Studies On The Change Of PD And The Appearance And Function Of Ectodesmata-like Structure In Garlic Scape During The Domancy Development

Plasmodesmata (PD) are the intercellular organelles that provide the major pathways for direct and convenient cell-to-cell communication in plants. The characteristic and changes of PD and the parenchyma cells of the garlic (Aliiurn saLivum L. ) have been systematically observed during the dormancy development by the transmission electron microscope(TEM). Adenosine triphosphatase(ATPase) was also localized by the cytochemical method. The function of ectodesmata-like was researched by Confocal Laser Scanning Microscopy(CLSM).PD, one of the organelles, underwent dramatic changes in morpha, structure and function, which are the same orderly changes to other organelles during the plant development. The diameter of PD extended from normal 40nm during maturation period to 100nm during germination period. PD which were in the breaking state during dormancy stage changed into the ectodesmata-like state during germination period, which indicated that the different states of PD were physiological conformance to the developpment of garlic clove during different periods. By Confocal Laser Scanning Microscopy(CLSM) and combined with fluorescence probe, 457Da Lucifer Yellow (LYCH)which was impermeable to the membrane, could enter the living parenchyma cell through ectodesmata-like. The result proved that ectodesmata-like still retained the function of the symplastic translocation.By the observation of the parenchyma cells, it was found that the various organelles underwent the dynamic changes in different periods-dormancy siage . releasing dormancy, germination period. The change of chromatin was the most obvious, which was the regularly well-distributed state during dormancy stage and then agglomerated and inclined to bordline at germination period. The nucleus distorted and disaggregatedat last. The plastids gradually disappeard. The degree of the vacuolation increased. The mitochondrion was the last one of the organnelles which disappeard . Associated with the ultrastructural localization of ATPase using the cytochemical method , it was demonstrated that the evacuation of the substance from the parenchyma cell was an initiative process in the parenchyma cell. It is speculated that the changes of the parenchyma cell of garlic in senescing belonged to the programmed cell death(PCD).