ARS | Publication request: The milkweed pod1 Gene Encodes a KANADI Protein That Is Required for Abaxial/Adaxial Patterning in Maize Leaves

Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2008
Publication Date: August 29, 2008
Repository URL: http://www.plantcell.org/cgi/reprint/20/8/2073?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=Hake&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
Citation: Candela Anton, H., Johnston, R., Gerhold, A., Foster, T., Hake, S.C. 2008. The milkweed pod1 Gene Encodes a KANADI Protein That Is Required for Abaxial/Adaxial Patterning in Maize Leaves. The Plant Cell. 20:2073-2087.

Interpretive Summary: Leaf primordia initiate from the shoot apical meristem with inherent polarity; the adaxial side faces the meristem while the abaxial side faces away from the meristem. Adaxial/abaxial polarity is thought to be necessary for the laminar growth of leaves, as mutants lacking either adaxial or abaxial cell types often develop radially symmetric lateral organs. The milkweed pod1 (mwp1) mutant of maize has adaxialized sectors that are confined to the sheath, the proximal part of the leaf. Ectopic leaf flaps develop where adaxial and abaxial cell types juxtapose. The distal portion of the leaf, the blade, is not affected. The phenotype of mwp1; Rld1 double mutants shows that both genes are also required early in leaf development to delineate leaf margins, as well as to initiate vascular and photosynthetic tissues, thereby contributing to the specialized functions of the abaxial and adaxial domains.

Technical Abstract: We positionally cloned mwp1 and found that it encodes a KANADI transcription factor. Double mutants of mwp1-R with a microRNA-resistant allele of rld1, Rld1-N1990, show a synergistic phenotype with polarity defects in sheath and blade, and a failure to differentiate vascular and photosynthetic cell types in the adaxialized sectors. Ectopic expression of the HD-ZIPIII gene rolled leaf1 (rld1) correlates with the adaxialized regions. The sectored phenotype, timing of the defect and misexpression of rld1 suggest that mwp1 is required late in leaf development to maintain abaxial cell fate.