To test the hypothesis that multiple integrated root phenotypes would co-optimize drought tolerance, we phenotyped the root anatomy and architecture of 400 mature maize (Zea mays) genotypes under well-watered and water-stressed conditions in the field. We found substantial variation in all 23 root phenes measured. A phenotypic bulked segregant analysis revealed that bulks representing the best and worst performers in the field displayed distinct root phenotypes. In contrast to the worst bulk, the root phenotype of the best bulk under drought consisted of greater cortical aerenchyma formation, more numerous and narrower metaxylem vessels, and thicker nodal roots. Partition-against-medians clustering revealed several clusters of unique root phenotypes related to plant performance under water stress. Clusters associated with improved drought tolerance consisted of phene states that likely enable greater soil exploration by reallocating internal resources to greater root construction (increased aerenchyma content, larger cortical cells, fewer cortical cell files), restrict uptake of water to conserve soil moisture (reduced hydraulic conductance, narrow metaxylem vessels), and improve penetrability of hard, dry soils (thick roots with a larger proportion of stele, and smaller distal cortical cells). We propose that the most drought-tolerant–integrated phenotypes merit consideration as breeding ideotypes.

为了检验多个整合的根表型可以共同优化耐旱性的假设，我们对400株成熟玉米（玉米）的根解剖结构和表型进行了表型分析。）田间在水分充足和水分胁迫条件下的基因型。我们发现所测的所有23种根酚均存在显着差异。表型的大量分离物分析表明，代表该领域表现最佳和最差的物质表现出明显的根表型。与最坏的体形相反，干旱下最好的体形的根表型由更大的皮质气孔形成，更多和更窄的后生木质部血管以及更厚的结根组成。分区对中位数的聚类揭示了几个与水分胁迫下植物生长相关的独特根表型簇。与提高的耐旱性相关的簇包括酚状态，它们可能通过将内部资源重新分配到更大的根部构造（增加的通气组织含量，更大的皮层细胞，更少的皮层细胞档案），限制水分吸收以保持土壤水分（降低的水力传导，狭窄的木质部血管），并改善坚硬，干燥的土壤的渗透性（厚厚的根，石碑比例更大，而远端皮层较小）细胞）。我们建议最耐旱的综合表型应考虑作为育种表型。