Impact of Increased Temperature on Delosperma Cooperi

Published Date: 29 Jan 2018

• Eunice Oh

The Impact of Increased Temperature due to Global Warming on Pollen Germination of Delosperma Cooperi

Introduction:

There have is an ongoing crisis that is beginning to influence ecosystems throughout the world, which may lead to been large scalemany natural disasters and impacts due to a rise in earth’s temperature, due to the rise in temperature from the global warming. According to NASA’s Goddard Institute for Space studies, 1.4 degrees Fahrenheit0.8°C have increased around the world since 1880. In addition, the increasing rise in temperature is pervasivedid not stop, andd it is is increasing at a faster rate in the last two decades (SITE1). This warming phenomenon fluctuates can disturb the ecosystems andd may lead to extinction in extreme cases. Such ecosystems are dependent on plant growth and proliferation to sustain itself. Therefore, an experiment on to observeing the effects of a significant rise in temperature on pollen germination can was conducted to predictbe used a the adaptability of Delopsperma cooperi, a common species of iceplant grown around the world, to this phenomenondeduction for a bigger picture.

The goal of this experiment was to observe the effect of temperature on the pollen germination of Delosperma cooperi (trailing iceplant) and was compared to Tulbaghia violacea (society garlic) to obtain a broader view of how different plants from the same environment would react to a distinct change in temperature. An increase of 10°C was chosen as the variable to perform analysis with the Q₁₀ temperature coefficient. Pollen is a fine powder that contains microgametophytes of seed plants and it produces the male gametes. tes. When pollination occurs, the pollen pollen grain germinates and a pollen tube is produced as a conduit to transport the male gametes from the stigma to the pistils of the ovule in flowering plants (SITE2). The pollen germination refers to the growth of a pollen tube from pollen grains. In nature, the germination happens occurs when the stigma is hydrated and from water sources (e.g. rain)is available. GerminationIt can also be achieved induced in vitro using a germination media and the hanging drop method (SITE 3). Three replicates were observed Tandhe the resultsdata wereas analyzed with statisticscally to confirm if the data is statistically significantmeasure the significance of the variable (via a T-test, and Dixon Q). by utilizing Q10 values and Dixon Q testThe plant’s temperature dependence was quantified with the Q₁₀ temperature coefficient. It hypothesized was predicted that the increase in temperature would result in a significant higher improvement of pollen germination percentage rate and longer pollen tubes than the room temperature control due to Delosperma cooperi’s adaptive traits (quote).

Materials and Methods:

The solutions used for this experiment includeGermination of Delosperma cooperi was induced in the basic germination media, composed of (1mM KCl, 0.1mM CaCl₂, 1.6mM H₃BO₃, 10% glucose,)and distilled water. Unique Standard lab equipments used were used: compound light microscope, garden gaskets, depression slides, slides warmer, petri dish, and kim wipes, micropipettes. The light microscope was used under the 10x objective to track the germination process and measure the elongation of pollen tubes. To accommodate for a large sample volume (50µL transferred using micropipettes), garden gaskets were employed to extend the capacity of the depression slides. A slides warmer was used to maintain the high temperature environment (37°C ) and wet petri dishes were utilized as germination chambers.and pipette tips.

The hanging drop method consists of several steps. The basic germination media was used to initiate the pollen germination and the hanging drop method was utilized for the observation. A gasket was placed on top of the slide in order to create an area for the hanging drop to be intact with the cover slide and held together with grease. The slides were placed in the humanity humidity chamber to allow germination and prevent the drying. Two sets of the hanging drops were prepared, which one were for the higher temperature (37 °Cdegrees celcius), and another for the room temperaturpositive control (27°C degrees celcius). The negative control was prepared by observing the pollen alone without any germination media.

Statistical analysis methodology:

The germination elongation rates were recorded by sampling five pollen tubes from each slide in 30 minutes intervals, up to 150 minutes. This data was analyzed using biostatistics. A Dixon Q test was performed to identify and remove outliers. The Dixon Q test was calculated using the equation, : Q= (gap)/ (range). The gap refers to the absolute difference between the outlier and the closest number to the outlier and the range is simply between the smallest and largest values (SCITE). After the elimination of outliers from the Dixon Q test, a student T-Test (with a 95% confidence interval) was performed to determine whether the variables were statistically significant in the difference of their elongation rates using P values (SITE). Finally, a Q₁₀ value was determined from the mean of elongation rates. It was calculated by using the following equation: Q₁₀ = (R₂/R₁)^10/(T2-T1). Q₁₀ is a unit-less measurement that quantify the change of a biological system due to temperature change.

