Study On Stems Structure And Photosynthetic Enzyme Activity Of Pkyuostachys Pubescens Duirng Rapid Growth Stage

Taking stems of Phyllostachys pubescens as experimental material, we determined the stemstructure using histological section and electron microscope; the distribution of chloroplast using laserscanning confocal microscope, and detected the changes of pigment content and photosynthetic enzymeactivity by colorimetric method in the stems during its rapid growth stage. The results are asfollowed：1. The stem of Phyllostachys pubescens consists of Epidermis, Hypodermis, Ground tissue andmany scattered Vascular bundle be surrounded with Fiber. Under the transmission electron microscope,it was found that the number of chloroplast in cell and its stroma lamella, grana lamella and starch grainhad increased increased with the growth of the stems of P. pubescens.2. Using laser scanning confocal microscope, we observed that the chloroplast mainly distributedin the ground tissues under epidermis, and it was also found in the cells around the vascular bundle,liking the Kranz anatomy in C4plant. The content of chlorophyll a, chlorophyll b and carotenoid in theouter layer stems was significantly (P <0.01) increased with the growth of the stems of Phyllostachyspubescens, and the content of pigment in the inner layer was low. In the differet growth stage, thecontent of chlorophyll in the outer layer expressed as Basal internode> Middle internode>Topinternode, the content of chlorophyll in the inner layer remained at a relatively approch.3. The activities of Rubisco initial, Rubisco total and RCA in the stems reached the highest levelafter10days, and they declined gradually with the growth of the stems. After30days, Rubisco activityin the outer layer stem remained at a relatively low level, the activity in the inner layer stem continuedecreased. In the early growth(10-30d), PEPC and NADP-ME activity in the stem of Phyllostachyspubescens declined gradually. At30rd days, PEPC and NADP-ME activity in different parts of outerlayer stems stablely at0.1466μmol·g-1·min-1nearby. At the same time, the ratio of PEPC/Rubisco in topinternode、middle internode and basal internode increased gradually, and they reached14.94、12.83and20.53at60th day, which was markedly higher than that in C3plant.Those results indicated that there was C4photosynthetic pathway in the stems, and the pathwaymay play an important role in the efficient photosynthesis and rapid growth of Phyllostachys pubescens.