Down regulation of ZmEXPB6 is correlated with salt mediated growth reduction in leaves of Zea mays L. [Plant Biology]

March 6th, 2015 by Geilfus, C.-M., Ober, D., Eichacker, L. A., M&uumlhling, K. H., Z&oumlrb, C.

Abstract The salt-sensitive crop Zea mays L. shows a rapid leaf growth reduction upon NaCl stress. There is increasing evidence that salinity impairs the ability of the cell walls to expand, ultimately inhibiting growth. Wall-loosening is a prerequisite for cell wall expansion, a process that is under control of cell wall located expansin proteins. In this study, the abundance of those proteins was analysed in dependency to salt stress using gel-based two-dimensional proteomics and two-dimensional Western blotting. Results show that ZmEXPB6 is lacking in growth-inhibited leaves of salt stressed maize. Of note, the exogenous application of heterologously expressed and metal-chelate-affinity-chromatography-purified ZmEXPB6 on growth-reduced leaves that lack native ZmEXPB6 under NaCl-stress partially restored leaf growth. In vitro assays on frozen-thawed leaf sections revealed that recombinant ZmEXPB6 acts on the capacity of the walls to extend. Our results identify expansins as factor which partially restores leaf growth of maize in saline environments.