Rubio M Belén, Pardal Alonso J, Cardoza Rosa E, Gutiérrez Santiago, Monte Enrique, Hermosa Rosa
Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain.
Area of Microbiology, University School of Agricultural Engineers, University of León, Ponferrada, Spain.
Front Microbiol. 2017 Nov 21;8:2273. doi: 10.3389/fmicb.2017.02273. eCollection 2017.
is a filamentous fungus well adapted to different ecological niches. Owing to its ability to antagonize a wide range of plant pathogens, it is used as a biological control agent in agriculture. Selected strains of are also able to increase the tolerance of plants to biotic and abiotic stresses. However, little is known about the regulatory elements of the transcriptional machinery and their role in the biocontrol by this species. We had previously reported the involvement of the transcription factor THCTF1 in the production of the secondary metabolite 6-pentyl-pyrone, an important volatile compound related to interspecies cross-talk. Here, we performed a subtractive hybridization to explore the genes regulated by THCTF1, allowing us to identify a multiprotein bridging factor 1 () homolog. The gene from T34 was isolated and characterized, and the generated overexpressing transformants were used to investigate the role of this gene in the biocontrol abilities of the fungus against two plant pathogens. The transformants showed a reduced antifungal activity against f. sp. race 2 (FO) and (BC) in confrontation assays on discontinuous medium, indicating that the gene could affect production of volatile organic compounds (VOC) with antifungal activity. Moreover, cellophane and dialysis membrane assays indicated that overexpression affected the production of low molecular weight secreted compounds with antifungal activity against FO. Intriguingly, no correlation in the expression profiles, either in rich or minimal medium, was observed between and the master regulator gene cross-pathway control (). Greenhouse assays allowed us to evaluate the biocontrol potential of strains against BC and FO on susceptible tomato plants. The wild type strain T34 significantly reduced the necrotic leaf lesions caused by BC while plants treated with the -overexpressing transformants exhibited an increased susceptibility to this pathogen. The percentages of Fusarium wilt disease incidence and values of aboveground dry weight showed that T34 did not have biocontrol activity against FO, at least in the 'Moneymaker' tomato variety, and that overexpression increased the incidence of this disease. Our results show that the overexpression in T34 negatively affects its biocontrol mechanisms.
是一种非常适应不同生态位的丝状真菌。由于其具有拮抗多种植物病原体的能力，它在农业中被用作生物防治剂。所选的菌株还能够提高植物对生物和非生物胁迫的耐受性。然而，对于该转录机制的调控元件及其在该物种生物防治中的作用知之甚少。我们之前报道了转录因子THCTF1参与次级代谢产物6-戊基-吡喃酮的产生，6-戊基-吡喃酮是一种与种间相互作用相关的重要挥发性化合物。在这里，我们进行了消减杂交以探索受THCTF1调控的基因，从而使我们能够鉴定出一种多蛋白桥接因子1（）的同源物。从T34中分离并鉴定了该基因，并使用产生的过表达转化体来研究该基因在真菌对两种植物病原体的生物防治能力中的作用。在不连续培养基上的对峙试验中，转化体对番茄枯萎病菌生理小种2（FO）和黄瓜炭疽病菌（BC）的抗真菌活性降低，这表明该基因可能影响具有抗真菌活性的挥发性有机化合物（VOC）的产生。此外，玻璃纸和透析膜试验表明，过表达影响了对FO具有抗真菌活性的低分子量分泌化合物的产生。有趣的是，在丰富培养基或基本培养基中，均未观察到与主调节基因交叉途径控制（）之间的表达谱相关性。温室试验使我们能够评估菌株对易感番茄植株上的BC和FO的生物防治潜力。野生型菌株T34显著减少了由BC引起的坏死叶损伤，而用过量表达转化体处理的植株对该病原体的易感性增加。枯萎病发病率百分比和地上部干重值表明，T34至少在“Money maker”番茄品种中对FO没有生物防治活性，而过表达增加了该病的发病率。我们的结果表明，T34中的过表达对其生物防治机制产生负面影响。
