When plants of the Atacama desert undergo episodic blooms, among the most prominent are succulent-leaved Cistanthe (Montiaceae). We demonstrate that two Cistanthe species, the perennial Cistanthe sp. aff. crassifolia and the annual/biannual Cistanthe sp. aff. longiscapa, can exhibit net CO₂ uptake and leaf acidification patterns typical of crassulacean acid metabolism (CAM). In C. sp. aff. crassifolia leaves, CAM expression was facultative. CAM-type nocturnal net CO₂ uptake and acid accumulation occurred in drought-stressed but not in well-watered plants. By contrast, CAM expression in C. sp. aff. longiscapa was largely constitutive. Nocturnal acid accumulation was present in leaves of well-watered and in droughted plants. Following water-deficit stress, net nocturnal CO₂ uptake was induced and the level of acid accumulated increased. Neither nocturnal CO₂ uptake nor acid accumulation was reduced when the plants were re-watered. δ¹³C values of a further nine field-collected Cistanthe species are consistent with a contribution of CAM to their carbon pools. In the Portulacinae, a suborder with eight CAM-containing families, Cistanthe becomes the sixth genus with CAM within the family Montiaceae, and it is likely that the ancestor of all Portulacineae also possessed CAM photosynthesis. In the stochastic rainfall landscape of the Atacama, carbon uptake in the dark is a water-use efficient mechanism that increases the carbon pool available for seed production or dormancy. The next rain event may be years away.

当阿塔卡马沙漠的植物进行阶段性的花朵，其中最突出的是肉质叶Cistanthe（Montiaceae）。我们证明了两种肉stan蓉，常年的肉stan蓉。aff。crassifolia和每年/半年的Cistanthe sp。aff。longiscapa可以表现出净的CO ₂吸收和典型的景天树酸代谢（CAM）的叶片酸化模式。在C中。sp。aff。景天叶片，CAM表达是兼职的。CAM型夜间网CO ₂在干旱胁迫下会发生吸收和酸积累，但在水分充足的植物中则不会发生。相反，CAM在C中的表达。sp。aff。longiscapa主要是组成性的。水分充足和干旱的植物中存在夜酸积累。在缺水胁迫之后，夜间净吸收CO ₂被诱导，酸的积累水平增加。重新给植物浇水时，夜间的CO ₂吸收和酸积累都没有减少。δ ^13个又一9现场采集的C值Cistanthe物种与CAM的其碳游泳池的贡献相一致。在马齿ula科中，一个有八个含有CAM的科的亚目Cistanthe成为菊科中CAM的第六属，所有Portulacineae的祖先也可能具有CAM光合作用。在阿塔卡马州的随机降雨景观中，黑暗中的碳吸收是一种节水高效的机制，可增加可用于种子生产或休眠的碳库。下一场降雨可能还需要几年的时间。