We examined whether crassulacean acid metabolism (CAM) is present in Trianthema portulacastrum L. (Aizoaceae), a pantropical, salt-tolerant C₄ annual herb with atriplicoid-type Kranz anatomy in leaves but not in stems. The leaves of T. portulacastrum are slightly succulent and the stems are fleshy, similar to some species of Portulaca, the only genus known in which C₄ and CAM co-occur. Low- level nocturnal acidification typical of weakly expressed, predominantly constitutive CAM was measured in plants grown for their entire life-cycle in an outdoor raised garden box. Acidification was greater in stems than in leaves. Plants showed net CO₂ uptake only during the light irrespective of soil water availability. However, nocturnal traces of CO₂ exchange exhibited curved kinetics of reduced CO₂ loss during the middle of the night consistent with low-level CAM. Trianthema becomes the second genus of vascular land plants in which C₄ and features of CAM have been demonstrated to co-occur in the same plant and the first C₄ plant with CAM-type acidification described for the Aizoaceae. Traditionally the stems of herbs are not sampled in screening studies. Small herbs with mildly succulent leaves and fleshy stems might be a numerically significant component of CAM biodiversity.

我们检查了景天酸代谢 (CAM) 是否存在于Trianthema portulacastrum L. (Aizoaceae) 中，这是一种泛热带、耐盐 C ₄一年生草本植物，在叶子中具有三倍体型 Kranz 解剖结构，但在茎中没有。马齿苋的叶子略带肉质，茎肉质，类似于马齿苋的某些物种，马齿苋是已知的唯一一种同时存在 C ₄和 CAM 的属。低水平夜间酸化是典型的弱表达、主要组成型 CAM 的典型特征，在室外高架花园箱中生长的植物的整个生命周期中进行了测量。茎的酸化程度大于叶。植物显示净 CO ₂仅在光照期间吸收，而与土壤水分的可用性无关。然而，CO ₂交换的夜间痕迹表现出在半夜减少CO ₂损失的弯曲动力学，这与低水平CAM一致。Trianthema成为第二个维管陆生植物，其中 C ₄和 CAM 的特征已被证明在同一植物中同时存在，并且是第一株为偶氮科描述的具有 CAM 型酸化的 C _4植物。传统上，在筛选研究中不会对草药的茎进行取样。具有轻度多汁叶子和肉质茎的小草本植物可能是 CAM 生物多样性的重要组成部分。