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Branch and trunk canker diseases have become prevalent on nut crops in Iran. During 2015 to 2018, extensive field surveys were conducted on 58 almond, 43 pistachio and 80 walnut orchards in Iran to study fungal pathogens associated with symptomatic trees. One hundred and fifty-six representative fungal isolates were selected and identified based on morphological characteristics and by phylogenetic comparison of DNA sequence data. Fungal species found were Collophorina hispanica, Pleurostoma richardsiae, nine species of Phaeoacremonium (namely P. angustius, P. cinereum, P. italicum, P. fraxinopennsylvanicum, P. minimum, P. parasiticum, P. scolyti, P. tuscanum and P. viticola), 11 species of Botryosphaeriaceae (namely Botryosphaeria dothidea, Diplodia gallae, D. mutila, D. seriata, Dothiorella plurivora, Do. sarmentorum, Do. viticola, Lasiodiplodia citricola, L. mahajangana, L. theobromae and Neofusicoccum parvum), four species of Diatrypaceae (namely Cryptosphaeria pullmanensis, Diatrype whitmanensis, Eutypella citricola and E. vitis) and two non-identified Eutypella spp. (Eutypella sp. 1 and Eutypella sp. 2). Some of these species represent new reports in Iran and/or are reported for the first time in their respective hosts. Pathogenicity tests demonstrated that most of these fungi were pathogenic to inoculated almond, pistachio and walnut shoots. Therefore, more importance should be given to fungal trunk pathogens in Iran, and specific management strategies should be included within the nut crops IPM management programs, with the aim of improving their sustainability.

Abstract The oxidation process of 2,6-dimethoxyphenol (2,6-DMP) by laccase from Botryosphaeria rhodina MAMB-05 and the corresponding enzyme-mediator systems was studied using cyclic voltammetry (CV). The enzyme was classified as a high oxidation potential laccase (> 0.70) V vs. NHE) based on its Redox potential at different pHs. The cyclic voltammograms for 2,6-DMP (− 58.7 mV pH−1) showed that its oxidation potential decreased more significantly compared to the enzyme (− 50.2 mV pH−1) by varying the pH. The 2,2′-azino-bis[3-ethyl-benzothiazoline-6-sulfonic acid] diammonium salt (ABTS) and 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO) mediators were effectively oxidized by laccase from B. rhodina MAMB-05. The influence of laccase on the comproportionation of ABTS and the ionic step of the oxidation of TEMPO was also studied using CV. A higher potential difference was observed between laccase and the substrate, and correlated with higher enzyme activity. For the laccase-mediator systems, there was no clear correlation of potential difference between laccase and mediators with enzyme activity towards 2,6-DMP. This observation suggests that there are other limiting parameters for enzyme activity despite Redox potential difference, especially during ionic steps of the mechanism.

The ATP-binding cassette (ABC) superfamily is involved in numerous complex biological processes. However, the understanding of ABCs in plant pathogen defense, particularly against Botryosphaeria dothidea , remains limited. In this study, we identified MdABCI17 that plays a positive role in apple resistance to B. dothidea . Overexpression of MdABCI17 significantly enhanced the resistance of apple calli and fruits to B. dothidea . Our findings revealed that the jasmonic acid (JA) content and the expression of genes associated with JA biosynthesis and signal transduction were higher in stable MdABCI17- overexpressing apple calli than that of wild-type after inoculation with B. dothidea . Similar results were obtained for apple fruits with transient overexpression of MdABCI17 . Our research indicates that MdABCI17 enhances apple resistance to B. dothidea through the JA signaling pathway. We further determined that MdABCI17 plays a crucial role in the apple’s response to JA signaling. Moreover, exogenous methyl jasmonate (MeJA) treatment significantly enhanced the effectiveness of MdABCI17 in boosting apple resistance to B. dothidea . We proposed a positive feedback regulatory loop between MdABCI17 -mediated apple resistance to B. dothidea and JA signal. In summary, our study offers new insights into the role of ABC superfamily members in the control of plant disease resistance.

During 2021 and 2022, a field investigation was conducted in Istria, Croatia, searching for trees exhibiting signs of Botryosphaeria dieback. Samples of symptomatic trees were collected from 26 different locations and analysed. Isolates that morphologically corresponded to species from the Botryosphaeriaceae family were selected, and detailed morphological characterisation and molecular identification of the isolates were conducted. Based on morphological characteristics and phylogenetic analysis using the internal transcribed spacer (ITS), beta-tubulin (TUB2), and translation elongation factor 1-alpha (TEF1-α) regions, six species of fungi from the Botryosphaeriaceae family were identified: Botryosphaeria dothidea (Moug. ex Fr.) Ces. & De Not.; Diplodia mutila (Fr.) Fr.; Diplodia seriata De Not.; Dothiorella iberica A.J.L. Phillips, J. Luque & A. Alves; Dothiorella sarmentorum (Fr.) A.J.L. Phillips, Alves & Luque; and Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips. This is the first report of D. mutila, Do. sarmentorum, and Do. iberica causing Botryosphaeria dieback on olive trees in Croatia, and the first study investigating the resistance of Croatian olive varieties to species from the Botryosphaeriaceae family. Pathogenicity testing of selected isolates and assessment of variety resistance were conducted on four different olive varieties, namely Buža, Istarska bjelica, Leccino, and Rosinjola, using representative isolates of the mentioned species. The most aggressive species was found to be N. parvum. Olive varieties exhibited differences in susceptibility depending on the fungus they were infected with.

