The biochemical and molecular processes involved in the habituation of maize cells to growth in the presence of the cellulose biosynthesis inhibitor dichlobenil （DCB） were investigated. DCB affects the synthesis of ...The biochemical and molecular processes involved in the habituation of maize cells to growth in the presence of the cellulose biosynthesis inhibitor dichlobenil （DCB） were investigated. DCB affects the synthesis of cellulose both in active and stationary growth phases and alters the expression of several CesA genes. Of these, ZmCesA5 and ZmCesA7 seem to play a major role in habituating cells to growth in the presence of DCB. As a consequence of the reduction in cellulose, the expression of several genes involved in the synthesis of hydroxycinnamates is increased, resulting in cell walls with higher levels of ferulic and p-coumaric acids. A proteomic analysis revealed that habituation to DCB is linked to modifications in several metabolic pathways. Finally, habituated cells present a reduction in glutathione S-transferase detoxifying activity and antioxidant activities. Plant cell adaptation to the disturbance of such a crucial process as cellulose biosynthesis requires changes in several metabolic networks, in order to modify cell wall architecture and metabolism, and survive in the presence of the inhibitor. Some of these modifications are described in this paper.展开更多
The habituation of cell cultures to cellulose biosynthesis inhibitors such as dichlobenil （DCB） represents a valu- able tool to improve our knowledge of the mechanisms involved in plant cell wall structural plastici...The habituation of cell cultures to cellulose biosynthesis inhibitors such as dichlobenil （DCB） represents a valu- able tool to improve our knowledge of the mechanisms involved in plant cell wall structural plasticity. Maize cell lines habituated to lethal concentrations of DCB were able to grow through the acquisition of a modified cell wall in which cellulose was partially replaced by a more extensive network of arabinoxylans. The aim of this work was to investigate the phenolic metabolism of non-habituated and DCB-habituated maize cell cultures. Maize cell cultures were fed [14C]cinnamate and the fate of the radioactivity in different intra-protoplasmic and wall-localized fractions throughout the culture cycle was analyzed by autoradiography and scintillation counting. Non-habituated and habituated cultures did not markedly differ in their ability to uptake exogenous [14C]cinnamic acid. However, interesting differences were found in the radiolabeling of low- and high-Mr metabolites. Habituated cultures displayed a higher number and amount of radiola-beled low-Mr compounds, which could act as reserves later used for polysaccharide feruloylation. DCB-habituated cultures were highly enriched in esterified [14C]dehydrodiferulates and larger coupling products. In conclusion, an extensive and early cross-linking of hydroxycinnamates was observed in DCB-habituated cultures, probably strengthening their cellulose-deficient walls.展开更多
文摘The biochemical and molecular processes involved in the habituation of maize cells to growth in the presence of the cellulose biosynthesis inhibitor dichlobenil （DCB） were investigated. DCB affects the synthesis of cellulose both in active and stationary growth phases and alters the expression of several CesA genes. Of these, ZmCesA5 and ZmCesA7 seem to play a major role in habituating cells to growth in the presence of DCB. As a consequence of the reduction in cellulose, the expression of several genes involved in the synthesis of hydroxycinnamates is increased, resulting in cell walls with higher levels of ferulic and p-coumaric acids. A proteomic analysis revealed that habituation to DCB is linked to modifications in several metabolic pathways. Finally, habituated cells present a reduction in glutathione S-transferase detoxifying activity and antioxidant activities. Plant cell adaptation to the disturbance of such a crucial process as cellulose biosynthesis requires changes in several metabolic networks, in order to modify cell wall architecture and metabolism, and survive in the presence of the inhibitor. Some of these modifications are described in this paper.
文摘The habituation of cell cultures to cellulose biosynthesis inhibitors such as dichlobenil （DCB） represents a valu- able tool to improve our knowledge of the mechanisms involved in plant cell wall structural plasticity. Maize cell lines habituated to lethal concentrations of DCB were able to grow through the acquisition of a modified cell wall in which cellulose was partially replaced by a more extensive network of arabinoxylans. The aim of this work was to investigate the phenolic metabolism of non-habituated and DCB-habituated maize cell cultures. Maize cell cultures were fed [14C]cinnamate and the fate of the radioactivity in different intra-protoplasmic and wall-localized fractions throughout the culture cycle was analyzed by autoradiography and scintillation counting. Non-habituated and habituated cultures did not markedly differ in their ability to uptake exogenous [14C]cinnamic acid. However, interesting differences were found in the radiolabeling of low- and high-Mr metabolites. Habituated cultures displayed a higher number and amount of radiola-beled low-Mr compounds, which could act as reserves later used for polysaccharide feruloylation. DCB-habituated cultures were highly enriched in esterified [14C]dehydrodiferulates and larger coupling products. In conclusion, an extensive and early cross-linking of hydroxycinnamates was observed in DCB-habituated cultures, probably strengthening their cellulose-deficient walls.
