Location: Corn Insects and Crop Genetics ResearchTitle: A pectin methylesterase ZmPme3 is expressed in Gametophyte factor1-s (Ga1-s) silks and maps to that locus in maize (Zea mays L.)
|Moran Lauter, Adrienne|
|MUSZYNSKI, MICHAEL - University Of Hawaii|
|HUFFMAN, RYAN - Iowa State University|
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2017
Publication Date: 11/7/2017
Citation: Moran Lauter, A., Muszynski, M.G., Huffman, R.D., Scott, M.P. 2017. A pectin methylesterase ZmPme3 is expressed in Gametophyte factor1-s (Ga1-s) silks and maps to that locus in maize (Zea mays L.). Frontiers in Plant Science. 8:1926. https://dx.doi.org/10.3389%2Ffpls.2017.01926.
Interpretive Summary: Corn pollen is carried by the wind and can pollinate corn that is planted in different fields, carrying the genes from one corn field into another. This type of contamination can be problematic when different market classes of corn are grown near each other. For example, contamination of organic corn fields by GMO pollen can significantly reduce the value of the organic corn, forcing producers to market it as normal commodity corn rather than a high value product for export. Contamination of white corn by yellow corn pollen or popcorn by field corn reduces the value of these products as well. A genetic system called gametophytic incompatibility can be used to prevent unwanted pollination. While this system has been studied for more than a century, it's molecular mechanism is still unknown. We identified a gene involved in gametophytic incompatibility and proposed a model for how this system works at a molecular level. This model will be important to scientists because it provides new hypotheses to test.
Technical Abstract: The ga1 locus of maize confers unilateral cross incompatibility, preventing cross pollination between females carrying the incompatible allele and males not carrying a corresponding compatible allele. To characterize this system at the molecular level, we carried out a transcript profiling experiment in which silks from near isogenic lines carrying the Ga1-s and ga1 alleles were compared. While several differentially expressed genes were identified, only one mapped to the known location of Ga1-s. This gene is a pectin methylesterase, which we designated as ZmPme3, and is present and expressed only in Ga1-s genotypes. While ZmPME3 is not present in the ga1 genotypes examined, a pectin methylesterase gene cluster is found in ga1 genotypes. The gene cluster in W22 contains 58 tandem full-length or partial PME pseudo genes. These data combined with a wealth of previously published data on the involvement of PMEs in pollen tube growth suggest a model in which gametophytic incompatibility is conferred by the presence of ZmPme3 in silk. Incompatibility would be overcome by expression of an inhibitor of ZmPme3 in pollen. Consistent with this model, a third allele Ga1-m, which lacks the female function of Ga1-s, has a mutationally inactivated version of ZmPme3.