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Dense rainforests, maple-blanketed mountains and sweeping coniferous forests demonstrate the growth and proliferation of trees adapted to specific conditions. The regional dominance of tree species we see on the surface now, however, might actually have been determined underground long ago.

Princeton University researchers report that the organization of forests worldwide — such as conifers in northern boreal forests or the broad-leafed trees of the tropics — are based on the ancient relationships that plant species forged with soil-dwelling microbes such as fungi and bacteria. These tiny organisms, known as symbionts, enhance the roots’ uptake of the crucial nutrients nitrogen and phosphorus.

The researchers reported in the journal Nature Ecology and Evolution that trees and shrubs came to dominate specific biomes by evolving the most competitive arrangement with local soil microbes — and cutting competing plants out of the action.

The biome-specific dynamics between plants and soil microbes could help scientists understand how ecosystems may shift as climate change brings about warmer temperatures that alter the interplay between trees, microbes and soil, the researchers report. Because the most competitive symbiotic arrangements for a particular biome triumph, scientists would only need to understand how an ecosystem is changing to gauge which vegetation will be moving in and which will be moving out. The research was supported by the Carbon Mitigation Initiative based within the Princeton Environmental Institute (PEI).

“The pattern we found can be used to tell us the landscapes that are more sensitive to human disturbance,” said senior author Lars Hedin, the George M. Moffett Professor of Biology and professor of ecology and evolutionary biology and the Princeton Environmental Institute. “It will predict what communities of trees will go where, their effect on the environment, and how they will respond in the future to climate change and increased carbon dioxide.”

First author Mingzhen Lu, a postdoctoral research associate in the Hedin lab, said that symbioses arose because plants needed microbes to unlock the nutrients — particularly nitrogen and phosphorus — released through soil decomposition. In return, the fungi and bacteria thrive on the carbohydrates that plants provide from photosynthesis. Lichen — the frilly white-green algae-fungus amalgamations that grow on rocks and trees — are an early example of this cooperation.

“The moment plants colonized the land, they formed symbioses,” Lu said. “The evolution of those new, powerful symbioses allowed plants to colonize new lands. This biology powers the global carbon and nutrient cycle.”

Lu and Hedin focused on trees and shrubs and found that as the plants spread across the globe, they carved out biomes using the nutrient advantage their relationship with microbes bestowed on them, Lu said. For example, maple trees will set conditions so that competing trees can’t grow in the areas maples inhabit.

“This is a perfect example of how biological organisms can shape the surrounding environment in favor of themselves,” Lu said. “This suggests to us that once the correct biological mechanisms are included, changes in the land can be predicted, but those forecasts need to capture belowground dynamics. By figuring out the most competitive symbiosis under specified conditions, we can determine how plant communities will evolve and develop in that biome in the future.”

Lu and Hedin used a game-theory model that allowed plants to use different belowground strategies for acquiring nutrients. Their model examined trees and shrubs — known as dominant vegetation — in tropical, temperate and boreal forests. They looked at biome conditions such as sunlight and nutrient turnover to examine the most competitive symbioses that will emerge if ecosystems are allowed to change and mutate naturally. They factored in the amount of carbon and nutrients that cycle through a particular biome, as well as how it responds to disturbances and how plant populations replace each other through succession.

Their model revealed that specific local interactions between plants, soil and nutrients are suitable for those areas. For instance, boreal trees have developed symbiotic relationships tailored for spongy boreal soils, but not the sodden soil of a tropical forest.

“Our findings show that the relationship between plants and their symbionts is central to understanding the organization and history of the land biosphere,” Hedin said.

The Hedin lab at Princeton previously found that plants may have a more active role in their evolution — and the formation of natural systems — than they are given credit for. In February 2018, Hedin and Lu reported in the journal Natur that the proliferation of plant life across the globe may have been propelled by root adaptations that allowed plants to become more efficient and independent.

In 2015, a paper in Nature Plants suggested that plants found in areas otherwise unsuitable for them — such as nitrogen-poor rainforest soils — use secretions to invite soil bacteria known as rhizobia to infect their roots cells. In a give-give relationship similar to that described in the latest publication, the rhizobia convert atmospheric nitrogen into fertilizer in exchange for carbohydrates. This interplay creates a nitrogen cycle that benefits surrounding vegetation.

