These scientists set out to “estimate loss of genetic diversity by loss of habitat” for different plant species “under different climate scenarios”. After analyzing nearly 10,000 samples from 27 plant species in Arctic environments of central Europe, it was shown that those species that used wind and birds for seed dispersal will preserve greater genetic diversity in a warmer climate than species that have more limited seed dispersion.  Additionally, the longer lifespan of species such as trees and shrubs are able to disperse their seeds more productively than shorter-lived species, such as herbs.

Genetic variation, in short, is essential for adaptation during a changing climate. Seed dispersion is one factor that will determine how various plant species fare with the upcoming climate changes. Some species may lose up to 80% of their habitat but will still  maintain most (90%) of their genetic diversity.  Others will lose 50% of their genetic diversity when their habitat is reduced by 65%.

These new findings will have important effects on the International Union for Conservation of Nature (IUCN) Red List that identifies threatened species. With future climate changes, this list will grow extensively.

Discussion Question: What are some other factors, in addition to seed dispersion, that could have an important impact on the survival fitness of Arctic plant species?

Also, how do you think the criteria of which plants make the Red List will be affected with these new findings?

News Source: http://www.sciencedaily.com/releases/2012/01/120117143758.htm
Journal Source: http://rspb.royalsocietypublishing.org/content/early/2012/01/03/rspb.2011.2363

Image Source: http://www.farnorthscience.com/wordpress/wp-content/uploads/2007/06/svalbardplants.jpg

Although pollen is microscopic, there still have the same evolutionary goals as all male beings, which is to produce offspring. In pine trees, pollen grains compete for access to the green nubbins of female plant tissue. This competition process is likened to the process of sexual selection that occurs in animals. There are many obvious examples of sexual selection among animals, but in plants the examples are subtler, such as molecular differences in pollen grains. Scientists are working to discover whether individual plants exercise choice among possible pollen grains to utilize and how males would compete among each other to be selected.

One finding that supports the theory of sexual selection within plants is that when pollinators drop off pollen onto female flower parts, the pollen grains that are utilized by the plant for reproduction are not an accurate representation of the sample of pollen that was dropped off. This shows a non-random utilization of pollen grains for reproduction.

Another finding is that some plants seem to selectively abort certain embryos rather than allow them to grow into seeds, perhaps because these embryos came from unfavorable pollen grains. The strongest piece of evidence for sexual selection in plants is that competitive displays actually shorten male life expectancy; this payoff is seen in animal sexual selection as well. If plants can show such signs of sexual selections, it is a mystery what other supposedly “animal” behaviors may appear if we search closely enough.

Discussion Question: Despite these findings, there have not been solid discoveries of the mechanisms by which pollen grains compete with each other. What do you propose these mechanisms could be?

News Article: http://www.sciencenews.org/view/feature/id/336229/title/Flirty_Plants
Journal Article: http://www.mendeley.com/research/extent-southnorth-pollen-transfer-finnish-scots-pine-7/
Image Credit : Susumu Nishinaga – http://www.sciencenews.org/view/access/id/336246/name/flirty_plants_primary.jpg

There seem to be two competing processes that are in play here. On one hand, studies have shown “altruism towards relatives” where siblings perform best in proximity to each other. Other studies have shown that a group of less-related plants growing together can outperform a group of siblings growing together. Studying these two processes together may address some important questions in understanding this complex behavior.

There are great challenges in deciphering the social interactions of plants because they can’t be interpreted as easily as interactions between animals. The author suggests that researchers tend to only look at the output and fitness of the plant when looking at competition, rather than also understand how specific traits affect output and fitness.

Discussion Question: How can these questions of social interactions between plants be used in the fields of agriculture and plant communities?

News Article: http://www.sciencedaily.com/releases/2011/11/111109115816.htm
Journal Article: http://rspb.royalsocietypublishing.org/content/early/2011/11/03/rspb.2011.1995

Image Source: http://en.wikipedia.org/wiki/File:Iris_sanguinea_2007-05-13_361.jpg

For Joseph Ecker and his colleagues at the Salk Institute, the organism in question is Arabidopsis thaliana, an otherwise unexceptional plant species known primarily for its use as a “lab standard.” In their study, the team, along with scientists at Scripps Research Institute, isolated a population of the plant and recorded its epigenetic changes over thirty generations of its clones. Watching in particular for an epigenetic change called methylation, which influences the expression of underlying genes, researchers identified all methylation sites on the DNA molecule. They then tracked changes to these sites over the thirty generations.

