Root axial conductance which describes the ability of water to pass throw the xylem, contributes to the rate of water uptake from the soil throughout the whole plant lifecycle. In a 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 harboring 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 introducing wild alleles to reshape the wheat root system architecture for greater adaptability under changing climate.

中文翻译：

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破解小麦精根解剖的遗传基础，揭示祖先轴向电导等位基因

根轴电导率描述了水通过木质部的能力，有助于整个植物生命周期从土壤吸收水分的速率。在雨养的小麦农业系统中，通常在水供应量下降（即极端干旱）期间发生谷物充实。因此，在灌浆过程中保持土壤水分可以作为关键的适应性状。我们假设较低的小麦根轴电导率可以在终端干旱下促进较高的单产。来自硬质小麦和其直接祖先野生Emmer小麦杂交的隔离种群被用来支持精根结构和功能性状的遗传基础。我们检测到75个与精根形态，解剖和生理特征相关的QTL，有几个热点包含共同定位的QTL。我们进一步使用野生基因渗入系验证了轴向电导和中央木质部QTL。基于轴向电导率的基因型的基于场的表征表明，低轴向电导率是谷物灌浆过程中节水的一种机制，因此提高了谷物的粒径和产量。我们的发现强调了引入野生等位基因重塑小麦根系结构以在气候变化下具有更大适应性的潜力。基于轴向电导率的基因型的基于场的表征表明，低轴向电导率是谷物灌浆过程中节水的一种机制，因此提高了谷物的粒径和产量。我们的发现强调了引入野生等位基因重塑小麦根系结构以在气候变化下具有更大适应性的潜力。基于轴向电导率的基因型的基于场的表征表明，低轴向电导率是谷物灌浆过程中节水的一种机制，因此提高了谷物的粒径和产量。我们的发现强调了引入野生等位基因重塑小麦根系结构以在气候变化下具有更大适应性的潜力。