Growth-related changes in subcellular ion patterns in maize leaves (Zea mays L.) under salt stress.
Na+ accumulation in the leaf apoplast has been suggested to lead to dehydration, later wilting and finally, the death of the affected leaves. Our aim has been to evaluate whether the reduction in the plant growth of sensitive maize in response to salinity is correlated with higher amounts of Na+ and Cl) concentrations in the leaf apoplast. Subcellular ion patterns in intact leaves were investigated by using deionised water infiltration. We found an increase in soluble Na+ and Cl) concentrations of about 16- and 4-fold, respectively, compared with the control. These concentrations characterized the apoplasts of expanding leaves that had entirely developed under salinity. Interestingly, the K+ concentration was significantly reduced by 64 % compared with its control in the symplast under salinity. Our finding of a significantly decreased Ca2+
concentration in shoots suggested a possible association of Ca2+ concentration with the reduction in leaf expansion under salinity. As the absolute increase in the apoplastic Na+ concentration during salt treatment was much lower compared with the increase in the symplastic Na+ concentration, salt treatment in maize appears not to result in osmotic stress imposed by a high apoplastic Na+ concentration as has been suggested for other plant species (Oertli hypothesis).
Shahzad, M.; Witzel, K.; Zörb, C.; Mühling, KH. 2012. Growth-related changes in subcellular ion patterns in maize leaves (Zea mays L.) under salt stress. Journal of Agronomy and Crop Science 198 (1), 46-56.