The role of membrane transporters in crop improvement

A recent Nature article, "Using membrane transporters to improve crops for sustainable food production," highlights recent advancements in the science of transporters and potential uses to make crops more resistant to adverse conditions and more efficient in nutrient use. Membrane transporters are proteins or protein complexes that span the lipid membranes that surround plant cells. Transporters shuttle molecules and ions from soil water to inside cells, from one cell to another, and between cells and plant vessels like xylum and phloem. These molecules range in size and charge, which relates to the mechanisms transporters use for their transfer. Scientists can manipulate the types and numbers of transporters expressed through genetic modification. The article goes over advances in several transporter topics, summarized here.

Aluminum Tolerance

In acidic soils, aluminum exists in a form that can be toxic to plants, especially by killing growing root tips. Transporters can help plants cope with aluminum toxicity by shuttling organic compounds out of roots and into the soil. The exuded organic compounds bind with aluminum and render it safe for the plant. If a scientist increases the number of these transporters, then more compounds can be pumped out, or the transporters can even be swapped between species to give new abilities. Another method uses transporters to take up aluminum from the cell into small compartments in the cell called vacuoles where aluminum can't do any harm.

Salt Tolerance

Salt in high concentrations in the plant is toxic. One class of transporters shuttles salt out of xylum vessels, which contain the water solution being sent from roots to leaves, before they can cause damage in the leaves. Another class takes salt out of leaf cells and into vacuoles. That seems like a common trick, huh?

Pathogen Resistance is SWEET

SWEET transporters move sugar, the product of photosynthesis, throughout the plant. Pathogens feed off this sugar. Plants that can keep the sugar from the pathogens can be more resistant. SWEET transporters used in the right time and place can accomplish this.

Iron and Zinc Fortification

Transporters for iron and zinc can be used to make crop products have higher levels, which can be beneficial for malnourished individuals.

Phosphorus and Nitrogen Efficiency

Nitrogen and phosphorus are the first and second most abundant nutrients in plants, respectively. Farmers dump on tons of fertilizer in industrialized nations, while in poor countries farmers get low yields because of their scarcity in soil. Transporters might be able to help improve their uptake from the soil, and their internal use within the plant. RB Note: Research has shown that phosphorus is limited not by the speed of its uptake from soil water, where transporters would come in, but by diffusion within the soil. Researchers need to be careful here and consider soil properties as well.