Cryptococcus laurentii controls gray mold of cherry tomato fruit via modulation of ethylene-associated immune responses

This research aimed to investigate the roles of phytohormone ethylene in cherry tomato fruit immune response against gray mold caused by Botrytis cinerea. Pretreatment with antagonistic yeast Cryptococcus laurentii resulted in a significantly decreased disease incidence of B. cinerea infection, and accompanied by a burst of ethylene production in the whole fruit. Blocking the ethylene perception by adding 1-MCP (5 μL L^-1 or greater) remarkably weaken the protection ability of fruit itself and suppressed the C. laurentii-stimulated host immune response. 5 μL L^-1 1-MCP prefumigation decreased the expression of ethylene biosynthesis and perception related genes SlACO1, SlACS2, SlERF1, SlPti5 and SlMPK3, and ethylene production in C. laurentii treated fruit. Consequently, the expressions of SlCHI9, SlGlub, SlPAL3, SlPR1 and SlPR5 up-regulated by the yeast were all impaired to different degrees by the 1-MCP prefumigation. These findings demonstrate that ethylene contributes to fruit immunity and C. laurentii-mediated immune responses of cherry tomato.

Application of Exogenous Ethylene Inhibits Postharvest Peel Browning of 'Huangguan' Pear

Peel browning disorder has an enormous impact on the exterior quality of 'Huangguan' pear whereas the underlying mechanism is still unclear. Although different methods have been applied for inhibiting the peel browning of 'Huangguan' pear, there are numerous issues associated with these approaches, such as time cost, efficacy, safety and stability. In this study, to develop a rapid, efficient and safe way to protect 'Huangguan' pear from skin browning, the effect of exogenous ethylene on peel browning of pear fruits stored at 0°C was evaluated. Results showed that ethylene treatments at 0.70-1.28 μL/L significantly decreased the browning rate and browning index from 73.80% and 0.30 to 6.80% and 0.02 after 20 days storage at 0°C, respectively, whereas ethylene treatments at 5 μL/L completely inhibited the occurrence of browning. In addition, ethylene treatments at 5 μL/L decreased the electrolyte leakage and respiration rate, delayed the loss of total phenolic compounds. Furthermore, ethylene (5 μL/L) treatment significantly enhanced the activity of catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) and increased the 1, 1-diphenyl-2-picrylhydrazyl inhibition rate, but inhibited the activity of polyphenol oxidase (PPO) and peroxidase (POD). Our data revealed that ethylene prevented the peel browning through improving antioxidant enzymes (CAT, APX and SOD) activities and reducing PPO activity, electrolyte leakage rate and respiration rate. This study demonstrates that exogenous ethylene application may provide a safe and effective alternative method for controlling browning, and contributes to the understanding of peel browning of 'Huangguan' pear.

Influence of Harvest Dates on Quality, Storage Capacity and Sensory Attributes of European Plum cv. Green Gage

The aim of this work was to determine storage capacity and changes in quality and consumer acceptance in plum harvested at different dates as well as to determine which instrumental parameters show good correlation with consumer acceptance and sensory properties. Both harvest date and storage time played a significant role in quality and sensory characteristics. Incidence of internal breakdown (IB) was significantly higher in fruit harvested last and increased significantly until the end of storage. Market life of ‘Green Gage’ plum varies from 20 days in fruit harvested on the last harvest date to 40 days in fruit harvested on earlier dates. When storage is needed, firmness, the best harvest index, should be higher than 42 N in order to extend market life and prevent IB damages in ‘Green Gage’ plums. However, fruit from early harvest dates has a lower consumer acceptance than fruit from late harvest dates (low TSS:TA). Thus, a minimum quality threshold based on TSS:TA (18.9) has been established over which consumer liking for European plums cv. Green Gage improves significantly. High linear regression between a* and TSS:TA would allow to use the a* color parameter as a nondestructive measurement to estimate consumer acceptance.