Trichomes in Arabidopsis are single-celled hairs that exhibit a regular spacing pattern. Here, the role of TRIPTYCHON ( TRY ) in the generation of this spacing pattern is studied. By using genetic mosaics, we demonstrate that the formation of trichome clusters in try mutants is not correlated with cell lineage, indicating that TRY is required to single out trichome cells in a process involving cellular interactions. The genetic interactions of TRY , GLABRA1 ( GL1 ), and TRANS-PARENT TESTA GLABRA ( TTG ) in trichome patterning are assessed by determining the cluster frequency in various genetic combinations. It is shown that TRY acts as a negative regulator of GL1 -and TTG -dependent pathways. Furthermore, it is demonstrated that trichome initiation in ttg-1 , a strong ttg allele, is rescued almost to wild-type levels in a try background in which GL1 is expressed under the control of the cauliflower mosaic virus 35S promoter, indicating that TTG acts upstream of GL1 and TRY . These findings are incorporated into a model to explain the generation of a trichome spacing pattern from a homogeneous population of epidermal cells.

No abstract

The ANGUSTIFOLIA (AN) gene is required for leaf hair (trichome) branching and is also involved in polarized expansion underlying organ shape. Here we show that the AN gene encodes a C-terminal binding proteins/brefeldin A ADP-ribosylated substrates (CtBP/BARS) related protein. AN is expressed at low levels in all organs and the AN protein is localized in the cytoplasm. In an mutant trichomes, the organization of the actin cytoskeleton is normal but the distribution of microtubules is aberrant. A role of AN in the control of the microtubule cytoskeleton is further supported by the finding that AN genetically and physically interacts with ZWICHEL, a kinesin motor molecule involved in trichome branching. Our data suggest that CtBP/BARS-like protein function in plants is directly associated with the microtubule cytoskeleton.

Trichomes (plant hairs) in Arabidopsis thaliana are large non-secreting epidermal cells with a characteristic three-dimensional architecture. Because trichomes are easily accessible to a combination of genetic, cell biological and molecular methods they have become an ideal model system to study various aspects of plant cell morphogenesis. In this review we will summarize recent progress in the understanding of trichome morphogenesis.

Trichomes in Arabidopsis are single-celled hairs that exhibit a regular spacing pattern. Here, the role of TRIPTYCHON (TRY) in the generation of this spacing pattern is studied. By using genetic mosaics, we demonstrate that the formation of trichome clusters in try mutants is not correlated with cell lineage, indicating that TRY is required to single out trichome cells in a process involving cellular interactions. The genetic interactions of TRY, GLABRA1 (GL1), and TRANSPARENT TESTA GLABRA (T TG) in trichome patterning are assessed by determining the cluster frequency in various genetic combinations. It is shown that TRY acts as a negative regulator of GL1- and TTG-dependent pathways. Furthermore, it is demonstrated that trichome initiation in ttg-1, a strong ttg allele, is rescued almost to wild-type levels in a try background in which GL1 is expressed under the control of the cauliflower mosaic virus 35S promoter, indicating that T TG acts upstream of GL1 and TRY. These findings are incorporated into a model to explain the generation of a trichome spacing pattern from a homogeneous population of epidermal cells.