Symmetry, asymmetry, and the cell cycle in plants: known knowns and some known unknowns

Abstract

The body architectures of most multicellular organisms consistently display both symmetry and asymmetry. Here, we discuss some of the available knowledge and open questions on how symmetry and asymmetry appear in several conspicuous plant cells and tissues. We focus, where possible, on the role of genes that participate in the maintenance or the breaking of symmetry and that are directly or indirectly related to the cell cycle, under an organ-centric point of view and with an emphasis on the leaf.

NAC-MYB-based transcriptional regulation of secondary cell wall biosynthesis in land plants

“…In plants, the majority of MYB proteins have only two domains and thus are called R2R3-MYB proteins; R2R3-MYB proteins are encoded by 126 genes in Arabidopsis (Stracke et al, 2001 ; Dubos et al, 2010 ), 109 in rice (Yanhui et al, 2006 ), 141 in eucalyptus (Soler et al, in press ), and 192 in poplar (Wilkins et al, 2009 ). These R2R3-MYB family genes function in a wide range of developmental processes, stress responses, and metabolism (Jin and Martin, 1999 ; Stracke et al, 2001 ; Larkin et al, 2003 ; Grotewold, 2006 ; Lepiniec et al, 2006 ; Valliyodan and Nguyen, 2006 ; Bergmann and Sack, 2007 ; Chinnusamy et al, 2007 ; Ishida et al, 2008 ; Dubos et al, 2010 ; De Geyter et al, 2012 ; Grima-Pettenati et al, 2012 ; Muñoz-Nortes et al, 2014 ).…”

A role for LAX2 in regulating xylem development and lateral-vein symmetry in the leaf

“…In certain scenarios, restoration of the individual's homeostasis cannot be fully reached, leaving a permanent mark on developmental patterning (Leamy and Klingenberg, 2005). Ecologists have largely recorded this environmental footprint in the development of organ symmetry, such as symmetry of wings and embryos in Drosophila (Klingenberg et al, 1998;Houchmandzadeh et al, 2002), mandibles in mice (Leamy et al, 2002), and leaf-lamina (Muñoz-Nortes et al, 2014;Graham et al, 2015) and leaf-venation patterning (Aloni et al, 2003) in plants. Developmental gene regulatory networks play a central role in the resilience to environmental stress.…”

Calpain DEK1 acts as a developmental switch gatekeeping cell fate transitions

“…FOR1D Vidali et al, 2009; SPR2 Leong et al, 2018). Plant Rho GTPases (ROP) are key regulators of cellular polarization and are involved in several symmetry breaking mechanisms (Eklund et al 2010; Muñoz-Nortes et al 2014). Activated ROP binds effector proteins e.g.…”

“…Activated ROP binds effector proteins e.g. to initiate remodelling of the cell wall (Cheng et al 2020) or the cytoskeleton (Muñoz-Nortes et al 2014). Sometimes they act as transducers for receptor-like kinases (Jose et al, 2020).…”