Phytopathology. 2003 Jan;93(1):54-63. doi: 10.1094/PHYTO.2003.93.1.54.
ABSTRACT Natural suppressiveness of soils to take-all disease of wheat, referred to as take-all decline (TAD), occurs worldwide. It has been postulated that different microbial genera and mechanisms are responsible for TAD in soils from different geographical regions. In growth chamber experiments, we demonstrated that fluorescent Pseudomonas spp. that produce the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) play a key role in the natural suppressiveness of two Dutch TAD soils. First, 2,4-DAPG-producing fluorescent Pseudomonas spp. were present on roots of wheat grown in both of the TAD soils at densities at or above the threshold density required to control take-all of wheat; in a complementary take-all conducive soil, population densities of 2,4-DAPG-producing Pseudomonas spp. were below this threshold level. Second, introduction of 2,4-DAPG-producing strain SSB17, a representative of the dominant geno-typic group found in the Dutch TAD soils, into the take-all conducive soil at population densities similar to the densities of indigenous 2,4-DAPG producers found in TAD soils provided control of take-all similar to that observed in the TAD soil. Third, a mutant of strain SSB17 deficient in 2,4-DAPG production was not able to control take-all of wheat, indicating that 2,4-DAPG is a key determinant in take-all suppression. These results show that in addition to the physicochemically different TAD soils from Washington State, 2,4-DAPG-producing fluorescent Pseudomonas spp. are also a key component of the natural suppressiveness found in Dutch TAD soils. Furthermore, it is the first time since the initial studies of Gerlagh (1968) that at least part of the mechanisms and microorganisms that operate in Dutch TAD soils are identified. Although quantitatively similar, the genotypic composition of 2,4-DAPG-producing Pseudomonas spp. varied between the Dutch TAD soils and the TAD soils from Washington State.
摘要 土壤对小麦全蚀病的天然抑制作用，称为全蚀衰退（TAD），在世界范围内普遍存在。有人假设，不同地理区域土壤中的 TAD 可能由不同的微生物属和机制引起。在生长室实验中，我们证明了产生抗生素 2,4-二乙酰基间苯三酚（2,4-DAPG）的荧光假单胞菌在两种荷兰 TAD 土壤的天然抑制作用中起着关键作用。首先，在两种 TAD 土壤中，生长的小麦根部都存在密度达到或高于控制小麦全蚀病所需阈值密度的 2,4-DAPG 产生荧光假单胞菌；而在全蚀促进土壤中，2,4-DAPG 产生假单胞菌的种群密度低于该阈值水平。其次，在与 TAD 土壤中发现的土著 2,4-DAPG 产生菌相似的种群密度下，将荷兰 TAD 土壤中优势基因型组的代表性菌株 SSB17 引入全蚀促进土壤中，可提供与 TAD 土壤中观察到的相似的全蚀病控制效果。第三，缺乏 2,4-DAPG 产生能力的 SSB17 突变体不能控制小麦全蚀病，表明 2,4-DAPG 是抑制全蚀的关键决定因素。这些结果表明，除了华盛顿州具有物理化学性质不同的 TAD 土壤外，2,4-DAPG 产生的荧光假单胞菌也是荷兰 TAD 土壤天然抑制作用的关键组成部分。此外，这是自 Gerlagh（1968 年）最初研究以来，首次确定了在荷兰 TAD 土壤中起作用的部分机制和微生物。尽管数量上相似，但荷兰 TAD 土壤和华盛顿州 TAD 土壤中 2,4-DAPG 产生假单胞菌的基因型组成存在差异。
