C3 and C4 plants, as their intermediates, respond differently to short-term changes in environmental conditions. This difference is linked to contrasting levels of phenotypic plasticity and photosynthetic apparatus specialization. Phenotypic plasticity is an underexplored topic although its understanding is crucial to predict plant behaviour in future climatic scenarios. In this research, the phenotypic plasticity of anatomical traits and its influence to carbon uptake efficiency was studied in plants with different photosynthetic types, under contrasting water regimes. Oryza sativa cvs. Soberana (drought-sensitive) and Douradão (drought-tolerant) (C3), Homolepis isocalycia (C3 proto-Kranz) and Andropogon gayanus (C4), grown at three water treatments (100, 75 and 50% of substrate water holding capacity), were phenotyped for leaf anatomy and gas-exchange parameters. The results showed that plasticity trends indicated different strategies between O. sativa cultivars to deal with water shortage, explaining their classification as drought-sensitive or tolerant. We also mapped typical characteristics of C3–C4 intermediate plant, H. isocalycia, mainly in the ratio mesophyll:bundle sheath cells and hypothesize how it may influence photosynthesis. Finally, we have confirmed previous claims that C4 carbon uptake advantages may be limited under severe drought conditions, as A. gayanus have drastically reduced its photosynthetic rates at lower water levels. By studying C3–C4 intermediates, this study may also be a starting point to unravel the trade-offs of anatomical changes during the evolutionary process from C3 to C4 photosynthesis, and also improve the understanding of their impact in carbon uptake in different water conditions.

C3和C4植物作为中间体，对环境条件的短期变化有不同的反应。这种差异与表型可塑性和光合设备专业化的对比水平有关。尽管对表型可塑性的理解对于预测未来气候情景下的植物行为至关重要，但它是一个尚未被探讨的话题。在这项研究中，在不同的水合作用条件下，研究了具有不同光合类型的植物的解剖学特征的表型可塑性及其对碳吸收效率的影响。Oryza sativa cvs。Soberana（对干旱敏感）和Douradão（对干旱耐受）（C3），Homolepis isocalycia（对Cran -Kranz认证）和Andropogon gayanus（C4）在三种水处理条件下生长（分别占基质保水量的100％，75％和50％），对叶子的解剖结构和气体交换参数进行表型分析。结果表明，可塑性趋势指示了水稻品种之间应对缺水的不同策略，解释了其对干旱敏感或耐旱的分类。我们还绘制了C3–C4中间植物H. isocalycia的典型特征，主要是叶肉：束鞘细胞的比例，并推测了它如何影响光合作用。最后，我们已经确认了先前的说法，即在严重干旱条件下，如A. gayanus，C4的碳吸收优势可能会受到限制。在较低的水位下已大大降低了其光合速率。通过研究C3–C4中间体，该研究也可能是阐明从C3到C4光合作用的进化过程中解剖变化的权衡取舍的起点，也可以增进对不同水分条件下碳吸收的影响的理解。