Pathogenicity and virulence on mango tissues

Pathogenicity and virulence on mango tissues. Selected isolates were used for pathogenicity and virulence tests on detached fruits and leaves of mango (cv. Tainong) in controlled conditions. Isolates were incubated on PDA plates for 7-10 days at 25°C in laboratory. Fresh young leaves and fresh harvested mango fruits without visible disease from Tiandong (Guangxi province) were used for inoculation. The leaves and mango fruits were washed with running water, surface sterilized in 70% ethanol for 30 s and 1% NaClO for 1 min, and finally rinsed with sterile distilled water.
After air drying, detached young healthy leaves (12-15 cm) were placed into plastic containers (252 mm X 174 mm X 93 mm) lined with moist absorbent paper and, six stab wounds were made in the mid-region forming a circle with a 5 mm diameter using a sterilized needle. Hyphal plugs from actively growing margins of PDA cultures were placed on each wound spot on the leaves. The experiment was completely randomized with three replicates per isolate involving five leaves per replicate. Fifteen leaves were inoculated for each isolate, and in controls, leaves were treated with sterile agar plugs. The containers were partially sealed in plastic and incubated at 25°C in the dark in a growth chamber. Virulence was assessed by measuring lesion diameter at 7 days post inoculation (DPI) in two perpendicular directions on each leaf.
After washing and air drying, almost ripened mango fruits (?100 g) were wounded in the protruding fleshy parts by stabbing with a sterilized needle through the skin to a depth of 3 mm forming a circle with 5 mm diameter. Mycelial plugs of 6 mm diameter from PDA cultures were placed on the wounds. Sterile agar plugs were used as control treatments. Inoculated fruits were placed in plastic containers (252 mm X 174 mm X 93 mm) overlaid with moist absorbent paper to maintain humidity. The containers were placed in a growth chamber and incubated at 25°C in the dark. Fruits were checked for development of symptoms up to 10 days. Isolates were considered pathogenic when lesions expanded beyond the 5 mm diameter on the initial wounds. Virulence was evaluated by measuring lesion diameter at 10 DPI in two perpendicular directions. Statistical analysis was performed using Data Processing System software (DPS 7.0) for Windows (Zhejiang University, Hangzhou, China) (Tang and Zhang, 2013), and data were subjected to analysis of variance (ANOVA) followed by Fisher’s Least Significant Difference (LSD) tests for means separation.

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