Phytomer development in a C4 grass

The morphology of almost all grasses can be conceptualized as a hierarchical arrangement of subunits, termed phytomers. Therefore, knowledge of phytomer growth and development serves as a basis to elucidate the rhythm of grass growth. A recent study published in AoB PLANTS by Yang et al. provides systematic analyses of the process of phytomer development of Cleistogenes squarrosa, a perennial C4 grass.

Schematic of a mature phytomer and its components, and arrangement of phytomers along a tiller of C. squarrosa.
Schematic of a mature phytomer and its components, and arrangement of phytomers along a tiller of C. squarrosa. The ligule (or collar; data not shown) marks the blade-sheath junction, and the node forms the site of insertion of the leaf on the stem. Immature, growing phytomers are situated at the tip of the tillers (note: for simplicity, the scheme depicts only two growing phytomers, but up to five concurrently expanding phytomers in different developmental stages are found along the distal part of tiller axis upon dissection). Image credit: Yang et al.

The invariant coordination of elongation within and between phytomers was a stable developmental feature across treatments, thus the quantitative coordination rules are applicable for predicting morphological development of C. squarrosa under contrasting levels of nitrogen nutrition or vapour pressure deficit.

Reference

Yang, F., Gong, X. Y., Liu, H. T., Schäufele, R., & Schnyder, H. (2016). Effects of nitrogen and vapour pressure deficit on phytomer growth and development in a C4 grass. AoB Plants, 8, plw075. http://dx.doi.org/10.1093/aobpla/plw075