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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Crop Bioprotection Research » Research » Publications at this Location » Publication #329002

Title: Characterization of Peronospora belbahrii on basil under light and scanning electron microscopy

item Zhang, Guirong
item Thompson, Arthur - Art
item Schisler, David

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/3/2016
Publication Date: 8/3/2016
Citation: Zhang, G., Thompson, A.R., Schisler, D.A. 2016. Characterization of Peronospora belbahrii on basil under light and scanning electron microscopy. Meeting Abstract. ..

Interpretive Summary:

Technical Abstract: Basil (Ocimum spp.) downy mildew caused by Peronsoora belbahrii is a major yield-limiting disease of sweet basil (O. basilicum) production worldwide. In this study, sweet basil was grown in a soilless potting mix in plant growth chambers and inoculated with sporangia of P. belbahrii harvested from previously infected plants. Plants in punnets were placed in closed, clear plastic bags and leaves harvested over time and observed using light and scanning electron microscopy. As early as 3 days after inoculation, sporangia germinated myceliogenically on abaxial and adaxial leaf surfaces. Germ tubes and the tips of hyphae ramifying on leaf surfaces directly penetrated basil leaves to initiate the infection process. Hyphal growth was not observed to gain entrance to the interior of leaves through the stomatal cavity, though growth over stomatal pores was observed frequently. Seven days after inoculating leaves, one or more sporangiophores grew through stomatal pores to produce new sporangia on both the abaxial and adaxial surfaces of leaves. Macroscopic signs of infection were visible 14 days after infection on both sides of leaves under the bioassay conditions of this study. These results contribute to a better understanding of the infection process and spread of P.belbahrii and should contribute to the development of more effective measures for reducing the severity of basil downy mildew.