Abstract: Chitosan (CTS) can effectively enhance the tolerance of plants to salt stress, but its role in driving the responses of vegetable soybean seedlings to salt stress at proteomic level is still unclear. Here, both 200 mmol·L^-1 CTS and distilled water were used to spray the leaves of vegetable soybean ‘Lvlingtezao' seedlings. After 5 days of induction, NaCl stress and nutrient solution without NaCl were treated. Chloroplast proteins were extracted from leaves on the third day of NaCl treatment and analyzed by using the isobaric tags for relative and absolute quantification (iTRAQ). The result showed that CTS significantly increased net photosynthetic rate (P_n) of vegetable soybean seedlings under NaCl stress. Totally 549 reliable quantitative information proteins were identified, of which 442 existed in at least two biological repeats, including 26 up-regulated proteins and 4 down-regulated proteins associated with the effects of CTS on vegetable soybean response to NaCl stress. In addition, enrichment analysis of molecular function and metabolic pathway showed that up-regulated proteins were mainly related to molecular functions, including electron transport, chlorophyll binding, electron carrier activity, and were enriched in the pathways of photoreaction, carbon reaction and glyoxylic acid and dicarboxylic acid metabolism. Down-regulated proteins were mainly related to poly (U) RNA binding. Our results suggested that CTS could affect photosynthesis of vegetable soybean seedlings under NaCl stress through multiple pathways.

Key words: exogenous chitosan, NaCl stress, vegetable soybean, chloroplast proteome