Controlling the inflorescence architecture of barley

The appearance of the flowers of grasses – which include barley – is controlled by “meristems”, which contain the stem cells of the plants. Biologists from Heinrich Heine University Düsseldorf (HHU) have now identified a specific peptide and the associated receptor, which determine inflorescence growth along two axes. In a study in the scientific journal Nature Communications, they explain that the number of barley grains formed is also dependent on these elements.

Grasses have evolved a wide variety of inflorescences, in which the seeds are arranged in many different ways: Some types form complex, branched inflorescences with multiple seeds, while others – such as barley – have much simpler inflorescences. In barley, each individual grain forms on a short axis called a “rachilla”.

These differences in inflorescence architecture are determined early on in the development of the plant, with the size, position and longevity of the meristems ultimately determining the form of the inflorescence.

A team of scientists headed by Professor Dr Rüdiger Simon from the Institute of Developmental Genetics at HHU has now identified a signalling pathway, which regulates the activity of distinct meristems in barley. In Nature Communications, they describe that a small peptide called HvFCP1, which is secreted by cells of the rachilla, interacts with a receptor called HvCLV1 localised on the plasma membrane and thus controls the growth of the meristems along the vertical and horizontal axes. This ultimately determines the inflorescence architecture.

The researchers also examined what happens when the genes responsible for the formation of HvFCP1 or HvCLV1 mutate. In these cases, the plants develop enlarged inflorescences and rachillae. The inflorescences of these barley mutants then display a similar architecture to the inflorescences of wheat – with the formation of multiple flowers (and later grains) from one rachilla.

In their research, the authors of the study combined a gene function analysis at cellular level with a detailed phenotypical characterisation using scanning electron microscopy and fluorescence microscopy. Professor Simon: “The ‘Center for Advanced Imaging’ (CAi) of the HHU is an outstanding facility enabling this kind of research.”

The lead author of the study, Dr Isaia Vardanega, says: “Our discovery now enables us to re-design the inflorescences of grasses. By gaining a more precise understanding of the stem cell system of barley, we can for example increase the number of grains and thus contribute to increased agricultural production.”

Professor Simon adds: “This work lays the foundation for new, targeted breeding approaches. Our knowledge of the genetic regulation of the architecture of barley will make it possible to generate new, high-yield varieties more quickly by means of genome editing.”

The research is a collaborative project realised by the “Cereal Stem Cell Systems" (CSCS) research unit, which is funded by the German Research Foundation, and the CEPLAS Cluster of Excellence on Plant Sciences at HHU.

Original publication

Vardanega, I., Maika, J.E., Demesa-Arevalo, E., Lan, T., Kirschner, G.K., Imani, J., Acosta, I., Makowska, K., Hensel, G., Ranaweera, T., Shiu, S.H., Schnurbusch, T, von Korff, M. and Simon, R. CLAVATA signalling shapes barley inflorescence by controlling activity and determinacy of shoot meristem and rachilla. Nature Communications 16, 3937 (2025).

DOI: 10.1038/s41467-025-59330-z