TEMPERATURE AFFECTS EXPANSION RATE OF MAIZE LEAVES WITHOUT CHANGE IN SPATIAL-DISTRIBUTION OF CELL LENGTH - ANALYSIS OF THE COORDINATION BETWEEN CELL-DIVISION AND CELL EXPANSION

We have analyzed the way in which temperature affects leaf elongation rate of maize (Zea mays L.) leaves, while spatial distributions (obser ved at a given time) of cell length and of proportion of cells in DNA replication are unaffected. We have evaluated, in six growth chamber e xperiments with constant temperatures (from 13 to 34 degrees C) and tw o field experiments with fluctuating temperatures, (a) the spatial dis tributions of cell length and of leaf elongation rate, and (b) the dis tribution of cell division, either by using the continuity equation or by flow cytometry. Leaf elongation rate was closely related to merist em temperature, with a common relationship in the field and in the gro wth chamber. Cell division and cell elongation occurred in the first 2 0 and 60 mm after the ligule, respectively, at all temperatures. Simil ar quantitative responses to temperature were observed for local cell division and local tissue expansion rates (common x intercept and norm alized slope), and both responses were spatially uniform over the whol e expanding zone (common time courses in thermal time). As a consequen ce, faster cell elongation matched faster cell division rate and faste r elongation was compensated for by faster cell displacement, resultin g in temperature-invariant profiles of cell length and of proportion o f dividing cells. Cell-to-cell communication, therefore, was not neces sary to account for coordination.