Protein identification at each growth stage based on early-stage expression in 'Niitaka' pear fruits

Identifying quantitative changes in proteins at different stages of fruit growth is critical for understanding their overall growth and development. This study conducted quantitative proteomic analyses on 'Niitaka' pear fruits throughout their growth and development, comparing protein expression levels to those observed 30 days after full bloom (DAFB). From 30 to 180 DAFB in 2022, fruit flesh tissue was sampled at 15-day intervals from a pear orchard in Naju, Korea. Rapid growth was observed between 75 and 180 DAFB. The proteomic analysis unveiled significant growth-stage-dependent alterations in 217 proteins. These proteins were clustered into five groups based on their expression profiles using K-means clustering, and each protein's function was identified. Some identified functions were specific to a single cluster: Cluster K1, vesicle trafficking; Cluster K2, metabolism; Cluster K3, cell division and multi-process regulation; and Cluster K5, plant reproduction. The overall protein expression patterns differed among clusters, showing notable increases or decreases around 75 DAFB. In conclusion, early-expressed proteins exhibited marked changes in expression at 75 DAFB, aligning with an inflection point seen in fruit growth. Decoding the functions of these early-expressed proteins in future studies could significantly enhance our comprehension of their influence on early fruit growth and development.