Biology Department, Radford University, Radford, Virginia 24142-6931 USA.
Am J Bot. 2009 Jul;96(7):1245-54. doi: 10.3732/ajb.0800276. Epub 2009 May 28.
Although cells that synthesize crystals are known throughout the plant kingdom, their functional significance is still unknown. Mechanical support, mineral balance, waste sequestration, and protection against herbivores have all been proposed as crystal functions. To seek clues to their role(s), I systematically examined all organs except fruit of Dieffenbachia seguine (Araceae) for crystals. Crystals were found in nearly every organ. Raphides (long, slim, pointed crystals) were most common, but druses (crystal aggregates) and prisms were also found. Raphides varied in size by a factor of 10 and also in organization from tightly bundled to loosely organized. Biforines, a type of cell capable of expelling raphides, or biforine-like cells, were found in nearly all organs, but especially in leaves, spathes, and anthers. Different organs had different crystal complements, and characteristic crystals were found at specific locations, such as among pollen, along the undersides of leaf veins, and at root branch points. All crystals appeared to be composed of calcium oxalate, based on acid solubility. Possible roles of the crystals are discussed in light of these findings.
虽然在整个植物界都知道合成晶体的细胞，但它们的功能意义仍不清楚。晶体的功能曾被提出有机械支撑、矿物平衡、废物隔离和防止食草动物侵害等。为了寻找线索来了解它们的作用，我系统地检查了除凤梨科 Dieffenbachia seguine（天南星科）的果实以外的所有器官的晶体。几乎在所有器官中都发现了晶体。针晶（长而细、尖的晶体）最为常见，但也发现了晶簇（晶体聚集体）和棱柱体。针晶的大小相差 10 倍，组织也从紧密捆绑到松散排列不等。能够排出针晶的双尖细胞或双尖细胞样细胞几乎存在于所有器官中，但尤其存在于叶片、佛焰苞和花药中。不同的器官有不同的晶体组合，特征晶体存在于特定的位置，如花粉中、叶脉下方和根系分支处。所有晶体似乎都是由草酸钙组成，这基于酸的溶解度。根据这些发现，讨论了晶体的可能作用。
