The Observation of Fusarium Growth Under Different Conditions

Introduction

Fusarium is a genus of soil fungi that is pathogenic to numerous economically important plant species. Because the fungi are so geographically widespread, species have been observed to exhibit variations in growth patterns due to environmental conditions.

This experiment entails growing Fusarium with media of varying carbon concentrations and with media incubated at varying temperatures. The effect each condition has on growth will be evaluated through visual observations, measurements of radial growth and presence of sporulation. NEED TO HAVE MORE BACKGROUND INFO ON PATHOGEN IN INTRODUCTION, SIGNS/SYMPTOMS, HOW DOES IT AFFECT PLANTS.

Materials and Methods

Fusarium fungal cultures for this experiment were obtained from pre-plugged cultures. The carbon source study in this experiment utilized three plates of Yeast Dextrose Agar (YDA) with low, medium, and high dextrose concentrations of 0.5g, 2.5g, and 10g, respectively. The temperature study in this experiment utilized four plates of Potato Dextrose Agar (PDA), one to be grown at each 5°C, 25°C, 25°C with light, and 35°C. A millimeter ruler and compounding microscope were used to measure growth and make observations.

Using aseptic technique, a single plug of culture was transferred to each treatment plate and placed in the center. All plates were wrapped with Parafilm. Each plate was placed into its respective container for incubation. After one week, growth patterns for all treatments were evaluated.

Results

Observations of growth patterns were observed after one week of incubation (Table 1).

Table 1: Observations After 1 Week

Treatment Observations Average Radial Growth (cm) Sporulation Present?

H-YDA Very high density, bright yellow color, spread to entire plate, opaque, fuzzy white on top center 8 None

M-YDA Yellow color, semi-translucent, nearly covers plate, fuzzy white on top center 11.625 None

L-YDA Pale yellow/brown color, translucent, branching around edge, fuzzy white on top center 5.6 Yes, Minimal

5°C PDA No Growth No Growth None

25°C PDA Bright yellow, non-uniform, branching, dense white fuzz on top 7 Yes, Moderate

25°C PDA w/ light Non-uniform, bright color 2.833 Yes, High-Density

35°C Non-uniform, dark yellow/brown, glossy on top 6.5 Yes, Minimal

Conclusions

The Fusarium fungi in the carbon source study exhibited maximum radial growth on YDA with the highest dextrose concentration (H-YDA), and radial growth decreased with decreases in dextrose concentration. However, sporulation was only observed on media with the lowest dextrose concentration (L-YDA). In the temperature study, no growth or sporulation occurred at the lowest temperature treatment. At the 25C treatment, Fusarium exhibited more vegetative growth in dark than in light. However, more sporulation was present in the 25C light treatment than in the dark treatment. At the highest temperature treatment, vegetative growth and sporulation were both minimal.

The results indicate that high levels of carbon sources support maximum vegetative growth, while low levels of carbon sources support maximum sporulation. Additionally, the cultures thrived at warm temperatures and were completely inhibited at cold temperatures, suggesting that the fungal isolate is likely from a warm environment.