ABSTRACT

Sunflower (Helianthus annuus L.), one of the most important oilseed crops worldwide, is greatly damaged by downy mildew disease caused by Plasmopara halstedii. Trichoderma harzianum (TRIC8) isolate, isolated from soils of Tekirdağ/Turkey, was tested to determine its effect on hypocotyl length and sporulation density of the pathogen on cotyledon leaves of seedlings grown in pots. The ability of T. harzianum to induce the accumulation of metabolites in roots during its interaction with the pathogen was also studied using gas chromatography/mass spectrometry (GC/MS). In the experiments, seeds were coated with TRIC8 and the roots of three-day old seedlings were inoculated with P. halstedii. TRIC8 treatment significantly enhanced hypocotyl length as compared with untreated control (sterile distilled water) and fungicide (ai: Metalaxyl-m) treatments; reduced sporulation density of pathogen (76.30%) was comparable to the fungicide (76.55%) in pot experiments. TRIC8 increased the accumulation of heptanoic acid (carboxylic acid), methyl palmitate (ester) and 10,12 octadecadiynoic acid (fatty acid) especially in roots challenged with P. halstedii when compared with untreated control. Additionally, 17 metabolites [an alcohol: Z-2-dodecen-1-ol; an alkyl halide: 1-bromocyclohexane; an amide: N,N'-thylenebis(N-nitroacetamide); an anhydride: trans-(2-octenyl)succinic anhydride; three corbocyclic acids: butanedioic acid, capric acid, 4-hydroxy benzoic acid; a coumarin derivative: 6-tert-butyl-4-methylcoumarin, six esters: ethyl n-heptadecanoate, ethyl linolenate, 2-hydroxyethyl prop-2-enoate, isopropyl phenylacetate, (Z,Z)-5,16-octadecadien-1-ol acetate, undecyl trichloroacetate; a heterocyclic compound: dendrolasin; a ketone: 4-ethoxycyclohexanone; a phenol: 3,5-di-tert-butylphenol], which were not present in roots of other treatments, appeared as specific to TRIC8 treatment. Our study suggests that these metabolites might be involved in enhancement of hypocotyl length and in protection of sunflower against P. halstedii.

摘要

向日葵 ( Helianthus annuus L.) 是世界上最重要的油料作物之一，受到由Plasmopara halstedii引起的霜霉病的严重破坏。对从土耳其 Tekirdağ/土耳其土壤中分离的哈茨木霉(TRIC8) 分离株进行了测试，以确定其对盆栽幼苗子叶叶上病原体的下胚轴长度和孢子形成密度的影响。还使用气相色谱/质谱 (GC/MS) 研究了哈茨木霉在与病原体相互作用期间诱导代谢物在根中积累的能力。在实验中，种子用TRIC8包被，三天大的幼苗的根部接种了P. halstedii. 与未处理的对照（无菌蒸馏水）和杀菌剂（ai：甲霜灵-m）处理相比，TRIC8处理显着增加了下胚轴长度；在盆栽实验中，病原体孢子形成密度的降低 (76.30%) 与杀菌剂 (76.55%) 相当。TRIC8 增加了庚酸（羧酸）、棕榈酸甲酯（酯）和 10,12 十八碳二炔酸（脂肪酸）的积累，尤其是在受到P. halstedii攻击的根中与未处理的对照相比。此外，还有 17 种代谢物 [一种酒精：Z-2-dodecen-1-ol；卤代烷：1-溴环己烷；酰胺：N,N'-亚苯基双(N-硝基乙酰胺)；酸酐：反式-(2-辛烯基)琥珀酸酐；三种碳环酸：丁二酸、癸酸、4-羟基苯甲酸；香豆素衍生物：6-叔丁基-4-甲基香豆素，六种酯：正十七酸乙酯、亚麻酸乙酯、2-羟乙基丙-2-烯酸、苯乙酸异丙酯、(Z,Z)-5,16-octadecadien-1 -醇乙酸酯，三氯乙酸十一烷基酯；杂环化合物：树皮苷；酮：4-乙氧基环己酮；a phenol: 3,5-di-tert-butylphenol]，在其他处理的根中不存在，似乎对 TRIC8 处理具有特异性。P. halstedii。