Effects of improved sodium uptake ability on grain yields of rice plants
under low potassium supply
Abstract
Sodium uptake is a factor that determines potassium use efficiency in
plants as sodium can partially replace potassium in plant cells. Rice
(Oryza sativa) roots usually exclude sodium but actively take it
up when the plant is deficient in potassium. In rice roots, a sodium
transporter OsHKT2;1 mediates the active sodium uptake. We previously
revealed that variation in the expression of OsHKT2;1 underlie
the variation in sodium uptake between a low-sodium-uptake indica
cultivar, IR64, and a high-sodium-uptake japonica cultivar, Koshihikari.
In the present study, we evaluated IR64 and its near-isogenic line
IR64-K that carrying OsHKT2;1 and neighboring genes inherited
from Koshihikari for grain yields. IR64-K had a greater average grain
yield and harvest index than IR64 in a pot culture experiment with three
levels of potassium fertilizer. The differences were most significant
under treatment without potassium fertilizer. IR64-K also showed a
slightly higher grain yield than IR64 when grown in a paddy field
without potassium fertilizer application. These results suggest that the
enhanced ability of sodium uptake improves grain yields of rice plants
under low-potassium-input conditions.