Eduardo Blumwald - US grants

Environmental stress due to salinity is one of the most serious factors limiting the productivity of agricultural crops, which are predominantly sensitive to the presence of high concentrations of salts in the soil. A comparison of ion distribution in cells and tissues of various plant species indicates that a primary characteristic of salt tolerant plants is their ability to exclude sodium out of the cell and to take up sodium and to sequester it in the cell vacuoles. Dr. Blumwald's work has identified a family of vacuolar Na+/H+ antiports that play a paramount role in the ability of plants to grow in high NaCl concentrations. These antiports actively move ions into the vacuole, removing the potentially harmful ions from the cytosol. These ions, in turn, act as an osmoticum within the vacuole, which then maintain water flow into the cell, thus allowing plants to grow in soils containing high salinity. The cloning of plant Na+/H+ antiports and the generation of transgenic Arabidopsis thaliana plants with enhanced salt tolerance provides a unique opportunity to study the role of these transporters in salt tolerance and ion homeostasis in vivo. Dr. Blumwald's proposed research aims to identify and characterize proteins regulating the vacuolar Na+/H+ antiport activity, providing insights on the role of Ca2+-dependent transduction processes in the regulation of intracellular ion balance. The second objective will serve to identify mechanisms regulating the transcription of the antiports in salt tolerant plants that could be used to design crops with enhanced salt tolerance. The third objective, will use knockout mutants and RNA interference to determine the physiological role of the vacuolar antiports in K+ nutrition.

This award provides partial support for the purchase of a confocal laser scanning microscope (CLSM) with spectral imaging capabilities, and an image analysis system to be housed in the Division of Biological Sciences-Microscopy and Imaging Facility at the University of California, Davis Campus. The instrument will enhance several research projects in basic and applied plant biology, including: (i) Elucidation of the molecular constituents that comprise the unique plasmodesmata-based non-cell-autonomous translocation pathway of plants, (ii) Characterization of the pathways involved in establishing cell fate in Arabidopsis organs, (iii) Identification of the Arabidopsis genes required for gametogenesis and embryogenesis, (iv) Molecular basis of ovule development and evolution, (v) Analysis of Aux/IAA degradation in plants, (vi) Regulation of compound leaf development. (vii) Phytochrome engineering in living cells, (viii) The role of molecular motors in the phragmoplast and during cotton fiber development, (ix) Identification of endogenous and viral component involved in plant systemic infection, (x) Analysis of signal transduction pathways underlying the operation of a tonoplast transport systems involved in plant response to salt stress, and (xi) Kinase signaling in the XA21-mediated plant defense response.

Cation/proton antiporters play a major role in pH and Na ion homeostasis of cells throughout the biological kingdom, from bacteria, algae, fungi and worms to higher plants and humans. These proteins are integral membrane proteins residing in the plasma membranes and endomembranes of different cells. Although the functional analysis of amino acid residues of mammals and bacteria plasma membrane-bound sodium/proton antiporters is emerging, little is known about the specific amino acids that are involved in cation/proton exchange, pH sensing, ion specificity, etc. There is no vacuolar or lysosomal transporter (animal, yeast or plant) whose topology, structure and mode(s) of action have been characterized to date. The main purpose of this research is to address this lack of critical information. The research will use a multidisciplinary approach that will combine biochemistry, molecular biology, membrane transport, heterologous expression in yeast and plants, and crystallography. The specific goals are: (i) Determine the topology of the Arabidopsis vacuolar antiporters AtNHX1 and AtNHX5; (ii) Structure/functional analysis of AtNHX1 and AtNHX5 in order to gain insight into key amino acids and regions of the protein responsible for ion binding, ion selectivity, pH regulation and transport activity; and (iii) Determine their three-dimensional structure.

Broader impacts: Plant vacuolar cation/proton antiporters have been shown to play important roles in ion homeostasis and plant development. The ectopic overexpression of AtNHX1 and AtNHX5 has been shown to confer salt tolerance in Arabidopsis and other plants. An understanding of the antiporter mode(s) of action together with the identification of factors affecting its activity will augment our capability of producing plants with enhanced salt tolerance. These plants would provide an important tool for crop production in large areas of the world affected by salinity. In addition, the nature of this project provides excellent opportunity for interdisciplinary training at all levels from high school students and teachers to post-doctoral trainees.

0234721
Bohnert

Description: This project supports a U.S.-Pakistan Workshop on Molecular Biology, Genetics, Genomics and Breeding, with Focus on Abiotic Stress Tolerance of Cereal Crops, to be held in Lahore, Pakistan in March 2003. The U.S. organizer is Dr. Hans Bohnert, Department of Biology and Crop Science, University of Illinois, Urbana-Champaign, Illinois. The Pakistani organizers are Dr. Tayyab Husnain, Center of Excellence in Molecular Biology, Punjab University, Lahore, Pakistan and Dr. Kauser Malik, Member/Biology, Pakistan Atomic Energy Commission, Islamabad, Pakistan. The workshop themes are "the physiological and agronomical parameters determining stress responses, and the integration of traditional breeding techniques with molecular marker technology," and "the exchange of information about genomic type studies directed towards the understanding of stress tolerance determinants and the application of results from mutational studies in model plants to cereal crops and their improvement." The subjects to be covered include: mechanism of stress tolerance, functional genomics related to stress tolerance, and plant transformation for introduction of stress tolerance traits. The proceedings will identify selected areas of high priority, as well as a literature guide for cooperative research.

