In most terrestrial plants, large quantities of water inevitably are diffused into the air via open stomata for CO₂ absorption during photosynthesis. It is difficult to reduce such an intrinsic demand of water for transpiration but still maintain photosynthesis. Interestingly, the xerophyte Zygophyllum xanthoxylum evolves an outstanding ability to resolve this dilemma by accumulating Na⁺ to stimulate growth while reducing transpiration. However, the underlying mechanisms are still unclear. Two-week-old Z. xanthoxylum plants were treated with 50 mM NaCl (Na) for 7 days to investigate their growth, gas-exchange related parameters, chlorophyll fluorescence parameters, leaf anatomical characteristics, and related biochemical traits. NaCl treatment reduced the stomatal opening and transpiration but markedly enhanced the plant biomass. Analysis showed that a higher efficiency of intrinsic water use (WUE_i) and photosynthetic chlorophyll (P_Chl) in leaves of Na-treated plants. A lower CO₂ partial pressure in substomatal cavities, mainly accounting for higher WUE_i, which efficiently facilitates CO₂ extraction from air via partially opening stomata in leaves of Na-treated plants, may be largely due to increased internal cell surface and reduced CO₂ diffusion path between chloroplasts and corresponding cell wall, in addition to increased expression of aquaporin and induced C₄ or CAM-like metabolism. Increased leaves area, reduced chlorophyll content per unit weight, and enhanced operating efficiency of Photosystem II allowed more efficient light harvesting, deeper light penetration and more light using efficiency, and so would also benefit this water-saving photosynthesis. Our data demonstrate that Z. xanthoxylum efficiently rematches both CO₂ intake and light use to fulfill vigorous growth under significantly reduced stomatal aperture and markedly decreased water consumption. The mechanisms that Z. xanthoxylum uses to achieve more biomass while using less water give a valuable clue for future improvement of agricultural production in water-limited areas.

在大多数陆生植物中，在光合作用过程中，大量的水不可避免地通过开放的气孔扩散到空气中以吸收CO ₂。很难减少蒸腾作用对水的这种内在需求，但仍保持光合作用。有趣的是，旱生植物Zygophyllum xanthoxylum通过积累 Na ⁺来刺激生长同时减少蒸腾作用，进化出解决这一困境的杰出能力。然而，其潜在机制仍不清楚。两周大的Z. xanthoxylum植物用 50 mM NaCl (Na) 处理 7 天，以研究它们的生长、气体交换相关参数、叶绿素荧光参数、叶片解剖特征和相关生化特性。NaCl 处理减少了气孔开放和蒸腾作用，但显着提高了植物生物量。分析表明，Na 处理植物叶片的内在水分利用 (WUE _i ) 和光合叶绿素 ( P _Chl )效率更高。气孔下腔中较低的 CO ₂分压，主要是较高的 WUE _i，这有效地促进了 CO ₂通过部分打开 Na 处理植物叶片中的气孔从空气中提取，除了增加水通道蛋白的表达和诱导 C ₄或 CAM外，可能主要是由于内部细胞表面增加和叶绿体和相应细胞壁之间的CO ₂扩散路径减少- 像新陈代谢。增加叶片面积，降低单位重量叶绿素含量，提高光系统 II 的运行效率，使光收集效率更高，光穿透更深，光利用效率更高，因此也有利于这种节水光合作用。我们的数据表明，Z. xanthoxylum有效地重新匹配了 CO ₂在显着减少气孔孔径和显着减少用水量的情况下，摄入和光照以实现旺盛的生长。Z. xanthoxylum用于在使用更少水的同时获得更多生物量的机制为未来在缺水地区改善农业生产提供了宝贵的线索。