Differential response of Cucumis melo to Fusarium oxysporum f. sp. melonis race 1.2 isolates

• Published in: Crop protection Vol. 44; pp. 91 - 94
• Main Authors: Oumouloud, A., González Torres, R., Garcés-Claver, A., Chikh-Rouhou, H., Alvarez, J.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2013
• Subjects: Artificial inoculation; crops; Cucumis melo; death; Fusarium oxysporum; Fusarium wilt; leaves; Melon; Melonis; melons; pathotypes; Race-specific resistance; races; seedlings; seeds; wilting; Artificial inoculation; Race-specific resistance; Fusarium wilt; Melon
• ISSN: 0261-2194; 1873-6904
• DOI: 10.1016/j.cropro.2012.10.001

Fusarium wilt incited by Fusarium oxysporum f. sp. melonis (Fom) causes severe losses in melon crops. Four physiological races of Fom have been identified: 0, 1, 2 and 1.2. In most cases, resistance to race 1.2 has been described as recessive, polygenic and not race specific. However, some evidence of race-specific effects within melon resistance to race 1.2 has been reported. In this work, we study these effects and assess whether they are due to race-specific resistance. Seeds were obtained from 14 melon accessions that exhibit some level of resistance to race 1.2, and from the lines ‘Charentais-Fom1’ (resistant to races 0 and 2), ‘Charentais-Fom-2’ (resistant to races 0 and 1), and ‘Dinero F1’ (with partial resistance to Fom race 1.2). Melon seedlings were artificially inoculated using two different procedures: ‘continuous shaking’ and ‘tray immersion’. Symptom severity was assessed on leaves using a rating scale from 0 (no symptoms) to 4 (death of the plant). Symptoms were recorded weekly over the four-week period following the first appearance of symptoms and the area under the disease progress curve (AUDPC) was calculated. Six Fom isolates (3 from pathotype Y and 3 from pathotype W) were used in the inoculation. The less aggressive ‘tray immersion’ procedure seems to be more appropriate for detecting the typically small resistance factors of this type of polygenic partial resistance. ‘Kogane Nashi Makuwa’, ‘BG-5384’, ‘Shiro Uri Okayama’, ‘C-211’ and the control, ‘Dinero F1’, showed a high level of resistance to all Fom isolates. However, some genotype × isolate effects were also detected. ‘Baza’, when inoculated with isolate Fom 9302, and ‘Korça, when inoculated with Fom 37mls.1.2W, showed resistance levels similar to that of ‘Dinero F1’; this effect was not observed when ‘Baza’ and ‘Korça’ were inoculated with other isolates. These results are characteristic of race-specific resistance and offer evidence for the presence of this type of resistance to Fom race 1.2 in melons. ► The ‘continuous shaking’ procedure for inoculating melon with Fom is too aggressive to detect the resistance to race 1.2. ► The ‘tray immersion’ inoculation method detects better the resistance to Fom race 1.2. ► Some race-specific effects are present in the resistance of melon to race 1.2 of Fom.