“Plants have long created the conditions for their own success. What’s important is that we are now better understanding how this works based on our models,” Hedin said.

“Our new model shows that plants have competed for soil resources and in doing so they have harnessed the help of symbiosis and this has made them successful,” he said. “The resulting relationship has been so powerful that not only have they helped other trees and plants, but they also have transformed the environment.”

Read the paper: Nature Ecology and Evolution

Article source: Princeton University

Image: Mingzhen Lu, Princeton Ecology and Evolutionary Biology

Pre-crop values for a high number of previous and following crop combinations originating from farmers’ fields are, for the first time, available to support diversification of currently monotonous crop sequencing patterns in agriculture. The groundbreaking method utilizing satellite images was developed by Natural Resources Institute Finland (Luke) in collaboration with Finnish Geospatial Research Institute (FGI).

Luke has developed together with FGI a dynamic method to derive Normalized Difference Vegetation Index (NDVI) values to estimate pre-crop values on a field parcel scale from open Copernicus Sentinel-2 data. “The method is based on estimation of NDVI-gap, which was originally developed for Luke’s Land Use Optimization -tool available for each Finnish farmer on EconomyDoctor-portal”, says Research Professor Pirjo Peltonen-Sainio.

Pre-crop value is a measure that indicates the benefits of a previous crop for a subsequent crop in crop sequencing. Thereby, understanding on pre-crop values facilitates diversification of crop production. This again is a core measure for sustainable intensification of agricultural systems.

Digitalization can replace resource intensive field experimentation

Traditionally, long-term multi-locational field experiments are needed to identify pre-crop values. Such experiments are very resource intensive and therefore, they evaluate pre-crop values only for a limited number of previous and subsequent crops. With the new method data on pre-crop values can be updated and expanded every year, and implemented across continents.

“To develop the novel method, a total of 240.000 NDVI-values were used. With such vast data pre-crop values were determined for an exceptionally high number of previous and subsequent crop combinations”, describes Luke’s Senior Scientist Lauri Jauhiainen.

For the test-region in the South-West of Finland, the pre-crop values ranged from +16% to -16%. Especially grain legumes and rapeseed were valuable as pre-crops, which is well in line with results from field experiments.

Many opportunities – also rising from limitations

The method had some limitations as well. “For example, there is insufficient data on crops mostly cultivated in monoculture rotations for estimation of the value of a high number of alternative previous crops”, says Peltonen-Sainio. This was especially true for potatoes and sugar beet in Finland, for which spring and winter cereals were the only pre-crops with sufficient data for their pre-crop values.

“Data on pre-crop values can, however, be updated and regionally expanded every year. Now we just concentrated on developing the method per se”, reminds Jauhiainen. Scarce knowledge on pre-crop choices may limit farmers’ actions towards diversification of monotonous potato and sugar beet sequencing. On the other hand, these findings emphasize that the future experiments should focus on estimating pre-crop values for such previous and following crop combinations which suffer from insufficient on-farm data.

Read the paper: Frontiers in Plant Science

Article source: Natural Resources Institute Finland (Luke)

Image: CCO Public domain

What will a three-degree-warmer world look like? How will plants fare in more extreme weather conditions? When experiencing stress or damage from various sources, plants use chloroplast-to-nucleus communication to regulate gene expression and help them cope.

Now, Salk Institute researchers have found that GUN1—a gene that integrates numerous chloroplast-to-nucleus retrograde signaling pathways—also plays an important role in how proteins are made in damaged chloroplasts, which provides a new insight into how plants respond to stress. The paper was published in the Proceedings of the National Academy of Sciences (PNAS), and may help biologists breed plants that can better withstand environmental stressors.

“Climate change holds the potential to affect our food system dramatically. When plants are stressed, like in a drought, they produce lower crop yields. If we understand how plants respond to stress, then perhaps we can develop a way to increase their resistance and keep food production high,” says Salk Professor Joanne Chory, director of the Plant Molecular and Cellular Biology Laboratory and senior author of the paper.

