Problem 5 - Campbell Biology

Question

The grass Dichanthelium lanuginosum lives in hot soils and houses fungi of the genus Curvularia as endophytes. Researchers tested the impact of Curvularia on the heat tolerance of this grass. They grew plants without (E-) and with (E+) Curvularia endophytes at different temperatures and measured plant mass and the number of new shoots the plants produced. Draw a bar graph for plant mass versus temperature and interpret it. $$ \begin{array}{|c|c|c|c|} \hline \text { Soil Temp. } & \text { Curvularia + or }- & \text { Plant Mass (g) } & \text { No. of New Shoots } \\ \hline 30^{\circ} \mathrm{C} & \mathrm{E}- & 16.2 & 32 \\ \hline & \mathrm{E}+ & 22.8 & 60 \\ \hline 35^{\circ} \mathrm{C} & \mathrm{E}- & 21.7 & 43 \\ \hline & \mathrm{E}+ & 28.4 & 60 \\ \hline 40^{\circ} \mathrm{C} & \mathrm{E}- & 8.8 & 10 \\ \hline & \mathrm{E}+ & 22.2 & 37 \\ \hline 45^{\circ} \mathrm{C} & \mathrm{E}- & 0 & 0 \\ \hline & \mathrm{E}+ & 15.1 & 24 \\ \hline \end{array} $$

Step-by-Step Solution

Answer

Plant mass is consistently higher in E+ conditions across all temperatures. E+ plants better withstand higher temperatures compared to E- plants.

Step 1: Understand the Data

The table provides plant mass (in grams) for Dichanthelium lanuginosum with (E+) and without (E-) the Curvularia endophytes under different soil temperatures: 30°C, 35°C, 40°C, and 45°C.

Step 2: Extract Plant Mass Data

For each soil temperature, note the plant mass values for both E+ and E- conditions: 30°C: E- 16.2g, E+ 22.8g35°C: E- 21.7g, E+ 28.4g40°C: E- 8.8g, E+ 22.2g45°C: E- 0g, E+ 15.1g

Step 3: Draw the Bar Graph

Construct a bar graph with soil temperature on the x-axis and plant mass on the y-axis. Use different colors or distinguishable patterns for E+ and E- bars. Label each bar with respective plant mass values.

Step 4: Interpret the Graph

Observe and interpret trends in the graph. Across all temperatures, the plant mass is consistently higher for plants with Curvularia endophytes (E+) compared to those without (E-). Notably, the E- plants experience a drastic reduction in plant mass at higher temperatures (40°C and 45°C), while E+ plants maintain higher mass even at these temperatures.

Key Concepts

Plant-Fungi Symbiosis

Plants and fungi often form beneficial partnerships, known as symbiosis. These relationships can offer plants various advantages such as enhanced nutrient uptake and better stress tolerance. This is particularly evident in the relationship between Dichanthelium lanuginosum and Curvularia fungi. The Curvularia endophytes live inside the grass and provide it with increased heat tolerance. The symbiosis allows the grass to survive and even thrive in extremely hot soils where it would otherwise struggle or die.
Curvularia helps the grass maintain higher plant mass at elevated temperatures. This symbiotic relationship effectively boosts the grass's ability to grow by providing essential support that it normally wouldn't have under stressful conditions. The mutual benefits underscore the importance of understanding plant-fungi interactions for agricultural and ecological applications.

Heat Tolerance in Plants

Heat tolerance is crucial for plants in hot environments. It determines how well a plant can sustain its growth and reproduction under high temperatures. The experiment with Dichanthelium lanuginosum and Curvularia endophytes showcases the importance of heat tolerance. Without the fungi, the grass's mass significantly drops as the soil temperature increases. This indicates that fungi play a vital role in helping the plant cope with heat stress.
The Curvularia endophytes enhance the plant’s physiological processes, making it more robust against thermal stress. By facilitating better water retention and nutrient absorption, the fungi contribute to maintaining stable plant growth. This knowledge is valuable for developing crop varieties that can withstand climate change and extreme weather conditions.

• Improved water retention
• Enhanced nutrient uptake
• Better growth under stress

Understanding these principles can lead to advancements in agricultural technology, ensuring food security in areas threatened by rising temperatures.

Plant Mass Measurement

Measuring plant mass is a fundamental method to assess plant health and growth. In the context of the experiment, plant mass provides a clear indicator of the impact of heat stress and symbiotic relationships on Dichanthelium lanuginosum. Accurate measurement involves carefully weighing the plant after removing any soil or external material.
The collected data shows distinct variations in plant mass between the E+ (with fungi) and E- (without fungi) groups. By analyzing these differences, researchers can draw meaningful conclusions about the benefits of fungal symbiosis. Typically, measurements should be consistent and repeated to ensure reliability. This process not only helps in understanding plant resilience but also serves as a predictive tool for crop performance under different environmental conditions.

• Consistent measurement methods
• Analysis of data for trends
• Correlation with environmental factors

Overall, plant mass measurement is a critical metric in both experimental and real-world agricultural settings, contributing significantly to our understanding and optimization of plant growth.