Plant Pathology Students by Day……. Pathology Investigators by Afternoon!

By Ashley Kroeger

Today May 30th, 2017… the UAB Outpace Team took a field trip…. to the UAB Community Gardens! Just located a mere block or two from the UAB’s campus, our team traveled to put to fruition our investigative and prove our skills of identifying plant pathogens. Our research team was split into four groups assigned designated categories of plants. Group 1 observed: Eggplants, Peppers, and Tomatoes/Potatoes, Group 2 observed: squash, cucumbers, and watermelon. Lastly, Group 3 observed bean leaves. Each group was then given packets specific to their category of origin and common pathogens to be observed within each section. The goal of this trip was to observe viral infections of plants and determine the validity of an actual presence of pathogens.


Figure 1. Photo of UAB Community Garden


Figure 2. Outpace Pathology Research Student looking for observable signs of infection.

Due to the recent temperament of the weather including frequent raining and ample moisture coupled with sunlight served as a pertinent environment for viral pathogenic growth. From a holistic stand-point the physical attributes associated with: viral, bacterial, and fungal diseases often intersect which proved as a slight curveball for pathogenic leaves. The main attributes associated with specifically viral infections are not limited to: wilting, a yellow discoloration of leaves, and often a mosaic appearance on leaf surface. Some plants had been freshly planted with limited presence of any pathogenic cultivation, while others were extremely engulfed with infection.


Figure 3. Squash leaves exhibiting the yellowish appearance to surface, curling, and withering.

After proceeding to collect 4-5 leaves of infected suspect viral pathogens the leaves were examined by utilizing  a “ Adgia Pathology Kit”. The kit operates much like that of the exams utilized for pregnancy. A small cross section approximately the size of your pinky finger-nail tip was placed between a liquid solvent and plastic mesh medium. The leaf’s surface area was completely submerged in the solvent, sealed, and grated utilizing a sharpie to press along the outside surface of the mesh. The effect of this mimics grinding leaf tissue utilized for serial dilutions of pathogens. The breaking down of leaf tissue into the solvent allowed for the release of any pathogenic microbes to be brought to surface. After prolonged scraping of leave tissue, an opaque green color was observed in the medium. An immune strip was then submerged into the liquid of extracted leaf tissue. As the strip absorbed the solution, line indicators would be observed to firstly tell validity of test, and secondly verify to correct pathogen to test.


Figure 4. Technique of leaf extraction.


Figure 5. Test strip negative results for pathogen.

As previously staged analogy, the test operate as follows. If one red line was observed, the test was often valid for operation. The presence of double lines indicated a valid test, and a positive match of exam to pathogen. Although none of our samples derived a positive match, we did indicate the presence of transgenic crops!

This testing method seems to be observably the fastest for a presence of a pathogen, but you are not always concluded a complete 100% match. The trip was an overall success and I believe I am now more versed to the presence of viral infections within the phenotype exhibited by plants.


Figure 6. Summer 2017 Outpace Plant Pathology Research Team.



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