Root axial conductance, which describes the ability of water to move through the xylem, contributes to the rate of water uptake from the soil throughout the whole plant lifecycle. Under the rainfed wheat agro-system, grain-filling is typically occurring during declining water availability (i.e., terminal drought). Therefore, preserving soil water moisture during grain filling could serve as a key adaptive trait. We hypothesized that lower wheat root axial conductance can promote higher yields under terminal drought. A segregating population derived from a cross between durum wheat and its direct progenitor wild emmer wheat was used to underpin the genetic basis of seminal root architectural and functional traits. We detected 75 QTL associated with seminal roots morphological, anatomical and physiological traits, with several hotspots harbouring co-localized QTL. We further validated the axial conductance and central metaxylem QTL using wild introgression lines. Field-based characterization of genotypes with contrasting axial conductance suggested the contribution of low axial conductance as a mechanism for water conservation during grain filling and consequent increase in grain size and yield. Our findings underscore the potential of harnessing wild alleles to reshape the wheat root system architecture and associated hydraulic properties for greater adaptability under changing climate.
Bibliographical noteFunding Information:
We thank members of the Peleg lab for helpful comments during the preparation of this manuscript. We would like to thank Dr. R. Hayouka for her technical support with the phenotyping experiments, and L. Shemesh for the roots illustration. This study was partially supported by the Israel Ministry of Agriculture and Rural Development (grants # 20‐10‐0066; 12‐01‐0005), the U.S. Agency for International Development Middle East Research and Cooperation (grant # M34‐037), and the Dutch Ministry of Foreign Affairs under Dutch development/foreign policy (Project WheatMAX).
© 2021 John Wiley & Sons Ltd.
- axial conductance
- root anatomy
- root hair
- wheat seminal roots
- wild emmer wheat