A Proteomic Study on Seed Germination of Nitraria roborowskii Kom.

Owing to the dormancy of the seeds of Nitraria roborowskii Kom., which results in a low germination rate in nature, germination takes a long time, and natural regeneration is difficult. Therefore, there is a need to study the molecular mechanism by which the seeds of N. roborowskii release dormancy. In this study, the differentially expressed proteins of N. roborowskii seeds before and after dormancy and germination were quantitatively and qualitatively analyzed via two-dimensional high-performance liquid chromatography tandem mass spectrometry (LC–MS) and TMTTM. Differentially expressed proteins from dormant and germinated seeds were characterized and enriched via bioinformatics to determine the functions and pathways of the differentially expressed proteins. The results revealed that seed dormancy was regulated by multiple metabolic pathways, including protein synthesis, nutrient utilization and phytohormone signal transduction pathways. A comparison of the dormant and germinated N. roborowskii seed samples revealed 1082 differentially expressed proteins with FC ≥ 1.5 and p values ≤ 0.05, among which 191 proteins were upregulated and 891 proteins were downregulated in the seeds of the germinated group, and proteins more closely related to the key genes of the germinated N. roborowskii seeds were involved in the activity of D-threo-aldose 1-dehydrogenase. Four proteins (WD40, cystatin, AMP binding protein, and helicase) were involved in the positive regulation of seed germination. The release of N. roborowskii seed dormancy is a complex biological process involving cell differentiation, formation, cellular transport, signaling and resistance, etc. The interactions of multiple metabolic pathways, such as carbon fixation, glycolysis/gluconeogenesis, the pentose phosphate pathway, endoplasmic reticulum protein processing and pyruvic acid metabolism in photosynthetic organisms, constitute a complex regulatory mechanism for dormancy release.