Symptomatology and Seed Transmission of Columnea latent viroid and Pepper chat fruit viroid in Melon

Abstract

Columnea latent viroid (CLVd) and Pepper chat fruit viroid (PCFVd) are important quarantine pests, causing damage to agricultural products, especially tomato, potato, pepper, and some cucurbits. This work was to study the symptoms and seed transmission of CLVd and PCFVd in melon to provide information for observing abnormal symptoms that might occur in melon growing fields. Melon cultivars were mechanically inoculated at the seedling stage, self-pollinated and seeds harvested for seed transmission investigation. It was found that CLVd and PCFVd could cause disease in melons with 25 – 86 and 0 – 100% infection rates, respectively. All four cultivars of CLVd-infected melon displayed symptoms at 8 weeks post inoculation (wpi) with stunting, shorten internodes, small and stacked leaves, small male flowers with abnormal petals, and abundance of non-developed male and female flowers. While two of three tested cultivars of PCFVd-inoculated melon expressed symptoms at 6 wpi with apical shoot stunting, and fully clustering flowers without of fruit setting. For grow out test in a greenhouse, seed transmission rate of CLVd-infected melon was 0.5% in Melon-2 cultivar only. However, PCFVd seed transmission was not found in all the PCFVd-infected melon cultivars in this study. The current findings of viroid melon diseases could be useful for routine disease observation and immediate eradication of CLVd and PCFVd infected plants to reduce disease dissemination and viroid seed contamination especially in CLVd.