Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2001
Publication Date: N/A
Technical Abstract: 'Golden Delicious' apples were treated postharvest with 0 or 4% solutions of calcium chloride and stored at 0 degree C for 2 months. Fruit were then inoculated with Colletotrichum acutatum, held at 20 degrees C, and lesion size measured over a 16 days period. Fungal growth and polygalacturonase (PG) expression were determined in Richard's solution supplemented with cell walls extracted from calcium- treated or control fruit. After 16 days there was a 64% decrease in the area of decay in the fruit treated with the 4% calcium chloride solution compared with nontreated fruit. Fungal growth and PG activity in the presence of cell walls extracted from calcium-treated fruit were approximately 40% less than in the nontreated control. Using known, conserved polygalacturonase sequences, degenerate primers were designed and used to amplify sequences from acutatum. Sequencing of the resulting cloned fragments revealed the presence of two independent PG genes. The effect of calcium on the expression of these genes will be discussed.