Analysis of cell wall hardening and cell wall enzymes of salt-stressed maize (Zea mays) leaves

It has been indicated that salinity inhibits maize (Zea mays L.) leaf growth and leaf cell expansion by increasing the apparent yield threshold of the cell wall. We tested whether this increase in the apparent yield threshold was a physical property of cell walls, using in vitro creep-type assays. Salinity had no significant effects on cell wall structural properties based upon several different in vitro assays. In support of these results, there were no differences between control and salt-stressed plants in their total apoplastic concentration of cell wall proteins, in the activity of apoplastic peroxidases or xyloglucan endotransglycosylase. We conclude that short-term salinity does not appear to inhibit maize leaf elongation by hardening the physical structure of the cell walls of the growing zone.