Fresh water constitutes less than 1% of the surface water on earth, yet the importance of this simple molecule to all life forms is immeasurable. Water represents the most vital reagent for chemical reactions occurring in a cell. In plants, water provides the structural support necessary for plant growth. It acts as the carrier for nutrients absorbed from the soil and transported to the shoot. It also provides the chemical components necessary to generate sugar and biomass from light and carbon dioxide during photosynthesis. While the importance of water to plants is clear, an understanding as to how plants perceive water is limited. Most studies have focused on environmental conditions in which severe limitation (drought) or severe excess (flooding) of water is simulated. While these are important stress conditions, the plant may also sense and respond to differences in moisture content under non-stress conditions. Much as how light can act as a signal or a stress depending on the intensity, water may also have such a dual effect. In support of this hypothesis, work on hydrotropism has shown that roots have the ability to sense moisture gradients and direct growth towards favorable conditions.

Current studies indicate that moisture signaling may extend beyond hydrotropism and regulate nearly every aspect of root development. In a process we term "hydropatterning", local contact of the root tip with a liquid or air environment has the ability to cause stark differences in the development of tissues. Hydropatterning is observed in Arabidopsis thaliana as well as other flowering plants. The goal of our current research is to establish a foundation for understanding hydropatterning by characterizing the changes in growth and development that are directly affected. Using developmental and cell-type specific approaches along with genetic and genomic tools, our research will identify the key pathways through which moisture signaling acts to affect these processes.

Scientific Area: 
Plant Science
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the sea anemone Aiptasia pallida that is hosting the algae, which are responsible for the red fluorescence spots observed in the body of the animal. Image courtesy of Tingting Xiang.
Investigating coral and algal “matchmaking” at the cellular level
June 19, 2019

Palo Alto, CA—What factors govern algae’s success as “tenants” of their coral hosts both under optimal conditions and when oceanic temperatures rise? A Victoria University of Wellington-led team of experts that includes Carnegie’s Arthur Grossman investigates this question.

Corals are marine invertebrates that build large exoskeletons from which colorful reefs are constructed. But this reef-building is only possible because of a mutually beneficial relationship between the coral and various species of single-celled algae called dinoflagellates that live inside the cells of coral polyps.

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A teosinte plant growing in a corn field on the Stanford University campus, courtesy of Yongxian Lu.
How corn’s ancient ancestor swipes left on crossbreeding
May 24, 2019

Palo Alto, CA— Determining how one species becomes distinct from another has been a subject of fascination dating back to Charles Darwin. New research led by Carnegie’s Matthew Evans and published in Nature Communications elucidates the mechanism that keeps maize distinct from its ancient ancestor grass, teosinte.

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Plant cells under microscope. Shutterstock.
How plant cells neutralize the potential for self-harm
May 23, 2019

Palo Alto, CA—Photosynthesis makes our atmosphere oxygen-rich and forms the bedrock of our food supply. But under changing or stressful environmental conditions, the photosynthetic process can become unbalanced, resulting in an excess of highly reactive oxygen molecules that could cause cellular damage if they aren’t neutralized.  

New work in Proceedings of the National Academy of Sciences led by Carnegie’s Shai Saroussi and Arthur Grossman explores how the photosynthetic algae Chlamydomonas shields itself from this potential danger. Understanding how plants minimize self-inflicted harm in this scenario could help scientists engineer crops with improved

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Two New Venture Grants Awarded
May 16, 2019

The Office of the President has selected two new Carnegie Venture Grants. Peter Driscoll of the Department of Terrestrial Magnetism and Sally June Tracy of the Geophysical Laboratory were awarded a venture grant for their proposal Carbon-rich Super-Earths: Constraining Internal Structure from Dynamic Compression Experiments. Plant Biology’s Sue Rhee and Global Ecology’s Joe Berry and Jen Johnson were awarded a Venture Grant for their project Thermo-adaptation of Photosynthesis in Extremophilic Desert Plants.

