Endophytes Modulate Plant Genes: Present Status and Future Perspectives

Purpureocillium lilacinum SBF054: Endophytic in Phaseolus vulgaris, Glycine max, and Helianthus annuus; Antagonistic to Rhizoctonia solani; and Virulent to Euschistus heros

Microorganisms with multiple ecological functions can be a useful biotechnological resource in integrated pest- and disease-management programs. This work aimed to investigate the potential endophytic and virulent effects of a strain of Purpureocillium lilacinum on organic cultivation in Brazil. Specifically, the strain's ability to establish itself as an endophyte in common bean, soybean, and sunflower plants when inoculated via seed was evaluated. Furthermore, its antifungal activity against phytopathogens and its pathogenicity and virulence against insects of the order Lepidoptera, Coleoptera, and Hemiptera were evaluated. Furthermore, the strain was evaluated for its biochemical and physiological characteristics. For virulence bioassays, the experiments were conducted under a factorial scheme (2 × 3), with the following factors: (a) fungal inoculation and control without inoculum and (b) types of inocula (blastospores, aerial conidia, and metabolites). The treatments were sprayed on insect species at different stages of development. In summary, it was found that the SBF054 strain endophytically colonized the common bean, with partial recovery from the root tissues of soybean and sunflower plants, 30 days after inoculation; suppressed 86% of Rhizoctonia solani mycelial growth in an in vitro assay; and controlled eggs, nymphs, and Euschistus heros adults. These multifunctional abilities are mainly attributed to the strain's mechanisms of producing metabolites, such as organic acids, soluble nutrients, and hydrolytic enzymes.

Host Response of Arabidopsis thaliana Interaction with Fungal Endophytes Involves microRNAs

Plant and fungus interaction is a complex process involving many molecular factors determining the nature of relationship. The enigmatic methodology by which fungal endophytes are able to colonise a plant harmoniously is still inexplicable. Small RNAs have been identified as major regulatory elements under various biotic interactions. However, their role in endophytic plant-fungal interactions remain to be elucidated. Therefore, transcript expression data available on Gene Expression Omnibus for Arabidopsis thaliana was utilised for miRNAs identification under endophytism. The analysis predicted 15 miRNAs with differential expression of which the ath-miRNA398b modulation was significant. Application of psRNAtarget, C-mii, pmiREN, and TarDB provided a pool of 357 target genes for these miRNAs. Protein-protein interaction analysis identified major hub proteins, including BTB/POZ domain-containing protein, beta-Xylosidase-2 (AtBXL2), and Copper/Zinc Superoxide Dismutase-2 (AtSOD2). The quantitative real-time PCR validated the computational prediction and expression for selected target genes AtSOD2, AtBXL2, and AtRCA along with ath-miRNA398b under endophytism. Overall, results indicate that miRNAs have a significant role in regulating Arabidopsis thaliana-endophytic fungal interaction.