Ginkgo Conducting Tissue Development, Transcellular Transport And Waterlogging Stress

Use electronic microscope and energy spectrum analyses to study the development of sieve elements in gymnosperm gingko(Ginkgo biloba . L)root phloem. The results showed that the development of sieve elements in gingko root phloem had the typical course of PCD. What was different from the cells in most of other animal and plant was that the ruined cell organelle did not disappear, which remained in sieve elements and developed into P-protein body(it had been thought the P-protein body did not exist in gymnosperm );according to the observation of electronic microscope, plasmodesmata hadn't been seen in parenchyma of all ginkgo vegetative tissue. Pit fields in the cell wall of parenchyma were symmetric simple pit. There were many cell organelles around the pit fields, especially the mitochondria,which showed the pit fields were active. The study of endocytosis in endocytosis proved the foundations of caveolae and fluid phase endocytosis in the transcytosis in parenchyma cells of the vegetative tissue of ginkgo;most cell organells in seedlings root of ginkgo had rule changes under flooding, among which the cell nucleus was changed first and vaculation kept the most stable changes; along with the flooding extension, the root system activity went down gradually, and applicate FTIR to analyzing the variations of biochemical matter in leaves, which found that the contents of protein and polyamines were increased. Specially as follows:1. The inside wall had a large retention of small grains with a diameter of 3~4μm, and the outside wall membrane structure wrapped P-protein body with a kernel of high electronic density; The growth had the typical process of programmed cell death (PCD),i.e.the cell karyoplasm condensed, chromatins congealed and contracted and gradually agglomerated to the periphery of the nuclear membrane, and accordingly a nuclear of malformation appeared; the endoplasmic reticulum extended and connected and merged mutually, and the shallow part fused with the cell membrane. After packing the cell organelle, the endoplasmic reticulum divided the cell into several combined necrotic corpuscles of different sizes, the cell organelles collapsing with the cell and gathering abundantly in the inside cell wall. There were two kinds of degradation for the mitochondria: One was that the electronic density of the matrix decreased, the ridges died out to be cavitations gradually, and the double-layer membrane broke and ruined; the other was that parts of the territorial structure of the membrane broke, and the substance it contained escaped;The ultrastructure of the course of gingko root phloem developing from cell with protein thin wall into sieve elements might make out that the P-protein body was produced in PCD and developed with retention in the combined necrotic corpuscle; The P-protein had higher contents of S, K, P than the sieve elements wall tissue, and the percentage composition of S was 4.64%, which was more than twice the composition in the cell wall with 2.14%.According to the observation through transmission electron microscope that showed the P-protein had high electronic density, we might affirm that it was a P-protein body with S, P. The composition of K was 21.62%, 1.52 times that of the cell wall which was 14.23%. The existing of high quantity of P, S, K in P-protein body showed P-protein body was the main cell organelle for nourishment material in phloem, especially for sugar transportation.2. There were two possible ways of transcytosis in morphological characteristics: the transportation of pit fields , endocytosis and exocytosis. Plasmodesmata hadn't been seen in parenchyma of all ginkgo vegetative tissue;Pit fields in the cell wall of parenchyma were symmetric simple pit, usually 3-5 of them join together to beads form. The thickness of closer cell walls was about 1um, the diameter of the narrowest pit field was only 0.2-0.3 um. Cellular organelle was conferted near the pit. The endocytosis and exocytosis of parenchyma cells were very active. There were two ways at least about endocytosis: receptor-mediated endocytosis and fluid phase endcytosis, separately imbibe the ellipse or the circular microcyst whose diameter was approximately 0.05-0.1 um size and the big macro-molecule liquid phase substance which dissolves in the matrix. when endocytosis and exocytosis began, the partial plasma membrane which was next to the cell wall sinked and formed ligand coated pits, afterwards wrapped the receptor of caveolae, plasma membrane which near the cell wall adhered and was separated from with the plasma membrane to form coated vesicies, then entered the cell. At last, ligand decomposes partially or entirely, caveolae entered the cell by lysosomes. In the mesophyll cell, the plasma membrane extended gemma after sinked, partially formed the sub-gemma and separated with the venter-gemma to enter the plasma. When endocytosis, the sub-gemma vesicies had two types: one whose electron density was low likes the liquid phase, and another had rich fibrous stripe structure.3. Under the flooding, the quantity of mitochondria increased. The structure was deformed with the double membranes destroyed and inner ridges degradated. A large number of osmiopilic globules appeared dramatically. The increased number and volume. of starch grain made mitochondria become the amyloplast.; Cell nucleus was also deformed gradually. The nucleolus disappeared and nucleoplasm was condensed. Cell nucleus was the first affacted by flooding;Endoplasmic reticulum cistern dilated, which then formed phagocytic vacuole and packed cytoplasmic matrix into vacuoles. Some formed a ring to surround the degraded mitochondria; Plasmolysis and endocytosis appeared in cell membrane, and endocytosis became dramatically at last; Vaculation happened in the cell. The vacuoles were melted with each other. Vacuoles was the only cell organelle to keep stable change under flooding ; Abundant compact crystalline P-proteins were gathered around partial dismemberment of cell wall; Siderosome was swallowed into vacuole, number of which was reduced gradually, and disappeared at last.4.Useα-Naphthylamine oxidation to determine the root system activity of ginkgo seedling under the flooding condition, and the first-time to applicate FTIR to analyzing the variations of biochemical matter in leaves. The result showed that: along with the flooding extension, the root system activity went down gradually; comparing with ck, The absorbance of samples treated at 3404cm-1,2924cm-1,1651cm-1,1558cm-1,1747cm-1,1242cm-1,1068cm-1and 720cm-1was enhanced. The peak at 3404cm-1was attributable to the methyl groups of polysaccharide. The peak near 2924cm-1 was attributable to the stretching vibration of CH2—. The dominating bands near 1651-1 and 1558cm-1 were assigned to amideⅠand amidⅡrespectively. The peak at 1747cm-1 was caused by the stretching vibration of C=O,and 1242cm-1 caused by the stretching vibration of C—N and bending vibration of N—H was amideⅢ.The high peak near 1068cm-1was assigned the vibration of C-O of polysaccharide. A weak peak appeared in 720cm-1by the reason of more than four -CH2- in long chain in a molecule. Protein was characterized by the band of 1651cm-1,1558cm-1,and the typical band of polyamines should appear in the stretching vibration of–NH in 3404cm-1 and bending vibration of–CH in 720cm-1,which all indicated the contents increased.