Diaporthe species associated with the maritime grass Festuca rubra subsp. pruinosa

Abstract

Festuca rubra subsp. pruinosa is a perennial grass growing in sea cliffs where plants are highly exposed to salinity and marine winds, and often grow in rock fissures where soil is absent. Diaporthe species are one of the most abundant components of the root microbiome of this grass and several Diaporthe isolates have been found to produce beneficial effects in their host and other plant species of agronomic importance. In this study, 22 strains of Diaporthe isolated as endophytes from roots of Festuca rubra subsp. pruinosa were characterized by molecular, morphological, and biochemical analyses. Sequences of the nuclear ribosomal internal transcribed spacers (ITS), translation elongation factor 1-α (TEF1), beta-tubulin (TUB), histone-3 (HIS), and calmodulin (CAL) genes were analyzed to identify the isolates. A multi-locus phylogenetic analysis of the combined five gene regions led to the identification of two new species named Diaporthe atlantica and Diaporthe iberica. Diaporthe atlantica is the most abundant Diaporthe species in its host plant, and Diaporthe iberica was also isolated from Celtica gigantea, another grass species growing in semiarid inland habitats. An in vitro biochemical characterization showed that all cultures of D. atlantica produced indole-3-acetic acid and ammonium, and the strains of D. iberica produced indole 3-acetic acid, ammonium, siderophores, and cellulase. Diaporthe atlantica is closely related to D. sclerotioides, a pathogen of cucurbits, and caused a growth reduction when inoculated in cucumber, melon, and watermelon.

Symbiotic fungi from a wild grass (Celtica gigantea) increase the growth, grain yield and quality of tritordeum under field conditions

“…The genus Diaporthe contains numerous species that can behave as plant pathogens, saprobes or endophytes ( Gomes et al 2013 ; Norphanphoun et al 2022 ). The Diaporthe T6 strain was recently identified as a member of a newly described species, Diaporthe iberica ( Toghueo et al 2023 ). D. iberica T6 has several in vitro characteristics that could be related to plant growth promotion, for instance, this strain can produce ammonium as an end product of protein degradation, has amylase and cellulase activities, which can degrade complex carbohydrates, and siderophores, which can sequester iron ( Toghueo et al 2023 ).…”

“…The Diaporthe T6 strain was recently identified as a member of a newly described species, Diaporthe iberica ( Toghueo et al 2023 ). D. iberica T6 has several in vitro characteristics that could be related to plant growth promotion, for instance, this strain can produce ammonium as an end product of protein degradation, has amylase and cellulase activities, which can degrade complex carbohydrates, and siderophores, which can sequester iron ( Toghueo et al 2023 ). Such properties could favour plant growth by increasing the availability of nutrients in the rhizosphere.…”

Diaporthe atlantica enhances tomato drought tolerance by improving photosynthesis, nutrient uptake and enzymatic antioxidant response

“…pruinosa, collected in a natural population on the northern coast of Galicia, Spain (Pereira et al, 2019). This strain belongs to Diaporthe atlantica, a newly described species (Toghueo et al, 2023).…”

“…Most Diaporthe atlantica strains, including EB4, do not sporulate on laboratory media (Toghueo et al, 2023), for this reason, fungal mycelium was used as inoculum. To produce Diaporthe EB4 mycelial inoculum, 30 g of sugar beet pulp pellet mixed with 9.0 g CaCO 3 , 4.5 g CaSO 4 and hydrated with 60 ml of water were autoclaved in widemouth glass bottles for 30 minutes at 121°C (Vaźquez de Aldana et al, 2020).…”

“…When inoculated in agricultural grasses, a Diaporthe strain ameliorated salt stress, increasing proline, nutrient uptake, and phytohormones, resulting in plant growth improvement (Toghueo et al, 2022). That fungal strain belongs to Diaporthe atlantica, a dominant species of the genus in Festuca roots (Toghueo et al, 2023). Symbiotic microorganisms from saline environments might benefit plants in their adaptation to drought stress (Rodriguez et al, 2008;Hosseyni Moghaddam et al, 2021).…”