Characterization of Genes from and Its Function in Response to Dark-Induced Leaf Senescence.

The Bcl-2-associated athanogene (BAG) family is a group of evolutionarily conserved cochaperones involved in diverse cellular functions. Here, ten putative genes were identified in tomato. and have the same gene structure and conserved domains, along with highly similar identity to their homologs in , , and . The qPCR data showed that and were highly expressed in stems and flowers. Moreover, both genes were differentially expressed under diverse abiotic stimuli, including cold stress, heat stress, salt treatment, and UV irradiation, and treatments with phytohormones, namely, ABA, SA, MeJA, and ETH. Subcellular localization showed that SlBAG2 and SlBAG5b were located in the cell membrane and nucleus. To elucidate the functions in leaf senescence of BAG2 and BAG5b, the full-length CDSs of and were cloned, and transgenic tomatoes were developed. Compared with WT plants, those overexpressing and had significantly increased chlorophyll contents, chlorophyll fluorescence parameters and photosynthetic rates but obviously decreased ROS levels, chlorophyll degradation and leaf senescence related gene expression under dark stress. Conclusively, overexpression and could improve the tolerance of tomato leaves to dark stress and delay leaf senescence.