The researchers identified six million sites on the DNA molecule of the plant that could undergo methylation and result in epigenetic variation. Within the population of clones examined, they found that several thousand sites could be altered within a single generation, noting that the rate of epigenetic variation exceeded the rate of genetic variation by a factor of five. Their conclusion: even without pressure from the environment, the clone’s “epigenetic code,” and therefore its phenotype, could change rapidly.

The Salk team is eager to abstract from their findings on the Arabidopsis thaliana to other, more challenging organisms, such as human beings, in whom they suspect a similar influence of epigenetic variation on trait expression. With no specific evidence to restrain their claims, the prospect is hopeful. And, if, as the research indicates, epigenetic codes change faster and more spontaneously than their genetic counterparts, more than just our genes is at work in determining who, and how, we are. As Ecker himself muses, “genes are not our destiny.”

Discussion Question: What are some other factors that may affect an organism’s phenotype?

News Article: http://www.sciencedaily.com/releases/2011/09/110916152401.htm
Journal Article: http://www.sciencemag.org/content/early/2011/09/14/science.1212959

Image Source: http://commons.wikimedia.org/wiki/File:Arabidopsis_thaliana_rosette.png

Scientists have long since understood the function of stomata, but have not understood how the even spacing of stomata on a plant surface comes to be. An article published in Science shows that stomata cell growth follows a pattern of stem cell behavior similar to that of some animal cells. Only one of the two daughter cells in each division preserves the ability to divide further and form stomata by keeping a protein called SPEECHLESS (SPCH) active. This daughter cell is maintained at the center of the surrounding cells through a “molecular dance” in which the polarities of surrounding cells switch at each division. The SPCH-containing daughter cell continues to form stomata and ends up surrounded by SPCH-lacking cells, effectively ensuring that stomata are evenly spaced out.

Through computer modeling, scientists were able to confirm this discovery in Arabidopsis by tracking fluorescent markers to see patterns in growing leaves.  These new findings could lead to research in the area of modifying the number and spacing of stomata in plants for different environments and temperatures.

Discussion Questions: What variables in the cellular respiration of plants will scientists be able to regulate with this new knowledge? What, if any, problems do you foresee with this regulation?

News Article: http://www.sciencedaily.com/releases/2011/09/110908145057.htm
Journal Article:http://www.sciencemag.org/content/333/6048/1436

Image Source:http://en.wikipedia.org/wiki/File:Plant_stoma_guard_cells.png

At the start of its life, each mustard plant inherits five chromosomes from each parent for a total of ten chromosomes. Through a process known as endoreduplication, the cells of the plant can create new copies of their chromosomes without going through mitosis. After multiple rounds of endoreduplication, the researchers found some cells contained as many as 320 chromosomes.

The researchers cultivated and examined two different types of mustard plants—Columbia and Landsberg erecta. They mimicked herbivory in the laboratory by clipping the plants and then observed the plants’ responses to the stress of being “eaten” or grazed.

Columbia responded by accelerating endoreduplication. As a result, Columbia that were clipped grew larger and even yielded as much as three times more seeds than those that were not clipped.

Landsberg, on the other hand, did not respond to the simulated grazing with accelerated endoreduplication. The clipped Landsberg plants thus fared worse than those that were unclipped.

Discussion Question: Why might some plants not have evolved the ability to undergo endoreduplication? Under what conditions might the lack of endoreduplication be advantageous?

News Article: http://www.sciencedaily.com/releases/2011/08/110801094715.htm
Journal Article:http://www.esajournals.org/doi/abs/10.1890/10-2269.1

Image Source: http://en.wikipedia.org/wiki/File:White-tailed_deer_(Odocoileus_virginianus)_grazing_-_20050809.jpg

How? By using whole genome sequencing, a method of analysis that interprets an organism’s entire genome in one take. What they found in the deciphered genomes of thalecress clones (thalecress, or Arabidopsis, is a small flowering plant) tied Harberd’s “visible variation” to high rates of mutation in the clone DNA. These mutations were not derived from any parent. For the Oxford scientist and his colleagues, the implication is clear: clonal variation in plants may not share its underlying cause with that of animals, in which environmental factors rather than incidence of mutation affect gene expression. In other words, although both plant and animal clones may show phenotypic variation, the mechanisms driving those variations differ. For plants, it’s all about the frequency of mutations.

