Otte Marinus L, Wilson Graham, Morris James T, Moran Bridget M
Wetland Ecology Research Group, Department of Botany, University College Dublin, Belfield, Dublin 4, Ireland.
J Exp Bot. 2004 Aug;55(404):1919-25. doi: 10.1093/jxb/erh178. Epub 2004 Jun 4.
Dimethylsulphoniopropionate (DMSP) is produced in high concentrations in many marine algae, but in higher plants only in a few salt marsh grasses of the genus Spartina, in sugar canes (Saccharum spp.), and in the Pacific strand plant Wollastonia biflora (L.) DC. The high concentrations found in higher plants (up to 250 micromol g(-1) dry weight) suggest an important role, but though many functions have been suggested (including methylating agent, detoxification of excess sulphur, salt tolerance, and herbivore deterrent), its actual functions remain unclear. The fact that the ability to produce DMSP in high concentrations is found in species that have no taxonomic or ecological relationship suggests that the compound evolved independently and serves different functions in different plants. This is supported by observations that DMSP in W. biflora behaves differently from that in Spartina species. While DMSP concentrations in W. biflora have been found to increase with increasing salinity, suggesting a role in osmotic control, such a relationship has not been found for DMSP in Spartina species. Recent observations on tissue culture showed that, while undifferentiated tissue of W. biflora produced DMSP, such material of Spartina alterniflora Loisel. did not. Ongoing studies with tissue culture of both species have opened up new avenues of research on DMSP in higher plants, ultimately to elucidate the functions of this enigmatic compound.
二甲基巯基丙酸内盐(DMSP)在许多海洋藻类中大量产生,但在高等植物中,仅在少数米草属的盐沼草、甘蔗(甘蔗属物种)以及太平洋沿岸植物双花蟛蜞菊(Wollastonia biflora (L.) DC.)中存在。在高等植物中发现的高浓度DMSP(高达250微摩尔/克干重)表明其具有重要作用,尽管人们提出了许多功能假设(包括甲基化剂、过量硫的解毒、耐盐性以及食草动物威慑作用),但其实际功能仍不清楚。在没有分类学或生态关系的物种中都发现了高浓度产生DMSP的能力,这一事实表明该化合物是独立进化的,并且在不同植物中发挥不同功能。这一点得到了以下观察结果的支持:双花蟛蜞菊中的DMSP与米草属物种中的DMSP表现不同。虽然已发现双花蟛蜞菊中的DMSP浓度随着盐度的增加而升高,表明其在渗透调节中发挥作用,但在米草属物种中未发现DMSP与盐度有这样的关系。最近对组织培养的观察表明,双花蟛蜞菊的未分化组织能产生DMSP,而互花米草(Spartina alterniflora Loisel.)的未分化组织则不能。对这两个物种进行的组织培养正在进行的研究为高等植物中DMSP的研究开辟了新途径,最终目的是阐明这种神秘化合物的功能。