Oral Annual Conference of the Genetics Society of Australasia with the NZ Society for Biochemistry & Molecular Biology

the transcription factor petal loss suppresses growth between sepals in arabidopsis (527)

David R Smyth 1 , Aydin Kilinc 1 , Edwin R Lampugnani 1 , Martin O'Brien 1 , Tezz Quon 1
  1. Monash University, Clayton, VIC, Australia

Flowers develop from hemispheres of undifferentiated cells called floral meristems. Organs arise on the meristem flanks in defined numbers and identities. We have been characterising the role of a transcription factor gene called PETAL LOSS in regulating the development of sepals, the outer leaf-like organs, using the model species Arabidopsis thaliana. PETAL LOSS is a member of the plant-specific trihelix family. Loss of function mutants show additional growth between sepals, and outgrowth of the sepal edges. PETAL LOSS is specifically expressed in these regions, and its role seems to be to help maintain space between the four sepals, and to limit their lateral growth. Physical interactions occur between PETAL LOSS and AKIN10, the low-energy sensing kinase SnRK1 (orthologous to Snf1 of yeast and AMPK1 of animals). PETAL LOSS also interacts genetically and physically with ROXY1, a glutaredoxin. These proteins can sense hypoxic regions and some activate transcription factors by reducing dithiols.  Our working hypothesis is that PETAL LOSS is the target of such sensors of energy deficit and/or hypoxia in specific regions of the developing flower, and that it then induces the expression of growth-suppressing genes. Loss of PETAL LOSS function also leads to the loss of some petals, but this is likely an indirect disruption of auxin signalling of petal initiation. The intricate architecture of the flower may depend on the interplay of many regulatory genes like PETAL LOSS that, together with hormones like auxin, define its blueprint and the diverse development of its floral organs.