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水生禾本科植物从陆地到水中进化转变过程中的C光合作用修饰。

C photosynthetic modifications in the evolutionary transition from land to water in aquatic grasses.

作者信息

Keeley Jon E

机构信息

Division of Environmental Biology, National Science Foundation, Arlington, VA 22230 USA e-mail:

出版信息

Oecologia. 1998 Aug;116(1-2):85-97. doi: 10.1007/s004420050566.

Abstract

Cladistic analysis supports the conclusion that the Orcuttieae tribe of C grasses reflect evolution from a terrestrial ancestry into seasonal pools. All nine species in the tribe exhibit adaptations to the aquatic environment, evident in the structural characteristics of the juvenile foliage, which persist submerged for 1-3 months prior to metamorphosis to the terrestrial foliage. Aquatic leaves of the least derived or basal genus Neostapfia have few morphological and anatomical characteristics specialized to the aquatic environment and have retained full expression of the C pathway, including Kranz anatomy. Orcuttia species have many derived characteristics and are more specialized to the aquatic environment. These latter species germinate earlier in the season and persist in the submerged stage longer than Neostapfia and evidence from the literature indicates length of submergence is positively correlated with fitness components. Aquatic leaves of Orcuttia species lack Kranz or PCR bundle sheath anatomy, yet C-pulse chase studies indicate >95% malate + aspartate as the initial products of photosynthesis and these products turn over rapidly to phosphorylated sugars, indicating a tight coupling of the C and C cycles. Presence of the C pathway is further supported by enzymological data. Contemporary dogma that Kranz anatomy is a sine qua non for operation of the C pathway is contradicted by the patterns in Orcuttia; however, it is unknown whether the pathway acts as a CO concentrating mechanism in these aquatic plants.

摘要

分支系统学分析支持这样的结论

C4禾本科的奥库蒂草族反映了从陆生祖先向季节性水池的进化。该族中的所有九个物种都表现出对水生环境的适应性,这在幼年叶片的结构特征中很明显,这些叶片在变态为陆生叶片之前会持续淹没1至3个月。最原始或基部属新斯塔菲草属的水生叶几乎没有专门适应水生环境的形态和解剖特征,并且保留了C4途径的完整表达,包括花环解剖结构。奥库蒂草属物种具有许多衍生特征,并且对水生环境更具特异性。后一类物种在季节早期发芽,并且在淹没阶段比新斯塔菲草属持续更长时间,文献中的证据表明淹没时间与适合度成分呈正相关。奥库蒂草属物种的水生叶缺乏花环或磷酸烯醇式丙酮酸羧化酶束鞘解剖结构,然而,C4脉冲追踪研究表明,苹果酸 + 天冬氨酸作为光合作用的初始产物超过95%,并且这些产物迅速转化为磷酸化糖,表明C4和C3循环紧密耦合。酶学数据进一步支持了C4途径的存在。奥库蒂草属的模式与当代教条即花环解剖结构是C4途径运行的必要条件相矛盾;然而,尚不清楚该途径在这些水生植物中是否作为一种二氧化碳浓缩机制起作用。

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