Plant diseases cause losses of approximately 16% globally. Thus, management measures must be implemented to mitigate losses and guarantee food production. In addition to traditional management measures, induced resistance and biological control have gained ground in agriculture due to their enormous potential. Endophytic fungi internally colonize plant tissues and have the potential to act as control agents, such as biological agents or elicitors in the process of induced resistance and in attenuating abiotic stresses. In this review, we list the mode of action of this group of microorganisms which can act in controlling plant diseases and describe several examples in which endophytes were able to reduce the damage caused by pathogens and adverse conditions. This is due to their arsenal of molecules generated during the interaction by which they form a kind of biological shield in the plant. Furthermore, considering that endophytic fungi can be an important tool in managing for biotic and abiotic stresses due to the large amount of biologically active substances produced, bioprospecting this class of microorganisms is tending to increase and generate valuable products for agriculture.

Pochoniachlamydosporia and Purpureocilliumlilacinum are fungal bioagents used for the sustainable management of plant parasitic nematodes. However, their production through submerged liquid fermentation and their use in seed treatment have been underexplored. Therefore, our goal was to assess the effect of different liquid media on the growth of 40 isolates of P. lilacinum and two of P. chlamydosporia. The most promising isolates tested were assessed for plant growth promotion and the control of the two-spotted spider mite (Tetranychus urticae) and the soybean cyst nematode (Heterodera glycines). Most isolates produced > 10⁸ blastospores mL⁻¹ and some isolates produced more than 10⁴ microsclerotia mL⁻¹. Microsclerotia of selected isolates were used to inoculate common bean (Phaseolus vulgaris L.) seeds in greenhouse trials. All fungal isolates reduced the T. urticae fecundity in inoculated plants through seed treatment, while P. chlamydosporia ESALQ5406 and P. lilacinum ESALQ2593 decreased cyst nematode population. Purpureocillium lilacinum was more frequently detected in soil, whereas P. chlamydosporia colonized all plant parts. Pochonia chlamydosporia ESALQ5406 improved the root development of bean plants. These findings demonstrate the possibility of producing submerged propagules of P. chlamydosporia and P. lilacinum by liquid culture, and greenhouse trials support the applicability of fungal microsclerotia in seed treatment to control P. vulgaris pests.

In July 2020, during a survey carried out in a small farm located in Laranjal Paulista, state of São Paulo (Brazil), more than 20 white pitahaya plants [Hylocereus undatus (Haw.) Britton and Rose (syn. Selenicereus undatus (Haw.) D.R. Hunt] were found with stunting symptoms and showing chlorotic-yellowish stems, some of them already decaying. Roots exhibited numerous galls, indicating Meloidogyne sp. infection. Nematodes were recovered from 200 cm³ and 7 g of roots: 1.7 Meloidogyne juveniles (J2) per cm³ of soil and 954 eggs + J2 per g of roots were found. The perineal pattern of 10 females pointed to M. incognita. Additionally, esterase phenotype was obtained through isozyme electrophoresis, using another 10 females, which identified M. incognita. To our knowledge, this is the first report of M. incognita infesting pitahaya plants (Hylocereus spp.) and, based on our results, M. incognita could be a potential threat to the crop.

Aphelenchoides besseyi is an emerging and yet overlooked plant parasite of many economically important crops, including cotton, soybean and common bean. It presents an economic risk to these crops in several countries, notably in Brazil. Although first reported infecting strawberries in the United States as early as 1942, it was only identified to be the causal agent of green stem and foliar retention (GSFR) disease in Brazil in 2017. Currently, there are no chemical nematicides registered in Brazil against A . besseyi , and no known sources of genetic resistance. Here, we review the biology of A . besseyi , its spread across Brazil, its relevance to the country's current and future agriculture and the limited control measures. We describe control measures that have been successfully used to manage infestations of other plant‐parasitic nematodes and could potentially be extended to use in the control of A . besseyi . We also review and discuss potential future control measures, such as RNA interference and genome editing, for the development of crops with enhanced resistance to A . besseyi .

Plants have evolved diverse adaptations in signal perception, hormone regulation, and organ development that enable the formation of specialised structures such as nematode-induced galls, rhizobia-induced nodules, and host-induced parasitic plant haustoria that facilitate both parasitic and mutualistic symbiosis. Despite their differences, these organs share common gene regulatory mechanisms with lateral root development. By comparing their mechanisms of hormonal regulation, we illuminate the shared genetic underpinnings and how plants repurpose vegetative development pathways in response to biotic stimuli. This adaptive retooling positions plants along the symbiotic spectrum from exploited hosts to mutualistic partners and strategic predators. Comparative analysis of the hormonal mechanisms that drive symbiotic organogenesis highlights the plasticity of developmental processes and the interplay between internal signalling and external environmental cues.

The study evaluated the effectiveness of Trichoderma harzianum and Purpureocillium lilacinum in the management of Ralstonia solanacearum on eucalyptus seedlings. For each biological control agent, the following treatments were conducted: plants with their roots immersed in a cell suspension of the biological control agent (SI+I); plants in pots containing the biological control agent in hydrogel (SI+H); plants in pots previously drenched with the biological control agent (SI+IR), and plants in pots where the biological control agent was applied directly into the planting hole (SI+PO). Control treatments consisted of plants in pots infested and pots not infested with R. solanacearum (PC and NC, respectively). All treatments were carried out with two eucalyptus clones (SR and 144). The analyzed variables were mortality rate of eucalyptus seedlings and dry weight of plants. The most effective treatment had the activity of peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase (PAL) measured at 7, 14 and 21 days after inoculation. The method of incorporating the biological control agent influenced R. solanacearum control. Results revealed that SI+H and SI+IR were the most effective treatments. Using T. harzianum, mortality was only 12% for clone SR and 0% for clone 144 in the treatments SI+H and SI+IR, respectively. In the treatment SI+H, using P. lilacinum, 25% and 20% dead seedlings were obtained for clone SR and clone 144, respectively. Both biological agents increased the dry mass of plants. The activity of peroxidase, polyphenol oxidase and PAL was higher at 14 days after inoculation with T. harzianum in the treatments SI+IR and SI+H, for clones SR and 144, respectively. Using T. harzanium can serve as a support for the sustainable management of areas where cases of R. solanacearum have previously occurred.