Alteration of juglone content of some commercial walnut cultivars and genotypes in response to Aceria tristriata (Nalepa)
Paper ID : 1065-IPCA4 (R1)
Mohammad Ahmad-Hoseeini *1, Mohammad Khanjani2
1Department of Plant Protection, College of Agriculture, Bu–Ali Sina University, Hamedan, Iran
2Department of Plant Protection, Faculty of Agriculture, University of Bu-Ali Sina, Hamadan, Iran.
Walnut is one of the most important fruit crops in Iran. Various phytophagous mite and insect species feed on walnut trees. Persian walnut leaf blister mite Aceria tristriata (Nalepa) is one of the most important pests of walnut orchards in western Iran. Due to the adverse effects of pesticides on human health and the environment, recent studies are focused on the exploration of eco-friendly pest control strategies like selection of resistant plants. A study aimed to evaluate resistance of six cultivars (Chandler, Hartly, Pedro, Jamal, Franquette and Lara), four genotypes (Tahghighat, B21, Z60 and Z53) and Seedling (plants without transplants) in relation to Aceria tristriata was carried out. Three years old plants of walnut cultivars and genotypes were planted singly in 15 kg pots and kept under the same natural conditions. Then, each of these plants was artificially infested in 6 replications with 10 g of crushed galled leaves containing an average of 9650±43 (SE) mites. To evaluate juglone content, leaf samples were collected 15 days after artificial infestation, and amount of juglone was investigated by using HPLC with UV detector and detection was followed at 420 nm. Based on the leaf damage index (number of galls per leaf and plant, percentage of infested leaves and percentage of leaf injury area) showed after infestation, walnut cultivars were classified in four groups as: (i) ‘susceptible’, i.e., seedlings; (ii) ‘semi-susceptible’, i.e., Hartly, Lara, Z60 and Z53; (iii)‘semi-resistant’, i.e., Pedro, Franquette, Tahghighat and B21; (iv)‘approximately resistant’, i.e., Chandler and Jamal. The amount of juglone in leaves was significantly affected by A. tristriata infestation (F10 = 23.24, P <0.0001) and infested plants had a higher content of this compound than non-infested plants. In fact, the juglone content in resistant cultivars Chandler, Jamal and Pedro was, respectively, 51.78, 41.08 and 22.23 in non-infested plants, and 64.88, 61.22 and 61.58 mg per 100 g of leaf fresh weight in infested plants. The content of this compound in the susceptible and semi-susceptible plants of Seedling and Hartley cultivars was, respectively, 4.58 and 15.19 in non-infested plants, and 15.84 and 19.08 in infested plants. Considering the role of juglone in the resistance of walnut to the agent of blight and anthracnose diseases, as well as its more content in resistant cultivars showed in this study, it can be concluded that this compound plays a role in the resistance mechanisms of assayed walnut cultivars to walnut leaf gall mite.
Keywords: plant resistance, Persian walnut leaf gall mite, defense compounds, phenolic compound.
Status : Abstract Accepted (Oral Presentation)