Programmed Cell Death in Plants: Ultrastructural Changes in Pea Guard Cells

Abstract

Treatment with cyanide of epidermal peels isolated from pea leaves resulted in destruction of nuclei in the guard cells of stomata, which is visible with a light microscope. The process was accelerated by illumination. Electron microscopy revealed significant CN--induced changes in the ultrastructure of guard cells, which increased with time. Margination of chromatin, which is one of the first signs of apoptosis, was observed in the guard cells even after 1 h incubation of the isolated epidermis with CN-. Subsequent chromatin condensation, swelling of the endoplasmic reticulum with formation of large tanks covered with ribosomes, changes in the structure of dictyosomes, and a slight swelling of mitochondria were observed after 3 h of the epidermis incubation with CN-. After 6 h of incubation with CN-, the bulk volume of the guard cells was filled with vacuoles, the cytoplasm occupied the thin marginal layer, the nucleus was in the center similarly to the control experiment, but it was polylobal, extended in narrow cytoplasmic bands, and, despite the loss of the nuclear envelope integrity, appeared to be a self-dependent structure. In the envelope-free open regions of the nucleus, mitochondria and chloroplasts directly contacted with chromatin. Much like the cell nucleus, chloroplasts lost the integrity of the membrane, but did not swell and retained the stroma and integrity of the thylakoid system. An antioxidant di-tert-butyl-4-hydroxytoluene prevented ultrastructural changes in the cells observed after 6 h of incubation with CN-. Thus, the CN--induced death of the guard cells of stomata occurs through the mechanism of apoptosis.

Differential timing of defense‐related responses induced by cerato‐platanin and cerato‐populin, two non‐catalytic fungal elicitors

“…D). The early detection of PCD by TEM compared with other microscopy techniques is in agreement with previous studies (Bakeeva et al , Dzyubinskaya et al ).…”

More than Scales: Evidence for the Production and Exudation of Mucilage by the Peltate Trichomes of Tillandsia cyanea (Bromeliaceae: Tillandsioideae)

“…In mature bracts, the presence of trichomes exhibiting degenerating protoplasts and cells with empty lumens corroborates the ephemeral nature of secretory activity. The occurrence of chromatin condensation, as well as darkening and fragmentation of the cytoplasm due to swelling of endoplasmic reticulum, were previously considered as evidence of programmed cell death in plants [ 13 , 62 , 63 ], and indicate that a comparable process operates on the secretory indumentum of T. cyanea . In this context, the occurrence of vesiculation throughout the cytoplasm can be interpreted as profuse dilations of the endoplasmic reticulum rather than due to vacuome development.…”

5-Azacitidine Induces Cell Death in a Tissue Culture of Brachypodium distachyon

“…The traits described for cell death that were observed in this study indicate that it may be a vacuolar cell death, which is manifested by a gradual decrease in the volume of cytoplasm and a significant increase in the vacuole volume as well as volume presence of the cytoplasm content of the cells inside the vacuole compartment and the subsequent degradation of the cargo [ 40 ]. This type of cell death was also described during embryo development as well as during tissue and organ differentiation, which is either a normal part of the plant developmental program or a response to stressful conditions [ 41 , 42 , 43 , 44 , 45 ]. Interestingly, in our research, we observed the increasing number of plastoglobuli, which may be linked with the upregulation of plastid lipid metabolism in response to oxidative stress provoked by 5-azaC.…”