Taxonomic Significance And Seasonal Varitions Of Lipid From Bamboo Leaf And Its Phytolith

Genetic and environmental factors influences wax quantity and composition. The wax production can be used in plant chemotaxonomy and paleoenvironment reconstruction. Studying the formation and compositon of leaf waxes and lipid in phytoliths, the relationships between compostion and quantity of leaf wax and environment factors and evaluating the early diagenesis effect of leaf waxes are the theoretic basis of carbon recycle and paleoenvironment reconstruction research. This work presented and disccused the leaf wax chemotaxonomy of bamboo from Xishuangbanna Tropical Rain Forest in Southwest China, the carbon isotope variation in n-alkanes and in chemical compostion of wax from the leaves of Bamboo N. affinis (Rendle) Keng f. with season changes and in plan-soil system, especially in soil. In additional, the lipid was extracted from phytolith by HF acid acidolysis.The chemotaxonomy significance is disputant because the leaf wax composition might be affected by grow conditions such as temperature, humidity, light, CO2 concentration and nutrition that might affect the leaf composition. In order to minimize the effects of differences in growth conditions the whole fully-developed leaves were collected in the same light conditions and approximately at the same height from Xishuangbanna tropical botanical garden. The leaf n-alkanes, identified in 23 species of woody bamboos from the Xishuangbanna tropical rain forest in South China, show a distribution in carbon number ranging from C23 to C35, with a strong odd-over-even predominance. The distribution pattern of leaf n-alkanes is distinctively different at the subgenus level of woody bamboos we investigated:The leaf waxes of individual species in the Bambusa subgenus contain a wide range of dominant compounds, including C27, C29, C31, C33 and C35 n-alkanes. The average chain length, ACL, of the eight species we analyzed varies from 29.2 to 31.6 and has an average value of 30.4. They have high proportion of C30+ alkanes. All of the leaf waxes of the nine species from the Dendrocalamus subgenus that we studied are dominated by only two n-alkanes, C27 and C29. The ACL values in this subgenus range from 27.0 to 28.8 and have an average value of 28.3. They have small proportion of C30+ alkanes. Unlike those of the Bambusa and Dendrocalamus species, the distributions of the n-alkanes in the Dendrocalamopsis subgenus do not follow a single, simple pattern. The distributions of three of the species we studied contain a range of dominant n-alkanes (C27, C29, C31 and C33), whereas the distributions of two others are dominated by C27 and C29 and that of a third by C25 and C27. The ACL values for the Dendrocalamopsis species vary from 27.4 to 30.0 with the mean value of 29.0. The leaf n-alkane patterns easily distinguish the Bambusa species from the Dendrocalamus species. Howver, the Dendrocalamopsis species have more complicated n-alkane distributions; some species are comparable with the Bambusa species and others with the Dendrocalamus species. It is possible to join species based on the main holomogues of n-alkanoic acid distributions:Bambusa with C24, Dendrocalamus with C22, some species of Dendrocalamopsis with C24 and the others with C22-The results of cluster analysis based on the n-alkanoic acid distributions are consistent with the classification by peak carbon number and morphological characters.The species of Bambusa and Dendrocalamus can be distinguished by the n-alkane and n-alkanoic acid distribution. However, the n-alkane and n-alkanoic acid distribution patterns are relative complicated in Dendrocalamopsis species. Some are simlar to subgenus Bambusa and the others are compared with subgenus Dendrocalamus.Our lipid data suggest that Dendrocalamopsis might be assigned as an independent genus separated from the Bambusa genus. The differences in the dominant n-alkanes and the ACL values suggest that the Dendrocalamus species might be more evolutionarily advanced than the Bambusa species, with the Dendrocalamopsis species being a transitional one. The evolution and classification of the woody bamboos inferred from leaf n-alkanes are consistent with morphological investigations reported before, indicating that the leaf wax components could be used as a chemotaxonomic tool for these bamboo plants.It is complicated the composition and concentration of leaf waxes, especially the distributions and carbon isotope compositons (ACL and CPI) of n-alkanes reponses to environments. The mensal variations of leaf wax in N. affinis (Rendle) Keng f. was investigated to make clear the relationships between the variations of leaf wax concentritions and composition, and its n-alkanesδ13C value, and plant growth or eviromental in two years.Cuticular wax composition and concentration varies among different organs of N. affinis (Rendle) Keng f.. The concentration of n-alkanes, alkenes, n-fatty acids, n-alkanols and stenol increases from stem to branch and leaves. While the concentration of n-alkanols and stenols decreases from stem to root and no n-alkanes was detected in roots. Generaly, trends to longer average n-fatty acids and n-alkanol chains and more sterol (C29:1) are evident from roots over stems to leaves. While the short-chain sterol (C28:1) and unsaturated sterol (C29:2) show the decreasing trend. Shorter n-fatty acids and n-alcohols are present in root than that in other parts. The proportion of C29 n-alkane gets depressed, and the dominant homologues are more dispersed in more caron numbers from stems over branches to leaves. The concentrations of a great member of components in leaf wax and hydrophobic members increased from root over stem and branch to leaves maybe be related to plant transpiration. The plant maybe can regulate compositon and concentration of leaf wax to adapt to the transpiration intensity. However, the distributions of n-alkanes in different organs seem not consistent with other compounds. This maybe due to the other function of n-alkanes covering up the role of resisting water lose. The polycyclic aromatic hydrocarbons with 4 rings or less than 4 rings can be detected in N. affinis (Rendle) Keng f.. The ratios of lower ring PHSs indicate their sources are major from combustion of coal, and little from wood, and that of higher ring PHSs maybe are not appropriate to indicate their source.The contents and distributions of the leaves wax from N. affinis (Rendle) Keng f. reponse seasonal changes well. The rising temperature and enhangcing evaporation and leaf growth evoked the elevated concentritions of alkanes and alkenes which reveal the maximum in July and August following a valley.. The phase between November and March with cold and dry climate, another peak value of alkanes and alkenes appeared. In hot summer and early-autumn, n-alkanes have longer averaged carbon chains. The ACL also increase lightly in cold winter with low air humidity. Short-chain n-fatty acids (