title: Root exudates from grafted-root watermelon showed a certain contribution in inhibiting Fusarium oxysporum f. sp. niveum.
abstract: Grafting watermelon onto bottle gourd rootstock is commonly used method to generate resistance to Fusarium oxysporum f. sp. niveum (FON), but knowledge of the effect of the root exudates of grafted watermelon on this soil-borne pathogen in rhizosphere remains limited. To investigate the root exudate profiles of the own-root bottle gourd, grafted-root watermelon and own-root watermelon, recirculating hydroponic culture system was developed to continuously trap these root exudates. Both conidial germination and growth of FON were significantly decreased in the presence of root exudates from the grafted-root watermelon compared with the own-root watermelon. HPLC analysis revealed that the composition of the root exudates released by the grafted-root watermelon differed not only from the own-root watermelon but also from the bottle gourd rootstock plants. We identified salicylic acid in all 3 root exudates, chlorogenic acid and caffeic acid in root exudates from own-root bottle gourd and grafted-root watermelon but not own-root watermelon, and abundant cinnamic acid only in own-root watermelon root exudates. The chlorogenic and caffeic acid were candidates for potentiating the enhanced resistance of the grafted watermelon to FON, therefore we tested the effects of the two compounds on the conidial germination and growth of FON. Both phenolic acids inhibited FON conidial germination and growth in a dose-dependent manner, and FON was much more susceptible to chlorogenic acid than to caffeic acid. In conclusion, the key factor in attaining the resistance to Fusarium wilt is grafting on the non-host root stock, however, the root exudates profile also showed some contribution in inhibiting FON. These results will help to better clarify the disease resistance mechanisms of grafted-root watermelon based on plant-microbe communication and will guide the improvement of strategies against Fusarium-mediated wilt of watermelon plants.
authors.affiliation: Agricultural Ministry Key Lab of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Ling
authors.forename: Wenwen
authors.initials: W
authors.lastname: Zhang
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Wang
authors.forename: Jiugeng
authors.initials: J
authors.lastname: Mao
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Huang
authors.forename: Shiwei
authors.initials: S
authors.lastname: Guo
authors.forename: Qirong
authors.initials: Q
authors.lastname: Shen
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002109:Caffeic Acids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D002726:Chlorogenic Acid / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D019662:Cucurbitaceae / Q000737:chemistry* / Q000276:immunology / Q000382:microbiology; D046508:Culture Techniques; D060467:Disease Resistance; D005670:Fusarium / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D010935:Plant Diseases / Q000382:microbiology; D053147:Plant Exudates / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry* / Q000276:immunology / Q000382:microbiology; D058441:Rhizosphere; D020156:Salicylic Acid / Q000737:chemistry / Q000302:isolation & purification; D012988:Soil Microbiology; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development
chemical_list: D000935:Antifungal Agents; D002109:Caffeic Acids; D053147:Plant Exudates; D002726:Chlorogenic Acid; D020156:Salicylic Acid; C040048:caffeic acid