Figure 2.

Schematic model of actin dynamics in individual cell growth and plant development in response to environmental stresses. (A) Short-term salt stress can trigger the assembly and formation of microfilament bundles in Arabidopsis. However, the polymerization of microfilaments is inhibited in susceptible seedlings subjected to long-term or high salt stress. (B) Exposure to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) induces two distinct changes in the arrangement of the cortical actin network. At 6 h post-inoculation (hpi), cells show an increase in the overall density of actin filament network. Later, ~24 hpi, a reduction in the number of individual filaments or an increase in the extent of actin filament bundling is obvious. (C) Under high external pH conditions, microfilament depolymerization is induced, which is associated with the inhibition of Arabidopsis root growth. (D) Damages caused by heat stress to actin filaments mainly concern the actin array present in the subapex, a region critical for regulating the organelle and vesicle distribution in the pollen tube apex. (E) The Arabidopsis hypocotyl epidermal cell exhibits actin microfilament aggregation in response to mechanical stimulation, and this applied pressure is utilized to simulate the attack by fungal or oomycete hyphae.