Monitoring Spongospora subterranea development in potato roots reveals distinct infection patterns and enables efficient assessment of disease control methods
Spongospora subterranea is responsible for significant potato root and tuber disease globally. Study of this obligate (non-culturable) pathogen that infects below-ground plant parts is technically difficult. The capacity to measure the dynamics and patterns of root infections can greatly assist in determining the efficacy of control treatments on disease progression. This study used qPCR and histological analysis in time-course experiments to measure temporal patterns of pathogen multiplication and disease development in potato (and tomato) roots and tubers. Effects of delayed initiation of infection and fungicidal seed tuber and soil treatments were assessed. This study found roots at all plant developmental ages were susceptible to infection but that delaying infection significantly reduced pathogen content and resultant disease at final harvest. The pathogen was first detected in roots 15–20 days after inoculation (DAI) and the presence of zoosporangia noted 15–45 DAI. Following initial infection pathogen content in roots increased at a similar rate regardless of plant age at inoculation. All fungicide treatments (except soil-applied mancozeb which had a variable response) suppressed pathogen multiplication and root and tuber disease. In contrast to delayed inoculation, the fungicide treatments slowed disease progress (rate) rather than delaying onset of infection. Trials under suboptimal temperatures for disease expression provided valuable data on root infection rate, demonstrating the robustness of monitoring root infection. These results provide an early measure of the efficacy of control treatments and indicate two possible patterns of disease suppression by either delayed initiation of infection which then proceeds at a similar rate or diminished epidemic rate.
Funding
Horticulture Innovation Australia
History
Publication title
PLoS One
Volume
10
Issue
9
Article number
e0137647
Number
e0137647
Pagination
1-18
ISSN
1932-6203
Department/School
Tasmanian Institute of Agriculture (TIA)
Publisher
Public Library of Science
Place of publication
United States of America
Rights statement
Copyright 2015 Thangavel et al. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/