ARABIDOPSIS PM19-LIKE 1 GENE IS INVOLVED IN DORMANCY AND GERMINATION AND IS LOCALISED IN COTYLEDON CELLS
Barrero, J.M., Dorr, M., Talbot, M., White, R. and Gubler, F.
CSIRO Agriculture and Food, GPO Box 1700, Canberra ACT 2601, Australia
Contact: Jose M. Barrero, firstname.lastname@example.org
Increasing seed dormancy is a major goal for cereal breeders around the world, because the premature germination of grains before harvest is a serious problem in all wheat growing regions. This problem arises because of the lack of grain dormancy in modern wheat varieties which produce grain prone to germinate on the mother plant following rain. Recently, we have characterised two wheat genes, TaPM19-A1 and A2, finding that their expression positively correlates with grain dormancy. Although a role for these genes in regulating grain dormancy is clear, the function of AWPM19 (ABA-induced wheat plasma membrane) gene family is unknown. The expression of PM19 genes is under the control of the hormone abscisic acid (ABA), which is a well-known dormancy promoting factor. Previous studies in wheat indicated that PM19 encodes a protein localised in the plasma membrane, and other indirect studies in Arabidopsis suggested that could also be found in the seed oil bodies. We have taken advantage of the model plant Arabidopsis to study the function of this class of genes. In this work we have identified the Arabidopsis orthologous gene PM19-Like 1 (PM19L1) and demonstrated that knockout mutations alter seed dormancy. Not only primary dormancy but also secondary dormancy in response to high temperature was increased by the PM19L1 mutation. We have used transgenic plants to over-express or repress the expression of PM19L1, which resulted in a decrease or an increase in seed dormancy, respectively. We have also investigated the function of PM19L1 by localising the PM19 protein to plasma membranes of cotyledon cells in Arabidopsis seeds. The function of PM19 could be related to the control of dormancy by changes in membrane characteristics in response to temperature.