Microbiology Commons^™

First Report Of Hog-Plum (Spondias Pinnata) Leaf Spot Disease, Kunal Mandal

Kunal Mandal

Hog–plum is a tree species with edible fruits. The plant is naturally distributed in the tropical areas of the Indian subcontinent. Our effort to introduce it in the semi– arid conditions of western India failed as the plants developed severe shot–hole type leaf spot symptoms. Association of a fungus with the disease was detected and its pathogenicity was established. The pathogen was identified to the genus level (Colletotrichum) based on the morphological and molecular markers.

Impact Of Crop And Residue Management On The Physical And Chemical Stabilization Of Soil Organic Matter At Farm Level, Ana B. Wingeyer

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This dissertation explores changes over time in soil organic matter (SOM) stabilization of two irrigated production fields: a continuous maize sequence that was converted from no-till to conservation deep tillage (Site 1), and a no-till maize-soybean rotation (Site 2). An integrated approach using humic acid extractions and density-based physical fractionation of SOM within aggregate size classes was developed to evaluate the changes in SOM stabilization (physical protection, organo-mineral associations and humification). At Site 1, loss of SOM in the surface layer was compensated for by increased SOM in deeper soil layers with no net change in C stocks. Whole field …

Analysis Of Turnip Crinkle Virus Effects On The Innate And Adaptive Immunity In Arabidopsis Thaliana, Teresa J. Donze

School of Biological Sciences: Dissertations, Theses, and Student Research

The ability to understand the interactions between plants and the variety of pathogens they encounter on a daily basis is an important area of research. In the following work presented in this dissertation, I sought to better understand the mechanisms that Turnip crinkle virus (TCV) employs to elude the defense responses of the host plant Arabidopsis thaliana. It was previously determined that TCV coat protein (CP) interacts with a transcription factor, TIP, within the about 10 amino acid region near the N-terminus of the CP called the R-domain. When this interaction was disrupted by making single amino acid substitutions …

Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath

Undergraduate Research Opportunities Program (UROP)

Serpentinites, perhaps more than any other rock type, control the composition and evolution of the development of the surrounding ecosystems. The bulk chemistry of serpentinite rocks, high in Mg and trace elements, and low in nutrients such as Ca, K, P, and N, causes an extreme and stressful environment for ecosystems. However, the role that those serpentine ecosystems play in development of serpentine soils has not been examined.

Due to the unusual chemistry of serpentine soils, serpentine ecosystems have deeper and better-developed root systems than other ecosystems. The rhizosphere of serpentine systems, documented to produce abundant organic acids and siderophores, …

What (Or Who) Lives Inside Scotch Broom Roots?, Lisa Fazzino

Summer Research

Scotch broom (Cystis scoparius) is invading the South Puget lowlands, presumably with help from the nitrogen-fixing symbiotic bacteria that are found in its root nodules. With this nitrogen source, Scotch broom is not limited by low nitrogen levels in the soils like many other plants. The goals of our research are 1) to identify the nodulating bacteria of Scotch broom in the Northwest, British Columbia, and Canberra, Australia to explore the diversity of Scotch broom symbionts and 2) to explore the possibility of multiple occupancy in Scotch broom nodules. Using 16s rRNA sequencing, we will identify the bacteria of Scotch …

Gata-Family Transcription Factors In Magnaporthe Oryzae, Cristian F. Quispe

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The filamentous fungus, Magnaporthe oryzae, responsible for blast rice disease, destroys around 10-30% of the rice crop annually. Infection begins when the specialized infection structure, the appressorium, generates enormous internal turgor pressure through the accumulation of glycerol. This turgor acts on a penetration peg emerging at the base of the cell, causing it to breach the leaf surface allowing its infection.

The enzyme trehalose-6- phosphate synthase (Tps1) is a central regulator of the transition from appressorium development to infectious hyphal growth. In the first chapter we show that initiation of rice blast disease requires a regulatory mechanism involving an …

Phenotypic, Pathogenic, Molecular And Phylogenetic Comparisons Of Bacteria Causing Aloe Rot From Three Countries, Yogeshwar Kumar, Jatindra Nath Samanta, Kunal Mandal, Narendra A. Gajbhiye

Kunal Mandal

Bacterial soft rot disease of Aloe caused by heterogeneous genus Erwinia was reported from different parts of the world. In the recent past the genus underwent major taxonomic modifications. In the present study, four Aloe pathogenic bacterial strains isolated from India, The Netherlands and Yugoslavia have been compared. Different cultural, biochemical, physiological and pathological characters and protein/lipid profiles indicated that the strains belonged to two different genera, Pectobacterium and Dickeya. Species specific amplification of pel gene sequences also supported this. Phylogenetic analysis of rRNA gene (rDNA) sequence placed these Dickeya strains close to D. dieffenbachiae and D. zeae. On the …

Dryland Residue And Soil Organic Matter As Influenced By Tillage, Crop Rotation, And Cultural Practice, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Tonthat, Jalal D. Jabro, Robert T. Lartey, Robert G. Evans, Brett L. Allen

Andrew W. Lenssen

Novel management practices are needed to increase dryland soil organic matter and crop yields that have been declining due to long-term conventional tillage with spring wheat (Triticum aestivum L.)-fallow system in the northern Great Plains, USA. The effects of tillage, crop rotation, and cultural practice were evaluated on dryland crop biomass (stems + leaves) yield, surface residue, and soil organic C (SOC) and total N (STN) at the 0–20 cm depth in a Williams loam (fine-loamy, mixed, superactive, frigid, Typic Argiustolls) from 2004 to 2007 in eastern Montana, USA. Treatments were two tillage practices [no-tillage (NT) and conventional tillage (CT)], …