AUTHOR=Chaiwongsar Suraphon , Strohm Allison , Su Shih-Heng , Krysan Patrick J.

TITLE=Genetic analysis of the Arabidopsis protein kinases MAP3Kε1 and MAP3Kε2 indicates roles in cell expansion and embryo development

JOURNAL=Frontiers in Plant Science

VOLUME=3

YEAR=2012

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2012.00228

DOI=10.3389/fpls.2012.00228

ISSN=1664-462X

ABSTRACT=<p><italic>MAP3Kε1</italic> and <italic>MAP3Kε2 </italic>are a pair of <italic>Arabidopsis thaliana</italic> genes that encode protein kinases related to cdc7p from <italic>Saccharomyces cerevisiae</italic>. We have previously shown that the <italic>map3kε1;map3kε2</italic> double-mutant combination causes pollen lethality. In this study, we have used an ethanol-inducible promoter construct to rescue this lethal phenotype and create <italic>map3kε1</italic><sup>-/-</sup>;<italic>map3kε2</italic><sup>-/-</sup> double-mutant plants in order to examine the function of these genes in the sporophyte. These rescued double-mutant plants carry a yellow fluorescent protein (<italic>YFP</italic>)<italic>-MAP3Kε1</italic> transgene under the control of the alcohol-inducible <italic>AlcA</italic> promoter from <italic>Aspergillus nidulans</italic>. The double-mutant plants were significantly smaller and had shorter roots than wild-type when grown in the absence of ethanol treatment. Microscopic analysis indicated that cell elongation was reduced in the roots of the double-mutant plants and cell expansion was reduced in rosette leaves. Treatment with ethanol to induce expression of <italic>YFP-MAP3Kε1</italic> largely rescued the leaf phenotypes. The double-mutant combination also caused embryos to arrest in the early stages of development. Through the use of YFP reporter constructs we determined that <italic>MAP3Kε1</italic> and <italic>MAP3Kε2</italic> are expressed during embryo development, and also in root tissue. Our results indicate that <italic>MAP3Kε1</italic> and <italic>MAP3Kε2 </italic>have roles outside of pollen development and that these genes affect several aspects of sporophyte development.</p>