Thesis
Species and population diversity of powdery mildews on grain legumes in the US Pacific Northwest
Washington State University
Master of Science (MS), Washington State University
2008
Handle:
https://hdl.handle.net/2376/100110
Abstract
Powdery mildew is a serious disease of pea (Pisum sativum L.) and other food legumes in most temperate production regions of the world. Powdery mildew of pea is caused by Erysiphe pisi, a biotrophic ascomycetous fungus belonging to the order Erysiphales. Managing powdery mildew relies on planting resistant cultivars and applying fungicides. In pea breeding programs for powdery mildew resistance, a given breeding line may respond differently to powdery mildew infection under different conditions. Some pea breeding lines showed resistance in the greenhouse, but were susceptible in the field. Such inconsistent responses might be due to different pathogen populations found in various environments. The objectives of this research were to study the pathogen variation of pea powdery mildew found in greenhouse and field conditions using morphological and sequences of the internal transcribed spacer (ITS) region and to find alternative hosts of pea powdery mildews. Powdery mildew samples were collected from infected pea plants as well as other cultivated and wild legumes such as lentil, black medic, and sweet clover from production fields, greenhouses, and natural ecosystems in the Palouse region. Pea powdery mildew samples from fields exhibited morphological characteristics and ITS sequences in agreement with those of E. pisi. Samples obtained from greenhouse-grown pea plants contained either E. pisi or E. trifolii depending on the season of sampling and greenhouse location. E. trifolii was the cause of lentil powdery mildew. This is the first report of E. trifolii from lentil and pea. In addition, Leveillula taurica is reported for the first time on chickpea in Washington State. These data suggest that more than one Erysiphe species infect pea. Therefore, the powdery mildew pathogens infecting pea are more diverse than previously assumed. These findings may explain the inconsistent responses of pea breeding lines in various environments. Powdery mildews from Medicago lupulina and Melilotus albus yielded ITS sequences virtually identical to each other and to E. trifolii from lentil and to some greenhouse-originated pea. These weedy legumes could be inoculum sources for pea powdery mildews in greenhouses and potentially serve as alternative hosts for powdery mildew of cultivated legumes.
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Details
- Title
- Species and population diversity of powdery mildews on grain legumes in the US Pacific Northwest
- Creators
- Renuka Nilmini Attanayake Kithul-Pelage
- Contributors
- Weidong Chen (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900524878101842
- Language
- English
- Resource Type
- Thesis