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Category: Botany

Seagrasses biomass-density relationship and ecological indicator

Seagrasses are marine flowering plant that comprises more than 60 different species. It grows by rhizome extension forming like grassland. Seagrasses also photosynthesize in submerged photic zone that mostly occur in shallow coastal water. In productive ecosystem seagrasses beds are diverse that can accommodate hundreds of associated species like fishes, macroalgae, mollusks and nematodes. However, biomass-density relationship becomes the center of research that describes the health of seagrass meadows.  Concurrently, biomass-density upper boundaries determined the maximum efficiency of space occupation. In which each distance reflects effective competence in packing biomass which proved as reliable ecological indicators.

 

Biomass-Density of Seagrasses

The researchers gathered 32 studies on 10 seagrasses species distributed worldwide reveals that seagrasses are limited by boundary line. Upon using the applied metric system on this particular research each stand of seagrass distance are perpendicular to the boundary.  However, seagrasses shows poor occupier of space compared to terrestrial plants and algae wherein less volume exploited per unit stand surface. Due to some reasons such as short shoot heights, wasted volume due to internodes length larger than shoot widths.

 

Seagrass comprises different species which shows diverse efficiency in space occupation. However, it occupies different bands of biomass-shoot density signifying conditional differentiation of co-occurring seagrass species. Furthermore, high shoot density dominates in favorable environments compare to harsh environment. As a result, this space occupation revealed as a good tool in understanding aspects of seagrasses ecology. Therefore, it serves as the basis to review fundamental aspects including clonal growth pattern, seasonality, competition and depth distribution.

 

Biomass-density of seagrass meadows is limited by interspecific boundary line making a maximum efficiency of space occupation. Though, species tends to differentiate the bands each scatter plot showing conditional differentiation. Moreover, during summer it shows the most favorable season and lower intertidal in correspond to depth. Therefore, the competence of space occupation requires biomass and shoots density of stands measured by vertical distance to the seagrasses.

 

Source: Prepared by Joan Tura from BMC Ecology

Volume 18: 24, October 19, 2018

Reproductive Success of Medicago sativa: Pollen and Resource limitation

Medicago sativa is a perennial flowering plants that belongs to a legume family.  This plant is known in forage crop, grazing, silage, green manure and cover crop.  Medicago sativa develops potential for medicinal uses and thrive mostly in an arid climate. The aim of this particular research is to determine the floral traits and pollinators visitation activities that affect pollen limitations. It also identifies possible effects of resource allocation on pollen supplementation and the impacts of pollen on flower opening.

 

Medicago sativa floral traits and pollinators

Plant reproduction is limited due to pollen resources, floral traits and pollinator activities. Medicago sativa was observed at about 120 hours by collecting pollens and nectars. The pollinator type was then noted. It was then recorded the visitation frequency and behavior of flowers based on insects as effective pollinators or occasional pollinators. The pollinators then, captured using insect nets to find out the presence of pollen grains.

 

The result shows a positive relationship between pollinators visitation frequency and the number of open flowers. It also found out that, it is more efficient for pollinators to visits opening flowers. Since, filaments of Medicago sativa will dry easily particularly in an arid regions. Moreover, flowers of Medicago sativa was completely open and the pollen released between 09:00 to 14:00 hours. Additionally, some insects identified as effective pollinators because it can collect more pollen and visit more often. However, a reduction of pollinators will decline the amount of pollens and reduced the probability of cross pollen transfer.

 

Overall, this research found out that pollen resources is the limiting factor for the reproductive success of Medicago sativa. It also shows that resource reallocation can increase pollen limitation and plants might reallocate among flowers. However, insufficient pollen deposition is typically caused by pollinators assemblage, visitation and abundance.  In which flowers is the main effects of resource limitations and pollinators plays an important role in outcrossing.

 

Source: Prepared by Joan Tura from BMC Ecology

Volume 18:28 August 29, 2018

 

 

 

 

 

 

 

 

 

 

Plant sets off “SOS” for plant defense when it gets hurt

When herbivore, such as an insect, nibbles a plant leaf, the plant sets off an “SOS” or distress signal as one of the various plant defense strategies. This was based on what a team of researchers headed by Masatsugu Toyota observed. Accordingly, the injured leaf makes the distant undamaged leaves aware that it is being eaten.

 

Masatsugu Toyota worked with Simon Gilroy, Professor of Botany in the University of Wisconsin-Madison.1 Now, Toyota is at Saitama University in Japan and collaborated with a team of researchers from the Japan Science and Technology Agency, Michigan State University and the University of Missouri. Their research findings can be accessed online via the journal Science. 2

 

 

 

Rapid signaling in plant defense mechanism

plant defense
Calcium propagating across the plant after supplying glutamate at the tip of the leaf. Image taken from the video of Toyota, Gilroy, et al. depicting one of the data from their recent study on a mutant Arabidopsis. 1

Previously, Toyota et al. knew that when a plant gets wounded, it releases signaling molecules that fired an electrical charge, and then spread across the plant. However, they did not know what was behind the system.3 Now, the research team deduced that the signal may have been calcium since it carries a charge, and capable of producing such signal. 1

 

The research team worked on a mutant Arabidopsis. They designed a mutant model plant that would synthesize protein that fluoresces, but only around calcium. In so doing, they can track calcium in real time.

