increasing small organic molecules to regulate cell osmotic to against the salt stress.2. The phosphoproteomics of chloroplast in different periods under salt stress revealed16phosphorylated proteins with significantly changed expression. Analysis of these identified proteins revealed most proteins were involved in photosynthesis, energy metabolism, carbon metabolism and translation processes.3. Comparative proteomics of cassava leaves in different periods of salt stress uncovered58differential proteins. These proteins were involved in energy metabolism, carbon metabolism, photosynthesis, resistance and protein modifications.4. Analysis of the expression of some genes which related to salt resistance proteins demonstrated the expressions of gene and proteins are somewhat different. Because of the complexity of gene regulation to the function protein according the level of transcription, the post-transcriptional medication might play a crucial role in the regulation process of plant under salinity.In summary, cassava can change its leaf shape to adapt the salt stress environment, and it can also increase the content of small organic molecules to regulate cell osmotic potential to adapt the salt stress. Chloroplast phosphoproteome analysis and cassava leaf proteome found that protein phosphorylation may play an important role in the process of salt resistance in cassava. These results provided a foundation for the study of certain aspects of cassava salt tolerant mechanism in the future.