| The karst system in southwestern China is fragile and has the special particularities, such as calcium-rich and water leakage. Rock desertification occurs there under the impact of anthropogenic activities. In order to harness the rock desertification at karst area in southwest China, our government carried out many rehabilitation projects and called on the local people to plant perennial Flos Lonicerae. Perennial Flos Lonicerae is not only adaptable to karst environment, but also can be as medical herb due to its flower containing many kinds of officinal ingredients. In the past, many distinguished rehabilitation results are got, but the relationship between Flos Lonicerae and the karst environment and the ecology adaptation character of Flos Lonicerae is not clear due to lack of experimental data. Then, Flos Lonicerae is selected as intermedia in this paper to research the mechanism of cross-adaptation to water stress in plants at karst area in southwestern China and understand the structural and functional responses of plant to environmental stress. The research mainly includes the relationship between the elements character of Flos Lonicerae and the karst biogeochemistry, the drought-resistant mechanisms of Flos Lonicerae on their leaf-structure, the photosynthetic physiological ecology of Flos Lonicerae, the distribution character of Ca2+ in the cell of Flos Lonicerae and the modulation of calcium.1) In order to study the characteristics of element values in the cell of plants and soils and their relationship, which to evaluate the biogeochemical effect of soil on the element contents in the cells of plants in the same environment of southwestern China, the soil samples were collected for analysis and the weight and atom percent of elements (WT% and AT%) in the leaves of two different species of Flos Lonicerae was analyzed by the electron probe. From the results of soil analysis, it can be seen that though the total element values in soil of different layers were arranged in SiO2>Fe>Ca>Mg>K>Na>Mn>P>Zn>B>Cu, the nutrient element contents in the soil were determined by the liable content of elements, which were arranged in Ca>Mg>Cu>Mn> K>Na> P>B>SiO2> Zn>Fe. That is to say, the karst environment is composed of soluble rock, soil scarcity and calcium-rich. Moreover, the migratory velocity and availability of elements were also determined by their coefficient variability. According to statistical results, Ca, Mn and P in the soil have high coefficient variability, which reflects its background of karst soil. The content of Ca is higher while the content of Mg is lowest in the cell of two different species of Flos Lonicerae (r=-0.156,P<0.05) and the content of P in the cell is inferior to Ca (r=0.868,P<0.01). By studying the relationship of soil and the plants, it can be seen that the above result perhaps is caused by the character of local biogeochemistry. Ca is mainly absorbed by plant with the help of transpiration and accumulated in the cell, which becomes the highest element in the cell. Under the accumulation of Ca in cell of plant, it will affect the absorbency and the content of other elements in the cell of Flos Lonicerae. As a result, the content of other elements in the Flos Lonicerae appears different by synergistic action and antagonistic action, which affects its quality and officinal value.2) The leaf epidermis of Lonicera japonica Thunb. and Lonicera confusa in the genus of Flos Lonicerae were mainly observed by scanning electron microscopes (SEM) to study the characteristics of stomata, trichomes and dermal cell, etc.. The results showed that stoma exists only on the lower epidermis and its distribution is irregular, and leaf epidermis consist of epidermis cells, stoma complexes and bushy trichomes including glandular hair and non-glandular hair. On the upper epidermis, anticlinal wall caves in sinuous groove to countercheck the transpiration. Evidences from leaf morphological structures serve as another proof on drought-resistant mechanisms. Some strumaes distributing regularly are hypothesized as oxalic calcium on the lower epidermis under laser scanning confocal microscopy (LSCM) with Fluo-3/AM, which can increase their endurance to drought stress. Therefore, the above characteristics of Flos Lonicerae can reduce the loss of water and make Japanese honeysuckle and Wild Honeysuckle adapt to the droughty environment at karst area in southwest China. However, there are some differences of the two species.3) During the drought stress and the rewatering process, Flos Lonicerae can increase the content of MDA, proline, soluble sugar and chlorophyll and improve the activity of peroxide enzyme. With the soil losing water, the modulation of Flos Lonicerae decreases. However, when soil pre-treatment with the suitable Ca2+ concentration (about 15mmol/L) during drought stress could increase peroxide enzyme activity and soluble sugar content,alleviate cell membrane leakage and chlorophyll decomposition.Then , Flos Lonicerae have the low transpiration and high photosynthesis at this kind of soil pre-treatment, which shows the positive correlation with the chlorophyll, proline content and the activity of peroxide enzyme and the negative correlation with MDA, soluble sugar contents.4) By studying the distribution of Ca2+ in the cell of Flos Lonicerae, it can be seen that Ca2+ mainly appears in chlorophyll pigments and connects with PS II, which can explain the plant at karst area with high photosynthesis characters.5) By analysis the genetic relationship between the genotypes of Flos Lonicerae and their relatives based on RAPD distances, it can be seen that the experimental plants can stand by their original environment. Moreover, by comparing the cDNA of CaM from Flos Lonicerae, it shows that the difference of CaM leads to their different acclimation.From the above results , it can be seen that in order to adapt the karst environment, Flos Lonicerae have the drought leaf-structure, the high photosynthetic physiological character and the osmotic modulation, which can adjust by the Ca-CaM.
|
PDF Full Text Request