1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID DEAMINASE MUTANTS OF THE PLANT-GROWTH PROMOTING RHIZOBACTERIUM PSEUDOMONAS-PUTIDA GR12-2 DO NOT STIMULATE CANOLA ROOT ELONGATION
Br. Glick et al., 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID DEAMINASE MUTANTS OF THE PLANT-GROWTH PROMOTING RHIZOBACTERIUM PSEUDOMONAS-PUTIDA GR12-2 DO NOT STIMULATE CANOLA ROOT ELONGATION, Canadian journal of microbiology, 40(11), 1994, pp. 911-915
The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 wa
s mutagenized with nitrosoguanidine and three separate mutants that we
re unable to utilize 1-aminocyclopropane-1-carboxylic acid (ACC) as a
sole nitrogen source were selected. These mutants are devoid of the AC
C deaminase activity that is present in wild-type P. putida GR12-2 cel
ls. Only wild-type cells, but not any of the ACC deaminase mutants, pr
omoted root elongation of developing canola seedlings under gnotobioti
c conditions. These results are interpreted in terms of a model in whi
ch P. putida GR12-2 promotes root elongation by binding to germinating
seeds and sequesters and hydrolyzes some of the unbound ACC, thereby
lowering the level of ACC and hence the endogenous ethylene concentrat
ion, allowing the roots to grow longer.