Abstract
Ploidy effects have been described macroscopically for many aspects of plant growth, but how an increase in ploidy quantitatively influences cell proliferation and cell volume growth remains to be elucidated. We have established polyploid series of four strains of Arabidopsis thaliana, and with these, quantitatively analyzed the ploidy effects on primary root growth by the kinematic method. The kinematic data have been further analyzed by our original mathematical model to estimate efficiencies for three aspects of root growth; cell proliferation, volume growth, and organ maintenance. In the Columbia strain, there were increases in cell size and cell volume growth rate of tetraploid plants compared to diploids, while no significant differences were found in cell proliferation and size of cell proliferation zone. The model-assisted analysis additionally showed that tetraploids are more efficient than diploids in volume growth and organ maintenance, probably due to the increase in cellular biological activity, but less efficient in cell proliferation. Based on the results, we will discuss cellular mechanisms underlying growth modification by the ploidy level.