P-value:

Ris the rate and Tis the temperature inCelsiusdegrees orkelvins.

Results:

The purpose of the experiment was to measure the elongation rates after every 30 minute interval, 32 points of data were obtained and analyzed. Overall, tThe elongation rates rate of Delosperma cooperi for the room high temperature control variable were was as much as about three3 times slower faster compared to the high temperature control temperature (0.686 µm/min vs. 0.278µum/min) in trial three vs.0.686 um/min).

The percent germination was also significantly differentnoticeably better for the high temperature variable versus the controlfor the two controls, which wherethe room temperature control hadit was approximately 60% compared to 20%~20% and the higher temperature control had ~60% germination after 120 minutes from the initiation.

From the list of data, the

Dixon Q-test result indicated the data point 0.780µ4um/min of the higher temperature control as an outlier with a 95% confidence level.since the P value was below the threshold point, 0.05.

The mean elongation rate for the room temperature was 0.31437µum/min and 0.45438µ um/min for the higher temperature control.

The student T-Test

yielded a The P value was of calculated to be 0.0447, which indicatesd that the result is statistically significant at a 95% confidence interval. since P is less than 0.05.

The

Q₁₀ temperature coefficient for was calculated by using the equation (R2/R1)^10/(T2-T1), where R is rate and T is temperature used from the experiment. The calculation was (0.674/0.188)^(10/37-27) and theQ₁₀Value forDelospermacooperi​​ was calculated to beis 3.59, categorized as a temperature dependent biological system..

Figure 1. The graph shows the average elongation rates of Delosperma cooperi at two different temperatures. The tubule elongation rate was 0.314µm/min for the control and 0.454µm/min for the variable. Error bars denote one standard deviation (0.152µm/min and 0.177µm/min, respectively) above and below the mean.

Figure 2. The graph shows the average elongation rates of Tulbaghia Violacea at two different temperatures. The tubule elongation rate was 17.4µm/min for the control and 3.00µm/min for the variable. Error bars denote one standard deviation (1.95µm/min and 0.279µm/min, respectively) above and below the mean.

Discussion:

The results appear to support the hypothesis, where Delosperma cooperi was positively affected by the increased temperature by approximately a 0.140µm/min and 40% germination improvement. The goal of this experiment was to observe the effect of the change in temperature on pollen germination, especially focusing on aspects of improving percentage germination and the pollen tube elongation.

The result shows that the higher temperature yielded in an improvement in both percentage germination and pollen tube length growth at a significant level (P<0.05). The percent germination was about three times faster when compared to the positive control. The improvement in pollen tube elongation was interesting, also much faster in the higher temperature control, with the highest rate observed 0.784 microns/ minute, well above the average of the control. SThe statistical analysis supports this data, since the P-value via the student T-Test at the 95% confidence interval is lower than 0.05 and Q₁₀ value is higher than 2. Q₁₀ is a unit-less measurement that allows establish a temperature coefficient that correlates a system’s change to temperature differenceo (of 10°C) verify if the change of a biological or chemical system is temperature dependent. ( SITE 4) In addition, the higher percentage germination was observed from the higher temperature control. These result correspond to the an published article, in which Delosperma cooperi is more adapted to a higher temperature environment due to increased metabolic rate under temperature stress (SITE 5).

The results of Delopserma cooperi were compared with Tulbaghia violacea and suggest that the increased temperature had the opposite effect on Tulbaghia violacea,was opposite from what was observed in Delosperma cooperi. wThere pollen germination percentage and pollen tube growth were more effective in the room temperature control. Tulbaghia violacea is known to be better suited in the colder environment while high temperatures restrict their germination , and therefore the data corresponds to this fact (SITE 6). However, the data was determined to be not significantly significantt. (P>0.6).

The source of error includes a part of basic germination media merging with the gasket. While observing and putting the observation slide back to the humidity chamber, the media moved and touched the gasket, which the result may not be as accurate as we wanted. In addition, due to the gasket, the pollens could not be observed under the 40x magnification. Although pollen tubes could be observed under the 10x magnification, the 40x could have yielded in more accurate pollen tube measurements. For the flower, even though the pollen seemed to be mature and powdery, some of the pollens seemed to be dead or too mature when observed under the microscope.

A possible future experiment includes testing various a greater variety of indigenous flower pollens under more temperature variances. The experiment provided a glimpse into how certain plants would respond to the consequences of global warming and more studies are needed for a more comprehensive overview.in both lower and higher temperature. In addition, it would be good if the gasket is not used, and therefore the observation can be done under the 40x magnification.

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