The family Botryosphaeriaceae is one of the most widespread and cosmopolitan endophytic group of fungi. Every year, species of this family cause severe damages on table and wine grape production, worldwide. However, this threat is still poorly known in Algeria. In this study, a large number of Botryosphaeriaceae-like isolates were obtained from symptomatic grapevines collected from eight regions with different ecological conditions, namely: Boumerdès, Médéa, Algiers, Tipaza, El Taref, Sidi Bel Abbes, Biskra and Adrar. The isolates were identified using DNA sequences of the translation elongation factor (tef1-α) and internal transcribed spacer (ITS) regions. Eleven species belonging to six genera, including Neofusicoccum parvum, N. algeriense, N. vitifusiforme, N. stellenboschiana, N. luteum, Diplodia seriata, D. olivarum, Lasiodiplodia theobromae, Dothiorella sarmentorum, Botryosphaeria dothidea and Neoscytalidium dimidiatum were identified. The spatial distribution of the Botryosphaeriaceae showed that D. seriata and N. stellenboschiana were the most widespread in the Algerian vineyards, while L. theobromae was recorded in the desert region of Biskra. Pathogenicity trials showed that all species were pathogenic on detached green shoots of grapevine, with N. parvum and L. theobromae being the most aggressive.

Species in the Botryosphaeriaceae have a cosmopolitan distribution, and occur on a wide range of annual and perennial hosts including grapevines. To date, morphological and taxonomic studies, as well as analyses of nucleotide sequences of multiple genes, have allowed the identification of at least 21 different species in the Botryosphaeriaceae occurring in grapevines worldwide. Grapevine disease symptoms caused by members of this family include leaf spots, fruit rots, shoot dieback, bud necrosis, vascular discoloration of the wood, and perennial cankers, and their current status as pathogens is reviewed. Additionally, the disease name Botryosphaeria dieback is proposed here to describe the different grapevine trunk disease symptoms caused by species of Botryosphaeriaceae. Much has been written during the last decade about the association between species in the Botryosphaeriaceae and grapevine trunk diseases, which has contributed to a better understanding of the role that these fungal taxa play in grapevine diseases. Although virulence has been shown to vary between species and isolates of the same species in different countries, these fungi have become well-recognized as important grapevine pathogens worldwide. Latest and novel findings from studies conducted in different countries, on disease etiology and species distribution, epidemiology and biology are discussed. Much progress has been achieved in the development and implementation of novel diagnostic and detection techniques. Vineyard sanitation techniques, as well as chemical, biological, and cultural control strategies available at the present time to reduce the infection caused by botryosphaeriaceous fungi, are presented in this review.

Among all causes of grapevine decline, Grapevine Trunk Diseases (GTDs) are major concerns for grape growers. This paper reviews knowledge and proposes hypotheses on two major GTDs, esca and Botryosphaeria dieback, and assembles a conceptual model. The objective was to collect information into a sequence, from grapevine nursery propagation processes, through foliar symptom expression, to plant death in mature vineyards. Pathogen infection and colonization steps in woody vine tissues, and the hypotheses that have been formulated to explain the outburst of foliar symptoms, are reported and discussed. Factors that could aggravate or repress GTD symptoms and incidence expansion are also addressed. Vine physiology and pathology together could expand understanding of these diseases. Knowledge and hypotheses that need validation are summarized, and a conceptual model is proposed to explain the occurrence of symptoms and the influencing factors. The model could be useful to cope with the complexity of GTDs, and as a starting point for research to unravel knowledge gaps and suggest new disease management strategies.

