Metabolite profiling and gene expression of Na/K transporter analyses reveal mechanisms of the difference in salt tolerance between barley and rice.

Barley (Hordeum vulgare) and rice (Oryza sativa) differ greatly in their salt tolerance, although both species belong to the Poaceae family. To understand the mechanisms in the difference of salt tolerance between the two species, the responses of ionome, metabolome and gene expression of Na and K transporters to the different salt treatments were analyzed using 4 barley and 4 rice genotypes differing in salt tolerance. In comparison with 4 rice genotypes, four barley genotypes showed better plant growth, lower shoot Na concentration and higher K concentration at the 9 day after salt treatments. There was a dramatic difference in absolute expression levels of SOS, HKT and NHX family genes between barley and rice, which might account for their difference in Na/K homeostasis and salt tolerance. Moreover, rice leaves accumulated excess Na under salt treatments, which caused serious damages to physiological metabolisms based on metabolomic analysis, but barley leaves had lower Na concentration and small changes in the most metabolites. These results provide useful insights into the molecular mechanism in the difference of salt tolerance between rice and barley.

Fu L ，Shen Q ，Kuang L ，Yu J ，Wu D ，Zhang G ... -  《-》

Na(+)/K(+) Balance and Transport Regulatory Mechanisms in Weedy and Cultivated Rice (Oryza sativa L.) Under Salt Stress.

Zhang Y ，Fang J ，Wu X ，Dong L ... -  《BMC PLANT BIOLOGY》

Comparative transcriptome analyses of barley and rice under salt stress.

Ueda A ，Kathiresan A ，Bennett J ，Takabe T ... -  《THEORETICAL AND APPLIED GENETICS》

Control of xylem Na(+) loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance.

Control of xylem Na+ loading has often been named as the essential component of salinity tolerance mechanism. However, it is less clear to what extent the difference in this trait may determine differential salinity tolerance between species. In this study, barley (Hordeum vulgare L. cv. CM72) and rice (Oryza sativa L. cv. Dongjin) plants were grown under two levels of salinity. Na+ and K+ concentrations in the xylem sap, and shoot and root tissues were measured at different time points after stress onset. Salt-exposed rice plants prevented xylem Na+ loading for several days, but failed to control this process in the longer term, ultimately resulting in a massive Na+ shoot loading. Barley plants quickly increased xylem Na+ concentration and its delivery to the shoot (most likely for the purpose of osmotic adjustment) but were able to reduce this process later on, keeping most of accumulated Na+ in the root, thus maintaining non-toxic shoot Na+ level. Rice plants increased shoot K+ concentration, while barley plants maintained higher root K+ concentration. Control of xylem Na+ loading is remarkably different between rice and barley; this difference may differentiate the extent of the salinity tolerance between species. This trait should be investigated in more detail to be used in the breeding programs aimed to improve salinity tolerance in crops.

Ishikawa T ，Shabala S 《-》

Comparative mapping of HKT genes in wheat, barley, and rice, key determinants of Na+ transport, and salt tolerance.

Huang S ，Spielmeyer W ，Lagudah ES ，Munns R ... -  《-》