IBIP seminar – MISTRAL Summer School

Tuesday, July 10, 2018
at 3:00 pm, amphi 206

 

Homeostatic mechanisms for tissue Na+ concentrations in rice under salt stress

Tomoaki Horie
Shinshu University

Soil salinization leads to invasive influx of Na+ and Cl into roots, and those ions in turn over-accumulate in leaves and eventually trigger ion toxicity. HKT1-mediated Na+ exclusion at xylem parenchyma cells has been found to be a key system to protect leaf blades from Na+ toxicity. Our studies demonstrated that OsHKT1;5, one of four HKT1 transporters in a japonica rice cultivar (Oryza sativa), plays a crucial role in Na+ exclusion not only at the cells surrounding xylem vessels in roots and leaf sheaths, but also at the phloem parenchyma cells in the diffuse vascular bundle of the basal node, to protect young leaf blades from salinity stress. On the other hand, OsHKT1;4 has also been proposed to contribute to Na+ exclusion from leaf blade of rice under salinity stress. Our studies, however, suggested that OsHKT1;4-mediated Na+ transport have a more dominant impact on leaf blade Na+ exclusion in the reproductive growth stage, but the impact might be minor in the vegetative growth stage in a japonica rice cultivar suffering salinity stress. Differences in the mechanisms of HKT1-mediated Na+ exclusion from leaves in rice and wheat will be summarized.
In addition to the above-mentioned studies of an essential salt tolerance mechanism of rice, we have started new projects to identify important genetic loci, which have a large impact on Na+ and Cl homeostasis of rice, using genetic resources of wild rice and salt tolerant landraces. A part of recent results will be presented and discussed.


Contact : Anne-Aliénor Véry