Document Type

Honors Thesis

Publication Date

Spring 5-2016

Abstract

Thekopsora minima, or leaf rust, is a fungal pathogen that infects Vaccinium angustifolium (lowbush blueberry), an economically important crop to the state of Maine. T. minima undergoes a complicated life cycle that contains five unique spore stages. It causes abscissions in the leaves of plants that may consequently lower yields in the next growing cycle if leaf drop is severe. Currently, growers are instructed to apply fungicides in late July to prevent further infection. However, this is often not effective due to poor timing. Data on spore release patterns would be beneficial to elucidate the infection period. However, microscopic identification of T. minima spores based on visualization of morphology alone is complicated. Therefore, prediction of major infection periods must be achieved by some other means to quickly identify the pathogen. In this regard, molecular methods involving the polymerase chain reaction (PCR) have potential as a solution. In this study, leaf samples that were suspected to be infected with rust fungus were collected, spores harvested, and DNA extracted from the gathered spores. Several different methods were utilized for this purpose and their efficacy is discussed. After amplification with universal fungal primers, DNA was confirmed to be from T. minima with 99 % identity to previously discovered sequences from highbush blueberry and confirm previous studies that reported a similar sequence from the same field site. Alignments of these data to similar species provided several sections of sequence unique to leaf rust that could serve as an aid in developing primers.

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