Afsharmanesh H, Ahmadzadeh M, Sharifi-Tehrani A, Javan-Nikkhah M, Ghazanfari K
Department of Plant Protection, College of Agriculture University of Tehran, Karaj, Iran.
Commun Agric Appl Biol Sci. 2005;70(3):151-5.
Fluorescent Pseudomonas species are an important group of PGPR that suppress fungal root and seedling disease by production of antifungal metabolites such as 2,4-diacetylphloroglucinol (2,4-DAPG), pyoluteorin, pyrolinitrin, siderophores and HCN. The compound 2,4-DAPG is a major determinant in biocontrol of plant pathogens. A 7.2 kbp chromosomal DNA region, carrying DAPG biosynthetic genes (phlA, phlC, phlB, phlD, phIE and phlF). Detecting the ph1 genes make them an ideal marker gene for 2,4-DAPG-producing fluorescent pseudomonad's. In this study we detected ph1A gene (that convert MAPG to 2,4-DAPG) using PCR assay with primers phlA-1r and phlA- f that enabled amplification of phlA sequences from fluorescent pseudomonad's from ARDRA group 1 and 3. We could detect phlA gene in P. fluorescens strains CHAO, Pf-44, Pf-1, Pf-2, Pf-3, Pf-17, Pf-62 and Pf-64, native isolates of Iran. The efficacy of this method for rapid assay characterizing rhizosphere population of 2,4-DAPG producing bacteria from soil of different area of Iran is in progress. We used a collection of 48 fluorescent pseudomonas strains in vitro, with known biological control activity against some soil born phytopathogenic fungi such as, Macrophomina phaseoli, Rhizoctonia solani Vericillium dahlia, Phytophthora nicotiana, Pythium spp. and Fusarium spp. and the potential to produce known secondary metabolites such as protease. Strains Pf-1, Pf-2, Pf-3, Pf-17, Pf-33 and Pf-44 showed the best antifungal activity against all fungi used in this study. Thirty-eight of 48 strains produced protease. The ability to rapidly characterize populations of 2,4-DAPG producers will greatly enhance our understanding of their role in the suppression of root disease.
荧光假单胞菌属是一类重要的植物根际促生细菌，它们通过产生抗真菌代谢产物（如2,4-二乙酰基间苯三酚（2,4-DAPG）、绿脓菌素、吡咯菌素、铁载体和HCN）来抑制真菌性根病和幼苗病害。化合物2,4-DAPG是植物病原菌生物防治中的一个主要决定因素。一个7.2 kbp的染色体DNA区域，携带DAPG生物合成基因（phlA、phlC、phlB、phlD、phlE和phlF）。检测ph1基因使其成为产生2,4-DAPG的荧光假单胞菌的理想标记基因。在本研究中，我们使用引物phlA-1r和phlA-f通过PCR检测ph1A基因（将MAPG转化为2,4-DAPG），该引物能够从ARDRA第1组和第3组的荧光假单胞菌中扩增phlA序列。我们能够在荧光假单胞菌菌株CHAO、Pf-44、Pf-1、Pf-2、Pf-3、Pf-17、Pf-62和Pf-64（伊朗的本地分离株）中检测到phlA基因。该方法用于快速分析伊朗不同地区土壤中产生2,4-DAPG细菌的根际菌群的效果正在研究中。我们在体外使用了48株荧光假单胞菌菌株，它们对一些土传植物病原真菌（如菜豆壳球孢菌、立枯丝核菌、大丽轮枝菌、烟草疫霉、腐霉菌和镰刀菌）具有已知的生物防治活性，并且有产生已知次生代谢产物（如蛋白酶）的潜力。菌株Pf-1、Pf-2、Pf-3、Pf-17、Pf-33和Pf-44对本研究中使用的所有真菌表现出最佳的抗真菌活性。48株菌株中有38株产生蛋白酶。快速鉴定2,4-DAPG生产者菌群的能力将极大地增进我们对它们在抑制根病中作用的理解。
