Plant Secretion & Reproduction (PlantSeR) Lab, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, Minas Gerais, Brazil.
New Phytol. 2019 Sep;223(4):1707-1711. doi: 10.1111/nph.15912. Epub 2019 Jun 7.
Calcium oxalate (CaOx) crystals occur as intravacuolar deposits in most angiosperm species. Different functions have been attributed to these crystals, some of which are very speculative, until now. Calcium regulation and homeostasis seem to be the most widespread function of CaOx crystals. Being rich in calcium, these crystals constitute a reserve of calcium for plants. However, despite being bioavailable, this reserve is functional in just a few situations due to the low mobility of calcium for phloem translocation. Therefore, CaOx crystals as a calcium reserve is a paradox because in most cases the reserve cannot be used. However, in most plants, these crystals occur in organs or tissues that will be discarded, which allows the elimination of excess calcium. This suggests that CaOx crystals have a functional role in excess calcium excretion. There is some evidence that, for calcium, this excretory function is relevant for plants since they lack an excretory system dedicated to discarding solid wastes, such as calcium salts.
草酸钙 (CaOx) 晶体作为细胞内的沉积物存在于大多数被子植物物种中。这些晶体的功能多种多样，其中一些直到现在还只是推测，尚未得到证实。钙的调节和平衡似乎是 CaOx 晶体最广泛的功能。这些晶体富含钙，是植物钙的储备库。然而，尽管它们具有生物利用性，但由于钙在韧皮部转运中的迁移率低，这种储备仅在少数情况下具有功能性。因此，草酸钙晶体作为钙储备是一个悖论，因为在大多数情况下，储备无法被利用。然而，在大多数植物中，这些晶体存在于将被丢弃的器官或组织中，这使得过量的钙得以排出。这表明 CaOx 晶体在过量钙排泄中具有功能作用。有一些证据表明，对于钙来说，这种排泄功能对植物很重要，因为它们缺乏专门用于丢弃固体废物（如钙盐）的排泄系统。