In plant cells, structures called chloroplasts convert energy from sunlight into chemical energy (photosynthesis). Normally, the nucleus of the cell transmits information to the chloroplasts to maintain steady energy production. However, in a stressful environment, chloroplasts send an alarm back to the cell nucleus using retrograde signaling (creating a chloroplast-to-nucleus communication feedback loop). This SOS prompts a response that helps regulate gene expression in the chloroplasts and the nucleus to optimize energy production from sunlight.

Previously, the Chory lab identified a group of genes, including GUN1, that influence other genes’ expression in the cell when the plant experiences stress. GUN1 accumulates under stressful conditions but the exact molecular function of GUN1 has been difficult to decipher, until now.

“Plants often experience environmental stressors, so there must be a chloroplast-to-nucleus communication pathway that helps the plant know when to conserve energy when injury occurs,” says Xiaobo Zhao, first author and postdoctoral fellow in Chory’s lab. “GUN1 turns out to play a big role in this.”

To understand how GUN1 regulates chloroplast-to-nucleus communication, the scientists observed plants with functional and nonfunctional GUN1 under pharmacological treatments that could damage chloroplasts. In plants without GUN1, gene expression changed, as did RNA editing in chloroplasts. (RNA editing is a modification of the RNA that changes the identity of nucleotides, so that the information in the mature RNA differs from that defined in the genome, altering the instructions for making proteins.) Some areas of RNA had more editing and other locations had less editing—suggesting that GUN1 plays a role in regulating chloroplast RNA editing.

After further analysis, the team unexpectedly found that GUN1 partners with another protein, MORF2 (an essential component of the plant RNA editing complex), to affect the efficiency of RNA editing during chloroplast-to-nucleus communication in damaged chloroplasts. Greater activity of MORF2 led to widespread editing changes as well as defects in chloroplast and leaf development even under normal growth conditions (see image). During periods of stress and injury, MORF2 overproduction also led to disruption of chloroplast-to-nucleus communication.

“Taken together, these findings suggest a possible link between chloroplast-to-nucleus communication and chloroplast RNA editing, which are important regulatory functions for flowering plants, especially during stress,” says Chory, Howard Hughes Medical Institute investigator and holder of the Howard H. and Maryam R. Newman Chair in Plant Biology.

Next, the researchers plan to examine the mechanism of how the RNA editing changes in chloroplasts activate signals that can be relayed to the nucleus, and how these modifications alter the ability of the plant to respond to stress.

Other authors included Jianyan Huang, a postdoctoral fellow in the Chory lab.

Read the paper: PNAS

Article source: The Salk Institute

Image: Salk Institute

Brassica rapa plants pollinated by bumblebees evolve more attractive flowers. But this evolution is compromised if caterpillars attack the plant at the same time. With the bees pollinating them less effectively, the plants increasingly self-pollinate. In a greenhouse evolution experiment, scientists at the University of Zurich have shown just how much the effects of pollinators and pests influence each other.

In nature, plants interact with a whole range of organisms, driving the evolution of their specific characteristics. While pollinators influence floral traits and reproduction, herbivorous insects enhance the plant’s defense mechanisms. Now botanists at the University of Zurich have investigated the way these different interactions influence each other, and how rapidly plants adapt when the combination of selective agents with which they interact changes.

Experimental evolution in real time

In a two-year greenhouse experiment, Florian Schiestl, professor at University of Zurich’s Department of Systematic and Evolutionary Botany, and doctoral candidate Sergio Ramos have demonstrated a powerful interplay between the effects of pollinating insects and those of herbivores. For their experiment they used Brassica rapa, a plant closely related to oilseed rape, interacting with bumblebees and caterpillars as selective agents. Over six generations they subjected four groups of plants to different treatments: with bee pollination only, bee pollination with herbivory (caterpillars), hand pollination without herbivory, and hand pollination with herbivory.

