Durum wheat (Triticum durum Desf.) is a fundamental staple food for the countries of the Mediterranean basin. Climate change is predicted to cause a trend of increasing drought severity in this region in the near future, necessitating the improvement of durum wheat's resilience to drought stress. Using polyethylene glycol to simulate water scarcity, early vigour parameters in germinating seeds are quickly, easily and affordably assessed. Many screenings, however, only consider the seedling stage; consequently, genotypes identified as promising for cultivation in drought scenarios, may not show such features if drought appears in later phenological phases, as happens in Mediterranean climatic areas, generally prone to terminal drought. The correlation between drought stress resistance during the seedling stage (early vigour) and later stages in the life cycle is elusive due to the lack of scientific efforts. Here we used polyethylene glycol screening to classify fifty-five tetraploid wheat accessions into three clusters (susceptible, medium resistant and highly resistant to drought), based on morpho-physiological traits. These accessions included durum wheat cultivars and landraces, as well as ancestors like durum emmer wheat and wild emmer wheat. The results of the screenings were combined with subsequent pot experiments using nine randomly selected accessions, imposing terminal drought, and evaluating their performance. Principal component analysis was performed on data for net photosynthesis, stomatal conductance, transpiration and grain yield. Notably, the genotypes that performed best in the pot experiments were also those that performed well in the screening. Highly resistant candidates had in fact higher physiological and performance parameters than susceptible candidates. In summary, polyethylene glycol screening of germinating seeds resulted to be suitable to predictively evaluate drought resistance in tetraploid wheat accessions under terminal drought conditions, typical of Mediterranean climate zones. The reported data, thus evidence of how this inexpensive and simple method might be efficiently applied for large-scale phenotyping.

中文翻译：

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四倍体小麦种质早期干旱胁迫抗性的表型变异与最终干旱表现相关

硬粒小麦（Triticum durum Desf.）是地中海盆地国家的基本主粮。预计气候变化将在不久的将来导致该地区干旱加剧，因此需要提高硬粒小麦对干旱胁迫的抵御能力。使用聚乙二醇模拟缺水，可以快速、轻松且经济地评估发芽种子的早期活力参数。然而，许多筛选只考虑幼苗阶段；因此，如果干旱出现在较晚的物候阶段，被认为有希望在干旱情况下种植的基因型可能不会显示出这样的特征，就像地中海气候地区发生的那样，通常容易出现终末干旱。由于缺乏科学努力，幼苗阶段（早期活力）和生命周期后期的干旱胁迫抗性之间的相关性难以捉摸。在这里，我们使用聚乙二醇筛选，根据形态生理性状将 55 个四倍体小麦种质分为三类（易感、中抗和高度抗旱）。这些品种包括硬质小麦品种和地方品种，以及硬质二粒小麦和野生二粒小麦等祖先。将筛选结果与随后的盆栽实验相结合，使用九个随机选择的品种进行最终干旱，并评估其性能。对净光合作用、气孔导度、蒸腾作用和谷物产量的数据进行主成分分析。值得注意的是，在盆栽实验中表现最好的基因型也是在筛选中表现良好的基因型。事实上，高度耐药的候选者比易感的候选者具有更高的生理和性能参数。总之，发芽种子的聚乙二醇筛选适合于预测评估四倍体小麦种质在地中海气候区典型的终端干旱条件下的抗旱性。报告的数据证明了这种廉价且简单的方法如何有效地应用于大规模表型分析。