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rDNA-ITS sequence analysis of pathogens of cucumber downy mildew and cucumber powdery mildew


To determine the pathogens of cucumber downy mildew and cucumber powdery mildew by molecular marker, we amplified and sequenced the rDNA-ITS region of the pathogens of cucumber downy mildew and cucumber powdery mildew collected from the Shanghai region. The intra-/interspecific sequence difference was analyzed by rDNA-ITS sequence. The results show that the length of rDNA-ITS1 and rDNA-ITS2 of cucumber downy mildew’s pathogen was 141 bp and 406 bp, respectively, with GC contents of 41.13% in ITS1 and 46.8% (Minhang and Jinshan District, sm1 and sm2) or 46.55% (Pudong District, sm3) in ITS2. The rDNA-ITS sequence was intraspecific conservation. The interspecific difference was related with their kin relationship. The pathogen of cucumber downy mildew was identified as Pseudoperonospora cubensis by molecular marker. The length of rDNA-ITS1 and rDNA-ITS2 of cucumber powdery mildew’s pathogen was 136 bp and 89 bp, respectively, with GC contents being 59.56% and 66.29%, and rDNA-ITS sequence being highly conservative in this study that was the same as Sphaerotheca cucurbitae. But the sequence difference between the strains in the Shanghai region in this study with S. fuliginea was 4.5%, which was identified by morphology. It is suggested that the pathogen of cucumber powdery mildew should be further clarified and determined.

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  • Chen G Q, Han S J, Lai Y Q, Yu Y N, Zheng R Y, Zhao Z Y (1987). Flora Fungorum Sinicorum, Vol. 1, Erysiphales. Beijing: Science Press, 78, 316 (in Chinese)

    Google Scholar 

  • Hirata T, Cunnington J H, Paksiri U, Limkaisang S, Shishkoff N, Grigaliunaite B, Sato Y, Takamatsu S (2000). Evolutionary analysis of subsection Magnicellulatae of Podosphaera section Sphaerotheca (Erysiphales) based on the rDNA ITS sequences with special reference to host plants. Canadian Journal of Botany, 78: 1521–1530

    Article  CAS  Google Scholar 

  • Kiss L, Cook R T A, Saenz G S, Cunnington J H, Takamatsu S, Pascoe I, Bardin M, Nicot P C, Sato Y, Rossman A Y (2001). Identification of two powdery mildew fungi, Oidium neolycopersici sp. nov. and O. lycopersici, infecting tomato in different parts of the world. Mycological Research, 105(6): 684–697

    Article  Google Scholar 

  • Motoaki K, Takashi T (1995). Phylogeny of Alternaria fungi known to produce host-specific toxins on the basis of variation in internal transcribed spacers of ribosomal DNA. Current Genetics, 28: 491–498

    Article  Google Scholar 

  • Qiu W F (1979). Agricultural Plant Pathology. Beijing: Agricultural Press, 465 (in Chinese)

    Google Scholar 

  • Takamatsu S, Hirata T, Sato Y (1998). Phylogenetic analysis and predicted secondary structures of the rDNA internal transcribed spacers of the powdery mildew fungi (Erysiphaceae). Mycoscience, 39: 441–453

    Article  CAS  Google Scholar 

  • Takamatsu S, Hirata T, Sato Y (2000). A parasitic transition from trees to herbs occurred at least twice in tribe Cystotheceae (Erysiphaceae): evidence from nuclear ribosomal DNA. Mycological Research, 104: 1304–1311

    Article  CAS  Google Scholar 

  • Tetsuya H, Susumu T (1996). Nucleotide sequence diversity of rDNA internal transcribed spacers extracted from conidia and cleistothecia of several powdery mildew fungi. Mycoscience, 37: 283–288

    Article  Google Scholar 

  • Voglmayr H (2003). Phylogenetic relationships of Peronospora and related genera based on nuclear ribosomal ITS sequences. Mycological Research, 107(10): 1132–1142

    Article  Google Scholar 

  • Wei J C (1979). Fungi Identification Notebook. Shanghai: Shanghai Scientific & Technical Publishers, 49 (in Chinese)

    Google Scholar 

  • White T J, Bruns T, Lee S, Taylor J (1990). Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. California: Academic Press, 315–321

    Google Scholar 

  • Yi J P, Tao T D, Pan L W, Shen Y F, Yin L P, Zheng J Z (2002). Direct detection of Tilletia indica teliospores by nest PCR. Plant Quarantine, 16(4): 197–200 (in Chinese)

    Google Scholar 

  • Yu Z D, Zhang X Y, Cao Z M (2000). A review of the studies on ribosomal DNA internal transcribed spacer of fungi. Journal of Northwest Forestry University, 15(2): 107–112 (in Chinese)

    Google Scholar 

Download references

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Correspondence to Yajun Ma.

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Translated from Journal of Northwest A & F University (Nat. Sci. Ed.), 2007, 35(10): 155–158 [译自: 西北农林科技大学学报(自然科学版)]

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Wang, N., Ma, Y., Yang, C. et al. rDNA-ITS sequence analysis of pathogens of cucumber downy mildew and cucumber powdery mildew. Front. Agric. China 2, 317–320 (2008).

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  • cucumber downy mildew’s pathogen
  • cucumber powdery mildew⁉s pathogen
  • rDNA-ITS