Regulation of Division and Elongation During Root Growth

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

Cell division and expansion are fundamental processes, however the relationship between them has been little studied. In a developing organ, it is not understood how the zones of division and rapid expansion are delimited; nor is it understood how rates of elongation and division are coordinated. Based on preliminary data, the PI hypothesizes first, that division ends well before rapid expansion begins; second, that the abrupt onset of rapid expansion is caused by a synchronous up-regulation of proton efflux and hydraulic conductivity of cell membranes; and third, that division and expansion are regulated reciprocally, so that a change in one elicits a proportional change in the other. The specific aims of the proposal are to test these hypotheses. To do so, The PI will use the plant root because of its linear organization, indeterminate growth, and experimental accessibility. The PI developed a kinematic method to quantify the spatial profiles of velocity, relative elongation rate and cell division rate. Profiles of velocity, relative elongation rate, cell division rate, and fluxes of selected ions will be quantified for conditions and genotypes that affect root growth, including development and water deficit. The PI will then perturb elongation and division and will quantify how the measured parameters change. Supporting or refuting the hypotheses will increase our understanding of fundamental growth processes in higher plants.