Bolwerk Annouschka, Lagopodi Anastasia L, Lugtenberg Ben J J, Bloemberg Guido V
Leiden University, Institute of Biology Leiden, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands.
Mol Plant Microbe Interact. 2005 Jul;18(7):710-21. doi: 10.1094/MPMI-18-0710.
The soilborne fungus Fusarium oxysporum f. sp. radicis-lycopersici causes tomato foot and root rot (TFRR), which can be controlled by the addition of the nonpathogenic fungus F. oxysporum Fo47 to the soil. To improve our understanding of the interactions between the two Fusarium strains on tomato roots during biocontrol, the fungi were labeled using different autofluorescent proteins as markers and subsequently visualized using confocal laser scanning microscopy. The results were as follows. i) An at least 50-fold excess of Fo47over F. oxysporum f. sp. radicis-lycopersici was required to obtain control of TFRR. ii) When seedlings were planted in sand infested with spores of a single fungus, Fo47 hyphae attached to the root earlier than those of F. oxysporum f. sp. radicis-lycopersici. iii) Subsequent root colonization by F. oxysporum f. sp. radicis-lycopersici was faster and to a larger extent than that by Fo47. iv) Under disease-controlling conditions, colonization of tomato roots by the pathogenic fungus was significantly reduced. v) When the inoculum concentration of Fo47 was increased, root colonization by the pathogen was arrested at the stage of initial attachment to the root. vi) The percentage of spores of Fo47 that germinates in tomato root exudate in vitro is higher than that of the pathogen F. oxysporum f. sp. radicis-lycopersici. Based on these results, the mechanisms by which Fo47 controls TFRR are discussed in terms of i) rate of spore germination and competition for nutrients before the two fungi reach the rhizoplane; ii) competition for initial sites of attachment, intercellular junctions, and nutrients on the tomato root surface; and iii) inducing systemic resistance.
土传真菌尖孢镰刀菌番茄根腐专化型（Fusarium oxysporum f. sp. radicis-lycopersici）会引发番茄根腐病（TFRR），向土壤中添加非致病性真菌尖孢镰刀菌Fo47可对该病进行控制。为了更好地理解在生物防治过程中这两种镰刀菌菌株在番茄根上的相互作用，使用不同的自发荧光蛋白作为标记对真菌进行标记，随后利用共聚焦激光扫描显微镜进行观察。结果如下：i）要控制番茄根腐病，Fo47的数量至少要比尖孢镰刀菌番茄根腐专化型多50倍。ii）当幼苗种植在被单一真菌孢子侵染的沙子中时，Fo47的菌丝比尖孢镰刀菌番茄根腐专化型的菌丝更早附着在根上。iii）随后尖孢镰刀菌番茄根腐专化型在根上的定殖比Fo47更快且程度更大。iv）在病害控制条件下，致病真菌在番茄根上的定殖显著减少。v）当Fo47的接种浓度增加时，病原菌在根上的定殖在初始附着阶段就被阻止。vi）Fo47的孢子在番茄根际分泌物中体外萌发的百分比高于病原菌尖孢镰刀菌番茄根腐专化型。基于这些结果，从以下几个方面讨论了Fo47控制番茄根腐病的机制：i）在两种真菌到达根际之前，孢子萌发率和对养分的竞争；ii）对番茄根表面初始附着位点、细胞间连接和养分的竞争；iii）诱导系统抗性。
