title: Nitrate Protects Cucumber Plants Against Fusarium oxysporum by Regulating Citrate Exudation.
abstract: Fusarium wilt causes severe yield losses in cash crops. Nitrogen plays a critical role in the management of plant disease; however, the regulating mechanism is poorly understood. Using biochemical, physiological, bioinformatic and transcriptome approaches, we analyzed how nitrogen forms regulate the interactions between cucumber plants and Fusarium oxysporum f. sp. cucumerinum (FOC). Nitrate significantly suppressed Fusarium wilt compared with ammonium in both pot and hydroponic experiments. Fewer FOC colonized the roots and stems under nitrate compared with ammonium supply. Cucumber grown with nitrate accumulated less fusaric acid (FA) after FOC infection and exhibited increased tolerance to chemical FA by decreasing FA absorption and transportation in shoots. A lower citrate concentration was observed in nitrate-grown cucumbers, which was associated with lower MATE (multidrug and toxin compound extrusion) family gene and citrate synthase (CS) gene expression, as well as lower CS activity. Citrate enhanced FOC spore germination and infection, and increased disease incidence and the FOC population in ammonium-treated plants. Our study provides evidence that nitrate protects cucumber plants against F. oxysporum by decreasing root citrate exudation and FOC infection. Citrate exudation is essential for regulating disease development of Fusarium wilt in cucumber plants.
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Zechen
authors.initials: Z
authors.lastname: Gu
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Ruirui
authors.initials: R
authors.lastname: Wang
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Guomei
authors.initials: G
authors.lastname: Sun
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Shiwei
authors.initials: S
authors.lastname: Guo
authors.affiliation: Jiangsu Key Lab for Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China shenqirong@njau.edu.cn.
authors.forename: Qirong
authors.initials: Q
authors.lastname: Shen
mesh_terms: D019343:Citric Acid / Q000378:metabolism* / Q000494:pharmacology; D018553:Cucumis sativus / Q000378:metabolism* / Q000382:microbiology*; D005122:Exudates and Transudates / Q000378:metabolism; D005669:Fusaric Acid / Q000378:metabolism; D005670:Fusarium / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D009566:Nitrates / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D013172:Spores, Fungal / Q000254:growth & development / Q000378:metabolism
chemical_list: D009566:Nitrates; D019343:Citric Acid; D005669:Fusaric Acid
keywords: Citrate; Cucumber; Fusaric acid; Fusarium wilt; Nitrogen; Root exudates