Scope: The results of the workshop will include identifying joint research that would benefit the United States, Pakistan and other countries that must cultivate cereal crops under stressful plant growth conditions including drought, excessive heat, and salinity.

Arabidopsis 2010: Abiotic stress combination: Bridging the gap between Arabidopsis stress research and agriculture

The work undertaken on this project is designed to make significant contributions to the goals of the 2010 program - to understand the networking and function of every gene in Arabidopsis. The specific focus of the project is on abiotic stress combinations and the genetic and metabolic networks that respond to stress combinations such as drought and heat, drought and salinity and salinity and heat. Abiotic stress is the primary cause of crop loss world-wide, with losses in the US estimated at 14-19 billion dollars each year. While abiotic stress is routinely studied in Arabidopsis by applying a single stress condition such as drought, salinity or heat, this type of analysis does not reflect the conditions that occur in the field where crop plants are subjected to a combination of different stresses. The central objective of the project is to identify novel genes, gene networks and metabolic pathways that specifically respond to a combination of two different abiotic stresses. The hypothesis to be tested is that dedicated genes, networks and pathways are activated in plants that are simultaneously exposed to two different stress conditions. This project is designed to bring Arabidopsis into the front line of applied research on abiotic stress tolerance, and bridge the gap between stress studies conducted with Arabidopsis in the lab and the conditions that impact crops in the field. The two key "Broader Impacts" of the proposed research are: 1) Development and maintenance of a centralized website that will bring together agronomists, breeders and Arabidopsis molecular biologists (http://www.ag.unr.edu/Stress_Combination/). 2) Educational outreach for K-12 and multidisciplinary training to postdoctoral, graduate and undergraduates trainees. Both undergraduate and K-12 outreach and training activities will target the under privileged and under represented in Science. Historically, abiotic stress combinations, such as drought and heat, had the outmost devastating economical and sociological impacts on the US, with losses of 48.4 and 61.6 billion dollars in 1980 and 1988 respectively. The proposed project will pave the way for the development of crops with enhanced abiotic stress tolerance, contributing to ameliorate the consequences of future weather disasters that are likely to increase in frequency due to anticipated climatic changes.

Global changes due to increasing temperatures and greater variation in climate and precipitation patterns are expected to have major (negative) impacts on food, fuel, and fiber production in the U.S. and throughout the world. Water deficit and salinity are two of the most important environmental stresses affecting the crop productivity of agricultural systems with water deficit from drought being the leading cause of agricultural productivity losses. In order to develop stress-tolerant plants that can help to mitigate the impact of climatic variations, information flow between basic and applied research and discussion of strategies are essential. The Gordon Research Conference on Salt and Water Stress in Plants offers a unique platform for intensive information exchange and informal discussion between molecular biologists, physiologists, breeders and industrial representatives from all over the world. It facilitates a dialogue that is essential to achieve a seamless translational pipeline from the laboratory to the field, from the molecule to the crop. The organizers want to motivate the participation of young, talented early career stage scientists in this dialogue, and are further committed to raising the participation from underrepresented groups. The current program lists fifteen women as chairs or speakers. Representation of minority groups will be further promoted with the selection of additional speakers from the submitted poster abstracts.

Salt and water stress in plants caused by drought and soil salinisation restricts world food production. The problem is further exacerbated by climate change and additional pressure on land usage for biofuel production. Scientists have made and continue to make impressive progress in identifying the biological mechanisms underlying abiotic stress responses and resistance in plants. The knowledge gained now needs to be translated into crop improvement in the field. This is a research area where excellent fundamental science is met by considerable interest from breeding institutes, agricultural agencies and companies worldwide, and hence presents an opportunity for a concerted effort to achieve sustainable food and energy production worldwide. Success in this undertaking critically relies on a regular and open dialogue between all parties involved. This proposal requests funding to contribute costs for registration and travel of 10 -12 U.S. scientists to the 11th Gordon Research Conference on Salt & Water Stress in Plants, to be held from 3th and 8th of August 2014 at the GRC site "Sunday River Resort" in Newry, ME, USA. Additional funding from the GRC and private industry will be available to cover some of the registration and travel costs associated with the participation of scientists from other countries, especially those where salinity and drought cause serious problems for agriculture. NSF funds will be used to promote the attendance of U.S. scientists at the early stages in their careers. Particular attention will be given to the representation of minority groups. The GRC format provides ample opportunity for informal discussion and personal contact, and is therefore particularly beneficial for young researchers. Specific session topics of the 2014 meeting cover evolutionary aspects of stress adaptation, transcriptional and post-translational regulation of stress-related genes and proteins, stress perception and signal transduction, metabolic responses, ion and water homeostasis, co-ordination of the whole plant response, and crop improvement for a changing global environment. The Conference is unique in that it will bring together researchers from all over the world who conduct abiotic stress research at diverse scales of organization and it will foster synergistic interactions and long-term collaborations.