Involvement of LcmiR482e-LcACA2 mediated energy metabolism in senescence of harvested litchi fruit

Ca2+ ATPase is essential for plant senescence, but its function and modulation in litchi remain largely unknown. Exogenous ATP treatment effectively alleviated litchi pericarp browning, and promote Ca2+ ATPase activity. The change of Ca2+ ATPase activity was negatively correlated with browning index (BI) and was positively correlated with ATP content during storage, demonstrating its positive roles in energy homeostasis and in delaying litchi senescence. The 14 litchi Ca2+ ATPase coding genes were comprehensively characterized, including ten LcACAs and four LcECAs. Expression profiles of Ca2+ ATPase coding genes in four litchi cultivars with different storability suggested that litchi cultivars with higher LcACAs expression achieved better storability. Additionally, LcACA2 was identified as a target of LcmiR482e by in vivo experiment and degradome, exhibiting opposite expression pattern to LcmiR482e during storage. Furthermore, ATP application remarkably downregulated LcmiR482e expression, contributing to the delayed senescence. This study provides new insights into Ca2+ ATPase-mediated litchi energy metabolism and senescence especially in miRNA regulation aspect.