An endoplasmic reticulum response pathway mediates programmed cell death of root tip induced by water stress in Arabidopsis

Abstract

Summary• Drought induces root death in plants; however, the nature and characteristics of root cell death and its underlying mechanisms are poorly understood. Here, we provide a systematic analysis of cell death in the primary root tips in Arabidopsis during water stress.• Root tip cell death occurs when high water deficit is reached. The dying cells were first detected in the apical meristem of the primary roots and underwent active programmed cell death (PCD). Transmission electron microscopic analysis shows that the cells undergoing induced death had unambiguous morphological features of autophagic cell death, including an increase in vacuole size, degradation of organelles, and collapse of the tonoplast and the plasma membrane. The results suggest that autophagic PCD occurs as a response to severe water deficit.• Significant accumulation of reactive oxygen species (ROS) was detected in the stressed root tips. Expression of BAX inhibitor-1 (AtBI1) was increased in response to water stress, and atbi1-1 displayed accelerated cell death, indicating that AtBI1 and the endoplasmic reticulum (ER) stress response pathway both modulate water stress-induced PCD.• These findings form the basis for further investigations into the mechanisms underlying the PCD and its role in developmental plasticity of root system architecture and subsequent adaptation to water stress.

Regulation of reactive oxygen species generation under drought conditions in Arabidopsis

“…8,10,13 Disruption of ROS metabolism alters a variety of physiological processes, including cell death, leaf senescence and organ development. 8,11 Measurements of cell death by electrolyte leakage assays and trypan blue staining showed that after drought stress treatments, electrolyte leakage was slightly higher in the 35S:4ΔC plants but lower in the ntl4-1 mutants than that in Col-0 plants.…”

“…8,9 Drought stress stimulates ROS production, inducing programmed cell death in the root tips and enhancing drought tolerance through modification of the root system. 10 Increased ROS levels also induce leaf senescence, contributing to the maintenance of water balance within the whole plant and nutrient remobilization to the youngest leaves or sink organs. 11 We found that the NTL4 gene is induced in the presence of H 2 O 2 , suggesting that the NTL4 gene would be related with ROS response and/or signaling.…”

ABA mediates PEG-mediated premature differentiation of root apical meristem in plants

“…We have previously shown that plants are able to stimulate lateral root development with enhanced stress tolerance through programmed cell death of the root apical meristem (RAM) of the primary roots under severe water stress. 2 Recently, we reported that under mild and moderate water stresses, plant primary roots undergo root tip swelling and RAM premature differentiation resulting in cessation of the primary root growth. 3 We demonstrated that the RAM premature differentiation of primary roots and subsequent lateral formation are directly correlated to plant stress tolerance.…”

Programmed Cell Death as a Response to High Light, UV and Drought Stress in Plants

“…Recent studies have shown that the water deficit triggers PCD not only in green tissues but also in plant root tips. Apical meristem cells of primary roots undergoing PCD, demonstrate increased size of vacuole, degradation of organelles and the collapse of plasma membrane [188].…”