Exploring the potential in postharvest preservation of sweet potato: 2-methylbutanoic acid, isobutyric acid, perillaldehyde and salicylaldehyde, to control Rhizopus stolonifer

Soft rot caused by Rhizopus stolonifer is one of the most destructive postharvest diseases inducing massive loss of sweet potato tuberous roots (TRs). Inhibitory effects of 2-methylbutanoic acid (2-ME), isobutyric acid (IS), perillaldehyde (PE) and salicylaldehyde (SA) against R. stolonifer was investigated, to explore their potential in postharvest preservation of sweet potato. The 2-ME, IS, PE and SA completely inhibited mycelial growth and spore germination, destroyed cell membrane integrity, and induced nucleic acids and proteins leakage of R. stolonifer. Compared to 2-ME and IS, SA caused the most severe ultrastructure damage to R. stolonifer, enhanced cell membrane permeability, reduced mitochondrial membrane potential, and induced more endogenous ROS production, followed by PE. In addition, SA better controlled R. stolonifer infection, decreased MDA content and increased disease-resistant enzyme activities in TRs during 15 d of storage. Therefore, SA might be a promising alternative to fungicides in postharvest preservation of sweet potato TRs.