Arbuscular mycorrhizal fungus (AMF) can mediate physiological adaptation of higher plants to drought stress, including wheat. Yet, it is unclear how AMF affects reproductive output via mediating crop physiological vitality at the evolutionary scale. To clarify this issue, a growth environment-controlled experiment was conducted using four primitive wheat genotypes and four modern ones with or without AMF (Funneliformis mosseae) inoculation. Two water regimes (80 % and 40 % field water capacity, FWC80 (well-watered) and FWC40 (drought stress)) were included. The data indicated that AMF inoculation significantly improved leaf area, photosynthetic rate, stomatal conductance and water use efficiency under drought stress, compared to the non-AMF group (CK). Regardless of soil moisture, the relationship between reproductive biomass vs. vegetative biomass (R-V), and between leaf biomass vs. shoot biomass, all fell into a typical allometric pattern (α>1, P<0.001) in primitive wheat. In contrast, in modern wheat, the R-V relationship tended to an isometric pattern (α≈1, P<0.001), showing lower α values in all treatments relative to primitive ones. Furthermore, AMF inoculation significantly promoted the maintenance rate of yield and biomass under drought stress, suggesting greater drought tolerance as induced by AMF in modern wheat compared to primitive ones. These findings illuminated a key evolutionary strategy to enhance reproductive allocation via activating physiological activities under drought stress from primitive to modern wheat.

中文翻译：

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丛枝菌根真菌激活原始和现代小麦在干旱胁迫下提高小麦的生理学水平


丛枝菌根真菌 （AMF） 可以介导高等植物对干旱胁迫的生理适应，包括小麦。然而，目前尚不清楚 AMF 如何通过在进化尺度上介导作物生理活力来影响生殖产出。为了阐明这个问题，使用四种原始小麦基因型和四种现代基因型进行了一项生长环境对照实验，接种或不接种 AMF （Funneliformis mosseae）。包括两种水情 （80 % 和 40 % 的田间水容量，FWC80 （浇水良好）和 FWC40 （干旱胁迫））。数据表明，与非 AMF 组 （CK） 相比，AMF 接种在干旱胁迫下显著提高了叶面积、光合速率、气孔导度和水分利用效率。无论土壤湿度如何，原始小麦的生殖生物量与营养生物量 （R-V） 之间的关系，以及叶片生物量与地上部生物量之间的关系都属于典型的异速生长模式 （α>1， P<0.001）。相反，在现代小麦中，R-V 关系趋于等长模式 （α≈1， P<0.001），相对于原始处理，所有处理的 α 值都较低。此外，接种 AMF 显著提高了干旱胁迫下产量和生物量的维持率，表明 AMF 诱导的现代小麦比原始小麦具有更高的耐旱性。这些发现阐明了一种关键的进化策略，即通过激活从原始小麦到现代小麦在干旱胁迫下的生理活动来增强生殖分配。