Competition and antibiosis in the biological control of potato scab.
Competition and antibiosis in the biological control of potato scab.
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DOI：
10.1139/w01-010
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发表时间：
2001-04
影响因子：
2.8
通讯作者：
Eric C. Neeno-Eckwall;L. Kinkel;J. Schottel
中科院分区：
文献类型：
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作者：
Eric C. Neeno-Eckwall;L. Kinkel;J. Schottel
非致病性的、产生抗生素的链霉菌被证明当添加到致病土壤中时可以减少马铃薯赤霉病。已分离到致病性链霉菌RB4的自发突变株，它们对非致病抑菌菌株PonSSII和S.scabies PonR产生的至少一种抗生素活性产生抗药性。为了确定抗生素在这个生防系统中的重要性，在温室试验中，研究了这些突变体在两种病原菌拮抗剂存在的情况下致病的能力。在两个抑制菌株的存在下，其中一个突变菌株引起的疾病减少，而其他五个突变菌株引起的疾病在两个抑制菌株中都没有显著减少。此外，还分离到一株致病突变株RB4，该突变株在土壤中与病原菌共接种时，不产生体外检测到的抗菌活性，降低了致病亲株的致病能力。在土壤中接种单株时，病原菌的种群密度始终低于抑制菌株。当病原菌与抑制菌株共接种时，盆栽中的链霉菌总密度总是低于单独接种抑制菌株时的观察结果。当病原菌单独接种到土壤中时，种群密度与病情严重程度呈正相关。在病原菌和抑制菌的共接种实验中，链霉菌总密度越高，发病率越低。
Nonpathogenic, antibiotic-producing streptomycetes have been shown to reduce potato scab when added to disease-conducive soil. Spontaneous mutants of the pathogenic Streptomyces scabies RB4 that are resistant to at least one antibiotic activity produced by the nonpathogenic suppressive isolates Streptomyces diastatochromogenes strain PonSSII and S. scabies PonR have been isolated. To determine the importance of antibiosis in this biocontrol system, these mutants were investigated for their ability to cause disease in the presence of the two pathogen antagonists in a greenhouse assay. Disease caused by one of the mutant strains was reduced in the presence of both suppressive isolates, whereas disease caused by the other five mutants was not significantly reduced by either suppressive strain. In addition, a nonpathogenic mutant of S. scabies RB4 was isolated, which produced no detectable in vitro antibiotic activity and reduced disease caused by its pathogenic parent strain when the pathogen and mutant were coinoculated into soil. Population densities of the pathogen were consistently lower than those of the suppressive strains when individual strains were inoculated into soil. When a pathogen was coinoculated with a suppressive strain, the total streptomycete population density in the pot was always less than that observed when the suppressive isolate was inoculated alone. When the pathogens were inoculated individually into soil, a positive correlation was seen between population density and disease severity. In coinoculation experiments with pathogen and suppressive strains, higher total streptomycete population densities were correlated with lower amounts of disease.