ANGUSTIFOLIA contributes to the regulation of three-dimensional morphogenesis in the liverwort Marchantia polymorpha

Abstract

mutants deficient in ANGUSTIFOLIA (AN) exhibit several phenotypes at the sporophyte stage, such as narrow and thicker leaves, trichomes with two branches, and twisted fruits. It is thought that these phenotypes are caused by abnormal arrangement of cortical microtubules (MTs). AN homologs are present in the genomes of diverse land plants, including the basal land plant , and their molecular functions have been shown to be evolutionarily conserved in terms of the ability to complement the mutation. However, the roles of ANs in bryophytes, the life cycle of which includes a dominant haploid gametophyte generation, remain unknown. Here, we have examined the roles of AN homologs in the model bryophyte (MpAN). Mp knockout mutants showed abnormal twisted thalli and suppressed thallus growth along the growth axis. Under weak blue light conditions, elongated thallus growth was observed in wild-type plants, whereas it was suppressed in the mutants. Moreover, disordered cortical MT orientations were observed. Our findings suggest that MpAN contributes to three-dimensional morphogenesis by regulating cortical MT arrangement in the gametophytes of bryophytes.

Two ANGUSTIFOLIA genes regulate gametophore and sporophyte development in Physcomitrella patens

“…Complementation analyses confirmed that PpAN1‐1 and PpAN1‐2 functions are similar to those conserved in angiosperm AN s, because they rescued an‐1 phenotypes (Figure ). Past experiments with AN knockout mutants in A. thaliana and M. polymorpha have shown that deficient phenotypes only appeared in dominant generations: the gametophyte generation in M. polymorpha and the sporophyte generation in A. thaliana (Kim et al , ; Folkers et al , ; Furuya et al , ). Therefore, Furuya et al () assumed that ANs, involved in gametophyte morphogenesis in bryophytes were recruited for sporophyte morphogenesis in vascular plants during the evolution of land plants, specifically the transition in dominance from the gametophyte (haploid) to sporophyte (diploid) phases.…”

“…The A. thaliana and M. polymorpha AN LOF mutants also showed similar phenotypes to the defects in cell expansion observed in P. patens . In A. thaliana an leaves, cell width expansion was reduced in epidermal and palisade tissue (Tsukaya et al , ; Hülskamp et al , ; Tsuge et al , ), whereas epidermal cell expansion was suppressed when Mpan knockout lines were cultured under conditions of enhanced thallus elongation (Furuya et al , ). Although an mutants in A. thaliana and M. polymorpha shared similar defects in cell expansion, effects on cortical MTs differed.…”

“…Plant ANs from the angiosperm Ipomoea nil (Japanese morning glory), the gymnosperm Larix gmelinii (Dahurian larch) and the liverwort Marchantia polymorpha ( MpAN ) have been shown to rescue the narrow leaf phenotype of the A. thaliana an‐1 mutant, suggesting that the molecular functions of AN are conserved in land plants (Cho et al , ; Lin et al , ; Minamisawa et al , ). Among these genes, knockout lines have been generated for M. polymorpha (Furuya et al , ). In contrast to tracheophytes (vascular plants), the bryophyte life cycle is dominated by a gametophyte that has a simpler morphology than vascular plants.…”

“…Thalli grow via repeated dichotomous branching (bifurcation) of apical notches, which are sites of cell proliferation (Shimamura, ). MpAN knockout mutants ( Mpan ) exhibit abnormal twisted thalli and suppressed thallus growth along the growth axis (Furuya et al , ), as well as disordered cortical MT orientations, suggesting that MpAN is involved in cell expansion via regulation of cortical MT arrangement in bryophyte gametophytes (Furuya et al , ).…”

Excess Pyrophosphate Restrains Pavement Cell Morphogenesis and Alters Organ Flatness in Arabidopsis thaliana

“…Cell Phenotype Are Synergistically Enhanced in an-1 fugu5-1 ANGUSTIFOLIA (AN) is the sole homolog of CtBP/BARS in Arabidopsis. The CtBP/BARS protein family has diverse functions, intercellular localization, and developmental role in a wide range of land plants (Kim et al, 2002;Minamisawa et al, 2011;Furuya et al, 2018;Hashida et al, 2019). AN regulates the width of Arabidopsis leaves by controlling the polar elongation of leaf cells.…”