The Characteristics Of Tissue Anatomy And Sugar Metabolism During The Rapid Growth Of Fargesia Yunnanensis Shoots

In order to explain the rapid growth mechanism of bamboo plants,we did a series of studies.The morphological characteristics of nuclei and the secondary wall deposition in parenchyma and fiber cells during the whole bamboo growth cycle from shoots to old culms,were described and analyzed.And the content of soluble sugars and enzyme activity related to sugar metabolism in Fargesia yunnanensis shoots,which were at different developmental stages,were researched by the methods of spectrophotometer,HPLC and so on.The results showed that:The fiber wall thickness was initially less than the parenchyma cell thickness in young shoots,but increased significantly after 1 year.Fibers elongated earlier than both their nuclei and parenchyma cells.Fiber nuclei also elongated and presented the spindle shape in longitudinal section.The formation and elongation of long cells were involved in the fast elongation of internodes.In mature culms,the ways of secondary wall deposition for fibers depended on their diameter and positions.Large diameter fibers usually had more cell wall layers than narrow fibers.The variation of the glucose,fructose,sucrose and maltose are significant during the developing bamboo culms,especially in Y3 period,which are in the inner zone or middle position of internode,have higher content,the sucrose existed in outer zone of internode,and also the top or bottom of internode.The methods of Hepes-NaOH is suitable for SAI of bamboo shoot.And the solution acid intervase(SAI)mainly existed in 60% saturation ammonium sulfate solution.During the developmental stages of bamboo shoots,the enzyme activity of SAI at earliest shoots is highest,the middle of shoots is higher,and back shoots is lowest.The activity of SAI is far higher than neutral intervase(NI)or cell wall-bound intervase(CWI)at middle shoots.The variation of enzyme activity for sucrose phosphate synthase(SPS)is significant at different positions and developmental stages.The inner zone or bottom position has higher activity,because they are immature,and those are similar to sucrose synthase(SuSy).The higher the developmental degree of bamboo shoots,the lower the activity of SPS.Initially,the outer zone and top of internodes have higher activity of SPS,and then the inner zone and bottom of internodes also have higher activity of that.There is much higher activity of SPS in immature tubes.And the main function of SuSy is to cleave the sucrose during the development of bamboo shoots in F.yunnanensis.The activities of SuSy are high at synthesis direction,while those are low at cleavage direction from M1 Top to M1 Bottom.