engleski

Morphological and proteomic analyses of sugar beet cultures and identifying putative markers for cell differentiation

Normal (N), habituated nonorganogenic (HNO), and tumour (T) sugar beet cell lines were analysed in order to establish specific patterns of extracellular proteins and iden- tify protein markers that might explain the distinct pheno- typical characteristics. Electron microscopy showed that the ultrastructure of N cells corresponds to that of parenchyma cells, and that these cells contain plastids with large starch grains. HNO and T cells had enlarged, lobed nuclei with an increased number of nucleoli ; the number of nuclei in HNO cells was greater than in T cells. The T plastids were elon- gated, with reduced thylakoids and abundant phytoferritin deposits, while HNO plastids were small and vacuolated, with an irregular, underdeveloped thylakoid system. The extra- cellular proteome of the cells was separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Greater differences in protein expression were observed between the HNO and N lines than between the T and N lines. Sixteen of the most prominent bands differentially expressed among the cell lines were cut out from the gel and analyzed by mass spectrometry. Cell wall-modifying enzymes were identified, including a peroxidase whose expression was twofold higher in N and T tissue than in HNO tissue ; pectinesterase, which was expressed at a level threefold lower in the T line than in the other cell lines ; and xyloglucan endotransglucosylase, which was expressed at a level sixfold higher in HNO and T tissue. Three proteins belonged to the chitinase gene family and their expression was higher in HNO and T tissue than in N tissue. The differential expression of these proteins suggests that these play a role in cell line-specific cell wall composition and cell-to-cell adhesion.

Beta vulgaris; cellular ultrastructure; cell wall; electrophoresis; extracellular proteins; plastids

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