Balance between attraction and defense

After this experimental evolution study, the plants pollinated by bumblebees without herbivory were most attractive to the pollinators: they evolved more fragrant flowers, which tended to be larger. “These plants had adapted to the bees’ preferences during the experiment,” explains Sergio Ramos. By contrast, bee-pollinated plants with herbivory were less attractive, with higher concentrations of defensive toxic metabolites and less fragrant flowers that tended to be smaller. “The caterpillars compromise the evolution of attractive flowers, as plants assign more resources to defense,” says Ramos.

Combined impact on reproduction

The powerful interplay between the effects of bees and caterpillars was also evident in the plants’ reproductive characteristics: In the course of their evolution, for example, the bee-pollinated plants developed a tendency to spontaneously self-pollinate when they were simultaneously damaged by caterpillars. Plants attacked by caterpillars developed less attractive flowers, which affected the behavior of the bees so that they pollinated these flowers less well.

Better understanding of the mechanisms of evolution

The study shows the importance of interactive effects in the evolution of diversity. If the combination of selective agents changes, for example through loss of habitat, climate change, or a decline in pollinators, it can trigger rapid evolutionary change in plants. “The environmental changes caused by humans affect the evolutionary fate of many organisms. This has implications in terms of ecosystem stability, loss of biodiversity, and food safety,” says Florian Schiestl. He believes that an understanding of these mechanisms has never been more important than it is now.

Read the paper: Science

Article source: University of Zurich

Image: Florian Schiestl/University of Zurich

Despite evolution driving a wide variety of differences, many plants function the same way. Now a new study has revealed the different genetic strategies various flowering plant species use to achieve the same status quo.

In flowering plants, stem cells are critical for survival. Influenced by environmental factors, stem cells direct how and when a plant will grow. Whether a plant needs deep-reaching roots, taller stems, or more leaves and flowers, it is the stem cells that produce new cells for the job.

That’s also why having too many or too few stem cells can disrupt a plant’s growth.

Responsible for all this is a “core genetic circuitry found in all flowering plants,” says Cold Spring Harbor Laboratory Professor and HHMI Investigator Zach Lippman.

In a paper published in Nature Genetics, Lippman and CSHL Professor David Jackson describe the genetic mechanisms that ensure “a deeply conserved stem cell circuit” maintains some function, even if defects occur in a signaling protein called CLV3, and the receptor with which it interacts, CLV1.

“Those players are critical for ensuring a plant has the right number of stem cells throughout life, and we discovered there are backup systems that kick in when these players are compromised through chance mutations,” explains Lippman.

The researchers determined that although the stem cell circuits are essential for flowering plants, the genetic backup systems can vary drastically from plant to plant.

If the gene producing CLV3 is disrupted by a mutation in a tomato, for instance, a related gene will stand in for it. However, Jackson’s team discovered that in the case of maize, two genes are working in parallel to produce the essential signaling protein.

“I like to compare it to a rowboat,” Lippman adds. “In tomato there are two people who can row, but only one is rowing. But if the main rower injures his arm, the second person can take up the oars. In maize, both are rowing all the time, though not necessarily with equal effort. And in Arabidopsis [rockcress] you have one main rower supported by seven, eight, or nine other rowers in the boat; and it looks like only one has a full-size oar. The rest are just using very small paddles.”

“We were surprised to see such big differences”, says Jackson, “but in retrospect it reveals the power of evolution in finding novel ways to protect critical developmental circuits.”

According to Jackson, Lippman and their colleagues, understanding these species-specific strategies for protecting key genetic interactions will be essential for achieving “intelligent crop design” and using genome editing to improve agricultural productivity and sustainability.

Read the paper: Nature Genetics

Article source: Cold Spring Harbor Laboratory

Image: Lippman Lab/Cold Spring Harbor Laboratory

Plant regeneration can occur via formation of a mass of pluripotent cells. The process of acquisition of pluripotency involves silencing of genes to remove original tissue memory and priming for activation by external input. Led by Professor Sachihiro Matsunaga from Tokyo University of Science, a team of scientists have shown that plant regenerative capacity requires a certain demethylase that can prime gene expression in response to regenerative cues.

