Dihydromyricetin inhibited DNA methyltransferases activity in citrus fruit to enhance resistance against Penicillium italicum infection

Citrus fruit is an important economic produce but vulnerable to blue mold that causes postharvest decay and serious economic loss worldwide. Dihydromyricetin (DHM) is a natural flavonoid widely presented in foods and phytomedicine. However, little information is available about the role of DHM in fruit resistance to postharvest diseases. In this study, DHM showed robust inhibition on DNA methyltransferases activity and suppressed disease phenotype of shatang mandarin blue mold caused by Penicillium italicum . Our results further suggested that DHM induced fruit defense by increasing the activities of phenylalanine ammonia lyase, β-1,3-glucanase and chitinase in response to P. italicum . Additionally, the content of hydrogen peroxide (H 2 O 2 ) as defense-related reactive oxygen species (ROS) was induced by DHM through accelerating H 2 O 2 production but repressing H 2 O 2 scavenging during P. italicum infection. In addition, inactivation of cell wall-related genes after DHM treatment might contribute to the inhibition of cell wall loosening/degradation. Meanwhile, DHM treatment resulted in higher energy status as a complementary strategy to prevent mandarin fruit from oxidative damage, indicated by higher capacity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging and lower malondialdehyde (MDA) content. Correlation analysis indirectly suggested that DHM treatment increased defense capacity by regulating the energy status. Moreover, genes involved in energy status and autophagy were regulated by DHM. Overall, this study is the first to highlight potential application of DHM in controlling postharvest fruit disease through epigenetic regulation.