| Swida wilsoniana, a member of Cornaceae,with important ecological and economic value and widely distribution. It's fruits enriched with oil and grease containing unsaturated fatty acid.Its an ideal biodiesel feedstock and edible oil. However, till to now most Swida wilsoniana resources were wild or planted with seedling.By means of exploiting existing wild resources and select breeding, elite germplasmbut resources can obtain but resources were limited. Hybridization and mutation breeding can increase genetic diversity and broaden the resource of genetic adaptability.Therefore, in this paper, three different clones of Swida wilsoniana were used as experimental materials, and their Megaspore and microspore development, morphology and structure characteristics, effects of exogenous hormone on vegetative growth and flowing were studied by means of field survey, paraffin section, and endogenous hormone determination and other methods. So as to observation and analysis the megaspore and microspore development progress along with morphology and structure change of Swida wilsoniana,which would be very important basis for cross-breeding, polyploidy induction and anther in vitro culture. To study the effects of exogenous on endogenous contents, vegetative growth of new branches and flowering, then to provid reference for developing cultivation practices of high yield.The results are as follows:1Megaspore and microspore development of Swida wilsoniana was typical dicotyledon megaspore and microspore developmentt.According to the characteristics of developmental processes of megaspore and microspore development.The megaspore development was typical dicotyledon megaspore, and the development progress was divided into four stages, including megaspore mother cell stage, tetrad stage, mononuclear embryo sac period and the multi-nucleate embryo sac stage. Microspore development was also divided into the following four stage: microsporocyte, tetrad, monokaryon microspore period and binucleate microspore period. The process of megaspore and microspore development is not synchronized, microspore development started9-12d earlier than megaspore development2. Pollen grains from different clones were morphologically different. Exterior structure of pollen grains from different clones of Swida wilsoniana was primarily common in shape. Morphologically, the pollen grain was prolate with tricolpate, the length of polar axis was about45μm to62μm and the length of equatorial axis was about25μm to32μm, which was median size pollen grain. The equatorial view was quadrilateral shape, and the polar view was tilobation sub-circular, approached to triangle. It had3strips germinal aperture furrow along the polar axis; however the equatorial view showed1-2straight line aperture furrows, which almost reached the two poles. From the polar view, the pollen grain showed3aperture furrows faintly, cyclic annular distribution. There was small holes sculpture scattering on the pollen grain's ektexine unevenly. However difference among pollen grains of different clones was existed in the ratio of polar axis length to the length of equatorial axis, the number of round aperatures sculpture and their scattering pattern on ektexine, to some the difference would be used as an index of classification of different clones of dogwood.3. Morphological characteristics of flower changed with development of megaspore and microsporeAlong with the development of megaspore and microspore, the colour and volum of inflorescence and flower varied:Inflorescence/bud size increased with the megaspore and microspore development. From megaspore mother cell to multi-uncleate embryo sac, the color of buds changed form light green into white; And for microspore development, started from microspore mother cell to binucleate state, the buds colour changed from dark green to white. During flower buds became light green, megaspore and microspore mother cell started meiosis which is the best period of polyploidy induce.4The starting time of megaspore and microspore development controlled by different clones and planting microenvironments4. The process and tissue structures were the same for megaspore and microspore development of different clones Swida wilsoniana. However starting time of development was different. Usually, plants had strong growth, plants growing at place getting enough sunlight started development erarly those had weak growth and getting a little sunlight. Also the external flower buds within cyme started development earlier than those locating inside.5. Exogenous hormone6-BA, CCC, PP333influenced vegetative growth and flowering of Swida wilsonianaSprayed different concentrations of exogenous hormone6-BA, CCC, PP333at different times have different effects on Swida wilsoniana vegetative growth and flower bud differentiation.100mg/L6-BA,200and300mg/LCCC,1000and1500mg/LPP333to some extend inhibited the annual growth of new branches;300mg/LCCC and1500mg/LPP333promoted flower buds differentiation significantly; Also exogenous hormone300mg/LCCC and1500mg/LPP333can enhanced the development of megaspore and microspore, but the effect on the morphology of the megaspore and microspore was little.6Different exogenous hormones had different effects on endogenous hormone contents of Swida wilsoniana leafIn late winter, Sprayed buds of Swida wilsoniana with exogenous hormone6-BA of50-200mg/L, inhibited the IAA synthesis, while the CCC promote IAA synthesis;100mg/L6-BA and300mg/LCCC to some certain enhance the synthesis of GA, Other exogenous hormones had little influence on endogenous GA content change. All the three tested exogenous hormone treatment inhibited ABA synthesis;50and100mg/L6-BA,200and300mg/LCCC,1000and1500mg/LPP333to some extent increased the ZR contents.200mg/L6-BA increased IAA+GA/ABA ratio, while300mg/LCCC and three concentrations of PP333increased IAA+GA/the ABA and IAA+GA+ZR/ABA ratio, decreased IAA+GA/ZR ratio.In spring, sprayed buds with different concentrations of exogenous hormone6-BA, CCC and PP333endogenous auxin of IAA, GA and ZR content were lower than that from the control plants; however, the the three different concentrations of exogenous hormones to some extent increased the synthesis of ABA;the tested three concentrations of6-BA,CCC and PP333processed ungerminated buds, endogenous Hormones of ratio IAA+GA/ABA, IAA,+GA+ZR/ABA were lower than that of the control group, while the IAA+GA/ZR ratio were higher than that of the control.7.Correlation between endogenous hormone and vegetative growth and flowering of Swida wilsoniana Sprayed exogenous hormone6-BA, CCC and, PP333in late winter and early spring changed the endogenous hormone content of IAA, GA, ABA and ZR. Their content and relative content to some extent related with the vegetative growth of new branches and flowering buds. Spraying exogenous hormone in winter, endogenous hormone content of GA had significant negative relationship with the legth of internodes; IAA+GA/ZR also had negative relationship with new leave's length/width; While the ratio of IAA+GA+ZR/ABA had significant negative correlation with the number of leaf buds and total number of buds.Sprayed exogenous hormones in Spring, the average internode length and total branches length significantly negative related with leaf endogenous hormones IAA+GA/ZR ratio,and positive with IAA+GA+ZR/ABA ratio.The flower bud number and total buds number related with the content of endogenous hormones ZR and ration of IAA+GA/ABA.To sum up:sprayed exogenous hormones100mg/L6-BA,200and300mg/LCCC,1000and1500mg/LPP333in winter and spring to some extent controlled the vegetative growth of annual new shoots;300mg/LCCC and1500mg/LPP333significantly increased the rate of flower buds,300mg/LCCC and1500mg/LPP333obviously advanced the development time of megaspore and microspore... |
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