Symplastic communication in the root cap directs auxin distribution to modulate root development

Abstract

Root cap not only protects root meristem, but also detects and transduces the signals of environmental changes to affect root development. The symplastic communication is an important way for plants to transduce signals to coordinate the development and physiology in response to the changing enviroments. However, it is unclear how the symplastic communication between root cap cells affects root growth. Here we exploit an inducible system to specifically block the symplastic communication in the root cap. Transient blockage of plasmodesmata (PD) in differentiated collumella cells severely impairs the root development in Arabidopsis, in particular in the stem cell niche and the proximal meristem. The neighboring stem cell niche is the region that is most sensitive to the disrupted symplastic communication and responds rapidly via the alteration of auxin distribution. In the later stage, the cell division in proximal meristem is inhibited, presumably due to the reduced auxin level in the root cap. Our results reveal the essential role of the differentiated collumella cells in the root cap mediated signaling system that directs root development.

Parallel auxin transport via PINs and plasmodesmata during the Arabidopsis leaf hyponasty response

“…The effect of reduced plasmodesmatal diffusion capacity could be tested by expressing the icals3m -module in mesophyll epidermis and endodermis cells. This would enable the induction of callose synthesis, and thereby the reduction of plasmodesmata permeability, at the relevant interfaces (Liu et al 2017 ; Li et al 2022 ).…”

Embryo sac development relies on symplastic signals from ovular integuments in Arabidopsis

“…Integument-specific expression of cals3m results in mitotic arrest during female gametogenesis and reduces fertility Because CTL1 mediates PD organization and thus is critical for symplastic signaling (Gao et al, 2017), we hypothesized that defective female gametophytic development in ctl1 was caused by hindered symplastic signaling from integuments. To test this hypothesis, we used ectopic expression of cals3m (Li et al, 2022;Liu et al, 2017;Vat en et al, 2011) under the INNER NO OUTER (INO) promoter. The promoter of INO is specifically active in outer integuments during its initiation and growth based on RNA in situ hybridization and promoter-GUS reporter analysis reported earlier (Balasubramanian & Schneitz, 2002;Liu et al, 2019;Villanueva et al, 1999;Wang et al, 2016), whereas ectopic expression of cals3m results in excess deposition of callose at PDs, leading to reduced PD permeability (Vat en et al, 2011).…”

“…Several proteins confined to PD and mediating PD permeability have been reported in Arabidopsis, including PLASMODESMATA CALLOSE BINDING PROTEINs (PDCBs), Choline transporter‐like 1 (CTL1), PLASMODESMATA‐LOCATED PROTEINs (PDLPs), or LYSIN MOTIF DOMAIN‐CONTAINING GLYCOSYLPHOSPHATIDYLINOSITOL‐ANCHORED PROTEIN 2 (LYM2) (Faulkner et al., 2013; Gao et al., 2017; Kraner et al., 2017; Lim et al., 2016; Simpson et al., 2009; Wang et al., 2017, 2020). In addition, the manipulation of callose deposition to PD neck by expressing a synthetic dominant mutant of CALLOSE SYNTHASE 3 ( CALS3 ) with cell‐specific promoters blocks symplastic communication among stele, quiescent center (QC), or root cap (Li et al., 2022; Liu et al., 2017; Vatén et al., 2011; Wu et al., 2016).…”

APP1/NTL9‐CalS8 module ensures proper phloem differentiation by stabilizing callose accumulation and symplastic communication

“…In plants, intercellular communication and molecular exchanges occur through apoplastic and symplastic pathways. Symplastic communication coordinates diverse signals during biological processes, including plant growth, development, and environmental responses (Faulkner, 2018; Gaudioso‐Pedraza et al ., 2018; Azim & Burch‐Smith, 2020; Mellor et al ., 2020; Li et al ., 2022; Wu et al ., 2023). Plasmodesmata provide a direct symplastic channel for cell‐to‐cell molecular transport and play roles in phloem development and root growth (Benitez‐Alfonso, 2014; Yadav et al ., 2014; Sevilem et al ., 2015; Lee & Frank, 2018).…”