An international research team led by the Leibniz Institute of Plant
Genetics and Crop Plant Research (IPK) has identified a genethat plays a
decisive role in the development of barley's slender inflorescences
called spikes. The COMPOSITUM1 (COM1) gene was discovered to have
acquired a new function during grass evolution.
The "spikelet meristem" (SM) plays a central role during the development
of the grass inflorescence. To do this, however, cells destined to
become SM must first attain the SM identity. This is achieved, among
other things, by gene regulation. Dr. Naser Poursarebani, first-author
of the study and discoverer of the COM1 gene explains that the COM1
barley mutant e.g. is compromised in a way that the corresponding cells
cannot perceive or convert the SM identity signal. The signal
transmission does not function properly so that the cells cannot attain
their correct cell identity, she added.
In barley, COM1 normally ensures that meristem cells develop into
spikelets by influencing the properties of their cell walls and thus
ultimately controlling cell growth. COM1's contribution to this identity
signal is also its newly discovered function, which is not found in
other grasses such as rice, maize, sorghum, or twigs (/Brachypodium
distachyon/L.). Barley COM1 function is fundamentally different from
those above-mentioned grass species, in which the gene rather promotes
the formation of inflorescence branches.