Early exposure to fluctuating water availability can alter a plants adaptability in later life stages but can also improve the plants’ performance under stressful or changing conditions. The findings are published in the British Ecological Society’s Journal of Ecology.
In a new study, published in the Journal of Ecology, researchers from Guizhou University and the University of Montana found fluctuating environmental conditions near the beginning of a plant’s life could alter its ability to respond to changing conditions down the line by altering its adaptive responses.
Previous studies have focused on how plants respond to environments within a certain developmental stage. However a plants life is continuous and spans many months or years, and its ability to adapt to new or changing environments may also change over time.
Shu Wang from Guizhou University and Ragan Callaway from the University of Montana studied the changes in plant plasticity, or the ability for an organism to change or adapt to its environment, on plants subjected to varying water availabilities at multiple stages within their life cycle. These changes in an organism’s ability to change under new, fluctuating, or stressful environments have been dubbed ‘plasticity in plasticity’.
The researchers studied a mix of native and exotic plant species from three different habitats subjected to either alternating drought and flooding conditions, or environments with a consistently moderate supply of water. The study was repeated over two stages within the plant’s life cycle to assess what effect changing water availability during early plant life had on plant plasticity later in life.
The author’s results provide direct evidence for changes in plant plasticity within their lifetime, which has previously been rarely addressed.
Early subjection to fluctuating water availability was found to not only alter plant plasticity in later life stages but can also improve the plants’ performance under stressful or changing conditions by changing its adaptive responses. In general, these plants experienced increased biomass and late growth, but different species can adopt different contrasting strategies to deal with the fluctuating environments.
Plants species native to environments with well-balanced water supplies initially suffered from decreased biomass immediately after subjection to environmental fluctuations but overcame this drop through increased growth later in life. Exotic species, however, experienced an immediate increase in biomass but did not undergo the same later growth spurt.
These results contribute to the understanding of many ecological and evolutionary problems and will have implications for important ecological issues such as habitat adaptation, species diversity and distribution and macroevolution.
Image: Early exposure to fluctuating water availability can alter plant adaptability in later life stages in several studied species. Credit: Andreas Rockstein.
The expansion of European countries across the world has had profound impacts on the landscapes and biodiversity. During this transformation, plant species native to the Mediterranean Basin and temperate Europe were transported. Exploring the abundance of these species in their native and introduced communities, can help us understand the processes and prioritize conservation measures.
Climate warming is linked to a widening interval between leaf unfolding and flowering in European trees, with implications for tree fitness and the wider environment, according to new research.
Being highly connected to a strong social network has its benefits. Now a new study is showing the same goes for trees, thanks to their underground neighbours. This study is the first to show that the growth of adult trees is linked to their participation in fungal networks living in the forest soil.
Plant life is expanding in the area around Mount Everest, and across the Himalayan region, new research shows. Scientists used satellite data to measure the extent of subnival vegetation – plants growing between the treeline and snowline – in this vast area.
A new study reveals a complex interplay between soil fungi and tree roots that could be the cause of rare-species advantage. The researchers found that the type of beneficial soil fungi living around tree roots in a subtropical forest in China determined how quickly the trees accumulated harmful, pathogenic fungi as they grew. The rate of accumulation of pathogenic fungi strongly influenced how well the trees survived when growing near trees of the same species.
Before Europeans arrived in America, longleaf pine savannas sprawled across 90 million acres from present-day Florida to Texas and Virginia. Today, thanks to human impacts, less than 3 percent of that acreage remains, and what’s left exists in fragmented patches largely isolated from one another.
Species of daisy that close their flowers at night, produce colour in their exposed lower petals that makes them harder to spot for herbivores, reducing herbivory rates of flowers. The findings are presented in the British Ecological Society journal Functional Ecology.
Researchers from Stellenbosch University, South Africa found that tortoises, one of the main herbivores of the daisies, were unable to distinguish the lower petal surfaces against a green leaf background. Tortoises prefer to eat protein-rich flowers over leaves, but when confronted with closed flowers, they showed no preference between them.
When the researchers modelled the colours of the lower petal surfaces in the vision of other herbivores, they also found these colours to be indistinguishable from leaves.
In contrast, species of daisy that do not close at night produced the same colouration on their lower petals as the upper petals exposed to pollinators.
Plants face an evolutionary conflict between having flowers that attract pollinators while avoiding herbivores. Often plants defend themselves chemically, but this can have adverse effects on pollination.
