Survival and colonization of rhizobacteria in a tomato transplant system

Abstract

Plant-growth-promoting rhizobacteria (PGPR) are used on crops most often as seed treatments; however, an alternative application method for transplanted vegetables is mixing PGPR into the soilless medium in which the transplants are grown. Studies were undertaken to compare root colonization and persistence of rifampicin-resistant mutants of PGPR strains Bacillus pumilus SE34 and Pseudomonas fluorescens 89B61, SE34r and 89B61r, on tomato as a function of application method. When the bacteria were incorporated into Promix soilless medium at log 6, 7, and 8 colony- forming units/g, populations of strain SE34r per gram of medium maintained the initial inoculum densities, while populations of 89B61r decreased approximately one to two orders of magnitude by 4 weeks after planting. The populations of each PGPR strain colonizing roots after application into the soilless medium showed a similar pattern at 6 weeks as that at 4 weeks after planting, with higher populations on the whole roots and lateral roots than on the taproots. Strain SE34r but not 89B61r moved upwards and colonized the phyllosphere when incorporated into the soilless medium. Following application as seed treatment, populations of SE34r were significantly higher on upper roots and on the taproot than were populations following application through the soilless medium. Conversely, populations were higher on lower roots and lateral roots following application through the soilless medium than were populations following application as seed treatment. While strain SE34 enhanced plant growth with application both to the medium and as seed treatment, the level of growth promotion was significantly greater with application in the soilless medium. The results indicate that PGPR can be successfully incorporated into soilless media in vegetable transplant production systems.

Endophytic Colonization of Vitis vinifera L. by Plant Growth-Promoting Bacterium Burkholderia sp. Strain PsJN

“…Similar results were reported for the colonization of tomato plants by P. fluorescens SE34r (70). The differences between stem and leaf populations that were observed can be explained by accumulation of bacterial cells in the leaf, which can be considered a sink, whereas the stem serves only for transition.…”

Advances in plant growth-promoting bacterial inoculant technology: formulations and practical perspectives (1998–2013)

“…Additionally, inoculants must overcome two major problems inherent to living microorganisms: (1) loss of viability during short storage in the grower's warehouse, and (2) long shelf life and stability of the product over a range of −5 to 30°C, within growers' storage conditions. Anith et al 2004;Bacilio et al 2003Bacilio et al , 2004Bashan et al 2006;Boruah and Kumar 2002;Cakmakci et al 2001Cakmakci et al , 2006Carrillo-Garcia et al 2000;Dominguez-Nuñez et al 2012;Egamberdiyeva 2007;Esitken et al 2003;Fürnkranz et al 2012;Guetsky et al 2002a, b;Guiñazú et al 2010;Hossain and Mårtensson 2008;Jetiyanon et al 2003;Khan et al 2003;Kurek and Jaroszuk-Ściseł 2002;Landa et al 2001;Lopez et al 2013;Madhaiyan et al 2010;Mehnaz et al 2010;Odee et al 2002;Ozturk et al 2003;Puente et al 2004aPuente et al , b, 2009aRajapaksha et al 2011;Singh et al 2011;Sigler et al 2001;Sudhakar et al 2000;Yan et al 2003;Yu et al 2011;Zafar et al 2012 Liquid (culture media or water) Clayton et al 2004a, b;Hamaoui et al 2001;Hungria et al 2010; Bashan et al 2002a, b;deBashan et al 2004;…”

Biodegradation of soil-applied pesticides by selected strains of plant growth-promoting rhizobacteria (PGPR) and their effects on bacterial growth

“…Soil samples were shaken at 150 rpm for 1 h and a suspension of 1 ml was taken from each flask for serial tenfold dilutions and plating in TSA plates. The samples were plated in triplicates and incubated at 28°C for 48 h (Yan et al 2003). …”