Carnegie Science Venture Grants ignore conventional boundaries and bring together cross-disciplinary researchers with fresh eyes to explore different questions.

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The fight on rice blight

Carnegie will receive Phase II funding through Grand Challenges Explorations, an initiative created by the Bill & Melinda Gates Foundation that enables individuals worldwide to test bold ideas to address persistent health and development challenges. Department of Plant Biology Director Wolf Frommer,  with a team of researchers from the International Rice Research Institute, Kansas State University, and Iowa State University, will continue to pursue an innovative global health research project, titled “Transformative Strategy for Controlling Rice Blight.”

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A family of metabolite sensors

Several years ago, Carnegie researchers  constructed genetically encoded FRET sensors for a variety of important molecules such as glucose and glutamate. The centerpiece of these sensors is a recognition element derived from the superfamily of bacterial binding protiens called periplasmic binding protein (PBPs), proteins that are primary receptors for moving chemicals  for hundreds of different small molecules. PBPs are ideally suited for sensor construction. The scientists fusie individual PBPs with a pair of variants and produced a large set of sensors, e.g. for sugars like maltose, ribose and glucose or for the neurotransmitter glutamate. These sensors have been adopted for

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Salinity and plants

Today, humanity is increasingly aware of the impact it has on the environment and the difficulties caused when the environment impacts our communities. Environmental change can be particularly harsh when the plants we use for food, fuel, feed and fiber are affected by this change. High salinity is an agricultural contaminant of increasing significance. Not only does this limit the land available for use in agriculture, but in land that has been used for generations, the combination of irrigation and evaporation gradually leads to increasing soil salinity.

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Digital genome

Revolutionary progress in understanding plant biology is being driven through advances in DNA sequencing technology. Carnegie plant scientists have played a key role in the sequencing and genome annotation efforts of the model plant Arabidopsis thaliana and the soil alga Chlamydomonas reinhardtii. Now that many genomes from algae to mosses and trees are publicly available, this information can be mined using bioinformatics to build models to understand gene function and ultimately for designing plants for a wide spectrum of applications.

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Moises Exposito-Alonso

Evolutionary geneticist Moises Exposito-Alonso joins the Department of Plant Biology as a staff associate in the summer of 2019. He investigates whether and how plants will evolve to keep pace with climate change by conducting large-scale ecological and genome sequencing experiments. He also develops computational methods to derive fundamental principles of evolution, such as how fast natural populations acquire new mutations and how past climates shaped continental-scale biodiversity patterns. His goal is to use these first principles and computational approaches to forecast evolutionary outcomes of populations under climate change to anticipate potential future

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Kamena Kostova

Staff Associate Kamena Kostova joined the Department of Embryology in November 2018. She studies ribosomes, the factory-like structures inside cells that produce proteins. Scientists have known about ribosome structure, function, and biogenesis for some time. But, a major unanswered question is how cells monitor the integrity of the ribosome itself. Problems with ribosomes have been associated with diseases including neurodegeneration and cancer. The Kostova lab investigates the fundamental question of how cells respond when their ribosomes break down using mass spectrometry, functional genomics methods, and CRISPR genome editing.

Kostova received a B.S. in Biology from the

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Sally June Tracy

Sally June Tracy applies cutting-edge experimental and analytical techniques to understand the fundamental physical behavior of materials at extreme conditions. She uses dynamic compression techniques with high-flux X-ray sources to probe the structural changes and phase transitions in materials at conditions that mimic impacts and the interiors of terrestrial and exoplanets. She is also an expert in nuclear resonant scattering and synchrotron X-ray diffraction. She uses these techniques to understand novel behavior at the electronic level.  Tracy received her Ph.D. from the California Institute of

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William Ludington

The Ludington lab investigates complex ecological dynamics from microbial community interactions using the fruit fly  Drosophila melanogaster. The fruit fly gut carries numerous microbial species, which can be cultured in the lab. The goal is to understand the gut ecology and how it relates to host health, among other questions, by taking advantage of the fast time-scale and ease of studying the fruit fly in controlled experiments. 
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