Swelling of root cell walls as an indicator of their functional stateстатья
Информация о цитировании статьи получена из
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Дата последнего поиска статьи во внешних источниках: 20 сентября 2013 г.
Аннотация:he swelling capacity of cell walls isolated from different parts of lupine root was investigated. The water content in fragments of intact roots (Q) and swelling coefficient of standardized samples of cell walls (K-cw) were determined, and the dependences of Q and K-cw on the distance from the root tip (L) were plotted. It was shown that the change in Q value along the stretch of the lupine root reaches its maximum at distances of 1.5-6 cm or 7-12 cm from the root tip in 7-day-old and 14-day-old seedlings, respectively, whereas the K-cw value distribution over the root length is virtually invariabie. In the radial direction. both the Q and K-cw values in cortex tissues are about twice higher than in the central cylinder. In our opinion, the changes of both Q and K-cw in the radial direction are associated with different degrees of cross-linking, between polymer chains in cell wall structures of root cortex and central cylinder The results of measurement of the K-cw value are consistent with the widely accepted mechanisms of water transport in roots in the radial direction. These data show that water transport through apoplast to the border between the cortex and central cylinder is accompanied bp an increase in the resistance to water flow. Among other factors, this increase is due to a greater degree of cross-linking between cell wall polymers in the central cylinder The results of measurement of the swelling coefficient of standardized cell wall samples in water and in 10 mM KCI at different pH values show that the swelling capacity of root cell walls varies according to the physicochemical properties of synthetic ion exchangers. Cell walls shrink (cell wall volume decreases) as ion concentration in solution increases and pH decreases. This causes an increase in the hydraulic resistance (or a decrease in the hydraulic conductivity) of apoplast. It was concluded that swelling is determined by the physicochemical properties of the cell wall, whereas the change in the swelling capacity induced by variation of external or internal conditions is an element of rbe mechanism of regulation of volume water now in roofs.