Dynamic phytomeric growth contributes to local adaptation in barley

Abstract

Vascular plants segment their body axis with iterative nodes of lateral branches and internodes. Appropriate node initiation and internode elongation are fundamental to plant fitness and crop yield formation; but how they are spatiotemporally coordinated remains elusive. We show that in barley (Hordeum vulgare L.), selections under domestication have extended the apical meristematic phase to promote node initiation, but constrained subsequent internode elongation. In both vegetative and reproductive axes, internode elongation displays a dynamic proximal - distal gradient, and among subpopulations of domesticated barleys at the global range, node initiation and proximal internode elongation are associated with latitudinal and longitudinal gradients, respectively. Genetic and functional analysis suggest that, in addition to their converging roles in node initiation, flowering time genes are repurposed to specify the dynamic internode elongation. Our study provides an integrated view of barley node initiation and internode elongation, and suggests that plant architecture has to be recognized as dynamic phytomeric units in the context of crop evolution.

Genetic control of stem elongation in legume crops and its potential relevance

“…Also, in environments where late phenology and an increased number of nodes are optimal for yield, problems of lodging may be exacerbated and negatively impact yield, and a specific reduction of elongation during the reproductive phase could be beneficial. This targeted reduction may also improve yield through reallocation of resources from later elongation to floral organs, as speculated in barley (Y. Huang et al., 2024).…”

“…It has been suggested that resource competition between phytomers and the shift to reproductive growth is driving these elongation patterns (Dale et al., 2023; Reddy et al., 1997). At the molecular level, flowering genes in some species have been shown to mediate elongation via stem sensitivity to GA and regulation of GA biosynthesis in rice (Gómez‐Ariza et al., 2019) and barley (Y. Huang et al., 2024), respectively. In legumes, evidence from soybean also broadly suggests a role for direct regulation of GA pathway‐related genes.…”

“…In cereals, the prospects and benefits of stage‐specific elongation control have been considered in a number of studies. These include the long‐coleoptile work mentioned above and others showing that early internodes are distinctly sensitive to light intensity and leaf area index (Zhong et al., 2020) or that proximal internode elongation is linked to reproductive efficiency (Y. Huang et al., 2024).…”