The 30th International Conference on Arabidopsis Research (ICAR 2019)

395 / 2019-02-21 21:52:11

Cell death in cells overlying lateral root primordia contributes to organ growth in Arabidopsis

Arabidopsis,Cell death,Development,Lateral root,Root,Lateral Root Primordium,Programmed Cell Death

Plenary track > Development

Unlike animal development, plant organ growth is widely accepted to be determined by cell division without any contribution of cell elimination. Even during Arabidopsis lateral root formation, when pericycle-derived lateral root primordia (LRP) must cross three cell layers (endodermis, cortex and epidermis), cell divisions in the LRP and cell wall remodeling of the overlying cells have been considered as to drive LRP growth without cell death. However, we observed the induction of marker genes for cell types undergoing developmental cell death in several cells overlying the growing LRP, prompting us to revisit the relation between cell death and LRP organ growth.

Transmission electron microscopy, viability histological staining, time-lapse confocal and light sheet microscopy techniques were used to establish that cell death occurred at least in a subset of endodermal LRP-overlying cells during organ emergence. LRP-overlying cell death was reduced and LRP growth was retarded in mutants lacking the positive cell death regulator ORESARA1 (ORE1). Significantly, LRP growth speed was restored in the ore1-2 mutant by genetically rescuing cell death in cells overlying LRP. Furthermore, using the optical tweezer technology we performed targeted laser ablation of LRP-overlying endodermal cells at early stages of LRP development, leading to an apparent increase in the speed of LRP growth. Hence, we conclude that cell elimination contributes to LRP organ growth.