In this study, confocal ratio analysis was used to image the relationship between cytoplasmic free @entity460 concentration ([ @entity141 ]c) and the development of root hairs of @entity958 . Although a localized change in [ @entity141 ]c that preceded or predicted the site of root hair initiation could not be detected, once initiated the majority of emerging root hairs showed an elevated [ @entity141 ]c (> 1 microM) in their apical cytoplasm, compared with 100-200 nM in the rest of the cell. These emerging root hairs then moved into a 3-5 h phase of sustained elongation during which they showed variable growth rates. Root hairs that were rapidly elongating exhibited a highly localized, elevated [ @entity141 ]c at the tip. Non-growing root hairs did not exhibit the [ @entity141 ]c gradient. The rhd-2 mutant, which is defective in sustained root hair growth, showed an altered [ @entity141 ]c distribution compared with wild-type. These results implicate [ @entity141 ]c in regulating the tip growth process. Treatment of elongating wild-type root hairs with the @entity141 channel blocker @entity1855 (50 microM) caused dissipation of the elevated [ @entity141 ]c at the tip and cessation of growth, suggesting a requirement for @entity141 channel activity at the root hair tip to maintain growth. Manganese treatment also preferentially quenched Indo-1 fluorescence in the apical cytoplasm of the root hair. As @entity921 is thought to enter cells through @entity141 -permeable channels, this result also suggests increased @entity141 channel activity at the tip of the growing hair. Taken together, these data suggest that although @entity141 does not trigger the initiation of root hairs, @entity141 influx at the tip of the root hair leads to an elevated [ @entity141 ]c that may be required to sustain root hair elongation.

Cytoplasmic free XXXX distributions during the development of root hairs of @entity958 .

@entity921 :: ('MESH:D008345', 'Chemical') :: ['manganese'] @entity958 :: ('3702', 'Species') :: ['Arabidopsis thaliana'] @entity1855 :: ('MESH:D014700', 'Chemical') :: ['verapamil'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+', 'Ca(2+)']
@entity460 :: (MESH:D002118,Chemical) :: ['calcium']
