Potential of Rhizobium and Bradyrhizobium species as plant growth promoting rhizobacteria on non-legumes: Effect on radishes (Raphanus sativus L.)

Abstract

Bradyrhizobia and rhizobia are symbiotic bacterial partners forming nitrogen fixing nodules on legumes. These bacteria share characteristics with plant growth promoting rhizobacteria (PGPR). Nodule inducing bacteria, like other PGPR, are capable of colonizing the roots of non-legumes and produce phytohormones, siderophores and HeN. They also exhibit antagonistic effects towards many plant pathogenic fungi. The potential of nodule inducing bacteria to function as PGPR, was examined by using radish as a model plant. Three percent of the 266 strains tested were found to be cyanogens, while a majority (83%) produced siderophores. Fifty eight percent of the strains produced indole 3-acetic acid (IAA) and 54% solubilized phosphorus. Some of the bacterial species examined were found to have a deleterious effect while others were neutral or displayed a stimulatory effect on radishes. Bradyrizobium japonicum strain Soy 213 was found to have the highest stimulatory effect (60%), and an arctic strain (N44) was the most deleterious, causing a 44% reduction in radish dry matter yield. A second plant inoculation test, performed in growth cabinets, revealed that only strain Tal 629 of B. japonicum significantly increased (15%) the dry matter yield of radish. This indicates that specific bradyrhizobia have the potential to be used as PGPR on non-legumes.

Rhizosphere microbiome assemblage is affected by plant development

“…(Junier et al, 2009), as well as symbiotic N-fixing bacteria (Bradyrhizobium) (Stacey et al, 1995) or Herbaspirillum which is involved in endophytic N fixation (Elbeltagy et al, 2001;Franche et al, 2009). It should be noted that in addition to fixing N through legume symbiosis, Bradyrhizobium promotes plant growth of nonleguminous plants (Antoun et al, 1998). The functional microbiome also expressed genes that aligned to the free N-fixing Cyanobacteria (Supplementary Table S3).…”

PGPR Improves Yield of Strawberry Species under Less-Fertilized Conditions

“…It has been reported that production of organic acids by PGPR contributes the conversion of insoluble form of P to soluble (H2 PO 4 , HPO 2 4 ) forms (Sundara et al, 2002;Richardson et al, 2009). PGPRs which enhance P solubilization have been isolated and their functions were studied in range of crops such as wheat, tomato and radish (Kim et al, 1998;Antoun et al, 1998;Singh and Kapoor, 1999;Kumar and Narula, 1999). In the case of other crops such as sugar cane, increase in brix has been reported as an indirect function of PGPR to control pathogen attack (Senthil et al, 2003).…”

Screening of PGPR Isolates for Plant Growth Promotion of Rosa damascena

“…This growth limiting behaviour may be observed due to excessive production of materials (IAA and similar substances) that are beneficial for plant growth at minor quantity (Antoun et al, 1998). In the same way, Alstrom and Burn (1989) have also reported for growth limiting effects on the growth of plants which is attributable due to the production of HCN at higher concentration.…”

“…As a result, plant growth promoting rhizobacteria (PGPR) with their growth promoting ability are spotlighted and are being applied widely to agricultural crops as this technology is quite suitable to increase plant growth and decrease the use of chemical inputs. Several mechanisms have also been reported by which PGPR can directly stimulate the growth of plants including (1) production of phytohormones like IAA, Gibberellin, Kinetin and Cytokinin (Noel et al, 1996;Antoun et al, 1998;Verma et al, 2001;Dey et al, 2004) and (2) enzymes generation that can alter growth and development of plants (Yang and Hoffman, 1984;Sharma et al, 2011). The production of growth promoting substances like gibberellins, cytokinins and auxins by inoculated bacteria have positive impact on plant growth and yield.…”