VERNALIZATION1 Modulates Root System Architecture in Wheat and Barley

Kai Voss-Fels ^1,2 Hannah Robinson ¹ Stephen Mudge ³ Cecile Richard ¹ Saul Newman ⁴ Benjamin Wittkop ² Andreas Stahl ² Wolfgang Friedt ² Matthias Frisch ⁵ Iulian Gabur ² Anika Miller-Cooper ¹ Bradley Campbell ³ Alison Kelly ⁶ Glen Fox ¹ Jack Christopher ¹ Mandy Christopher ⁶ Karine Chenu ¹ Jerome Franckowiak ⁷ Emma Mace ⁸ Andrew Borrell ¹ Howard Eagles ⁴ David Jordan ¹ José Botella ³ Graeme Hammer ¹ Ian Godwin ³ Ben Trevaskis ⁴ Rod Snowdon ² Lee Hickey ¹

¹Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Australia
²Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Germany
³School of Agriculture and Food Sciences, The University of Queensland, Australia
⁴Agriculture, CSIRO, Australia
⁵Department of Biometry and Population Genetics, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Germany
⁶Leslie Research Facility, Department of Agriculture and Fisheries, Australia
⁷Department of Agronomy and Plant Genetics, University of Minnesota, USA
⁸Hermitage Research Facility, Department of Agriculture and Fisheries, Australia

As the primary interface for resource acquisition, plant roots play a key role in growth regulation. Evidence from rice, maize and sorghum demonstrates that the below-ground plant architecture significantly impacts plant performance under abiotic constraints. Roots assume critical functions in water uptake, nutrient acquisition and anchorage, an essential characteristic to maintain plant stability under increased grain load. Despite their fundamental importance, knowledge about genetic control of root growth in major grain crops is limited and very little is known about interactions between below-ground and above-ground plant development. Here we demonstrate that VERNALIZATION1 (VRN1), a key regulator of flowering behavior in cereals, also modulates root architecture in wheat and barley. Associations of VRN1 haplotypes to root growth habit were discovered in wheat by genome-wide association studies, and confirmed by allelic analyses in wheat and barley populations. Functional characterization in transgenic barley confirmed that VRN1 influences root growth angle directly, via gravitropism. These discoveries provide unexpected insight into underground functions of a major player in the well-characterized flowering pathway, revealing the intersection of above-ground gene regulation with the largely unexplored genetic architecture of plant root development. Understanding the pleiotropic involvement of this key developmental gene in overall plant architecture will help to breed cereal cultivars adapted to specific environmental scenarios.