ACC deaminase from plant growth-promoting bacteria affects crown gall development

Abstract

In addition to the well-known roles of indoleacetic acid and cytokinin in crown gall formation, the plant hormone ethylene also plays an important role in this process. Many plant growth-promoting bacteria (PGPB) encode the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which can degrade ACC, the immediate precursor of ethylene in plants, to alpha-ketobutyrate and ammonia and thereby lower plant ethylene levels. To study the effect of ACC deaminase on crown gall development, an ACC deaminase gene from the PGPB Pseudomonas putida UW4 was introduced into Agrobacterium tumefaciens C58, so that the effect of ACC deaminase activity on tumour formation in tomato and castor bean plants could be assessed. Plants were also coinoculated with A. tumefaciens C58 and P. putida UW4 or P. putida UW4-acdS- (an ACC deaminase minus mutant strain). In both types of experiments, it was observed that the presence of ACC deaminase generally inhibited tumour development on both tomato and castor bean plants.

Evidence for the involvement of ACC deaminase from Pseudomonas putida UW4 in the biocontrol of pine wilt disease caused by Bursaphelenchus xylophilus

“…Similar results have been obtained with castor bean and tomato plants infected by Agrobacterium tumefaciens. While P. putida UW4 was able to decrease crown gall formation and subsequent damage and loss of plant biomass, the acdS knockout mutant had no significant impact on protecting tomato plants from the A. tumefaciens infection (Hao et al 2007;Toklikishvili et al 2010). These results suggest that ACC deaminase activity, and the consequent lowering of deleterious plant ethylene levels, is the mechanism responsible for P. putida UW4 plant growth promotion activity as well as its ability to protect plants against biotic as well as abiotic stress (Grichko et al 2000;Wang et al 2000;Cheng et al 2007;Glick et al 2007;Hao et al 2007;Gamalero et al 2010;Toklikishvili et al 2010).…”

“…While P. putida UW4 was able to decrease crown gall formation and subsequent damage and loss of plant biomass, the acdS knockout mutant had no significant impact on protecting tomato plants from the A. tumefaciens infection (Hao et al 2007;Toklikishvili et al 2010). These results suggest that ACC deaminase activity, and the consequent lowering of deleterious plant ethylene levels, is the mechanism responsible for P. putida UW4 plant growth promotion activity as well as its ability to protect plants against biotic as well as abiotic stress (Grichko et al 2000;Wang et al 2000;Cheng et al 2007;Glick et al 2007;Hao et al 2007;Gamalero et al 2010;Toklikishvili et al 2010). In addition, it has been previously demonstrated that transgenic plants that express a bacterial acdS gene under the control of a root specific promoter are more resistant to pathogen induced stress as well as abiotic stress caused by salt, flooding and metals (Robison et al 2001a, b;Grichko and Glick 2001;Grichko et al 2000;Stearns et al 2005;Sergeeva et al 2006).…”

“…This enzyme cleaves the ethylene precursor, ACC, into ammonia and a-ketobutyrate (Honma and Shimomura 1978) and thereby prevents ethylene levels in plants from rising to deleterious levels (Glick et al 1998. The ACC deaminase-producing bacterium Pseudomonas putida UW4 has been shown to be an effective PGPB protecting several different plant hosts from a variety of stress conditions including flooding, salt, pathogens and metals (Grichko et al 2000;Wang et al 2000;Grichko and Glick 2001;Cheng et al 2007;Hao et al 2007;Gamalero et al 2010;Toklikishvili et al 2010).…”

Enhancement of Festuca rubra L. germination and seedling growth by seed treatment with pathogenic Agrobacterium rhizogenes

“…Next, the cells were collected by centrifugation at 6,000g for 10 min at 4°C, rinsed twice with M9 minimal salts (without a nitrogen source), and subsequently resuspended in 10 ml of modified M9 minimal medium with 5 mM ACC and incubated at 200 rpm for 40 h at 28°C with shaking as described by Hao et al (2007). The ACC deaminase activity was measured in bacterial extracts prepared as described by Penrose and Glick (2003) and determined by measuring the production of a-ketobutyrate using a standard curve of the substrate between 0.1 to 1 lM (Honma and Shimomura 1978).…”

Micro-Level Management of Agricultural Inputs: Emerging Approaches

“…The plant growth promoting effects of ACC deaminase may be most effective during pathogen attack [94,[170][171][172] and in stressful environments (e.g., flooded and heavy-metal contaminated soils) [173,174]. Additionally, under stress conditions plant vitamin synthesis declines.…”