Bio‐control and plant growth promotion potential of siderophore producing endophytic Streptomyces from Azadirachta indica A. Juss.

Abstract

Three endophytic actinomycetes strains recovered from surface sterilized root tissues of Azadirachta indica A. Juss. (Meliaceae), plants were selected through tests for their potential as bio-control and plant growth promoting agents. It was also observed that the seed treated with the spore suspension of three selected strains of Streptomyces, significantly promoted plant growth and antagonized the growth of Alternaria alternata, causal agent of early blight disease in tomato plant. It was observed that the three selected strains prolifically produce IAA and siderophores that play vital role in promotion of plant growth and in suppression of Alternaria alternata. Interestingly, Streptomyces strain AzR-051 produced the highest amount of IAA at 13.73 μmol ml(-1) , compared to strains AzR-049 and AzR-010 9.22 μmol ml(-1) and 10.43 μmol ml(-1) respectively. It also produces siderophores higher than the other two strains. Thus these endophytic isolates have the potential as plant growth promoters as well as a bio-control agent, which is a useful trait for crop production in nutrient deficient soils.

Agricultural uses of plant biostimulants

“…The relation between siderophore production, plant growth promotion, and uptake of Fe has also been well documented for a variety of plants and microorganisms. Significant increases in tomato and rice growth parameters were reported using a siderophoreproducing strain of Streptomyces (Rungin et al 2012;Verma et al 2011). (Sharma et al 2013) reported that inoculation with a Pseudomonas putida strain increased iron uptake of rice due to siderophore production and increased the iron content in rice grains which enhanced the nutritional value of the rice.…”

In vitro Antimicrobial Assay of Actinomycetes in Rice AgainstXanthomonas oryzae pv. oryzicola and as Potential Plant Growth Promoter

“…The highest and strongest antagonistic activity of actinomycete strains (SS8, TKSC3, TKSB5 and SS9) based on in vitro assay tested against Xoc were grouped together in Cluster 1 in Figure 3, which proved that Streptomyces strains isolated from this study could be used as antibiotic and hydrolytic enzyme producers as well as plant growth promoters. Plant growth-promoting and biocontrol properties are both important traits in crop yield and production (Verma et al 2011) and their beneficial attributes are largely dependent on their capability of producing secondary metabolites (Kunoh 2002). Thus, preliminary screening via in vitro assay is important as initial step in selecting the best actinomycetes with multi beneficial attributes as plant growth regulators and biocontrol agent properties.…”

“…Biocontrol agent, which may function as plant growth-promoting agent at the same time stimulate plant growth directly by altering plant hormone levels, facilitating iron acquisition via siderophore production, fixing atmospheric nitrogen and solubilising minerals for plant uptake (Lugtenberg and Kamilova 2009). Utilization of actinomycete strains with biocontrol and plant growthpromoting characteristics in biofertilizers and biocontrol products are the best approach, which facilitate in sustainable plant cultivation (Verma et al 2011). Cutting-edge research on biocontrol and agents for pathogenic Xanthomonas spp.…”

Indole-3-acetic acid: A widespread physiological code in interactions of fungi with other organisms

“…In addition, fungal-produced IAA can beneficially affect plants indirectly by strengthening plant immune responses to suppress phytopathogenic strains and disease development. [57][58][59] Biological control of plant diseases by microorganisms has been studied for many years. Fungi can secrete plant growth-promoting substances such as IAA, which, in turn, induce systemic resistance mechanism in plants to prevent pathogen attack.…”

“…These strains significantly promoted tomato plant growth and antagonized the growth of Alternaria alternata, a causative agent of early blight. 57 The induction of plant defense responses by IAA-producing fungi depends on host -pathogen as well as host -fungi specificities. Therefore, future studies on their interactions and molecular basis would help to gain more insight into the actions of fungal-producing IAA in plant defense mechanisms.…”