Simple evaluation method for testing mango anthracnose virulence using uncured mango leaves and for screening anthracnose-resistant genetic resources of mango ( Mangifera indica L.)

Abstract

The main mango cultivar grown in Japan, cv. Irwin, is susceptible to Colletotrichum species that cause mango anthracnose and requires the application of fungicides several times a year before harvest. Increased consumer demand for safe, secure foodstuffs and the desire to reduce labor and costs are driving the development of mango cultivars with strong resistance to anthracnose. Therefore, in this study, we developed a simple, accurate method to evaluate the susceptibility of mango cultivars to anthracnose to identify anthracnose-resistant breeding stock. For 27 mango cultivars, uncured leaves that had chlorophyll SPAD values of 9.5~24.3 were inoculated with conidial suspensions of C. asianum (Nga-05) containing a minimum of 104 conidia/ml and incubated at 25° to 30°C for 5 days in the dark to promote lesion formation. Disease severity on each of the 27 cultivars was positively correlated with disease severity on inoculated fruits. Cv. Golden Nugget was identified as the most resistant to mango anthracnose. Based on these findings, we concluded that the developed method can be used to efficiently evaluate disease resistance and to identify disease-resistant varieties from genetic resources of mango and mango hybrid progeny.