Mechanism of cork spot formation: insights from integrated mineral, transcriptomic, metabolomic and hormone analyses

Abstract Pear cork spot disorder severely impairs pear fruit quality and yield, resulting in substantial economic losses for producers. However, the causes and underlying mechanisms of pear cork spot disorder remain unclear. In this study, a comprehensive investigation of the characteristics associated with cork spot disorder was conducted. We collected samples of healthy fruits as well as fruits in the early and late stages of cork spot disorder. By means of microstructure observation, determination of element and hormone contents and transcriptomic and metabolomic analyses, we provided a comprehensive elucidation of the differences between cork spot fruits and healthy fruits. Scanning electron microscopy observations showed that cork spot disorder arises from fruit cell rupture and subsequent collapse. Trace element analysis revealed that the contents of several elements, including calcium and boron, are closely associated with cork spot formation. Transcriptomic profiling indicated that cork spot development is strongly linked to pathways related to substance metabolism and plant hormone signalling Comparative metabolomic analyses between healthy and diseased fruit demonstrated that cork spot formation is significantly correlated with the accumulation of compounds such as phenolic acids, flavonoids and terpenoids. Moreover, significant differences were detected in the levels of major plant hormones between cork spot and healthy fruit. Notably, exogenous application of salicylic acid significantly reduced the incidence of cork spot disorder. Collectively, these findings provide valuable insights into the mechanisms underlying cork spot disorder and establish a theoretical foundation for its effective prevention and management.