1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase-containing rhizobacteria protect Ocimum sanctum plants during waterlogging stress via reduced ethylene generation

• Published in: Plant physiology and biochemistry 2012-09, Vol.58, p.227-235
• Main Authors: Barnawal, Deepti, Bharti, Nidhi, Maji, Deepamala, Chanotiya, Chandan Singh, Kalra, Alok
• Format: Article
• Language: English
• Subjects: 1-aminocyclopropane-1-carboxylate deaminase; 1-aminocyclopropane-1-carboxylic acid; ACC deaminase; Achromobacter xylosoxidans; Adaptation, Physiological; Amino Acids, Cyclic - metabolism; Bacteria - enzymology; Biological and medical sciences; Carbon-Carbon Lyases - metabolism; chlorophyll; ethylene; ethylene production; Ethylenes - biosynthesis; flooded conditions; Floods; Fundamental and applied biological sciences. Psychology; greenhouses; growth promotion; Herbaspirillum seropedicae; Hypoxia; lipid peroxidation; nutrient uptake; Ochrobactrum; Ocimum - growth & development; Ocimum - metabolism; Ocimum - microbiology; Ocimum sanctum; Ocimum tenuiflorum; Oxygen - metabolism; PGPR; plant growth; plant growth-promoting rhizobacteria; Plant physiology and development; Plant Proteins - metabolism; Plant Roots - metabolism; Plant Roots - microbiology; Rain; rhizosphere bacteria; Serratia; Soil Microbiology; Stress ethylene; Stress, Physiological; Water; Waterlogging
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2012.07.008

Ocimum sanctum grown as rain-fed crop, is known to be poorly adapted to waterlogged conditions. Many a times the crop suffers extreme damages because of anoxia and excessive ethylene generation due to waterlogging conditions present under heavy rain. The usefulness of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-containing plant growth promoting rhizobacteria was investigated under waterlogging stress. The comparison of herb yield and stress induced biochemical changes of waterlogged and non-waterlogged plants with and without ACC deaminase-containing microbiological treatments were monitored in this study. Ten plant growth promoting rhizobacteria strains containing ACC-deaminase were isolated and characterized. Four selected isolates Fd2 (Achromobacter xylosoxidans), Bac5 (Serratia ureilytica), Oci9 (Herbaspirillum seropedicae) and Oci13 (Ochrobactrum rhizosphaerae) had the potential to protect Ocimum plants from flood induced damage under waterlogged glass house conditions. Pot experiments were conducted to evaluate the potential of these ACC deaminase-containing selected strains for reducing the yield losses caused by waterlogging conditions. Bacterial treatments protected plants from waterlogging induced detrimental changes like stress ethylene production, reduced chlorophyll concentration, higher lipid peroxidation, proline concentration and reduced foliar nutrient uptake. Fd2 (A. xylosoxidans) induced maximum waterlogging tolerance as treated waterlogged plants recorded maximum growth and herb yield (46.5% higher than uninoculated waterlogged plants) with minimum stress ethylene levels (53% lower ACC concentration as compared to waterlogged plants without bacterial inoculation) whereas under normal non-waterlogged conditions O. rhizosphaerae was most effective in plant growth promotion. ► Four ACC deaminase-containing PGPRs reduced waterlogging induced damage in Ocimum. ► Inoculation with these PGPRs was found useful in enhancing root growth and yield. ► Reduction in damage could be correlated with lowering of stress ethylene. ► PGPR induced biochemical alterations were indicative of increased stress tolerance.