Thesis
THE EFFECT OF HEAT STRESS AND BACTERIA-DELIVERED PLANT ELICITORS ON PLANT IMMUNITY AGAINST ROOT-KNOT NEMATODES
Washington State University
Master of Science (MS), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000003125
Handle:
https://hdl.handle.net/2376/122352
Abstract
Plant-parasitic nematodes are one of the most economically important plant pathogens, especially for food crops in agriculture. Root-knot nematodes (RKNs) are especially destructive and are a prime focus of research for management strategies. The most common strategies for combating RKNs included nematicides and resistant crop cultivars. However, resistant cultivars may lose effectiveness at high temperatures and some commercial nematicides are being phased out due to health and environmental concerns. Our goal has been to look for novel means of nematode control and determining the effects of excessive heat on potato responses to RKNs. In terms of novel nematode control, it has been shown that bacteria can deliver plant elicitor peptides to the roots to prime plant immunity before nematode infection. Here we show that that Bacillus subtilis can be engineered to produce and secrete the tomato elicitor peptide, SlPep6. Application of this bacteria on tomato plant roots successfully reduced the galling caused by the RKN, Meloidogyne hapla. This bacteria delivery system of an elicitor activates defenses present in the host plant. Crop resistance is an established and effective management strategy for RKNs. However, there have been accounts of crop resistance breaking at high temperatures. This is concerning for growers who depend on resistant varieties to protect their crop plants, especially in light of rising temperatures due to climate change. The cultivated potato breeding line PA99N82-4 is normally resistant to the RKN, Meloidogyne chitwoodi race 1. PA99N82-4 potato plants exposed to excessive heat (36˚C) for 24 hours had significantly more M. chitwoodi galls on their roots than plants grown at 25˚C. This was also the case for plants exposed to three hours of heat (36˚C) for five consecutive days, mimicking realistic mid-day heat spikes that crop plants might undergo. This indicates that root resistance conferred in PA99N82-4 may not remain effective as temperatures rise. Priming plant immunity with transgenic bacteria as well as incorporating heat-stable resistance into crop cultivars are effective ways to diminish the damage caused by RKNs. These strategies should be considered for RKN management in order to better protect crop plants and improve global food security.
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Details
- Title
- THE EFFECT OF HEAT STRESS AND BACTERIA-DELIVERED PLANT ELICITORS ON PLANT IMMUNITY AGAINST ROOT-KNOT NEMATODES
- Creators
- Kristen Michelle Hamel
- Contributors
- Cynthia Gleason (Advisor)Kiwamu Tanaka (Committee Member)Hanu Pappu (Committee Member)
- 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
- Number of pages
- 82
- Identifiers
- 99900651899401842
- Language
- English
- Resource Type
- Thesis