Fungal endophytes associated with actinorhizal plant species, Elaeagnus latifolia (Elaeagnaceae) and evaluating their antagonistic potential against grey blight disease in tea [causal agent: Pestalotiopsis theae] in North-East India

The current investigation explores the antagonistic potential of endophytic fungal diversity
associated with Elaeagnus latifolia L., an actinorhizal plant species of North-east India against
Pestalotiopsis theae, the causal agent of grey blight disease in tea. A total of 17 endophytic fungal
isolates belonging to 14 different families and three phyla were isolated from various parts of the
target plant species. The fungal isolates were characterized using a culture-based approach and
microscopic tools and techniques, with particular emphasis on colony shape, size, spore
formation characteristics, and fruiting body features. Nigrospora sp. showed the highest species
density (0.5) amongst all of the fungal isolates. The highest isolation frequency (67%) was
observed for Fusarium sp., Nigrospora sp., Penicillium chrysogenum and Rhizopus sp. A higher
percentage of fungal isolates were obtained from the roots and stems (47% each) compared to
leaves (29%). The maximum species richness and diversity indices were observed in stems (15.0),
while the minimum values were found in leaves (9.0). The stem had the highest Shannon and
Simpson diversity indices (2.02 and 0.860, respectively), followed by the root (1.979 and 0.847,
respectively) and the leaves with the lowest values being 1.494 and 0.75, respectively. Among the
fungal isolates tested for plant growth-promoting traits, such as phosphate solubilization, starch
hydrolysis and efficiency in zinc solubilization, the isolate EF09 showed positive responses for all
the tested parameters. The isolate EF09 showed maximum antifungal potential (up to 87.1%)
against the significant tea pathogen, P. theae, in poisoned food technique in vitro. As there exists
limited research related to hitherto-unexplored fungal endophytes associated with endemic plant
species like E. latifolia, the current investigation holds sufficient promises in the isolation of novel bioactive molecules from these microbial isolates that might be useful in agriculture to develop
sustainable strategies in plant protection in tea.