GhRabA4c coordinates cell elongation via regulating actin filament–dependent vesicle transport

Abstract

Plant cell expands via a tip growth or diffuse growth mode. In plants, RabA is the largest group of Rab GTPases that regulate vesicle trafficking. The functions of RabA protein in modulating polarized expansion in tip growth cells have been demonstrated. However, whether and how RabA protein functions in diffuse growth plant cells have never been explored. Here, we addressed this question by examining the role of GhRabA4c in cotton fibers. GhRabA4c was preferentially expressed in elongating fibers with its protein localized to endoplasmic reticulum and Golgi apparatus. Over- and down-expression of GhRabA4c in cotton lead to longer and shorter fibers, respectively. GhRabA4c interacted with GhACT4 to promote the assembly of actin filament to facilitate vesicle transport for cell wall synthesis. Consistently, GhRabA4c-overexpressed fibers exhibited increased content of wall components and the transcript levels of the genes responsible for the synthesis of cell wall materials. We further identified two MYB proteins that directly regulate the transcription of GhRabA4c. Collectively, our data showed that GhRabA4c promotes diffused cell expansion by supporting vesicle trafficking and cell wall synthesis.

GhMPK9‐GhRAF39_1‐GhWRKY40a Regulates the GhERF1b‐ and GhABF2‐Mediated Pathways to Increase Cotton Disease Resistance

“…pBIN-35S::eGFP4, pBIN-35S::GhMPK9-eGFP4, and pBIN-35S::GhRAF39_1-eGFP4 were transiently expressed in N. benthamiana leaves following the infiltration method. [59] The pBIN-35S::eGFP4 or pBIN-35S::GhWRKY40a-eGFP4 was transiently co-expressed with nuclear-localized AtHTB2-mCherry. [60] After 3d infiltration, fluorescence in the tobacco epidermal cell was observed using a confocal laser scanning microscope at the specific excitation and emission wavelengths (eGFP, 488 and 507 nm; mCherry, 587 and 610 nm) (LSM 780, Zeiss, Germany).…”