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

452 / 2019-02-26 00:05:09

A Whole-Cell Electron Tomography Model of Vacuole Formation in Arabidopsis

Vacuole Biogenesis,Electron Tomography,Small Vacuole,Multivesicular Body,Root Cortex

Plenary track > Cell Biology

Plant vacuoles regulate growth and development. Despite their significant functions, multiple models of vacuole biogenesis have been proposed, which are mainly based on cellular studies of two-dimensional (2D) transmission electron microscopy (TEM) and 3D confocal imaging. Using 3D TEM technology at nanometre resolution, we study vacuole biogenesis in Arabidopsis root cortical cells of different stages of vacuole formation by the whole-cell electron tomography (WCET) analysis. We first identified unique small vacuoles (SVs; 400-1000 nm in diameter) as nascent vacuoles in early developmental cortical cells. The SVs contained intraluminal vesicles and were mainly derived/matured from multivesicular body (MVB) fusion. These SVs subsequently fused to lead the central vacuole formation. Further electron tomography analysis on mutants defective in MVB formation/maturation or vacuole fusion demonstrated that central vacuole formation required functional MVBs and membrane fusion machineries (Cui et al., 2019 Nature Plant). More recently, through WCET analysis on vacuole nature and formation from the cortex initial cell, we further investigated vacuole inheritance and dynamics during progenitor division as well as simultaneous de novo vacuole formation. Here we will present a complete model for vacuole building in Arabidopsis root cortex. Supported by grants from RGC of Hong Kong (CUHK14100818, C4011-14R, C4012-16E, C4002-17G and AoE/M-05/12) and NSFC (31670179 and 91854201).