In multicellular organisms, not all genes are expressed in all cells, meaning that not all cells make the same enzymes or proteins, and therefore not all cells have the same metabolism. This differentiation is a key process across multicellular organisms, including plants and fungi. But as cells specialize, they become unipotent, meaning that they lose the ability to form multiple cell types. For long, scientists have tried to reprogram mammal cells for pluripotency by drastic means such as nuclear transfer and induction of transcription factors. However, plants can acquire the same regenerative powers via external signal input such as hormones and stress. A part of the phenomenon is regulated by epigenetics, because these modifications are epi or “above” the genes.

Professor Matsunaga and his team used Arabidopsis thaliana, a small flowering plant commonly used in plant biology, to study genome-wide histone modifications. Histones are proteins that package together eukaryotic DNA, preventing it from being transcribed or decoded. Upon being modified, however, these proteins’ grasp around the DNA molecule loosens, making it easier for the DNA to be transcribed. The group of scientists found that it is the demethylation (the removal of a methyl group from the amino acid) of the histone H3 by the LDL3 enzyme that lends regenerative competency to the plant. This epigenetic mechanism allows the plant’s pluripotent cells to go back to its unipotent state and thus assume the identity of shoot meristems for differentiated tissues including leaves and stems.

Because no seeds are needed to grow these plants, this could potentially help scientists grow plants faster without flowering. “By strengthening the ability of plants to reproduce, even without seeds,” Professor Matsunaga indicated, “it is possible to increase the number of clonal plants with only leaves, stems, and parts of roots. It can address environmental problems by promoting greening and solve the global food shortage problem by increasing production of grains and vegetables.”

Read the paper: Nature Communications

Article source: Tokyo University of Science

Image: Alberto Salguero/Wikimedia

Pollen genes mutate naturally in only some strains of corn, according to Rutgers-led research that helps explain the genetic instability in certain strains and may lead to better breeding of corn and other crops.

Scientists at Rutgers University–New Brunswick and Montclair State University looked at gene mutations that arise spontaneously in corn plant pollen. Pollen grains are the male gametes, or reproductive cells, in corn plants. The scientists estimated there were several mutations per gene per million pollen grains, according to their study in the journal Proceedings of the National Academy of Sciences. The female gametes on corn ears had no detectable gene mutations.

Since a typical corn plant produces about 10 million pollen grains, a single plant in some lines, or strains, of the vital crop will produce mutations in every gene in its genome in one season. In other lines, mutations were not detected in either sex, said lead author Hugo K. Dooner, Distinguished Professor Emeritus at the Waksman Institute of Microbiology.

The United States is the world’s largest corn producer, with about 409 million tons grown on about 90 million acres in fiscal 2017-18, according to the U.S. Department of Agriculture. Feed grain consists of more than 95 percent of the production and use of corn in the United States. Corn also is processed into a wide range of food and industrial products, including cereal, alcohol, sweeteners and byproduct feeds.

In all organisms, mutations that happen spontaneously provide the raw material for natural selection and evolution. But mutations are so infrequent that scientists use special “mutation accumulation” lines to study them. The Rutgers-led team found that the mutations in pollen were caused primarily by mobile retrotransposons, which are like retroviruses in mammals, within the corn plant. Retroviruses invade cells, convert their viral RNA to DNA and merge it with the cells’ DNA.

“We found that spontaneous mutations in corn genes arise relatively frequently in the pollen of some but not all lines,” Dooner said.

Next steps are to investigate whether retrotransposon-induced mutations cause the genetic instability in corn lines previously reported by breeders, and whether activating retrotransposons in corn and other important crops could benefit them.

Rutgers co-authors include Qinghu Wang, Jun Huang, Yubin Li and Limei He at the Waksman Institute of Microbiology.

Read the paper: PNAS

Article source: Rutgers

Image: Hugo Dooner/Waksman Institute of Microbiology

Plant immune system detects bacteria through small fatty acid molecules.

Like humans and animals, plants defend themselves against pathogens with the help of their immune system. But how do they activate their cellular defenses? Researchers at the Technical University of Munich (TUM) have now discovered that receptors in plant cells identify bacteria through simple molecular building blocks.