 

 

 

Plant defense involving glutamate

In spite of the fact that the plants lack the nerves and a nervous system of an animal, the plants have a fairly similar systemic signaling system as part of plant defense mechanisms.

 

In animals, glutamate acts as one of the major and fast excitatory neurotransmitters of the central nervous system. Toyota et al. elucidated that, in plants, glutamate is also present. The injured leaf releases glutamate and this molecule is taken up by glutamate-receptor-like ion channels. Consequently, these ion channels led to a spike in calcium ion concentration. These calcium ions, then, spread out to other plant parts via the phloem vasculature and the plasmodesmata. 2

 

This video from UW-Madison Campus Connection shows the wave of calcium after supplying glutamate to the tip of a leaf. The plant fluoresces to indicate how the calcium spreads out across the plant.

 

 

 

 

Distress signal

In just a couple of minutes, the region receiving the distress signal responds by releasing chemicals. The release of defense-related hormones, for instance, turns the plant unpalatable to the herbivore. In another case, the plant emits volatile chemicals to call for insect allies, such as parasitic wasps. This is an indirect type of a plant defense strategy. The wasps recognize the distress signal that an herbivore feeds on the plant. They, then, go towards the plant to hunt for and lay eggs on the herbivore caterpillar host, thus, killing the latter eventually.4

 

 

 

Plants do not have the capacity to move around at will and in the same way that animals do. And certainly, they cannot run away from herbivores as a prey would to escape a predator. Nevertheless, the plants possess features that strategically protect them against their “predator” despite being firmly rooted in the field. One such plant defense mechanism entails chemicals. In particular, glutamate that acts similarly as neurotransmitter in animals. This demonstrates how a plant can likewise be complex, dynamic, and efficacious with regard to dealing with its “predators”.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 Hamilton, E. (2018 Sept. 13). Blazes of light reveal how plants signal danger long distances. University of Wisconsin-Madison News. Retrieved from https://news.wisc.edu/blazes-of-light-reveal-how-plants-signal-danger-long-distances/
2 Toyota, M., Spencer, D., Sawai-Toyota, D., Jiaqi, W., Zhang, T., Koo, A. J., Howe, G.A., &Gilroy, S. (2018). Glutamate triggers long-distance, calcium-based plant defense signaling. Science, 361 (6407): 1112. DOI: 10.1126/science.aat7744
3 Starr, M. (2018 Sept. 14). An Amazing Reaction Happens When a Plant Gets Hurt, Making Them More Similar to Animals. ScienceAlert.com. Retrieved from https://www.sciencealert.com/plant-damage-response-defence-calcium-ions-glutamate-fluorescent
4 Phillips, K. (2014 Sept. 22). Mown grass smell sends SOS for help in resisting insect attacks, researchers say. Retrieved from https://today.agrilife.org/2014/09/22/mown-grass-smell-sends-sos-for-help-in-resisting-insect-attacks-researchers-say/

Understanding the Venus flytrap through mathematical modelling

Venus flytrap is a carnivorous plant that catches its prey mostly insects and arachnids through snap-trap movement. It has a trapping structure that is triggered by tiny hairs in the inner surface of the plant leaves.  When insect crawling along, the plant trigger to close only if it caught a live insects worthy of consumption. This unique trapping mechanism drawn attention to scientific interest and called it “one of the most wonderful in the world”. However, only recently that snap-trap closure mechanism of the Venus flytrap fully understood. On the other hand it is also been studied the trade-off investment in snap-trap structures and its energetic benefits. But a little information has been established about prey selection and why the traps allow prey to escape. This paper provides the first mathematical cost-benefit model for carnivory in the Venus flytrap and understanding its ecology.

 

3 Stages of Venus flytrap prey captures and digestion

Venus flytrap captures and digests its prey into three stages.  Firstly, trap is open and the lobe stand at approximately right angle to each other waiting for prey to enter. In this stage when prey moves across the trap it generates stimuli a receptor potential then action potential. Secondly, after the signal for closure the trap shut and enters in a semi-closed state. It will remain semi closed until further mechanical stimuli to make sure that live prey has been caught. Thirdly, while the prey is struggling inside the trap it will further stimulate and cause the lobes to close tighter. In fully closed state the trap has essentially transformed into a stomach and start digesting.

 

The investigation reveals that Venus flytrap non- prey sources such as raindrops or wind caused trap closure. This mechanism is triggered once every two days and the trap wait for more than a month for a meal. However, bigger insect around 29mm will trap fully but smaller size less than 14.2mm can escape eventually. This carnivore plant is prey selective wherein the average size of prey is 20mm. Meaning, it utilizes 68.9% of its maximum potential. Moreover, optimal trap allows 76.8% of captured prey to escape indicating that Venus flytrap is highly selective in prey capture.

