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Engineering Plants to Survive Salt

saltAccording to the United Nations, over 12 million hectares of arable land are lost to drought and desertification every year. 12 million hectares is approximately the land area of Louisiana, and represents the potential loss of up to 20 million tons of grain that could have been grown in these areas. Salinity is also a huge problem for agriculture: nearly 25% of the irrigated land in the world now is now plagued by overly salty soil. These salt-filled soils are caused by factors like poor irrigation practices and saltwater intrusion from rising sea levels.

Most plant species, including essentially all farmed crops, are referred to as glycophytes. Glycophytes are not salt-tolerant and are damaged easily in high salinity environments. High salt concentrations in these species disrupt vital internal processes, eventually leading to the death of the plant. Their only defenses against salt are physical and chemical barriers in the root systems, but these features can only keep out low levels of salt. However, a few plant species (perhaps only 2% or so), are considered halophytes. Halophytes (literally: “salt plants”) are plants that can survive in high-salinity environments. Halophytes include species such as mangroves, quinoa, and Arabidopsis thaliana, a plant commonly used in genetic research. For comparison, crop plants like beans and rice can tolerate around 1-3 grams of salt per liter of water, while Salicornia bigelovii (dwarf glasswort, a halophyte) can flourish in water with salt concentrations as high as 70 grams per liter!

mangrove tree

Mangrove Tree

Eduardo Blumwald, a plant biologist at UC Davis, starting studying halophytes in the 1990s. An article from Scientific American discussed how he found that halophytes are able to handle additional salt levels by using special proteins called antiporters. The antiporters push sodium ions into special structures called vacuoles, which are sealed off areas within the cell structure that keep the salt from interfering with sensitive processes. In some halophyte species (including quinoa and arabidopsis), these vacuoles can become so large that they look like tiny translucent spheres on the surface of the plant and are sometimes referred to as salt bladders. Blumwald found that the genes that are responsible for this antiporter system can be genetically engineered into traditional crops like rice, wheat, barley, tomatoes, and cotton.

However, the process of making plants more salt-tolerant is more complicated than engineering a single protein. Plants have thousands of genes associated with surviving stress (including salinity), and many of these genes need to be modified to allow these engineered salt-tolerant species to survive in the field. To get a better picture of which genes are the most crucial for stress tolerance, Simon Barak from Ben-Gurion University of Negev built a stress gene database from published research data on Arabidopsis thaliana. He used the database to rank the importance of genes with respect to survival in harsh environments – drought, salt, heat, etc. Experiments are being run on mutants that have the most promising genes in the hopes that more salt-tolerant strains can be bred.

arabidopsis

Arabidopsis thaliana

Powers Scientific offers several different options when it comes to running experiments with plants. If your work involves micropropagation of Arabidopsis or other plant species, our Plant Tissue Culture Chambers were designed with you in mind. These chambers come with four slide out shelves, with low velocity conditioned air delivered uniformly under each shelf. There are six fixed lamp positions over each shelf to deliver high intensity visible light, visible/black light combinations, or other light combinations that can be stepped on/off.  The chambers can be run at temperatures as low as 7°C with lights on (for vernalization studies). It is also capable of functioning as an incubator, reaching temperatures of 40°C or higher, if needed.

If your work involves more traditional plant growth through seed germination, our Diurnal Plant Growth Chambers are a great option. These chambers offer digitally controlled temperature and lighting, with day/night cycles to simulate the nurturing environment seeds and plants need for successful growth, with a temperature range of 2-50°C. For plants or experiments with more rigorous requirements, many options can be selected, such as additional lights (vertically, horizontally, or both), installing a fresh air intake, including additive RH generation, or adding horizontal air flow ducts for better temperature uniformity under the lights.

For more information or to request a quote, visit our Contact Us page or call us at (800) 998-0500.