In odd-looking mutant, clues about how maize plants control stem cell number

Cold Spring Harbor, NY -- In plants, the growth of organs such as roots, leaves and flowers depends upon the activity of meristems. These reservoir-like compartments hold stem cells, which have the ability to develop into various different cell types. 

jackson_enlarged_corn This electron microscope image of the growing tip, or meristem, of a corn plant tassel shows how it is enlarged in plants in which the gene COMPACT PLANT2 (CT2) is mutated. Within the meristem are stem cells that can develop into various cell types. (click to enlarge)
At Cold Spring Harbor Laboratory (CSHL), Professor David Jackson studies naturally occurring mutations in plants to obtain insights about how plants regulate their growth. This work has powerful implications for efforts to increase the yield of basic food crops like maize (or corn, as it is called in North America).

Today, in a paper appearing online in Nature, Jackson and colleagues present first evidence of a functional interaction between an important class of signaling molecule called a G protein, which binds receptors, and an unexpected class of cell-surface receptors.

Working backward from an odd-looking maize mutant called COMPACT PLANT2 (CT2) that develops abnormally enlarged ears – a phenomenon called fasciation – Jackson, Peter Bommert, Ph.D., and others found this gene to encode a G protein called Gα. Further experiments indicated an unexpected interaction between Gα and a cell-surface receptor that is a part of the CLAVATA signaling pathway, known to control stem cell activation. 

jackson_corn_comparison Maize plants with CT2 mutations grow ears displaying a growth anomaly called fasciation. Compared to wild-type ears (left) the fasciated ears are stunted, but also contain more kernels (i.e., seeds), a consequence of stem cell dysregulation.
The “beginning” and “end” of the CLAVATA signaling pathway were known: receptors at the cell surface are activated by a small, secreted ligand to regulate a transcription factor called WUSCHEL inside the nucleus. The Jackson lab’s new research begins to fill in the gaps between these points. 

Contrary to prior assumptions based on examples in mammals and yeast, the new research suggests that in plants, Gα, which acts as a signaling switch, can be activated by a G protein-coupled receptor (GPCR) that belongs to a class of cell-surface receptors that pass the cell membrane only a single time.

“The idea that Gα interacts with a single-pass transmembrane receptor called FEA2 is at odds with the dogma that in yeast and mammals, Gα interacts with GPCRs of the type that pass through the membrane seven times – 7TM receptors. Further research should indicate whether this is true not only in maize but generally in plants,” Jackson says. 

The research described in this release was supported by a DFG grant, a BARD Post doctoral award, Dupont- Pioneer, and the National Science Foundation Plant Genome Program.

“The maize Gα gene COMPACT PLANT2 functions in CLAVATA signalling to control shoot meristem size” appears online ahead of print in Nature on September 11, 2013.  The authors are: Peter Bommert, Byoung Il Je, Alexander Goldshmidt and David Jackson. The paper can be accessed at

About Cold Spring Harbor Laboratory

Founded in 1890, Cold Spring Harbor Laboratory (CSHL) has shaped contemporary biomedical research and education with programs in cancer, neuroscience, plant biology and quantitative biology. CSHL is ranked number one in the world by Thomson Reuters for the impact of its research in molecular biology and genetics. The Laboratory has been home to eight Nobel Prize winners. Today, CSHL's multidisciplinary scientific community is more than 600 researchers and technicians strong and its Meetings & Courses program hosts more than 12,000 scientists from around the world each year to its Long Island campus and its China center. Tens of thousands more benefit from the research, reviews, and ideas published in journals and books distributed internationally by CSHL Press. The Laboratory's education arm also includes a graduate school and programs for middle and high school students and teachers. CSHL is a private, not-for-profit institution on the north shore of Long Island. For more information, visit

Written by: Peter Tarr, Senior Science Writer | | 516-367-8455