Improving arsenic tolerance in rice

Arsenic (As) is an extremely toxic metalloid, which occurs ubiquitously in nature but is particularly prevalent in South-East Asia. Human exposure to As is common in many areas of the world and occurs via drinking water and consumption of As containing crops, particularly rice. Plants readily take up As either as AsV (arsenate, a phosphate analogue that enters via phosphate transporters) or AsIII (arsenite, which resembles the important plant nutrients boric and silicic acid) which enters via aquaporins.
The overall project objective is to develop low-As crops which can be achieved by:
(i) Reducing As uptake at the root:soil boundary
(ii) Reducing As deposition in edible parts such as seeds and grains

To achieve (i) and (ii), we will focus on the membrane transporters that are involved in these processes in the crop plant rice. For (i), we will try and engineer a killifish aquaporin to have low As conductance while maintaining transport capacity for important nutrients like boric and silicic acid. The successfully engineered aquaporin will then be genetically introduced into rice. For (ii), recent work in Arabidopsis showed that inositol transporters (INTs) and specific NIP aquaporins greatly impact on deposition of As in the seed. We will test whether the effects of these two transporters is additive and we will seek to identify similar transporters in rice and study their role in the deposition of arsenic in the rice grain.