Isolation of endophytes that suppress pathogen growth of chickpea (Cicer arietinum L.)

Authors: NADEEM, A - Nuclear Institute For Agriculture And Biology; O Keeffe, Teresa; Cal, Andrew; Palumbo, Jeffrey - Jeff; ARSHAD, RUBINA - Nuclear Institute For Agriculture And Biology; BIBI, NOREEN - Nuclear Institute For Agriculture And Biology; Lee, Charles

Submitted to: Pakistan Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2021
Publication Date: 2/24/2022
Citation: Nadeem, A., O'Keeffe, T.L., Cal, A.J., Palumbo, J.D., Arshad, R., Bibi, N., Lee, C.C. 2022. Isolation of endophytes that suppress pathogen growth of chickpea (Cicer arietinum L.). Pakistan Journal of Botany. 54(5):1813-1820. https://doi.org/10.30848/pjb2022-5(22).
DOI: https://doi.org/10.30848/pjb2022-5(22)

Interpretive Summary: Plants are the target of several pathogenic species, and Fusarium is one of the most common pathogenic fungi. Members of this genus are responsible for causing a number of diseases in a wide variety of plants, such as wilt in chickpea and banana and head blight in wheat and barley. The primary approach to combating Fusarium is by chemical application, but the toxicity of fungicides, such as tebuconazole and carbendazim, towards humans is well documented. Endophytes are microbes that spend either their entire or a portion of their life cycle inside plant tissues without manifesting any apparent disease symptoms or damage, and these endophytes can be used in the “biocontrol” of plant diseases thus replacing toxic chemical pesticides. We isolated endophytes from several plant tissues and demonstrated their antimicrobial activity against Fusarium oxysporum and Fusarium verticillioides.

Technical Abstract: Plant microbial pathogens destroy a significant percentage of the world’s crops annually. The most common method of combating these pathogens is with chemical microbicides which can have toxic effects upon human health. Our objective was to isolate microbial biocontrol agents that had the ability to suppress plant pathogens. In this study, we isolated endophytic bacteria from leaves of tomato, potato, and pepper plants. Three of the strains were found to have antimicrobial activities and were identified as Bacillus megaterium, Bacillus subtilis and Staphylococcus caprae based on 16S rRNA sequencing. All three strains were tested for agar based antibacterial activity against Escherichia coli and antifungal activity against pure isolates of Fusarium oxysporum and Fusarium verticillioides. B. subtilis had the most robust antimicrobial potential, followed by S. caprae and B. megaterium. Both B. subtilis and S. caprae conferred antifungal resistance to chickpea seeds. HPLC analysis of cell free supernatants (CFS) from the endophytic bacteria cultured in different media demonstrated production of acetic, lactic, and propionic acid at various levels. Biochemical profiling by Biolog phenotypic microarray demonstrated that B. subtilis could utilize a wider range of carbohydrates, carboxylic acids, and amino acids as carbon sources compared to S. caprae. These endophytes can potentially be used as a pretreatment of chickpea seeds to reduce common fungal infections.