Two ANGUSTIFOLIA genes regulate gametophore and sporophyte development in Physcomitrella patens

Abstract

Summary In Arabidopsis thaliana the ANGUSTIFOLIA (AN) gene regulates the width of leaves by controlling the diffuse growth of leaf cells in the medio‐lateral direction. In the genome of the moss Physcomitrella patens, we found two normal ANs (PpAN1‐1 and 1‐2). Both PpAN1 genes complemented the A. thaliana an‐1 mutant phenotypes. An analysis of spatiotemporal promoter activity of each PpAN1 gene, using transgenic lines that contained each PpAN1‐promoter– uidA (GUS) gene, showed that both promoters are mainly active in the stems of haploid gametophores and in the middle to basal region of the young sporophyte that develops into the seta and foot. Analyses of the knockout lines for PpAN1‐1 and PpAN1‐2 genes suggested that these genes have partially redundant functions and regulate gametophore height by controlling diffuse cell growth in gametophore stems. In addition, the seta and foot were shorter and thicker in diploid sporophytes, suggesting that cell elongation was reduced in the longitudinal direction, whereas no defects were detected in tip‐growing protonemata. These results indicate that both PpAN1 genes in P. patens function in diffuse growth of the haploid and diploid generations but not in tip growth. To visualize microtubule distribution in gametophore cells of P. patens, transformed lines expressing P. patens α‐tubulin fused to sGFP were generated. Contrary to expectations, the orientation of microtubules in the tips of gametophores in the PpAN1‐1/1‐2 double‐knockout lines was unchanged. The relationships among diffuse cell growth, cortical microtubules and AN proteins are discussed.

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.…”

Two atypical ANGUSTIFOLIA without a plant‐specific C‐terminus regulate gametophore and sporophyte shapes in the moss Physcomitrium (Physcomitrella) patens

“…In our previous study (Hashida et al, 2020), we found four genes that were homologous to AtAN in the P. patens genome.…”

“…These data indicate that neither PpAN2 gene was highly expressed (RPKM > 1500). Because the values of RPKM were approximately 10-20 for the PpAN1 genes (Hashida et al, 2020), expression of the PpAN2 genes was relatively low.…”

“…We have termed all C-terminal domains bearing ANs as 'canonical AN', to distinguish them from Cterminal domain-less atypical PpAN2s. Promoters for both PpAN1-1 and PpAN1-2 are active in the stems of haploid gametophores and in the mid-to-basal region of the young sporophyte that develops into the seta and the foot (Hashida et al, 2020). Analyses of knockout lines of the PpAN1-1 and PpAN1-2 genes have indicated that both genes regulate cell elongation in haploid gametophore stems.…”

“…In wild-type (WT) Marchantia polymorpha thallus epidermal cells, cortical MTs were primarily oriented perpendicular to the direction of growth, whereas the cells of M. polymorpha AN gene knockout mutants (Mpan) showed reduced elongation and more diverse MT orientations (Furuya et al, 2018). In contrast, cortical MTs in the tips of gametophores of WT plants were oriented perpendicular to the growth direction and were unchanged in the PpAN1-1/1-2 double knockout (DKO) lines (Hashida et al, 2020).…”