Brassinosteroids promote growth, fruit quality and protection against Botrytis on Fragaria x ananassa

Brassinosteroids (BRs) are steroidal compounds involved in plant growth and development. The aim of this work was to evaluate the effect of 24-epibrassinolide (EP24) and a brassinosteroid spirostanic analogue DI-31 (BB16) on growth promotion, defense and fruit quality of strawberry (Fragaria x ananassa). Results showed that both BRs cause an increase in the leaf greenness, number of leaves and stolons, and the foliar area as compared to control plants. However, whereas plants treated with BB16 exhibited a dry weight increase, plants treated with EP24 did not show significant differences with respect to control plants. The effect of both BRs on the activation of a defense response was also evaluated in strawberry plants, and results revealed that both BRs exert a protective effect against Botrytis cinerea the causal agent of the gray mold disease. The effect of both BRs was also evaluated on strawberry fruits. Results showed that both BRs also reduced the incidence of postharvest infection due to native pathogens. It was further observed that both BRs were more effective at lower concentration (i.e. 0.1mgl(-1)). When analyzing the influence of BB16 and EP24 on the quality of the postharvest fruit, it was found that the treatment with both BRs yield fruits with lower acidity, and higher content of soluble solids on the third day after treatment. In addition, lower weight loss, and higher colour quality (i.e. lightness and intensity) were observed in treated fruits as compared with control fruits. These results suggest that BRs could be used as a new crop management strategy, and as alternative to agrochemicals.