On April 15th, Collins Aimuaenvbosa Agho defended his doctoral thesis at the Estonian University of Life Sciences, which focused on potato late blight.
Collins Aimuaenvbosa Agho's doctoral thesis "Transcriptomic and volatile organic compounds analysis of resistance mechanisms and diversity of late blight pathogen populations in the Baltic Sea Region" provided a better understanding of the molecular mechanisms underlying the high resistance of the Estonian potato variety 'Ando' to potato late blight.
Potato late blight is a significant reducer of potato yield and quality. The thesis investigated the spatio-temporal variability of the population structure of the potato late blight pathogen (Phytophthora infestans) in previously unexplored populations in Hiiumaa, Saaremaa, and Vormsi as well as in the nearby Pskov region of Estonia. It also addressed the reproductive methods, phenotypic and genotypic diversity, the impact of cross-border migration and gene flow on P. infestans populations.
The results of the study suggest a predominance of sexual reproduction in the populations of the pathogen, which is due to the high genetic diversity and abundance of unique genotypes (over 60%) in the studied regions. The study revealed that genotypic diversity was uniformly high across all studied years, regions, localities, and agricultural practices.
There was no relationship between SSR markers, which is common in populations where sexual reproduction dominates. The structural analysis of the combined populations from the Estonian islands and the Pskov region showed no genetic differentiation and mixing of isolates that would allow the exchange of genetic material.
The study of the populations of the potato late blight pathogen concludes the need for continuous monitoring to track changes in this highly adaptable and destructive pathogen in the region and over time. Additionally, the study examined the chemical profile diversity of potato varieties based on the emission of volatile organic compounds (VOCs) related to resistance to potato late blight.
The study found qualitative and quantitative differences between potato varieties and the dominance of terpenoids in the emission of volatile compounds. The emission of volatile compounds from infected potatoes in the composition of sesquiterpenes was variety-specific.
Interestingly, the mixture of volatile organic compounds accounted for a significant part of the variability, and the total emission of terpenoids and constitutive volatile compounds positively correlated with the variety's resistance to late blight. Measuring the emission of volatile compounds from potato leaves provides insights into the diversity of the foliar chemotype. This allows for the identification of potential non-invasive markers for phenotyping potato varieties in assessing resistance to late blight.
RNA sequencing technology provided a better understanding of the molecular mechanisms underlying the high resistance of the Estonian potato variety 'Ando' to potato late blight.
Collins Aimuaenvbosa Agho defended his PhD thesis on April 15th at 13:15 in room D239 at F. R. Kreutzwaldi 5. The dissertation supervisors are Professor Ülo Niinemets, Associate Professor Eve Runno-Paurson, Dr. Eve Kaurilind, and the opponent Professor Isaac Kwesi Abuley (Aarhus University, Denmark). The dissertation can be accessed in the digital archive of the Estonian University of Life Sciences, EMU DSpace.