Abstract: 【Objective】The changes of protein phosphorylation level during the growth and development of strawberry were analyzed in order to reveal the effect of protein phosphorylation on the growth and development of fruit during ripening and senescence.【Method】In this experiment, the protein phosphorylation level of strawberry fruit (Small green fruit stage, big green fruit stage, mature white stage, soft fruit stage, over-soft fruit stage) was analyzed by using iTRAQ-based (isobaric tags for relative and absolute quantification) quantitative proteomic and LC-MS/MS (liquid chromatography-mass spectrometry) methods. And the biological process classification, subcellular localization classification and molecular functional classification of these proteins were identified. The function of the phosphorylated proteins was predicted by comprehensive analysis of the results of multiple databases.【Result】 The results showed that the phosphorylation proteins at different developmental stages were different. During the period of big green fruit stage to soft fruit stage, the total number of phosphorylated protein and the number of proteins involved in the regulation of growth and development are more than at other developmental stage. Biological process classification results showed that most of these phosphorylated proteins were concentrated in the plant signal transduction pathway and the pathway of glucose metabolism. There were 17 phosphorylated proteins involved in signal transduction pathways, and 8 of them were involved in the process of glucose metabolism. Belonging to the MAPK cascade pathway are 101308592, 470122684, and 596127083. The phosphorylation level of 596127083 was relatively stable at various development stages, and 101308592 gradually increased with the development of phosphorylation, While the phosphorylation level of 470122684 began to decrease sharply from the soft fruit period. The results of subcellular localization showed that most of the phosphorylated proteins were localized in the nucleus and cytoplasm. Molecular functional classification showed that most of the phosphorylated proteins had the function of transcription regulation and phosphorylation. In this study, 24 phosphorylated proteins related to growth and development regulation were identified. Among them, four had the function of transcriptional regulation, six were involved in cell division, and there was also a part of the phosphorylated proteins involved in the regulation of the growth and development of hormone response. In addition, this study also identified 3 phosphorylated proteins related to the ripening and softening of fruit. In addition, a part of the protein has a variety of phosphorylation modification, SNF1 related protein kinase beta subunit has three kinds of phosphorylation modification, and its phosphorylation level is not the same.【Conclusion】There may be more than one kind of phosphorylation modification in the same kind of protein. Different phosphorylation modification methods are not the same. The dominant mode of modification in different periods is not only the same. Phosphorylation is not only involved in the regulation of transcription and cell division and differentiation, but also in response to plant hormones and the accumulation of sugars during fruit development. Even involved in the regulation of fruit ripening and softening.101308592 and 470122684 are likely to be involved in the regulation of fruit growth and development. In short, protein phosphorylation modification plays an important role in the growth and development of strawberry.

Key words: strawberry, fruit development, iTRAQ-based quantitative proteomic, phosphorylation, developmental regulation