The Mechanism Of Typical Plants Adaptative To Calcium Rich Environment In Karst Area Of Southwest China

The karst ecosystem is the ecosystem that is restrained by the karst environment,it has its own particularities, such as soluble rock, calcium-rich, alkaline, soil scarcity, double-layer structure, water leakage, and accordingly the karst vegetable have the features of petrophile, xerophile and calciphile on the surface. Research on the plant adaptation traits to karst environment is valuable to enrich the knowledge about plant adaption to the environment. And the beter understanding of the ecological habits of these adaptable plants will provide a new way for the rehabilitation of the fragile karst ecosystem. The present researchs were focused on the adaption traits of Lonicera confusa to karst environment by field investigation and indoor cultivatied pattern, especially on the L. confusa adapted to the Calcium rich environment. The results are as follows: Firstly, the elements in the leaves of Lonicera Japonica Thunb and L. confusa in different developing phase growing in southwest karst area were measured utilizing microwave digestion and Flame Atomic Absorption Spectrometry. The results showed that:(1) both of them have a high content of Ca and Mg, but have a great difference between each other. It reflected the difference of selectively absorb to metal elements; (2) Because of the different degree of growth, they have different metal elements in their leaves. Along with the growth of the plants, they have uptrend in collectivity.Secondly, the anatomical characters of L. japonica Thunb, L. confusa, Polygala japonica Houtt and Solidago decurrens Lour had been observed by the optical microscope and scanning electron microscope which were used to analyze the relationships between the morphological and anatomical structures and their ecological adaptability. The results were showed as follows: (1) The scanning electron microscope results showed that bushy hairs were distributing on the upper epidermis of L. japonica Thunb, L. confusa and Solidago decurrens Lour, some bushy hairs were distributing on the costa of L. Japonica Thunb and some stellate hairs were distributing on the upper epidermis of Solidago decurrens Lour, The stomas were located among the upper epidermis hairs of Lonicera Japonica Thunb, L. confusa and S. decurrens Lour, which could reflect the sunlight and decrease the transpiration to adapt high-intensity light and drought environment; (2) The leaves of P. japonica Houtt were fleshy, its stomas were distributing on both the upper epidermis and lower epidermis of leaves and obviously cryptopore, and the stomas especially distributed on the depression of epidermis. The structures were propitious to keep water. (3) The outside cell wall of all the upper epidermis cells appeared thicker or keratinized, which were helpful to decrease water transpiration. All the characteristics of these plants were the results of the adaption to Karst drought environment and the acclimatization tended to similarity.Thirdly, L. confusa was cultivated in two types of soil with controlled Ca levels. The ultrastructure of leaves at different developmental stages was observed, and their Ca contents analyzed by laser scanning confocal microscope and energy-dispersive X-ray spectroscopy. There was no significant difference in leaves between the two experimental groups at very early stages of development. The glands of leaves growing in Ca-rich soil became saturated and showed a steady increase of Ca content in the following stages. The Ca level in leaf trichomes also increased steadily, compared with those from Ca-poor soil. When the leaves matured, Ca salts were excreted via stomata of L. confusa from Ca-rich soil. Lonicera confusa had a special anatomical mechanism of responding to Ca-rich environments by excreting Ca salts via stomata, and storing Ca²⁺ in leaf glands and trichomes.Fourthly,the calcium excreted process of L. confusa was studied by Scanning Electron Microscope (SEM) and EDAX, and the different types of Ca crystals by self-assembly of secreted products, the compare study also be taken between the point scanning and line-by-line scanning of the Ca salt. The results showed as followed: Firstly, the Ca crystals are formed after Ca salt excreted by stoma of L. confusa; secondly, the Ca salt could self-assembly three type of crystal such as prisms, ball and crystal sand. The crystal have large amount of Ca and sulfur (S). We deduce that the crystal nucleus protein is rich in S element and it will take beneficial inspiration for the biomineralization of Ca-related crystal and others; thirdly, the EDX could be effectively used for micro probe analysis of plant leaves and identifying on the plant excreted products.Fifthly, the photosynsis and proteomics traits of L. confusa at different Ca-level cultivated condition were investigated. The results shows that chlorophyll content and Net photosynthesis in the calcareous soil planted L. confusa were much higher than that of sandstone soil planted materials. High level of calcium could decrease the transpiration and stomata conductance of L. confusa, these results indicated that a certain degree of calcium could obviously effect the transpiration and stomata conductance, which farther enhance the drought resistance of L. confusa. Net photosynthesis were significant positive correlation with photosynthetic active radiation and significant negative correlation with chlorophyll; on the condition of calcareous soil, Pn also significant negative correlation with CI (p<0.01), Pn positive correlation with PAR but not significant. The photosynthetic of L. confusa was non-stomata limitation. The proteomics results showed that the content of RuBisCO in leaves of L.confusa cultivated in calcareous soil is significance higher than sandsoil, the results confirm the preview results of Net photosynthesis in the calcareous soil planted L. confusa were much higher.Sixthly, The calmodulin gene of L. confusa have 450bp base-pair, and the calmodulin contains 148 amino acid,the protein forecast results indicated that the Molecular Weight of calmodulin of L. confusa is 16847.67Da, isoelectric pointvalue is 4.11, and homology result showed that the calmodulin of L. confusa and L. japonica were exactly the same, The calmodulin of L. confusa have no transmembrane region, the predicted Protein Localization Sites is cytoplasm; It have typical EF-hand motif,have four Ca²⁺ binding site, the 3-D structure of calmodulin gene of L confusa is stable.