Proteomics analysis of Cyclobalanopsis gilva provides new insights of low seed germination.

A valuable plant, Cyclobalanopsis gilva, (C. gilva) has a low germination rate (below 50%) under its natural habitations. In order to examine the reasons for the low germination rate, the seeds of C. gilva (germinated and non-germinated) were evaluated using comparative proteomics analysis. A total of 3078 differentially abundant proteins (DAPs) were identified through a label-free method; most DAPs up-accumulated in germinated seeds were related to carbohydrates metabolism. Furthermore the proteins related to the signals, stress, and protein metabolism showed up-accumulation in germinated and no abundance or down-accumulation in non-germinated seeds. Enzyme activity of HK, PGK, PFK, and PK from glycolysis in SG-Control samples were 1.7-, 1.1-, 1.4-, and 1.3-times higher compared with those in control ones while CS, NAD-MDH, α-KGDH, and ICDH from the TCA cycle in SG-Control samples were 3, 1.1, 1.2, and 1.2 times higher than those in NG-Control ones. The β-amylase activity was 4-fold higher in successfully germinated seeds compared to non-germinated seeds. Interestingly, α-amylase did not show significant changes in protein abundance and enzyme activity among the three samples. The present findings reveal that unsuccessful germination of C. gilva seeds is due to lack of energy.