Role of apyrase-mediated eATP signal in chilling injury of postharvest banana fruit during storage

Abstract

Apyrase (APY) might regulate the homeostasis of extracellular ATP (eATP) / intracellular ATP (iATP) and mediate plant growth and defense response, but little information on the roles of APY genes in eATP-mediated chilling response of banana fruit during storage has been available. This study identified a total of 10 full-length banana APY genes, analyzed cis-elements in promoters and potential miRNA target sites and found that these APYs had highly conserved functions and might regulate energy metabolism during banana fruit development, ripening and senescence. Exogenous ATP was used to investigate the roles of APY genes in chilling injury (CI) of banana fruit stored for up to 6 d at 6 °C. Application of 1 mM ATP solution effectively reduced CI symptoms, inhibited malondialdehyde (MDA) accumulation, improved antioxidant capacity, and relatively maintained the homeostasis of iATP / eATP of banana fruit during cold storage. Compared with non-ATP-treated fruit, transcriptional levels of MaAPYs were up-regulated whereas those of nucleoside transporter genes and purine permease genes were down-regulated in ATP-treated banana fruit during cold storage, suggesting that the ATP pretreatment could maintain the relative homeostasis of iATP / eATP. The results provided the new insights into the roles of apyrase-mediated eATP signal in regulating the cold tolerance of banana fruit during storage at low temperature.