Bernstein, Nirit .
Salinity effects on expression levels of NHX1, NHX4, H+-ATPase, and VPP1 during cell development in the maize leaf.
Maize leaves are well suited as a model system for studies into stress effects on growth, due to the relatively simple organization of their growing zone and its distinct location at the leaf base. The response to salinity is not uniform throughout the growing zone and a characteristic spatial profile of sensitivity exists along a tissue only few cm in length. This variability in response to salinity, in tissue of same genome, can be utilized to explore involvement of stress-induced alterations of molecular parameters in the generated cellular response. In the present study we evaluated the expression of two genes from the NHX family (NHX1 and NHX4) as well as H+-ATPase (V-ATPase) and VPP1 in discrete locations along the growing tissue of the maize leaf. Combination of expression analysis by Real-time PCR and northern blots with the methods of 'growth kinematics', which utilize the existence of the developmental gradient along the leaf, allowed mapping of stress induced changes in expression on the same temporal and spatial scale as cell response to salinity. NHX1 is more abundant in the growing tissue than NHX4. Its expression increased with cell age and under salinity. The expression of H+-ATPase and VPP1 was cell age dependent. H+-ATPase expression was highest at the young cells and considerably decreased past 40 mm from the leaf base. VPP1 expression was low near the leaf base and increased with cell age past 40 mm from the base. Under salinity, expression of VPP1 increased throughout cell development, while H+-ATPase expression increased only at the very young cells. Changes in expression levels will be discussed in relation to their possible involvement in salinity damage or tolerance mechanisms, with relation to the developmental stage of the growing cell.
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1 - Volcani Center, Institute of Soil Water and Environmental Sciences, PO Box 6,, Bet-Dagan, 50-250, Israel
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM