Temporal and spatial changes in Ca^(2+) distribution during the programmed cell death of tracheary elements

The changes in Ca2+ distribution in the tra-cheary elements (TEs) of the pepper leaves were studied using the cytochemical method of potassium antimonate. At the early stage of TEs formation, the vacuole and the nucleus held large volume, and antimonate Ca2+ deposits were observed mainly in the intercellular space and the cell wall. As the thickening of secondary wall occurred, the vacuole, nucleus and other organelles began to rupture, concomitant with the increase of calcium deposits in the cytosol, showing the influx of Ca2+ into the cell. With the further rupture of cytoplasm and other organelles, the number of calcium deposits at the non-thickening cell wall increased, but declined at the thickening bands of the secondary wall. When the cytoplasmic contents disappeared completely, the level of Ca2+ decreased at the non-thickening wall, but by contrast, increased at the thickening bands of the secondary wall. These observations indicated that the dynamic changes in Ca2+ distribution spatially and

The changes in Ca2+ distribution in the tra-cheary elements (TEs) of the pepper leaves were studied using the cytochemical method of potassium antimonate. At the early stage of TEs formation, the vacuole and the nucleus held large volume, and antimonate Ca2+ deposits were observed mainly in the intercellular space and the cell wall. As the thickening of secondary wall occurred, the vacuole, nucleus and other organelles began to rupture, concomitant with the increase of calcium deposits in the cytosol, showing the influx of Ca2+ into the cell. With the further rupture of cytoplasm and other organelles, the number of calcium deposits at the non-thickening cell wall increased, but declined at the thickening bands of the secondary wall. When the cytoplasmic contents disappeared completely, the level of Ca2+ decreased at the non-thickening wall, but by contrast, increased at the thickening bands of the secondary wall. These observations indicated that the dynamic changes in Ca2+ distribution spatially and temporarily might have a close correlation with its distinct roles played during the formation of the secondary walls.