Molecular mechanisms to reduce Arsenic in Rice

Food security is under pressure all over the globe. Abiotic stress is one of the
largest threats to crop production and amongst these, crop contamination with
arsenic (As) is prevalent in many areas of the world. Arsenic is an extremely
toxic metalloid and human exposure to As is common in many areas of the
world, occurring via drinking water and crop consumption, particularly rice. To
reduce the danger of diet contamination, it is imperative to reduce As in crops,
especially in the edible parts such as grain and seed.
This PhD project will continue studies into the role of membrane transporters
in uptake, distribution and seed deposition of As in plants. We, and other labs,
showed that specific aquaporins (from the NIP subfamily), are responsible for
arsenite uptake in plants. Recently, we showed that some of these (such as
AtNIP7;1 in Arabidopsis) play an important role in delivering As to the grain.
Other studies showed that specific sugar transporters (AtINT2 and AtINT4) are
also involved in this process. These exciting results suggest that specific NIPs
and INTs are important determinants of As deposition in seeds and that loss of
function in these proteins may help generate a healthier crop!
Another part of the project is concerned with aquaporin structure-function:
Several studies have shown that mutating plant aquaporins to reduce As
permeability also reduces uptake of beneficial nutrients such as silicon and
boron. However, a recent report demonstrated that a, as yet unique Killifish
aquaporin did not conduct AsIII and yet may have a high silicon permeability.
We will test this hypothesis in heterologous expression systems (Xenopus
embryos), measuring As and Si transport in wildtype and mutated forms of
Killifish and plant aquaporins.