Diversity, plant growth‐promoting traits, and biocontrol potential of fungal endophytes of Sorghum bicolor

Abstract

The diversity of fungal endophytes in Sorghum bicolor was investigated in samples collected from 10 different geographical regions of Karnataka state, India. A total of 360 endophytes were isolated from leaf, stem, and root tissues and were assigned to 26 fungal species based on morphology and molecular characterization using ITS sequences. All the endophytes belonged to the phylum Ascomycota. The diversity (Shannon H, 2.57; Simpson_1‐D, 0.92) and species richness (Margalef's, 4.68; Menhinick, 3.61) were found to be higher for the endophytes isolated from leaf tissues. The species evenness of the endophytic assemblage was strongly influenced by tissue type, followed by geographical location. The biocontrol potential of isolated endophytes was evaluated against economically destructive sorghum grain mould pathogens such as Fusarium thapsinum, Epicoccum sorghinum, Alternaria alternata, and Curvularia lunata using the dual culture method. Biocontrol potential was exhibited by 26 endophytic isolates, of which Trichoderma asperellum recorded broad‐spectrum activity against target pathogens, followed by E. nigrum and A. longipes. Most (82%) endophytes showed plant growth‐promoting traits. Biosynthesis of indole‐3‐acetic acid (IAA) was observed in 84% of isolates, and phosphate solubilization, siderophore production, and cellulase activity was observed in 69%, 23%, and 27% of isolates, respectively. Seeds treated with T. asperellum exhibited a significantly higher seed vigour index (2096), germination percentage (94%), and yield under greenhouse and field conditions. The results were substantiated by the confocal microscopy analysis, which clearly demonstrated the colonization of treated endophyte in root tissues. The present study reveals an ecofriendly approach to explore T. asperellum in sorghum disease management.

Fungal Endophytes as Growth Promoters and Inducers of Resistance in Tomato (Lycopersicon esculentum Mill.) against Alternaria solani

“…Similarly, many researchers have used the same method in order to isolate endophytic fungi from many medicinally important plants . [41][42][43][44]17,7 Further, all the isolates were evaluated for their antagonistic nature against the early blight pathogen A. solani by the dual culture method. From the results, it was noted that only five endophytic fungi revealed against the test pathogen with a maximum inhibition of 58.33% offered by P. microspora.…”

“…In corroboration with the findings of the study, seed treatment with conidial suspension of endophytic fungi isolated from medicinal plants was able to enhance seed germination, seedling vigor, vegetative and reproductive plant growth parameters in sorghum and turmeric plants. 14,7 The beneficial nature towards the enhancement in seed, vegetative and reproductive plant growth parameters from microbial endophytes is mainly correlated to the production of plant hormones and antimicrobial compounds, therefore, helping the plants in nutritional improvement which positively impacts plant growth. 49,50,17,15 In addition to plant growth-promoting studies, the application of fungal endophytic seed treatment was also able to induce disease resistance against the early blight pathogen in tomato.…”

“…26 The mechanism of induced resistance offered by these endophytic fungi involves antagonism, mycoparasitism, competition apart from the production of hormones/ bioactive metabolites that induce increased immunity of the host eventually resulting in protection against the invading pathothogens. 17,15,7…”

“…3,4 Among the plant stress, fungal pathogens are the principal source affecting crop yield in several plants globally. [5][6][7] Endophytes (both fungi and bacteria) are the microorganisms that inhabit inter/ intra cellularly within the host forming systemic or local associations showing mutuality to that of a symbiotic relationship without causing apparent disease symptoms. [8][9][10][11] These endophytes are often known to promote plants' growth, recycle nutrients, fitness and improve their ability to cope with stress.…”

The Sorghum Grain Mold Disease Complex: Pathogens, Host Responses, and the Bioactive Metabolites at Play

“…While similar systemic effects have not been shown in sorghum, a trend such as this would result in increased host favoritism of the many components of the flavonoid pathway that are related to SGM resistance, hypothetically resulting in increased SGM resistance at a potential cost of yield due to a change in photosynthate partitioning. While few endophyte-related host systemic changes have been shown in relation to sorghum host resistances, localized biocontrol of SGM pathogens by fungal endophytes has been demonstrated (Rajini et al, 2020). Rajini et al (2020) showed biocontrol effects were demonstrated by 26 endophytic isolates on common SGM complex pathogens: Fusarium thapsinum, Epicoccum sorghinum, Alternaria alternata, and Curvularia lunata.…”