Arabidopsis ADF7 inhibits VLN1 to regulate actin filament dynamics and
ROS accumulation in root hair development responses to osmotic stress
Abstract
Actin dynamics are essential for root hair development, however, the
underlying molecular mechanisms of actin binding protein cooperation and
plant abiotic stress responses are largely unknown. Here, genetic
analysis displayed that actin depolymerizing protein ADF7 and actin
bundling protein VLN1 are positively and negatively involved in root
hair development in Arabidopsis, respectively. Moreover, ADF7 acts
upstream of VLN1 in root hair development by the analysis of RT-qPCR,
Gus staining, Western blot and genetics. The observation of F-actin
dynamics shows that ADF7 inhibits VLN1, leading to the decline of
filament actin (F-actin) bundling and thick bundle formation and the
increase of F-actin turnover and depolymerization in epidermal cells of
root apices. Actin pharmacological experiments confirm that ADF7 and
VLN1 are via regulating F-actin dynamics to active root hair
development. Furthermore, F-actin depolymerization coregulated by ADF7
and VLN1 elevates the reactive oxygen species (ROS) level in root tips.
Additionally, F-actin depolymerization and ROS accumulation coregulated
by ADF7 and VLN1 are involved in osmotic stress-induced root hair
development. Our work reveals that ADF7 inhibits VLN1 to induce F-actin
turnover and depolymerization and ROS level in root tips, which play an
important role in root hair formation responses to osmotic stress .