 

Indeed, the ecology of Venus flytrap is not understood well that is why investigating capturing and digestion of prey is important. This research provides the building blocks on modelling its ecological mechanism which could incorporate various stages of trap. Since the plant is highly adaptive to its habitat the traps grow quickly.

 

Source: Prepared by Joan Tura from Journal of Theoretical Biology

Volume 444, 7 May 2018, Pages 1-10

Light Induces Petal Color Change in Quisqualis indica

Quisqualis indica is a spectacular vine that has yellow-green lance shaped leaves distributed mostly in tropical Asia. It is a perennial plant that normally grows in, low woods, riverside, rain forest and roadside. Yet, it can also be cultivated as ornamental plants because of its stunning flowers and mesmerizing fragrance at blooming. The flower of Quisqualis indica varies in three colors based on the flower age.  In which it started to blooms from white color petals then gradually darkens into pink then red as it reaches maturity. Moreover, the change of color in the flower is due to its potential role in attracting pollinators under cultivation conditions. However, the factors affecting these changes remain unknown. Therefore, the aim of this particular research is to determine some relevant factors affecting floral change color of Quisqualis indica.

 

Floral color change of Quisqualis indica

There were different parameters used in the study including pH, temperature, ethylene and light. It reveals that Quisqualis indica petal color changes reveals significantly in light rather than pH, temperature and ethylene. Wherein, it does not undergo color changes under dark condition regardless of temperature conditions. Light induced anthocyanin a gene that is responsible for color change in response to light. Thus, it implies that anthocyanin biosynthesis is regulated at the level of transcription in the presence of light.

 

Moreover, the pH value of Quisqualis indica over floral ontogeny did not influence the petal color change. Also flowers sprayed with ethylene did not reveals significant change suggesting that floral color change is not mediated with ethylene. On the other hand, the temperature of Quisqualis indica under 20–30 °C for four different light treatments did not change. In which at 15 °C or 35 °C the flowers did not open when exposed to constant temperature. Besides throughout the experimental period regardless of temperatures, floral color remains white.

 

Indeed, light is the primary factor that affects floral color change of Quisqualis indica rather than pH, ethylene and temperature. However buds and petals are sensitive to light yet flowers response highly to light than buds. But the final petal color is not expressed if only buds exposed to light which means that light during flowering period induce the final transcription.

 

Source: Prepared by Joan Tura from Plant Diversity 

Volume 40, Issue 1, February 2018, Pages 28-34

Anti-ulcerative colitis activity of Calotropis procera Linn

Calotropis procera Linn (Swallow wort) is a wild plant, highly branched perennial shrub that belongs to the family of Asclepiadaceae. It is believed  as medicinal plants that can be found in tropics growing on sandy and alkaline soils. Calotropis procera contains chemicals that have been used for antifungal, anticancer and insecticidal activity. It also exhibits antipyretic, anti-inflammatory, gastroprotective and antioxidant. The researcher on this study believed that Calotropis procera used as medicine in ulcerative colitis a bowel disease. The symptoms of disease is an inflammation of inner lining of the colon that caused bloody diarrhea, pus and abdominal cramping.

 

Effect on ulcerative colitis

Extracts of Calotropis procera were assess using rats to test its potentials as anti-ulcerative colitis. Results reveal that inflammatory indices improve better for five days after the introduction of the disease. Oral administration of Calotropis procera confers a relevant development of the disease signifying a possible treatment for ulcerative colitis. The extract of Calotropis procera contains low level of toxicity which means that other vital organs is not affected. Therefore, it is consider safe to intake orally as medicinal supplement for ulcerative colitis.

 

Related studies about Calotropis procera also have a positive results as anti-inflammatory because it contains useful chemicals and phytochemicals. On the other hand ulcerative colitis develops overtime and can be unbearable that sometimes leads to life threatening complications. Though, treatment is needed to lessen the signs and symptoms of the disease.

 

Overall, Calotropis procera has a potential to lessen the inflammation of ulcerative colitis and other diseases. Mostly the disease begins during adolescence and the severity of the inflammation changes over time. Relapses and remission also happens that last for months or years. Indeed ,Calotropis procera subsides the symptoms of ulcerative colitis and minimized the side effects to other vital systems.

 

Source: Prepared by Joan Tura from Saudi Pharmaceutical Journal

Volume 26, Issue 1, January 2018, Pages 75-78

 

 

Why Are There So Many Kinds of Plants?

Welcome to guest blogger, USF Botany Professor Fred Essig

Estimates vary, but there are about 300,000 named species of plants, with more being discovered daily.  There may ultimately be as many as 500,000, if and when all are catalogued. Some botanists include some 10,000 species of red and green algae in such estimates, but others include only the land plants. Either way, it’s a lot. (more…)