The Preliminary Protemic Study On Kenaf During Drought Stress

Kenaf(Hibiscus cannabinus L.),which belongs to the Malvaceae,is a short-day,annual,herb -aceous plant cultivated for the soft bast fiber in the stem. It has the advantages of excellent environment-stress tolerance,wide adaptability,high fiber yield and good quality. However, the ecological environment indispensable to plant is not always suitable. Drought,saline-alkaline and low temperature are three major abiological factors that strongly reduce crop yield. Among them, the loss caused by drought stress is more than the sum of other loss. With the development of molecular mechanism and biotechnology on plant drought-tolerance,the plant which is built by biotechnologies and gene engineering can grow well under drought stress. This is supplied another way to cultivate new drought- tolerance plants.The methods and technologies of proteomics are applied to this research. In order to investigate the biological function of special proteins,reveal the molecular mechnisms of drought adaptability in kenaf and clarify the law from gene to phenotype during the adaptation to drought, the proteome of kenaf leaves that collected from well-watered and drought-stressed plants were studied. The main results of this study are as follows:1 .Two kenaf cultivars differing in drought resistance(drought-resistant GA42 and drought-sensitive Yueyin I) were used to study the changes in water potential, free proline content and malonaldehyde content under water stress.Both cultivars subjected to water stress showed a great increase in free proline content and malonaldehyde content,while a rapid decrease in leaf water potential.Though the indexes mentioned above showed the same trend,they were different in variation range.2. The proteome of well-watered kenaf leaves were used as control. Many protein spots were detected in leaf extracts by two-dimensional electrophoresis. Of these proteins,fourteen spots showed a significant change in abundance under stress.3. All of the drought-responsive proteins were analyzed by MALDI-TOF-MS/MS and MS helped to identify eleven of them. The amino acid sequences of several random peptides were obtained. The eleven proteins related to drought stress are as follows:six ribulose-l,5-bisphos-phate carboxylase/oxygenase or its large subunit,which is the key enzyme in photosynthetic carbon assimilation; two rubisco activase,which widely exist in photosynthetic organism to regulate rubisco activity; one dimethylmenaquinone methyltransferase,which involved in methyl transfer; one putative plastidic glutamine synthetase,which is the key enzyme in plants ammonia assimilation; one ATP synthase beta subunit,which play role in converting other energy to ATP in all the living cells.The results obtained from this research could provide theoretical foundation for the further application of gene engineering to cultivate high drought tolerant varieties of kenaf.