“The immune system of plants is more sophisticated than we thought,” says Dr. Stefanie Ranf from the Chair of Phytopathology of the TU Munich. Together with an international research team, the biochemist has discovered substances that activate plant defense.

Until now, scientists have thought that plant cells – similar to those of humans and animals – recognize bacteria through complex molecular compounds, for example from the bacterial cell wall. In particular, certain molecules composed of a fat-like part and sugar molecules, lipopolysaccharides or LPS for short, were suspected of triggering an immune response.

In 2015, Ranf‘s team successfully identified the respective receptor protein: lipo-oligosaccharide-specific reduced elicitation, or LORE for short. All experiments indicated that this LORE protein activates the plant cell’s immune system when it detects LPS molecules from the cell wall of certain bacteria.

A throwback leads to the right track

“The surprise came when we wanted to study this receptor protein more closely,” recalls Ranf. “Our goal was to find out how LORE distinguishes different LPS molecules. For this we needed high-purity LPS. ”

The researchers found that only LPS samples with certain short fatty acid constituents triggered plant defense. Surprisingly, they found in all these active LPS samples also extremely strong adhering free fatty acid molecules. Only after months of experimentation was the team able to separate these free fatty acids from the LPS.

“When we finally succeeded in producing highly purified LPS, it became apparent that the plant cell did not respond to them at all! Thus, it was clear that the immune response is not triggered by LPS, but instead by these short fatty acids” said Ranf.

Targeting bacteria building blocks

The 3-hydroxy fatty acids are very simple chemical building blocks compared to the much larger LPS. They are indispensable for bacteria and are produced in large quantities for incorporation into diverse cellular components.

“The strategy of plant cells to identify bacteria through these basic building blocks is extremely sophisticated; the bacteria require these 3-hydroxy fatty acids and therefore cannot bypass the immune response,” summarizes Ranf.

Fitness program for plants

In the future, these results could help in breeding or genetically engineering plants with an improved immune response. It is also conceivable that plants treated with 3-hydroxy fatty acids would have increased resistance to pathogens.

Read the paper: Journal of Advances in Modeling Earth Systems

Article source: Science

Image: Astrid Eckert / TUM

New dynamic model better portrays how plant roots forage and adapt to resource fluctuation.

If you’ve ever tended a garden or potted a plant, you know a few simple truths about green things — they require water and nutrients to survive and their roots are good indicators of their overall health. So we water on a regular schedule, provide for root growth and add nutrient-rich soils to ensure a balanced diet.

In nature, plants don’t get that kind of care — it may not rain often enough, the earth may lack specific nutrients and there’s a lot of other vegetation vying for the same resources. While leaves and branches reach skyward to capture the sun’s energy, the roots are hard at work, scrounging for those vital water and nutrient sources.

“If a plant can adjust to environmental changes by increasing its access to resources, then it has a higher chance to survive or, more importantly, to thrive.” — Says Beth Drewniak, Argonne assistant climate scientist.

Environmental scientists have long used computer models to understand this root-to-resource dynamic, but until recently, these simplified models employed a fixed system of roots that doesn’t account for variations in resource stratification or, for that matter, the active foraging and adaption skills of roots.

A new root algorithm developed by Beth Drewniak, an assistant climate scientist with the U.S. Department of Energy’s (DOE) Argonne National Laboratory, is among the first to shed more light on the ability of plants to adapt to local changes in environment.

In a paper published in the Journal of Advances in Modeling Earth Systems, Drewniak describes a dynamic root model that she introduced into the Energy Exascale Earth System Land Model (ELM), a component of the DOE’s larger Energy Exascale Earth System Model (E3SM).

“The fixed approach has been popular in models because roots are hard to observe and study, making them difficult to understand,” says Drewniak. ​“By adding a dynamic root model component, the simulation of vegetation growth can respond to changes in resources, increasing availability of those needed resources.”

The model examines roots for all vegetation in ELM — trees, shrubs, grasses and crops — across many ecosystems and over different seasons. Where previous attempts at dynamic root models focused on either maximizing water uptake or nitrogen uptake, Drewniak’s addresses both.

