The adaptation of alfalfa to moisture-favourable and drought-prone environments and its underlying mechanisms have not been thoroughly investigated despite their crucial importance to maximize the crop breeding progress. The main aim of this study was to support breeding strategies by exploring the relationship of leaf morphophysiological traits assessed in three growth chamber experiments with the adaptive response of five cultivars (Mamuntanas; Demnat 203; Erfoud 1; Prosementi; SARDI 10) that showed large genotype × environment interaction (GEI) across 10 drought-prone to moisture-favourable Mediterranean environments. Changes in shoot and root metabolite profiles across moisture-contrasting conditions were assessed for two cultivars with contrasting adaptation pattern. The cultivar specifically adapted to drought-prone environments (Mamuntanas), compared with that specifically adapted to moisture-favourable environments (Demnat 203), displayed: (i) lower leaf wilting under drought stress; (ii) delayed leaf senescence under stress, assessed as limited chlorophyll reduction either in vivo from upper to central leaves or in vitro from control to polyethylene glycol-treated leaflets, (iii) greater leaf tolerance to desiccation, measured in vitro as less pronounced reduction of leaf dry weight from control to polyethylene glycol-treated leaflets, (iv) smaller leaves, (v) lower early root and shoot growth and (vi) lower leaf stomata density. The other cultivars exhibited different combinations and/or intermediate values of these traits. The metabolite profiles of Mamuntanas and Demnat 203 differed more in shoots than in roots. Mamuntanas accumulated more amino acids than Demnat 203 under moisture-favourable and drought conditions. The distinct and partly incompatible combination of traits featuring the cultivars that maximized the crop yield in favourable or drought-prone conditions (Mamuntanas and Demnat 203) improves our understanding of traits contributing to large GEI across moisture-contrasting environments and support the breeding for specific adaptation to either condition. We identified a few inexpensive morphophysiological traits that could be used for early selection targeting drought-prone environments.

中文翻译：

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生理和生化适应性状支持紫花苜蓿（Medicago sativa）在严重干旱胁迫或水分适宜的环境中进行特定育种

紫花苜蓿适应有利于水分和干旱的环境及其潜在机制尚未得到彻底研究，尽管它们对于最大限度地提高作物育种进程至关重要。本研究的主要目的是通过探索在三个生长室实验中评估的叶片形态生理性状与五个表现出大基因型的品种（Mamuntanas；Demnat 203；Erfoud 1；Prosementi；SARDI 10）的适应性反应之间的关系来支持育种策略× 跨 10 个易干旱至湿润有利的地中海环境的环境相互作用 (GEI)。评估了两个具有不同适应模式的品种在水分对比条件下芽和根代谢物谱的变化。特别适应干旱环境的品种 (Mamuntanas)，与特别适应有利于水分的环境的植物（Demnat 203）相比，表现出：（i）干旱胁迫下叶片萎蔫程度较低；(ii) 胁迫下叶片衰老延迟，评估为体内从上部叶片到中央叶片或体外从对照到聚乙二醇处理的小叶的叶绿素减少有限，(iii) 叶片对干燥的耐受性更高，体外测量为不太明显的减少从对照到聚乙二醇处理的小叶的叶片干重，（iv）较小的叶片，（v）较低的早期根和芽生长和（vi）较低的叶气孔密度。其他品种表现出这些性状的不同组合和/或中间值。Mamuntanas 和 Demnat 203 的代谢物谱在芽中的差异大于在根中的差异。在有利于水分和干旱的条件下，Mamuntanas 比 Demnat 203 积累了更多的氨基酸。在有利或易干旱条件下使作物产量最大化的品种的独特且部分不相容的性状组合（Mamuntanas 和 Demnat 203）提高了我们对在水分对比环境中有助于大 GEI 的性状的理解，并支持特定适应性育种任何一种情况。我们确定了一些廉价的形态生理特征，可用于针对易干旱环境的早期选择。在有利或易干旱条件下使作物产量最大化的品种的独特且部分不相容的性状组合（Mamuntanas 和 Demnat 203）提高了我们对在水分对比环境中有助于大 GEI 的性状的理解，并支持特定适应性育种任何一种情况。我们确定了一些廉价的形态生理特征，可用于针对易干旱环境的早期选择。在有利或易干旱条件下使作物产量最大化的品种的独特且部分不相容的性状组合（Mamuntanas 和 Demnat 203）提高了我们对在水分对比环境中有助于大 GEI 的性状的理解，并支持特定适应性育种任何一种情况。我们确定了一些廉价的形态生理特征，可用于针对易干旱环境的早期选择。