Paenibacillus polymyxa is a plant growth-promoting rhizobacterium that has immense potential to be used as an environmentally friendly replacement of chemical fertilizers and pesticides. In the present study, Paenibacillus polymyxa SK1 was isolated from bulbs of Lilium lancifolium. The isolated endophytic strain showed antifungal activities against important plant pathogens like Botryosphaeria dothidea, Fusarium oxysporum, Botrytis cinerea, and Fusarium fujikuroi. The highest percentage of growth inhibition, i.e., 66.67 ± 2.23%, was observed for SK1 against Botryosphaeria dothidea followed by 61.19 ± 3.12%, 60.71 ± 3.53%, and 55.54 ± 2.89% against Botrytis cinerea, Fusarium fujikuroi, and Fusarium oxysporum, respectively. The metabolite profiling of ethyl acetate fraction was assessed through the UHPLC-LTQ-IT-MS/MS analysis, and putative identification was done with the aid of the GNPS molecular networking workflow. A total of 29 compounds were putatively identified which included dipeptides, tripeptides, cyclopeptides (cyclo-(Leu-Leu), cyclo(Pro-Phe)), 2-heptyl-3-hydroxy 4-quinolone, 6-oxocativic acid, anhydrobrazilic acid, 1-(5-methoxy-1H-indol-3-yl)-2-piperidin-1-ylethane-1,2-dione, octadecenoic acid, pyochelin, 15-hydroxy-5Z,8Z,11Z, 13E-eicosatetraenoic acid, (Z)-7-[(2R,3S)-3-[(2Z,5E)-Undeca-2,5-dienyl]oxiran-2-yl]hept-5-enoic acid, arginylasparagine, cholic acid, sphinganine, elaidic acid, gossypin, L-carnosine, tetrodotoxin, and ursodiol. The high antifungal activity of SK1 might be attributed to the presence of these bioactive compounds. The isolated strain SK1 showed plant growth-promoting traits such as the production of organic acids, ACC deaminase, indole-3-acetic acid (IAA), siderophores, nitrogen fixation, and phosphate solubilization. IAA production was strongly correlated with the application of exogenous tryptophan concentrations in the medium. Furthermore, inoculation of SK1 enhanced plant growth of two Lilium varieties, Tresor and White Heaven, under greenhouse condition. In the light of these findings, the P. polymyxa SK1 may be utilized as a source of plant growth promotion and disease control in sustainable agriculture.

Botryosphaeria dothidea is a major postharvest causal agent of soft rot in kiwifruit. Methyl jasmonate (MeJA) is an important plant hormone that participates as a plant defense against pathogens from a signal molecule. However, the impact and regulatory mechanism of MeJA on the attenuation of kiwifruit fungal decay remains unknown. This work investigated the effects of exogenous MeJA on the enzyme activity, metabolite content and gene expression of the phenylpropanoid and jasmonate pathways in kiwifruit. The results revealed that MeJA inhibited the expansion of B. dothidea lesion diameter in kiwifruit ( Actinidia chinensis cv. ‘Hongyang’), enhanced the activity of enzymes (phenylalanine ammonia lyase, cinnamate 4-hydroxylase, 4-coumarate: coenzyme A ligase, cinnamyl alcohol dehydrogenase, peroxidase and polyphenol oxidase), and upregulated the expression of related genes ( AcPAL , AcC4H , Ac4CL , and AcCAD ). The accumulation of metabolites (total phenolics, flavonoids, chlorogenic acid, caffeic acid and lignin) with inhibitory effects on pathogens was promoted. Moreover, MeJA enhanced the expression of AcLOX , AcAOS , AcAOC , AcOPR3 , AcJAR1 , AcCOI1 and AcMYC2 and reduced the expression of AcJAZ . These results suggest that MeJA could display a better performance in enhancing the resistance of disease in kiwifruit by regulating the phenylpropanoid pathway and jasmonate pathway.

Botryosphaeria spp. occur on and cause diseases of Proteaceae, but accurate identification has been problematic due to the lack of clear species circumscriptions of members of this genus. In this study, 46 isolates of Botryosphaeria from proteaceous hosts growing in various parts of the world were studied, using morphology, cultural characters and sequence data from the ITS region of the rDNA operon. Five Botryosphaeria spp. were found to be associated with Proteaceae. Botryosphaeria lutea was isolated from Banksia and Buckinghamia spp. in Australia, and a single isolate was obtained from Protea cynaroides in South Africa. Botryosphaeria proteae was associated only with South African Proteaceae, but occurred in many parts of the world. Another Botryosphaeria sp. that occurred exclusively on South African Proteaceae represents a new taxon that is described as B. protearum. This pathogen was found on South African Proteaceae cultivated in Australia; Hawaii; Portugal, including the Madeira Islands; and South Africa. Botryosphaeria ribis was associated with both South African and Australian Proteaceae and was isolated from material collected in Australia, Hawaii and Zimbabwe. A single occurrence of B. obtusa as an endophyte was recorded from P. magnifica in South Africa. In addition to providing a taxonomic overview of Botryosphaeria spp. associated with Proteaceae, this paper clarifies for the first time the global distribution of these species. A key also is provided to facilitate their identification. A large number of new host and distribution records are made and a new species of Botryosphaeria from Proteaceae is described.