Study On Propogation Techonolgy Of Tropical Island Plants-Scaevola Taccada And Vitex Rotundifolia L

Scaevola taccada and Vitex rotundifolia are two representative plants in the tropical island and be consider as an important implemental plant in the vegetation restoration of tropical islands to make a great contribution on the restoration of plant community structure and ecological system.In this study,the S.taccad seed,S.taccad leaf,root and V.roundifolia stem were used as explants,and a model system for detecting seed viability and enhancing seed germination in S.taccada was developed and we also eatablished an efficient regeneration system via the pathway of somatic embryogenesis and adventitious shoot organogenesis in S.taccada and an efficient plant proliferation and regeneration system in V.rotundifolia.Results were as follows:1.The optimal detection of seed viability was possible when seeds were soaked for 3 h in 0.4%2,3,5-triphenyte-trazoliumchloride?TTC?.The viability of seeds that were dried naturally for 15 days exceeded 90.0%.Seeds that were stored indoors or at 4°C for 15-90days also showed high seed viability.However,when storage time was extended to 180days,seed viability declined sharply.The nutritious epicarp of intact S.taccada fruit is easily infected by mildew and decomposes rapidly in natural conditions,where air humidity is 60-90%,explaining the low SG%.When the epicarp was removed from fruits,this speeded up germination period by almost 8 days?SG initiated within 28 d and 36 d,respectively for the former and latter?,and also increased SG%.The SG%of seeds with their epicarp removed then soaked in seawater for 24 h was higher than seeds soaked in distilled water or 200 mg/L GA₃after sowing for 40 days,indicating that this semi-mangrove species favors growth in seawater.However,no significant differences were observed when sowing time was extended to 60 days.After 60 days'sowing,the seedlings were transferred to bags with yellow soil and peat?3:1,?:??.80.2%of seedlings survived after growth for 30 days.2.Different plant growth regulators?PGRs?have the different effects on the induction of somatic embryo and adventitious shoot from leaf explant and root explant.The medium supplemented with 3.0 mg/L benzyladenine?BA?alone had made a positive contribution on somatic embryo and adventitious shoot induction of leaf,the frequent of somatic embryo or adventitious shoot induction and the number of somatic embryo and adventitious shoot per leaves was 98.3%and 48.1 respectively.Lots of somatic embryo and adventitious shoot was obtained from roots on the medium supplenment with 1.5-2.5 mg/L thidiazuron?TDZ?alone.The frequent of somatic embryo or adventitious shoot induction and the number of somatic embryo and adventitious shoot per roots was 98.8%and 52.7 respectively.According to the histology observe that the somatic embryo or adventitious shoot can derived from both epidermis cell and mesophyll cell of leaves,and the somatic embryo or adventitious buds were mianly derived from parenchymal cell near epidermis in root explants.Both somatic embryo and adventitious shoots were proliferad and elongated on the medium supplemented with the conbination of 0.75 mg/L BA and 0.25 mg/L NAA or the conbination of 1.0 mg/L BA and 0.1 mg/L NAA.98.83%of shoots rooting with 23.0roots per plantlets after cultured on the half-strength MS medium supplemented with2.5-3.5 mg/L Indole-3-butyric acid?IBA?alone or the conbination of 1.0 mg/L IBA and 1.5mg/L NAA for 30 days.82.7%plantlets survived after transplanted into the sand for 45days.3.The formation of adventitious shoots can be regulated by cytokinins,0.5-2.5 mg/L kinetin?KIN?or trans-6-?4-hydroxy-3-methylbut-2-enylamino?purine?ZEA?,or 0.5 mg/L BA,which mainly induced the formation of adventitious shoots from normal stems,while a higher concentration of KIN,ZEA or BA not only induced the formation of adventitious shoots from normal stems,but also the development of fasciated stems which many adventitious shoots formed.NAA had a significant positive effect on shoot recovery from fasciated stems and adventitious shoot elongation.Adventitious shoots could be elongated to 3.0 cm after culture for 30 days on MS medium supplemented with 7.5-12.5 mg/L NAA.An anatomical analysis shown that the pith cells of fasciated stems developed laterally to0.05-0.08 mm,making stems become longer than in plant shoots,while the pith cells were usually 0.02-0.04 mm.Flow cytometry indicated no obvious changes in chromosomes among different types of shoots.In addition,70.5%of adventitious shoots rooted forming with an average of 86.3 roots per shoot after individually excised shoots were cultured on1/2 MS medium supplemented with 3.0 mg/L IBA and 3.0 mg/L NAA.After 30 days period of acclimatization in yellow soil and peat?3:1,?:??,86.0%of potted plantlets survived.