Abstract
Leaf expansion in Arabidopsis thaliana depends on polar elongation of leaf cells in the leaf-width and leaf-length directions. It is known that elongations in two directions are controlled independently. ANGUSTIFOLIA (AN), a plant homolog of animal CtBP/BARS, controls the polar elongation in the width direction and the trichome-branching pattern in A. thaliana. AN has a plant-specific long C-terminal region of about 200 aa. We isolated four AN homologous genes from the moss Physcomitrella patens (PpAN). While two PpAN proteins PpAN1-1 and PpAN1-2 are similar to AN in total region, PpAN2-1 and Pp2-2 have no plant-specific C-terminus. The promoter GUS analysis showed that PpAN1-1 and PpAN 1-2 genes were expressed at the center of the stem in gametophores, while transcripts for PpAN2-1 and PpAN2-2 were detected at the center of the stem and in the basal parts of leaves of gametophores. Northern blot analysis also indicated that transcripts were more abundant in gametophores than in protonemata for all AN genes. Single and double PpAN gene knockout lines were produced by a gene-targeting technique. We are now making the PpAN triple- and quadri-knockout mutants.
