Streptomyces sp. S-9 promotes plant growth and confers resistance in Pigeon pea (Cajanus cajan) against Fusarium wilt

Streptomyces sp. strain S-9 was studied for its effect in inducing systemic resistance in Pigeon pea against the plant pathogen Fusarium udum causing wilt. The 16S rRNA gene sequencing and phylogenetic analysis indicated that S-9 is closely related to genus Streptomyces for which it was referred to as Streptomyces sp. S-9. Streptomyces sp. S-9 caused 85% inhibition of the pathogen and showed various attributes of plant growth-promoting such as the production of IAA, P-solubilization, and $\beta$ -1, 3-Glucanase activity. Proline and malondialdehyde (MDA) content was significantly higher whereas the chlorophyll content decreased in the pathogen-infected plant when compared to S-9 treated Pigeon pea plants. The anatomical research assisted the biocontrol-mediated stress tolerance findings in the Pigeon pea plant through increased root epidermis and enhanced stress-related xylem tissues. Fungus inoculation elevated the antioxidative enzymatic activities of superoxide dismutase (SOD; 78%) and catalase (CAT; 56%). Marked reductions in antioxidant enzymes were associated with the antagonistic effects of the different treatments. Conclusions showed that S-9 bioinocula applied as a seed coating enhanced soil availability of nitrogen (N), phosphate (P), and potassium (K), indicating their suitability for direct application invigorating plant growth and persuade resistance in the plant Pigeon pea against Fusarium wilt.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-021-02989-0.