Allende-Molar Raul, Paulitz Timothy C, Thomashow Linda S, Mavrodi Olga V, Weller David M
Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, U.S.A.
United States Department of Agriculture, Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430, U.S.A.
Plant Dis. 2025 Aug;109(8):1713-1723. doi: 10.1094/PDIS-09-24-2041-RE. Epub 2025 Aug 20.
Take-all, caused by , and Pythium root rot, caused by a complex of spp., are important diseases of wheat in Washington State, U.S.A., and they often occur in the same plant. During wheat monoculture, a natural biocontrol of take-all known as take-all decline (TAD) develops from a buildup in the rhizosphere of 2,4-diacetylphloroglucinol (DAPG)-producing pseudomonads belonging to the complex. To determine whether TAD also suppresses Pythium root rot, wheat seedlings were grown in two TAD soils and their homologous noncropped virgin (conducive) soils amended with inoculum of , . () group I, () group IV, or . () TAD soils alone or mixed 1:9 with pasteurized conducive soil did not consistently reduce symptoms of Pythium root rot compared with their homologous conducive soils. In TAD and conducive soils, plant height, length of the first true leaf, number of root tips, and root lengths were similar. Wheat grown in -infested and noninfested TAD soils supported rhizosphere populations of DAPG-producing pseudomonads above 10 CFU g of root. Mycelial growth of the spp. was inhibited in vitro by both DAPG producers and synthetic DAPG. However, concentrations of DAPG required to inhibit mycelial growth of the spp. ranged from 15 to 30 μg ml, which is five to ten times greater than the dose reported to inhibit the take-all pathogen. In conclusion, Washington TAD soils do not suppress Pythium root rot of wheat.
全蚀病由[病原菌名称未给出]引起，腐霉菌根腐病由多种腐霉菌引起，它们是美国华盛顿州小麦的重要病害，且常发生于同一植株。在小麦连作期间，一种名为全蚀病衰退（TAD）的全蚀病自然生物防治机制会因属于[假单胞菌复合体名称未给出]的产2,4 - 二乙酰基间苯三酚（DAPG）的假单胞菌在根际积累而形成。为确定TAD是否也能抑制腐霉菌根腐病，将小麦幼苗种植在两种TAD土壤及其同源的未种植过作物的原始（发病适宜）土壤中，这些原始土壤用[病原菌名称未给出]I组、[病原菌名称未给出]IV组或[病原菌名称未给出]的接种物进行了改良。与同源的发病适宜土壤相比，单独的TAD土壤或与经巴氏消毒的发病适宜土壤按1:9混合的TAD土壤并不能持续减轻腐霉菌根腐病的症状。在TAD土壤和发病适宜土壤中，株高、第一片真叶长度、根尖数量和根长相似。在接种和未接种[病原菌名称未给出]的TAD土壤中生长的小麦，其根际产DAPG的假单胞菌数量均高于10⁶ CFU g根。DAPG产生菌和合成DAPG在体外均能抑制腐霉菌的菌丝生长。然而，抑制腐霉菌菌丝生长所需的DAPG浓度范围为15至30 μg/ml，这比据报道抑制全蚀病病原菌所需的剂量高五至十倍。总之，华盛顿州的TAD土壤不能抑制小麦的腐霉菌根腐病。
