The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
J Exp Bot. 2023 Sep 2;74(16):4862-4874. doi: 10.1093/jxb/erad059.
Water scarcity is the primary environmental constraint affecting wheat growth and production and is increasingly exacerbated due to climatic fluctuation, which jeopardizes future food security. Most breeding efforts to improve wheat yields under drought have focused on above-ground traits. Root traits are closely associated with various drought adaptability mechanisms, but the genetic variation underlying these traits remains untapped, even though it holds tremendous potential for improving crop resilience. Here, we examined this potential by re-introducing ancestral alleles from wild emmer wheat (Triticum turgidum ssp. dicoccoides) and studied their impact on root architecture diversity under terminal drought stress. We applied an active sensing electrical resistivity tomography approach to compare a wild emmer introgression line (IL20) and its drought-sensitive recurrent parent (Svevo) under field conditions. IL20 exhibited greater root elongation under drought, which resulted in higher root water uptake from deeper soil layers. This advantage initiated at the pseudo-stem stage and increased during the transition to the reproductive stage. The increased water uptake promoted higher gas exchange rates and enhanced grain yield under drought. Overall, we show that this presumably 'lost' drought-induced mechanism of deeper rooting profile can serve as a breeding target to improve wheat productiveness under changing climate.
水资源短缺是影响小麦生长和生产的主要环境限制因素，而且由于气候波动，这一问题日益加剧，威胁到未来的粮食安全。大多数旨在提高小麦耐旱性的育种工作都集中在地上部分的特性上。根特性与各种耐旱适应性机制密切相关，但这些特性的遗传变异尚未被开发利用，尽管它具有极大的提高作物抗逆性的潜力。在这里，我们通过从野生二粒小麦（Triticum turgidum ssp. dicoccoides）中重新引入祖先等位基因来研究这种潜力，并研究了它们在终端干旱胁迫下对根系结构多样性的影响。我们应用主动感应电阻抗断层扫描方法在田间条件下比较野生二粒小麦导入系（IL20）及其耐旱敏感轮回亲本（Svevo）。IL20 在干旱条件下表现出更强的根系伸长能力，从而从更深的土层中吸收更多的水分。这种优势在假茎阶段开始显现，并在向生殖阶段过渡时增加。增加的水分吸收促进了更高的气体交换率，并在干旱条件下提高了籽粒产量。总的来说，我们表明，这种可能“失去”的深层根系形成的干旱诱导机制可以作为一个育种目标，以改善气候变化下的小麦生产力。
