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1	Combating Fungal Pathogens (Helminthosporium solani, Pythium ultimum) with Secondary Metabolites of Streptomyces Bacteria Kemp, Erik W. 02 March 2022 (has links) Fungal diseases, Pythium ultimum (Pythium leak) and Helminthosporium solani (silver scurf) have detrimental effects on potato tuber (Solanum tuberosum) quality and yield. Tubers are the world’s fourth largest agricultural food crop and are crucial for feeding a growing population. Bacteria from the genus Streptomyces are known for producing a wide variety of secondary metabolites with antifungal properties. Isolates of Streptomyces have recently shown inhibitory effects towards P. ultimum and H. solani in Petri dish assays. These data suggest that Streptomyces may work as a biocontrol to protect tubers from P. ultimum and H. solani. We tested talc-based powder formulas for their ability to maintain viable Streptomyces spores in storage. The formula that maintained spores the longest was then used to coat varying Streptomyces isolates onto a tuber surface that contained, or would be exposed to P. ultimum or H. solani. Tests were conducted in a lab, greenhouse, and field setting. We found a powder formula that kept 50% of the added Streptomyces spores viable for a period of three to six months depending on the isolate. Isolates with inhibitory effects towards H. solani were applied as a powder on seed tubers infected with H. solani and grown in a greenhouse. Upon completion of the experiment, we found that progeny tubers from neither the treatment nor the control groups contained H. solani. Instead, we found a similar surface pathogen, Colletotrichum coccodes (Black dot), on many of the progeny tubers. While not the target pathogen of this study, some isolates significantly limited C. coccodes compared to the control. This experiment was repeated in a field setting where C. coccodes was again the primary disease found on the progeny tubers. In the field, isolates showed no inhibitory effect towards C. coccodes. Isolates with inhibitory effects towards P. ultimum were applied as a powder onto wounded tubers. One hour later the tubers were exposed to P. ultimum. Isolates did not limit P. ultimum compared to the control after a week of incubation. A follow up experiment revealed that the Streptomyces isolate used needed at least 24 hours of growth to produce antifungal secondary metabolites. Our data suggest that Streptomyces bacteria can easily be stored in a powder and that there are beneficial effects as a biocontrol against C. coccodes. Our data also suggest that timing Streptomyces application for maximum secondary metabolite production may improve its efficacy as a biocontrol. streptomyces biocontrol potato silver scurf pythium leak black dot Plant Sciences
2	Shift Arnold, Amanda Suzanne 03 August 2007 (has links) The following is a collection of original poetry. The manuscript consists of an introduction explaining influences and style, and four chapters of poems categorized by subject matter: object/nature, writing/creativity, relationships, and family/figures. INDEX WORDS: Poetry, Poem Giving Thanks Transportation 1:43 a.m. Our Heavenly Father Silver Lining Old Neighbor Halves December 1982 Medicate Friend Home Economics Missing Keeper Passing Dream Tango Lesson Words Edge Untitled Poem Get-away Poem If You Stay Puppy Moon Winter Pine Loneliness The Truth Bone Potato Slip Sad Kentucky Old Shirt Isolation Cleaning the Sink Manhattan Root Posture Keep How it is Personal Business Gun One and the Other Sestina Poets Snow Globe The Romantics Idea The Black Dot Dissection English Language and Literature

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Combating Fungal Pathogens (Helminthosporium solani, Pythium ultimum) with Secondary Metabolites of Streptomyces Bacteria

Shift