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Generation of a Spacing Pattern: The Role of TRIPTYCHON in Trichome Patterning in Arabidopsis

1999; Oxford University Press; Volume: 11; Issue: 6 Linguagem: Inglês

10.1105/tpc.11.6.1105

1532-298X

Arp Schnittger, Ulrike Folkers, Birgit Schwab, Gerd Jürgens, Martin Hülskamp,

Polysaccharides and Plant Cell Walls

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 (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.