Harpin Protein Treatment Makes a Positive Impact on Maintaining the Postharvest Quality of Strawberry Fruits
摘要
Harpin protein is a class of green and safe plant immune inducers that can improve fruit quality and effectively control post-harvest fruit decay. Strawberry fruits are fleshy flower receptacles that are difficult to preserve after harvest. This study investigated the effect of different concentrations of harpin protein on the post-harvest quality of strawberries. Results showed that 0.2 g·L⁻¹ harpin protein treatment significantly reduced strawberry fruit decay rate. During the storage process, the sucrose levels in the harpin protein groups were inferior to those in the control group. After 2 days of storage, treatments with 0.2 g·L− 1 and 0.8 g·L− 1 harpin protein treatments significantly promoted the accumulation of fructose and glucose, while treatments with 0.4 g·L− 1 harpin protein significantly reduced the citric acid content. We performed q-PCR analysis for the key genes of sugar-acid metabolism, which indicated that the increase in fructose and glucose was due to an increase in sucrose conversion and a decrease in citrate synthesis reduced acid content. Besides, treatment with 0.4 g·L− 1 harpin protein can maintain the antioxidant substances effectively in strawberry fruits after harvest and significantly increase the content of anthocyanidin and proanthocyanidin content after 2 days of storage. Total soluble solids (TSS) content and firmness were maintained, L*, a* values and 1,1-diphenyl-2-picrylbydrazyl (DPPH) values were significantly increased after 6 days of storage with 0.4 g·L− 1 harpin protein treatment. In conclusion, treatment with 0.4 g·L− 1 harpin protein can delay the senescence and decay of strawberry fruit after harvest, thereby maintaining its quality.