Evaluation of Streptomyces strains isolated from herbal vermicompost for their plant growth-promotion traits in rice

Abstract

Six actinomycetes, CAI-13, CAI-85, CAI-93, CAI-140, CAI-155 and KAI-180, isolated from six different herbal vermi-composts were characterized for in vitro plant growth-promoting (PGP) properties and further evaluated in the field for PGP activity in rice. Of the six actinomycetes, CAI-13, CAI-85, CAI-93, CAI-140 and CAI-155 produced siderophores; CAI-13, CAI-93, CAI-155 and KAI-180 produced chitinase; CAI-13, CAI-140, CAI-155 and KAI-180 produced lipase; CAI-13, CAI-93, CAI-155 and KAI-180 produced protease; and CAI-13, CAI-85, CAI-140 and CAI-155 produced ß-1-3-glucanase whereas all the six actinomycetes produced cellulase, hydrocyanic acid and indole acetic acid (IAA). The actinomycetes were able to grow in NaCl concentrations of up to 8%, at pH values between 7 and 11, temperatures between 20 and 40 °C and compatible with fungicide bavistin at field application levels. In the rice field, the actinomycetes significantly enhanced tiller numbers, panicle numbers, filled grain numbers and weight, stover yield, grain yield, total dry matter, root length, volume and dry weight over the un-inoculated control. In the rhizosphere, the actinomycetes also significantly enhanced total nitrogen, available phosphorous, % organic carbon, microbial biomass carbon and nitrogen and dehydrogenase activity over the un-inoculated control. Sequences of 16S rDNA gene of the actinomycetes matched with different Streptomyces species in BLAST analysis. Of the six actinomycetes, CAI-85 and CAI-93 were found superior over other actinomycetes in terms of PGP properties, root development and crop productivity. qRT-PCR analysis on selected plant growth promoting genes of actinomycetes revealed the up-regulation of IAA genes only in CAI-85 and CAI-93.

Plant growth-promotion by Streptomyces spp. in sorghum (Sorghum bicolor L.)

“…The reason for selecting only β-1,3-glucanase, IAA and siderophore traits for expression profiles is that these three traits are directly linked to growth promotion of the plants. Similar results were also reported by Gopalakrishnan et al (2013bGopalakrishnan et al ( , 2015a which support the PGP by Streptomyces strains.…”

Plant growth promotion by streptomycetes: ecophysiology, mechanisms and applications

“…Lastly, research to develop methods of bioinoculant delivery and timing must be carried out in the greenhouse and field to maximize the plant response to the applied bioinoculant. It has been found that applying streptomycetes is different to applying Gram-negative bacteria because better plant responses have generally been obtained when the streptomycete application to the soil or substrate occurred before sowing the seeds, thus allowing the selected strain to colonize and establish [6,137,138].…”

Probiotic potential Streptomyces species from the grains of pearl millet (Pennisetum glaucum)

“…Streptomyces spp. have been widely reported and demonstrated under field conditions as plant growth-promoters and biocontrol agents in both cereals and legumes (Tokala et al, 2002;Nassar et al, 2003;Sadeghi et al, 2012;Gopalakrishnan et al, 2013Gopalakrishnan et al, , 2014Gopalakrishnan et al, , 2015Gopalakrishnan et al, , 2016a. In the present investigation, when the Streptomyces spp.…”

“…They play an important role, not only on plant growth-promotion (PGP), antagonistic action against pathogens and insect pests and biofortification traits in many agriculturally important crops, but also on decomposition of organic materials and production of secondary metabolites (Glick, 2010). Plant growthpromoting properties of actinomycetes was reported on cereals (such as wheat (Sadeghi et al, 2012), rice (Gopalakrishnan et al, 2014) and sorghum (Gopalakrishnan et al, 2013)) as well as legumes (such as bean (Nassar et al, 2003), chickpea (Gopalakrishnan et al, 2015, pigeonpea and pea (Tokala et al, 2002). Actinomycetes have also been demonstrated for biocontrol of soil-borne pathogens (Mahadevan and Crawford, 1997;TrejoEstrada et al, 1998;Macagnan et al, 2008;Gopalakrishnan et al, 2011) and insect pests (Gopalakrishnan et al, 2016c;Sathya et al, 2016 a, b).…”