Jeremy Johnson

Zoom Recording

Uncovering the Protective Characteristics of Fungal Endophytes in Mangrove Trees

About The Presenter

Jeremy is currently a first-year master student in the USDA Grain Legume Genetics Physiology Research Unit in Pullman Washington. Jeremy completed his B.S. in Biochemistry at Washington State University. As an undergraduate Jeremy joined the research unit and has just reached his fifth year with the team as of April 2026. In his time with the unit, he assisted with research relating to disease resistance in chickpeas to different fungal diseases including Ascochyta blight and pythium seed rot. For his masters Jeremy is working to identify SNPs associated with disease resistance to Ascochyta blight utilizing the mini dome disease screening assay through GWAS. He is also working to identify Ascochyta blight resistant materials in new F₂  populations recently generated through the chickpea breeding program. In his free time Jeremy enjoys spending time with his friends and family, walking his dog Noelle, hiking, and volunteering with the Scouting America.

Abstract

Endophytes have diverse roles in supporting the survival of a host plant both directly and indirectly through nutrient acquisition, defense against pathogens, mediating adverse environmental conditions (4,5,6). Mangrove trees are species of woody plants that live in coastal and estuary zones of tropical and subtropical climates (5). Their ability to survive under harsh environmental conditions has sparked interest in their endophytic fungi (1,4) Two current research topics pertaining to mangrove endophytes focus on their role in bioremediation and advancing pharmacology (1,4,5,6).

Endophytes from polluted and undisturbed mangrove populations were examined to determine how water quality influenced endophyte diversity and their ability to solubilize phosphate and zinc (3). The polluted site had a more diverse community of fungal endophytes, which rejected the initial hypothesis that diversity would be greater in the community collected from undisturbed population. Only isolates from the polluted site demonstrated exceptionally high levels of phosphate solubility while isolates from both sites proficiently solubilized zinc. This study provided knowledge about the diversity of endophytes within mangrove ecosystems and identified endophyte species that may contribute to developing mangroves to manage agricultural and industrial pollution in coastal regions (4,5,6).

The endophyte Purpureocillium lilacinum A5 was investigated for its role in alleviating copper stress in the mangrove tree Kandelia candel (2). Purpureocillium sp. A5 altered the content of chlorophyll A and B, the Relative Water Content (RWC) and Water Saturation Deficit (WSD) in colonized leaves, which promoted plant growth compared to the uncolonized control. Plants colonized with Purpureocillium sp. A5 absorbed less copper than control plants. Significant differences were observed between soil from colonized and control plants in pH, quantity of toxic Cu+ ions, and the formation of carbonate-bound Cu, Mn–Fe complexes Cu, and organic-bound Cu. These results suggested mechanisms by which fungal endophytes can assist mangrove trees subjected to adverse soil conditions.

Endophytes from two different mangrove species, Rhizophora stylosa and Rhizophora mucronate, were screened for antimicrobial activity against human pathogenic bacteria and cytotoxic effects against cancer cells lines (7). Two isolates from R. mucronate showed significant effects at inhibiting microbial growth at concentrations between 0.015-1 mg/mL. Cytotoxicity screening identified five isolates between both mangrove species that displayed significant antitumor activity, with inhibitory concentrations (IC₅₀) values below 20 μg/mL. These results show promise for the future development of new pharmaceuticals derived from mangrove endophytes (1,4,6).