Apoplastic class III peroxidases PRX62 and PRX69 promote Arabidopsis root hair growth at low temperature.

Root Hairs (RHs) growth is influenced by endogenous and by external environmental signals that coordinately regulate its final cell size. We have recently determined that RH growth was unexpectedly boosted when Arabidopsis thaliana seedlings are cultivated at low temperatures. It was proposed that RH growth plasticity in response to low temperature was linked to a reduced nutrient availability in the media.

A cell surface arabinogalactan-peptide influences root hair cell fate.

Root hairs (RHs) develop from specialized epidermal trichoblast cells, whereas epidermal cells that lack RHs are known as atrichoblasts. The mechanism controlling RH cell fate is only partially understood. RH cell fate is regulated by a transcription factor complex that promotes the expression of the homeodomain protein GLABRA 2 (GL2), which blocks RH development by inhibiting ROOT HAIR DEFECTIVE 6 (RHD6).

Filling the Gaps to Solve the Extensin Puzzle.

Extensins (EXTs) are highly repetitive plant O-glycoproteins that require several post-translational modifications (PTMs) to become functional in plant cell walls. First, they are hydroxylated on contiguous proline residues; then they are O-glycosylated on hydroxyproline and serine. After secretion into the apoplast, O-glycosylated EXTs form a tridimensional network organized by inter- and intra-Tyr linkages.