And although, Harberd adds, “[w]here these new mutations come from is still a mystery,” scientists now have a clearer understanding of the mutations themselves, “which may arise during the regeneration process itself or during the cell divisions in the donor plant….We are planning further research to find out which of these two processes is responsible for these mutations.” Whichever explanation ultimately prevails, the team is poised to dispel one of the great confusions of modern botanical science: why are clones not always the same?

Discussion Question: How might scientists apply the team’s insights to human health and the fight against cancer?

News Article: http://www.sciencedaily.com/releases/2011/08/110804212931.htm
Journal Article: http://dx.doi.org/10.1016/j.cub.2011.07.002

Image Source: http://en.wikipedia.org/wiki/File:Cuttingsgreenhouse2.jpg

The rat achieves its toxicity by chewing the bark of the Acokanthera tree, thereby obtaining the poisonous substance, ouabain, from the tree. The rat then applies a slaver—the mixture of saliva and ouabain—into the absorbent fur of its flanks by grooming itself. When examined under a microscope, the rat’s lateral-line hairs appear uniquely suited to holding the slaver, as the contour of each strand is lined with vacuoles that facilitate absorption. As the vacuoles remain open, any contact with hairs saturated with slaver would result in exposure to the poison. Dogs that bite the toxic rat may lose coordination, froth at the mouth, collapse, and ultimately even die as the poison causes the heart to fail. Amazingly, the rat, however, appears to suffer no ill effects from chewing the poisonous bark.

Discussion Question: What evolutionary adaptations might the African crested rat have developed to prevent it from becoming ill while chewing the bark of the Acokanthera tree?

News Article: http://www.wcs.org/press/press-releases/african-crested-rat.aspx
Journal Article: http://rspb.royalsocietypublishing.org/content/

Image Source: http://commons.wikimedia.org/wiki/File:Acokanthera_oblongifolia_03.jpg

I usually deal with stress by getting some exercise or taking a nap. Plants, on the other hand, handle stress internally. Professor Stephen Howell at the Plant Sciences Institute at ISU has discovered a new part of the coping mechanism by which plants respond to environmental stress. He talks about how the farmer can’t control the unpredictable, changing climate and as a result plant yields are decreased.

Seed companies are trying to figure out ways to control the stress in plants. Research shows that plant cells transport proteins to different parts of the cell and proceed through the endoplasmic reticulum (ER) structure. Normally, the proteins are folded upon construction, but under stress, unfolded proteins arise. The ER carries a built-in “alarm” system that detects the altered protein structure, fighting the stress.

Likewise, other proteins, such as IRE1, cuts and splices an RNA molecule, which in turn activates a stronger stress response. Also, the plants are better able to preserve their energy, allowing the plant to survive. One drawback that scientists found was that despite the plants’ conservation of energy, it also inhibits plant growth.

Researchers are looking into ways to still sustain plant growth while eliciting a stress response. More studies of the plant and its pathways will allow them to better understand the internal retaliation at work.

Discussion Question: What are some different factors that might cause stress in plants?

News article: http://www.seeddaily.com/reports/Stressed_out_crop_impede_higher_agriculture_yields_999.html

Journal article:  http://www.plantcell.org/content/19/12/4111.short

We now have evidence that some plants may have, through evolution, changed the morphology of their leaves to attract pollinators that navigate via echolocation. According to researchers at the University of Bristol and the University of Erlangen and Ulm, Marcgravia evenia, a Cuban rainforest plant, has developed dish-shaped leaves, which reflect the sonar of bats more efficiently than flat leaves.

The researchers tested the effects of leaf shape by employing bats to locate hidden nectar under three distinct conditions: (1) nectar hidden with no leaf, (2) nectar hidden with an ordinary leaf, and (3) nectar hidden with a dish-shaped leaf. The bats took roughly the same amount of time to find nectar with no leaf as they took to find nectar with an ordinary leaf. However, the bats took only half that time to find the nectar hidden by a dish-shaped leaf.

Through the evolution of dish-shaped leaves, bats benefit by finding food more efficiently, and the plants benefit by attracting the pollinators they need to successfully reproduce.

Discussion Question: In what ways might a dish-shaped leaf disadvantage the plant?

News Article: http://www.sciencedaily.com/releases/2011/07/110728144717.htm, http://www.nytimes.com/2011/08/02/science/02obbat.html, http://news.sciencemag.org/sciencenow/2011/07/how-to-invite-bats-for-dinner.html
Journal Article: http://www.sciencemag.org/content/333/6042/631

Image Source: http://commons.wikimedia.org/wiki/File:Cloud_forest_Ecuador.jpg