“Ecosystems need to respond to many types of stress, including short- or long-term events like drought or nutrient loading,” says Drewniak. ​“If a plant can adjust to environmental changes by increasing its access to resources, then it has a higher chance to survive or, more importantly, to thrive.”

For example, changes in regional climate could result in less precipitation or shifts in the frequency of precipitation, she notes. The dynamic root model simulates how plants can acclimate to the new distribution of water in the soil by allocating roots to those layers with higher water content.

The new root distribution within the model is driven by water stress — how much water a plant needs versus how much water is available. When water stress is high, the plant focuses root growth where water is present in the soil. When the plant has ample water, root growth is concentrated where nitrogen exists. Changes to root distribution, notes Drewniak, affect a plant’s water uptake, which can impact evapotranspiration, photosynthesis, productivity, and other plant dynamics.

To gauge the model’s accuracy, Drewniak focused on how well the model performed compared with observations of root distribution and vegetation growth, as well as the model’s sensitivity to water stress. Overall, the dynamic root model was able to capture the vertical distribution of roots fairly well and improved the simulated productivity of vegetation compared with satellite observations.

Regions in which the model does not fare well include the Amazon, African tropics and southern Asia during their dry seasons, when plants typically rely on deep roots to extract water, which is not captured well by ELM.

While the dynamic root model has already made small but important improvements to ELM, it has the potential to allow it to model a more dynamic plant root response to extreme events, such as drought, that can have a big impact on the carbon and water cycle.

“The biggest lesson learned in this study is that there is more work to be done,” says Drewniak. ​“The model is improved because vegetation can respond to changes in the environment by foraging for water and nitrogen. But the study also revealed that there are other model development pieces necessary to fully capture vegetation response.”

Read the paper: Journal of Advances in Modeling Earth Systems

Article source: Argonne National Laboratory

Image: Roser Matamala, Argonne National Laboratory

Maize is a staple crop that came from humble beginnings. If you look at its wild ancestor, teosinte, the plant looks nearly unrecognizable. Human selection has persuaded the maize plant to grow in a way that produces higher yields and can be more efficiently harvested. But scientists and farmers are looking for ways, in the face of climate change, population growth, and other factors, to even further optimize maize yields.

Now, researchers at Cold Spring Harbor Laboratory (CSHL) have identified a relationship between crop yield in the maize plant and specific genetic activity associated with one of the plant’s metabolic pathways. The discovery has implications for plant breeding, potentially opening the door for increasingly resilient, higher-yield maize plants.

CSHL Professor David Jackson and his team have connected the RAMOSA3 gene to branching, which can affect its yield. When a maize plant has too many branches, it will expend more energy towards making those branches, and less towards making seeds. More branches often means lower or less efficient yields.

Ears, the part of maize that we eat, are normally not branched at all—they just form one straight cob. But maize mutants that don’t have the RAMOSA3 gene can end up with gnarly-looking branched ears.

Jackson and his team initially hypothesized that the enzyme that RAMOSA3 encodes, called TPP, and a sugar phosphate called T6P which TPP acts on, are likely responsible for the ear-branching. Although the precise function of T6P remains “largely elusive,” the scientists believe that it has signaling properties.

Then, in a surprising twist, they found that a related gene, TPP4, also helps to control branching, but that gene’s effect was unrelated to its enzymatic activity. They wondered if the same might be true for RAMOSA3 and its own enzymatic activity. To follow up on this, they blocked only the enzyme activity associated with RAMOSA3, and not the gene itself, and got normal-looking ears of maize. This indicates that although RAMOSA3 controls the activity of the enzyme, it seems the enzyme activity is not responsible for controlling branching. Thus, the gene may be “moonlighting” with a hidden activity, explains Jackson. The question of what that moonlighting may entail is a launching-off point for future research.

The team’s findings were published in Nature Plants. Their work could lead to better crop yields and more efficient harvesting for the maize plant, as well as for other crops, like rice and quinoa.

Read the paper: Nature Plants

Article source: Cold Spring Harbor Laboratory

Image: Cold Spring Harbor Laboratory