Arabidopsis thaliana SHAGGY-related protein kinases (AtSK11 and 12) function in perianth and gynoecium development

In higher plants, the correct patterning of the floral meristem in terms of organ type, number and form is the result of a concerted expression of a n etwork of genes. We describe phenotypes of flower patterning, resulting fro m a reduction of transcript levels of the Arabidopsis SHAGGY-related protei n kinase genes AtSK11(ASK alpha) and AtSK12(ASK gamma). The AtSK genes are plant homologues of the Drosophila shaggy (SGG) gene and the mammalian Glyc ogen-Synthase Kinase-3 (GSK-3). The SGG protein kinase is a key component o f the wingless signalling pathway and is required for the establishment of tissue patterning and cell fate determination. The expression patterns of t he AtSK11(ASK alpha) and AtSK12(ASK gamma) genes during wild-type Arabidops is inflorescence development, detected by in situ hybridisation, have been shown to be consistent with a possible role in floral meristem patterning. AtSK11(ASK alpha) and AtSK12(ASK gamma) transcripts were detected at the pe riphery of the inflorescence meristem and in the floral meristem. At later stages the expression of the AtSK genes became localised in specific region s of developing flower organ primordia. Furthermore, we have obtained and a nalysed transgenic plants containing AtSK11(ASK alpha) and AtSK12(ASK gamma ) gene specific antisense constructs. These plants developed flowers showin g a higher number of perianth organs and an alteration of the apical-basal patterning of the gynoecium.