Characterization and Identification of a Ripening-Related Gene in .

() is a kind of climacteric fruit that quickly softens and limits fruit shelf-life and commercial value. Therefore, it is of great significance to develop kiwifruit genotypes with an extended shelf-life of fruit. However, the ripening and softening mechanisms remain unclear in . Here, we demonstrated that a key polygalacturonase (PG)-encoding gene was involved in ripening through the degradation of the cell wall. Fruits were harvested at three developmental stages (S1, S2, and S3) for high-throughput transcriptome sequencing, based on which two candidate transcripts and were screened. The genome-wide identification of the PG gene family assigned and to correspond to and , respectively. The expression profiles of candidate genes at six preharvest stages of fruit showed significantly higher expression levels of than , indicating might be a key gene during fruit ripening processes. The subcellular localization displayed was located at the cytoplasmic membrane. The transient overexpression of in strawberry and the following morphological observation suggested played a key role in maintaining the stability of cell morphology. The homologous transient transformation in "RB-4" proved the crucial function of in fruit ripening processes by causing the rapid redness of the fruit, which was an indicator of fruit maturity. All in all, our results identified as a key candidate gene involved in cell wall degeneration, which provides a basis for the subsequent exploration of the molecular mechanisms underlying the ripening and softening of fruit.