Caloric restriction-mediated reproductive lifespan extension across multiple strains of the clonal aquatic plant Lemna turionifera

Abstract

Lifespan extension due to caloric restriction (CR) is a well-established aspect of animal senescence that has been observed in many taxa. Contrastingly, there is much less evidence in plants, even though it is straightforward to manipulate CR by restricting photosynthe- sis through reduction in light intensity. One of the few studies to report CR-mediated plant lifespan extension investigated reproductive lifespan in a single strain of the duck- weed Lemna minor, a tiny, floating, aquatic plant. Here, with an aim of beginning to test the generality of this phenomenon in plants, we considered a congeneric species, L. turionifera, and examined CR-mediated lifespan extension in eight strains collected from Alberta, Canada. We grew plants in the lab under axenic conditions, and manipu- lated light intensity (and hence, putatively, CR) with neutral density filters. Plants that grew under dimmer conditions had longer reproductive lifespans, on average, than those that grew under brighter conditions, consistent with CR-mediated lifespan extension. However, this came at the expense of a reduction in the capacity to contribute to popula- tion growth: plants in dimmer conditions produced about the same total offspring spread across their longer lifespans, leading to a reduced intrinsic rate of increase, measured at the level of the individual. Expanding the taxonomic scope of studies on CR-mediated life- span extension – especially in plants – remains an important goal in senescence research.