Development And Structures Of Aloe Stems And Leaves And Their Relations With The Accumulation Of Aloin

The plants of Aloe belong to Liliaceae, they are multiperennial, evergreen and succulent plants. The exudates of Aloe plants have been used as drugs or cosmetics widespreadly. The mainly biological activity constituents of the aloe exudates were anthraquinones ,such as aloin. In this study, we investigated the developments and structures of stems and leaves, fixed the storing location of aloin in aloe plant, determined the content of aloin by using anatomical, phytochemistry, histochemistry and fluorescent microscope multiply. Finally, the developments and structures of stems and leaves and their relations with the accumulation of aloin were discussed.The development of leaves consisted of three stages: promeristem, primary meristem and primary structure stage. Promeristem possessed the typical cell characteristics of meristem, with big nucleus, abundant of cytoplasm and thin cell wall. There were no intercellular space. Then the promeristem developed into primary meristem stage, the leaf primordium different into protodern, ground meristem and procambial bundles. Protodern was the outermost cells, it consisted of cells that fit closely together, nearly or quite without intercellular spaces. Ground meristem located at the center of leaf and a ring of procambial bundles embedded in ground meristem. The ground meristem located outside or inside of the ring of procambial bundles were different in cell volume and degrees of cell differentation. The ground meristem cells outside the ring of procambial bundles possessed small volume, big nucleus and started to vacuolization. In creast of, the ground meristem cells inside the ring of procambial bundles possessed big volume, small nucleus, developed vacuole and intercellular spaces. Finally, the leaf developed into primary structure stage. Protoderndeveloped into epidermis. Ground meristem outside the ring of procambial bundles developed into chlorenchyma and ground meristem inside the ring of procambial bundles developed into water storing tissue. The procambial bundles developed into vascular bundles.The development of vascular bundle and big phloem parenchymatous cells as fellow. The cells rounded the procambium bundle differentiated into bundle sheath at the initial stage when the procambium bundle developed into vascular bundle. When the sieve tube member emerged in protophloem, there were one or two lay of procambium bundle cells between the sieve tube member and bundle sheath, and these procambium bundle cells began to devise when metaphloem and metaxylem first appeared in the bundle. With the increase of volume and vacuolization, the cells between the sieve tube member and bundle sheath developed into big phloem parenchymatous cells. Because the big phloem parenchymatous cells shared the same origin development with the other phloem cells, the big phloem parenchymatous cells were special phloem parenchyma cells.The investigation of histochemistry showed that there were precipitate in the central vacuole of big phloem parenchymatous cells when the material was soaked in the liquid of 1% lead acetate [ Pb (CH3COO)2]. The observation of TEM showed that there were abundent of osmiophilic materials in the central vacuole of big phloem parenchymatous cells. The yellow fluorescence was observed in big phloem parenchymatous cells when the section of life material was investigated by fluorescent microscope with blue light. So the big phloem parenchymatous cells of vascular bundles were the mainly storage location of anthraquinones, such as aloin.The anatomical structures were studied in Aloe arborescens leaves according to leaf age. All leaves were consisted of epidermis, chlorenchyma, water storing tissue and vascular bundles. The different between young leaf and old leaf was that the young leaf with developed big phloem parenchymatous cells, whereas the old leaf with decrepit ones. The aloin content determined by HPLC decreased accompanying the increase of leaves age in the same plant. The young leaves had high aloin content,but their yiel...