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Research article2012Peer reviewed

Quantification of Phytophthora pisi DNA and RNA transcripts during in planta infection of pea

Hosseini, Sara; Karlsson, Magnus; Jensen, Dan Funck; Heyman, Fredrik

Abstract

Phytophthora pisi is a novel species of Phytophthora that causes root rot in pea and is a potentially devastating pathogen for the cultivation of pea in many parts of the world. The focus of the current study was to: (a) develop an in planta infection system of pea seedling roots; (b) develop a quantitative PCR method to measure P. pisi and pea DNA; and (c) test for differential gene expression of selected putative pathogenicity factors in P. pisi during infection of pea. P. pisi zoospores were attracted to the tips of the pea seedling roots and encysted within 30 min. After 6 h the pathogen had reached about five cortical cell layers using both inter- and intracellular growth, and water-soaked lesions were observed visually after 20 h. DNA-based detection of P. pisi and pea showed a gradual accumulation of P. pisi DNA in pea root tips up to 48 h post infection. Quantitative reverse transcriptase PCR showed induction of genes encoding putative enzyme inhibitors during the early phase of infection, between 2 h and 6 h post infection. Genes encoding putative cysteine protease, glucanase, pleiotropic drug transporter and crinkler proteins were induced during the late phase of infection. The induced P. pisi cysteine protease belonged to a cathepsin-L-like group from the C1A subfamily of peptidases and displayed a unique modular structure that included a MD-2-related lipid-recognition domain.

Keywords

Cysteine protease; Enzyme inhibitor; Gene expression; Oomycete/plant interaction; Root colonization; Quantitative PCR

Published in

European Journal of Plant Pathology
2012, Volume: 132, number: 3, pages: 455-468
Publisher: SPRINGER