Bohnert Lab Main Page

Molecular Physiology & Engineering of Plant Stress Tolerance

  • Why can some plants tolerate highly saline soils, or survive severe drought conditions, or grow at low temperature?
  • Asking the question differently - why can most plants NOT survive when exposed to severe abiotic stresses?
The second question is significant because of results coming from the sequences of plant genomes. From the genomic, complete DNA sequence of Arabidopsis thaliana (mustard cress) and the available, still partial, DNA sequence of Oryza sativa (rice) we learn that these abiotic stress-sensitive species include genes that have been associated with stress tolerance in other species. It seems that rice and arabidopsis have the complete genetic makeup to be stress tolerant!
  • So, what is missing in sensitive species? Is it that our understanding of gene functions is lacking, or that our appreciation of interconnected networks of genes is rudimentary - or are there some magical genes that are restricted to a few stress-tolerant species?
The lab seeks to provide answers to some of these questions in collaborations with a number of colleagues and their laboratories. The first rationale for engaging in such a project is curiosity. We would like to know why a plant like Mesembryanthemum crystallinum (ice plant) can successfully invade the dunes along the California coast, watered predominately by the mist drifting inland from the surf. Also, we would like to know how a barrel cactus in the Sonoran desert can go on for months without water in 100 degree heat and intense irradiation. The cactus being a CAM species (CAM - Crassulacean Acid Metabolism) might be quite efficient conserving water, yet what about the machinery that is necessary to prevent or repair damage by light, radical oxygen species, or high or low temperatures.

Our second rationale and justification of the work is the recognition that the major abiotic stresses - drought, termperature (low or high and freezing), and high salinity - cause a significant reduction in yield in most crop species. The effect of these stresses is economic hardship for farmers and it may be life-threatening for regions depending on subsistence farming. Some examples may highlight this problem. One example is rice production. Approximately half the rice consumed is obtained in dry-land, rain-fed cultivation. Drought can be devastating. Another example, more complex, is salinization. Some 15% of the worlds cultivated areas are irrigated and produce about one third of all products. Because long-term irrigation inevitably leads to increases in salinity (unless the excessions can be removed by large amounts of water) crop yields decline. Also, low or freezing temperature during germination or seedling establishment can cause problems later - slower or reduced vegetative growth can translate into lower seed or fruit production. Cumulatively, abiotic stresses are responsible for most of the discrepancy that exists between maximal and actual yield. Our focus has been on salt stress - to understand this stress, discern its osmotic and ionic stress components and to understand how (some) plants cope with this stress.

  • Does an understanding of abiotic stress defense mechanisms translate into growing corn in the sea, or rice and soybeans in the Kalahari Desert?
These are unlikely scenarios. Without water, in permafrost, or in highly saline soils or water, all plants tend to be extremely slow-growing with low productivity. Aiming for agriculture in such environments seems to be futile. Our aim is different! From understanding mechanisms to genetic makeup, gaining experience from transforming genes into model species, we hope to arrive at protection schemes that make sense in normal production system. The aim should be to enable plants to grow during short-term drought, early season low temperature or moderate ion imbalance in the US midwest, in Australia's wheat belt, or in northern China without or with lower yield loss.
Arabidopsis thaliana
Arabidopsis thaliana

Project Descriptions
Click to view individual projects in the lab.

Microarray of drought-stressed Barley roots
Detail of a microarray slide containing 2000 ESTs (cDNAs) from a cDNA library of drought-stressed barley roots. Each DNA element was printed four times. The hybridization compared control vs. drought-stressed transcripts. The false color representation indicates in red and white if a transcript is upregulated under drought conditions Öztürk et al. (2002) Plant Mol Biol, in press.
Mesembryanthemum crystallinum
Mesembryanthemum crystallinum

  Contact Information:
192 ERML
1201 W. Gregory Drive
Plant Biology / Crop Sciences Departments
University of Illinois, Urbana-Champaign
Urbana, IL 61801, USA
Tel: 217-265-5475

Page last updated:
28 September 2007