ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Measurements of H+ extrusion activity K+ influx, and Es bm in 3-d-old seedlings of the 5-2 mutant of Arabidopsis thaliana (which is partially insensitive to fusicoccin) showed the following, (i) The reduced response of 5-2 to fusicoccin (FC) does not depend on the penetration of FC to its site of action, or on decreased affinity of the FC receptor, (ii) The reduced response of H+ and K+ transport to FC does not depend on an impairment of the K+ absorption system, (iii) The mutation can influence the H+ extrusion system independently of the presence of FC. In the presence of factors other than FC known to activate the plasma membrane H+-ATPase (e.g. a cytosol-acidifying treatment), the response in 5-2 is about 50% lower than in wt. (iv) When both genotypes grow in optimal conditions, the rate of fresh weight increase and stem elongation is higher in wt than 5-2. These data indicate that the 5-2 mutation affects some intrinsic component of the H+-extrusion machinery, the limiting effect of which becomes considerable when either the physiological or the experimental conditions induce a high level of proton pump activity. An alteration either of the ATPase itself or of a factor controlling its activity is compatible with our observations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3040.1995.tb00566.x
