1:00 pm - 2:00 pm
Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Oluwabukunmi (Joshua) Lawal. This seminar is open to the general public to attend.
MSc with Drs. Guanqun (Gavin) Chen and John Laurie
Zoom Link: https://ualberta-ca.zoom.us/j/99188179821?pwd=myu1uwL8LxbgYGe0b6H2mREXUz0BCe.1
Meeting ID: 991 8817 9821
Passcode: 835996
Thesis Topic: Nanotechnology intervention for control of smut and bunt diseases in cereals
Abstract:
Covered smut disease caused by Ustilago hordei is a threat to barley and oat cultivation worldwide. Conventional control methods, such as the use of chemical fungicides, have been widely adopted to prevent spread of the disease. These chemical fungicides effectively block multiple fungal pathogens. However, they also hinder the use of beneficial microbes and their long-term effects on the soil microbiome are not well understood. Additionally, the toxicity of some of these fungicides raises concerns about their impact on the environment and human health. Therefore, there is a pressing need for alternative and sustainable methods to control smut and related bunt diseases. In this research, my aim was to exploit nanotechnology solutions to prevent the mating of U. hordei and thus infection of barley. Mating in U. hordei is controlled by a bipolar mating system that comprises a single mating type locus with two known specificities, MAT-1 and MAT-2. The MAT locus contains an “a” region that encodes pheromone (mfa) and receptor (pra) for recognition of compatible partners and a “b” region that controls pathogenicity by encoding proteins responsible for the switch from budding to filamentous growth. Using plate assays and seed coatings, I assessed different classes of Cell-Penetrating Peptides (CPPs) for their ability to deliver dsRNA for RNAi induction and for their ability to interfere with mating and infection. Although RNAi could not be induced to a sufficient level to effectively block mating, peptides on their own showed strong suppression capabilities. One peptide did not affect mitotic division of basidiospores, however in mixed cultures of compatible spores, it halted the formation of dikaryotic hyphae. Other peptides reduced the formation of dikaryon while also causing the basidiospores to shrivel up. Peptides of a particular class caused swelling of the basidiospores but did not interfere with the formation of dikaryotic hyphae in the mixed-spore mating cultures. Experiments on diploid teliospores show that several peptides inhibit the germination of teliospores and formation of basidia. Overall, the efficacy of the CPPs varied, depending on the stage of the fungus’s life cycle. This study provides a novel approach for control of covered smut in barley by utilizing a nanotechnology solution. I have demonstrated that certain peptides can disrupt mating and the infectious dikaryotic hyphae. I go further to show that seed coatings containing peptides can reduce the infection rate of U. hordei. Additionally, I have experimented with growth conditions and demonstrated that the use of long-day, short-night growth conditions is a useful tool for reducing the flowering time of barley allowing earlier disease detection. My research lays the groundwork for accelerating research on smut and bunt diseases and offers an environmentally-friendly means for control of these pathogens.
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