“When plants defend their flowers chemically, the pollination interactions can be negatively influenced. Our study shows a novel way in which flowers can avoid herbivores, without compromising pollination interactions.
“These flowers can potentially circumvent the conflict of attracting both pollinators and herbivores by producing attractive colours on the surfaces that are exposed to pollinators (when flowers are open) and cryptic colours that are exposed when herbivores are active (when flowers are closed).”
In Namaqualand, South Africa, where the research took place, daises bloom annually in a spring flowering. This makes preserving flowers, responsible for reproduction, particularly important.
The researchers examined the colouration of 77 Asteraceae species, modelling how they appear in the visual systems of chameleons, horses and goats as proxies for tortoises and larger herbivores in the area, like springbok. They then tested the preferences of real tortoises with both open and closed flowers against leaf backgrounds.
Not all Asteraceae species that close their flowers had cryptically coloured lower petal surfaces, but in the experiments, the tortoises did not readily eat these flowers. Dr. Kemp said, “One interesting question would be to test whether non-cryptic flowers have chemical defences, and whether these chemical defences are absent in the cryptic flowers.”
On further research Dr. Kemp said “Unfortunately, we could only do this using one plant family in one botanical region, it would be great to see if other plant species also use colour to avoid herbivores.”
The researchers would also have liked to use larger herbivores such as springboks in their behavioural experiments, but Dr. Kemp adds that “this was practically not possible.”
Another fantastic year of discovery is over – read on for our 2016 plant science top picks!
January
A Zostera marina meadow in the Archipelago Sea, southwest Finland. Image credit: Christoffer Boström (Olsen et al., 2016. Nature).
The year began with the publication of the fascinating eelgrass (Zostera marina) genome by an international team of researchers. This marine monocot descended from land-dwelling ancestors, but went through a dramatic adaptation to life in the ocean, in what the lead author Professor Jeanine Olsen described as, “arguably the most extreme adaptation a terrestrial… species can undergo”.
One of the most interesting revelations was that eelgrass cannot make stomatal pores because it has completely lost the genes responsible for regulating their development. It also ditched genes involved in perceiving UV light, which does not penetrate well through its deep water habitat.
Plants are known to form new organs throughout their lifecycle, but it was not previously clear how they organized their cell development to form the right shapes. In February, researchers in Germany used an exciting new type of high-resolution fluorescence microscope to observe every individual cell in a developing lateral root, following the complex arrangement of their cell division over time.
Using this new four-dimensional cell lineage map of lateral root development in combination with computer modelling, the team revealed that, while the contribution of each cell is not pre-determined, the cells self-organize to regulate the overall development of the root in a predictable manner.
Watch the mesmerizing cell division in lateral root development in the video below, which accompanied the paper:
In March, a Spanish team of researchers revealed how the anti-wilting molecular machinery involved in preserving cell turgor assembles in response to drought. They found that a family of small proteins, the CARs, act in clusters to guide proteins to the cell membrane, in what author Dr. Pedro Luis Rodriguez described as “a kind of landing strip, acting as molecular antennas that call out to other proteins as and when necessary to orchestrate the required cellular response”.
This plant root is infected with arbuscular mycorrhizal fungi. Image credit: University of Zurich.
In April, we received an amazing insight into the ‘decision-making ability’ of plants when a Swiss team discovered that plants can punish mutualist fungi that try to cheat them. In a clever experiment, the researchers provided a plant with two mutualistic partners; a ‘generous’ fungus that provides the plant with a lot of phosphates in return for carbohydrates, and a ‘meaner’ fungus that attempts to reduce the amount of phosphate it ‘pays’. They revealed that the plants can starve the meaner fungus, providing fewer carbohydrates until it pays its phosphate bill.
Author Professor Andres Wiemskenexplains: “The plant exploits the competitive situation of the two fungi in a targeted manner, triggering what is essentially a market-based process determined by cost and performance”.
The transition of ancient plants from water onto land was one of the most important events in our planet’s evolution, but required a massive change in plant biology. Suddenly plants risked drying out, so had to develop new ways to survive drought.
In May, an international team discovered a key gene in moss (Physcomitrella patens) that allows it to tolerate dehydration. This gene, ANR, was an ancient adaptation of an algal gene that allowed the early plants to respond to the drought-signaling hormone ABA. Its evolution is still a mystery, though, as author Dr. Sean Stevensonexplains: “What’s interesting is that aquatic algae can’t respond to ABA: the next challenge is to discover how this hormone signaling process arose.”
