Abstract
Variation in genome size (GS) has been linked to several facets of the plant phenotype. Recently it was shown that GS is significantly correlated with cell size and the duration of the cell cycle. Here we test the hypothesis that GS might also be a predictor of apical root meristem growth rate (RMGR). We studied eight species of eudicots with varying GS using time-lapse microscopic image analysis. A significant negative exponential relationship was observed between GS and RMGR. Our results show significantly decreased RMGR for large genome species. This relationship represents a significant consequence of GS expansion in plants and may partly explain why genome sizes tend to be small in eudicots. Interestingly, parasitic plants, which do not rely on root growth as much, often have large genomes.
Highlights
Genome size (GS) varies by three orders of magnitude in plants [1, 2]
Variation in cell division rate would lead to an exponential relationship between genome size and root meristem growth rate (RMGR); variation in cell elongation rate would lead to a linear relationship
Genome sizes for the species we studied were obtained from the plant DNA C-values database
Summary
Genome size (GS) varies by three orders of magnitude in plants [1, 2]. Correlations between GS and several facets of the phenotype and life history of plants have been documented [3, 4]. Others have observed correlations between the relative growth rate and genome size [4, 10, 11], but none have looked at growth dynamics (kinematics) in the root meristem. Where RMGR is a function of the number of initial cells (N), the division rate of these cells (R), the time it takes for a point to pass through the elongation zone (ΔT), and the change in length of a cell (ΔL) over the change in time (ΔT).
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