Endophytic Bacteria Improve Seedling Growth of Sunflower Under Water Stress, Produce Salicylic Acid, and Inhibit Growth of Pathogenic Fungi

Abstract

Endophytic bacterial strains SF2 (99.9% homology with Achromobacter xylosoxidans), and SF3 and SF4 (99.9% homology with Bacillus pumilus) isolated from sunflower grown under irrigation or drought were selected on the basis of plant growth-promoting bacteria (PGPB) characteristics. Aims of the study were to examine effects of inoculation with SF2, SF3, and SF4 on sunflower cultivated under water stress, to evaluate salicylic acid (SA) production by these strains in control medium or at Ψa = -2.03 MPa, and to analyze effects of exogenously applied SA, jasmonic acid (JA), bacterial pellets, and bacterial supernatants on growth of pathogenic fungi Alternaria sp., Sclerotinia sp., and Verticillum sp. Growth response to bacterial inoculation was studied in two inbred lines (water stress-sensitive B59 and water stress-tolerant B71) and commercial hybrid Paraiso 24. Under both water stress and normal conditions, plant growth following inoculation was more strongly enhanced for Paraiso 24 and B71 than for B59. All three strains produced SA in control medium; levels for SF3 and SF4 were higher than for SF2. SA production was dramatically higher at Ψa = -2.03 MPa. Exogenously applied SA or JA caused a significant reduction of growth for Sclerotinia and a lesser reduction for Alternaria and Verticillum. Fungal growth was more strongly inhibited by bacterial pellets than by bacterial supernatants. Our findings indicate that these endophytic bacteria enhance growth of sunflower seedlings under water stress, produce SA, and inhibit growth of pathogenic fungi. These characteristics are useful for formulation of inoculants to improve growth and yield of sunflower crops.

EXAMINATION OF CHITINOLYTIC BACTERIA IN ALGINATE-CHITOSAN ENCAPSULATION ON CHILI SEED AGAINST DAMPING OFF CAUSED BY <i>FUSARIUM OXYSPORUM</i>

“…The use of antagonist rhizobacteria belonging to Bacillus genus showed to stimulate plant growth and to increase crop yield of tomato (Hernandez-Suarez et al, 2011). Endophytic Science Publications AJABS bacterial strains SF2 (99.9% homology with Achromobacter xylosoxidans) and SF3 and SF4 (99.9% homology with B. pumilus) enhanced growth of sunflower seedlings under water stress and inhibited growth of pathogenic fungi (Forchetti et al, 2010). Tariq et al (2009) reported the dual role of Pseudomonas spp.…”

“…In addition, direct observation of the seedling showed that the seedling was more stout and fresh. Some bacterial control agent produce plant growth regulator to increase plant performance (Forchetti et al, 2010;Hernandez-Suarez et al, 2011). Fusarium wilt caused unhealthy seedlings by reducing seedling height to 6.08 cm and dry-weight to 2.42 g.…”

Characterisation of endophytic bacteria from a desert plant Lepidium perfoliatum L.

“…Currently, endophytic bacteria are attracting increasing attention not only for their promotion of plant growth and control of plant diseases (Hallmann et al 2011), but also for their stress tolerance and improvement of plant growth in an extreme environmen (Forchetti et al 2010;Jha et al 2011;Karthikeyan et al 2012;Ali et al 2014;Naveed et al 2014a, b;Qin et al 2014;Cherif et al 2015). Phoenix dactylifera L. root endophytic bacteria that were isolated from the environment of desert oasis promoted plant growth under drought conditions (Cherif et al 2015).…”

“…Plant growth promoting endophytic bacteria, for example, Burkholderia phytofirmans PsJN improve the growth of wheat and maize under drought conditions (Naveed et al 2014a, b). Endophytic bacterial strains Achromobacter xylosoxidans and Bacillus pumilus enhance the growth of sunflower seedlings under water stress (Forchetti et al 2010). The use of bacterial endophytes (Pseudomonas fluorescens YsS6 and P. migulae 8R6) has the potential to facilitate tomato plant growth under high salt contents (Ali et al 2014).…”

Beneficial Bacillus Strains Improve Plant Resistance to Phytopathogens: A Review

“…In this regard, some authors presented a B. amyloliquefaciens strain able to modulate gene expression in rice plants during salt stress [31]. For a similar purpose, Forchetti et al [32] mentioned two Bacillus pumilus strain producing salycilic acid that simultaneously helped plants during water stress, stimulated sunflower growth, and inhibited the growth of Alternaria sp., Sclerotinia sp., and Verticillum sp. pathogenic fungi.…”