Sometimes revisiting old ideas can pay off, as a US team revealed in June. In 1930, Ernst Münch hypothesized that transport through the phloem sieve tubes in the plant vascular tissue is driven by pressure gradients, but no-one really knew how this would account for the massive pressure required to move nutrients through something as large as a tree.
Professor Michael Knoblauch and colleagues spent decades devising new methods to investigate pressures and flow within phloem without disrupting the system. He eventually developed a suite of techniques, including a picogauge with the help of his son, Jan, to measure tiny pressure differences in the plants. They found that plants can alter the shape of their phloem vessels to change the pressure within them, allowing them to transport sugars over varying distances, which provided strong support for Münch flow.
BLOG: We featured similar work (including an amazing video of the wound response in sieve tubes) by Knoblauch’s collaborator, Dr. Winfried Peters, on the blog – read it here!
July
Preserved remains of rope, seeds, reeds and pellets (left), and a desiccated barley grain (right) found at Yoram Cave in the Judean Desert. Credit: Uri Davidovich and Ehud Weiss.
In July, an international and highly multidisciplinary team published the genome of 6,000-year-old barley grains excavated from a cave in Israel, the oldest plant genome reconstructed to date. The grains were visually and genetically very similar to modern barley, showing that this crop was domesticated very early on in our agricultural history. With more analysis ongoing, author Dr. Verena Schünemannpredicts that “DNA-analysis of archaeological remains of prehistoric plants will provide us with novel insights into the origin, domestication and spread of crop plants”.
BLOG: We interviewed Dr. Nils Stein about this fascinating work on the blog – click here to read more!
August
Another exciting cereal paper was published in August, when an Australian team revealed that C4 photosynthesis occurs in wheat seeds. Like many important crops, wheat leaves perform C3 photosynthesis, which is a less efficient process, so many researchers are attempting to engineer the complex C4 photosynthesis pathway into C3 crops.
This discovery was completely unexpected, as throughout its evolution wheat has been a C3 plant. Author Professor Robert Henrysuggested: “One theory is that as [atmospheric] carbon dioxide began to decline, [wheat’s] seeds evolved a C4 pathway to capture more sunlight to convert to energy.”
Professor Stefan Jansson cooks up “Tagliatelle with CRISPRy fried vegetables”. Image credit: Stefan Jansson.
September marked an historic event. Professor Stefan Jansson cooked up the world’s first CRISPR meal, tagliatelle with CRISPRy fried vegetables (genome-edited cabbage). Jansson has paved the way for CRISPR in Europe; while the EU is yet to make a decision about how CRISPR-edited plants will be regulated, Jansson successfully convinced the Swedish Board of Agriculture to rule that plants edited in a manner that could have been achieved by traditional breeding (i.e. the deletion or minor mutation of a gene, but not the insertion of a gene from another species) cannot be treated as a GMO.
Phytochromes help plants detect day length by sensing differences in red and far-red light, but a UK-Germany research collaboration revealed that these receptors switch roles at night to become thermometers, helping plants to respond to seasonal changes in temperature.
Dr Philip Wiggeexplains: “Just as mercury rises in a thermometer, the rate at which phytochromes revert to their inactive state during the night is a direct measure of temperature. The lower the temperature, the slower phytochromes revert to inactivity, so the molecules spend more time in their active, growth-suppressing state. This is why plants are slower to grow in winter”.
A fossil ginkgo (Ginkgo biloba) leaf with its modern counterpart. Image credit: Gigascience.
In November, a Chinese team published the genome of Ginkgo biloba¸ the oldest extant tree species. Its large (10.6 Gb) genome has previously impeded our understanding of this living fossil, but researchers will now be able to investigate its ~42,000 genes to understand its interesting characteristics, such as resistance to stress and dioecious reproduction, and how it remained almost unchanged in the 270 million years it has existed.
Author Professor Yunpeng Zhaosaid, “Such a genome fills a major phylogenetic gap of land plants, and provides key genetic resources to address evolutionary questions [such as the] phylogenetic relationships of gymnosperm lineages, [and the] evolution of genome and genes in land plants”.
The year ended with another fascinating discovery from a Danish team, who used fluorescent tags and microscopy to confirm the existence of metabolons, clusters of metabolic enzymes that have never been detected in cells before. These metabolons can assemble rapidly in response to a stimulus, working as a metabolic production line to efficiently produce the required compounds. Scientists have been looking for metabolons for 40 years, and this discovery could be crucial for improving our ability to harness the production power of plants.
