Cork Oak Endophytic Fungi as Potential Biocontrol Agents against Biscogniauxia mediterranea and Diplodia corticola

An increase in cork oak diseases caused by Biscogniauxia mediterranea and Diplodia corticola has been reported in the last decade. Due to the high socio-economic and ecologic importance of this plant species in the Mediterranean Basin, the search for preventive or treatment measures to control these diseases is an urgent need. Fungal endophytes were recovered from cork oak trees with different disease severity levels, using culture-dependent methods. The results showed a higher number of potential pathogens than beneficial fungi such as cork oak endophytes, even in healthy plants. The antagonist potential of a selection of eight cork oak fungal endophytes was tested against B. mediterranea and D. corticola by dual-plate assays. The tested endophytes were more efficient in inhibiting D. corticola than B. mediterranea growth, but Simplicillium aogashimaense, Fimetariella rabenhorstii, Chaetomium sp. and Alternaria alternata revealed a high potential to inhibit the growth of both. Simplicillium aogashimaense caused macroscopic and microscopic mycelial/hyphal deformations and presented promising results in controlling both phytopathogens' growth in vitro. The evaluation of the antagonistic potential of non-volatile and volatile compounds also revealed that A. alternata compounds could be further explored for inhibiting both pathogens. These findings provide valuable knowledge that can be further explored in in vivo assays to find a suitable biocontrol agent for these cork oak diseases.

Secondary Metabolites of Lasiodiplodia theobromae: Distribution, Chemical Diversity, Bioactivity, and Implications of Their Occurrence

Lasiodiplodia theobromae is a plant pathogenic fungus from the family Botryosphaeriaceae that is commonly found in tropical and subtropical regions. It has been associated with many hosts, causing diverse diseases and being responsible for serious damages on economically important crops. A diverse array of bioactive low molecular weight compounds has been described as being produced by L. theobromae cultures. In this review, the existing literature on secondary metabolites of L. theobromae, their bioactivity, and the implications of their occurrence are compiled. Moreover, the effects of abiotic factors (e.g., temperature, nutrient availability) on secondary metabolites production are highlighted, and possible avenues for future research are presented. Currently, a total of 134 chemically defined compounds belonging to the classes of secondary metabolites and fatty acids have been reported from over 30 L. theobromae isolates. Compounds reported include cyclohexenes and cyclohexenones, indoles, jasmonates, lactones, melleins, phenols, and others. Most of the existing bioactivity studies of L. theobromae metabolites have assessed their potential phytotoxic, cytotoxic, and antimicrobial activities. In fact, its host adaptability and its ability to cause diseases in plants as well as in humans may be related to the capacity to produce bioactive compounds directly involved in host–fungus interactions.

Sarocladione, a unique 5,10:8,9-diseco-steroid from the deep-sea-derived fungusSarocladium kiliense

Sarocladione was isolated from the deep-sea-derived fungusSarocladium kilienseas the first example of a 5,10:8,9-diseco-steroid.

Saroclazines A-C, thio-diketopiperazines from mangrove-derived fungi Sarocladium kiliense HDN11-84

Three new diketopiperazine derivatives (DKPs), saroclazines A-C (1-3) along with three known DKPs (4-6) were isolated from mangrove-derived fungi Sarocladium kiliense HDN11-84. Saroclazines A-B (1 and 2) possessed a free amide structure, which was first found in sulfur-containing aromatic DKPs. Their structures were elucidated by NMR, HRESIMS and X-ray. The cytotoxic activity of new compounds (1-3) was tested against HeLa cell lines, among which compound 2 showed an IC₅₀ value of 4.2 µM.

Two Additional New Compounds from the Marine-Derived Fungus Pseudallescheria ellipsoidea F42-3

Two additional new compounds, pseudellone D (1) and (5S,6S)-dihydroxylasiodiplodin (3), along with the two known compounds lasiodipline F (2), (5S)-hydroxylasiodiplodin (4) were isolated from the marine-derived fungus Pseudallescheria ellipsoidea F42-3 associated with the soft coral Lobophytum crassum. Their structures, including absolute configurations, were elucidated on the basis of the corresponding spectroscopic data and electronic circular dichroism (ECD) spectra.