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Date palm is the most important crop in Oman, occupying approximately 50% of the area devoted to agriculture. Little information is available on leaf spot diseases of date palm in Oman and in the world. This study was conducted to identify the most common fungal pathogens associated with leaf spot diseases of date palm. A total of 198 symptomatic leaf samples were collected from seven districts in Oman. Isolations revealed that most isolates belonged to the genus Alternaria. Molecular-based identification using multigene sequences revealed that the isolates belonged to Alternaria alternata, A. burnsii, A. tomato, Curvularia subpapendorfii, Didymella microchlamydospora, Fusarium brachygibbosum, F. incarnatum-equisetiand Nigrospora lacticolonia.In pathogenicity tests, A. alternatawas found to be the most aggressive. F. incarnatum-equisetiwas the least aggressive, only inducing symptoms in leaves injured prior to inoculation. The other species caused moderate leaf spot symptoms on the leaves. This study shows that several fungal species belonging to different genera can be found associated with leaf spot symptoms of date palms, and they vary in their aggressiveness on date palm leaves. It is the first study to report C. verruculosa, D. microchlamydospora,and N. lacticoloniaas leaf spot pathogens of date palm in the world.

ABSTRACTIn this study, endophytic fungi were isolated from Euphorbia laricaBoiss. and their antagonistic potential against phytopathogenic fungi viz. Fusariumsp., Rosellinia sanctae-crucianaand Cladosporiumsp. was evaluated using an in vitroconfrontation assay. A total of four endophytic fungi were isolated from the roots of E. larica. Among them, two fungal isolates (SQUCC-F1-1 and SQUCC-F6-2) showed inhibitory activity against Fusariumsp. None of the fungal endophytes restricted the growth of Rosellinia sanctae-crucianaand Cladosporiumsp. On the basis of multi-gene phylogenetic analysis, these two endophytic fungi were identified as Neocosmosporasp. (SQUCC-F1-1) and Alternaria alternata(SQUCC-F6-2). Scanning electron microscopic observation of hyphae of the phytopathogenic fungi from the dual culture plate revealed morphological abnormalities such as loss of turgidity, shrinkage and disintegration of the hyphae. Analysis of the metabolites produced by these endophytic fungi by GC-MS revealed the existence of various fatty acids, fatty acid methyl esters, hydrocarbons and alkanes, which have been previously demonstrated to have antimicrobial activity. The antagonistic activities of fungal endophytes from E. laricaare reported for the first time.

Date palm is the most widely cultivated crop in the United Arab Emirates (UAE). This study identified the main fungal root pathogens of date palms in the UAE. Isolations were established from 84 root samples and the recovered fungal isolates were identified using morphology and sequences of the internal transcribed spacer region of the ribosomal RNA gene (ITS rRNA) or the translation elongation factor gene (TEF1). The study revealed association of 10 fungal species with date palm roots, with Fusarium solani(82%), Lasiodiplodia hormozganensis(57%), Ceratocystis radicicola(7%) and L. theobromae(7%) being the most common. A pathogenicity test revealed that C. radicicolais the most aggressive, followed by L. hormozganensisand L. theobromae. These fungi resulted in rotting and development of necrosis on the roots as well as the development of wilt symptoms on 12-month old date palm seedlings. To our knowledge, this study is the first report of association of C. radicicolawith date palm root diseases in the UAE. It also appears to report for the first time three new fungal species in the UAE, Fusarium keratoplasticum, Cochliobolus hawaiiensisand Cephaliophora tropica.

Huanglongbing (HLB) is one of the most destructive diseases of Citrus. This study was conducted to characterize its etiological agent, ‘CandidatusLiberibacter’ spp., as well as the occurrence and distribution of HLB associated with acid lime (Citrus aurantifoliaSwingle) in Oman. A survey of different geographical areas in Oman has shown that HLB is present in some farms in the northern and southern parts of the country. Disease incidence was 71.8% in the surveyed lime trees with typical symptoms of HLB in Sohar and Wkaan, 40% in Al Jabal Al Akhdar and 62% in Salalah. Disease symptoms in some areas were observed all year round, but were more apparent from October to March. Phylogenetic analysis of the 16SrRNA gene of 38 isolates indicated an association of ‘CandidatusLiberibacter asiaticus’ (Las) with HLB-symptomatic acid lime trees. The analysis showed that Omani isolates clustered with isolates from Iran, India, USA and China. No ‘CandidatusLiberibacter’ spp. were detected in nursery seedlings imported from abroad. This study reports for the first time the association of HLB with acid lime in Oman. Extension programs and strict quarantine measures should be applied to help reduce the international spread of HLB.

With the advance to one scientific name for each fungal species, the generic names in the class Sordariomycetestypified by sexual and asexual morphs are evaluated based on their type species to determine if they compete with each other for use or protection. Recommendations are made for which of the competing generic names should be used based on criteria such as priority, number of potential names changes, and frequency of use. Some recommendations for well- known genera include Arthriniumover Apiospora, Colletotrichumover Glomerella, Menisporaover Zignoella, Microdochiumover Monographella, Nigrosporaover Khuskia, and Plectosphaerellaover Plectosporium.All competing generic names are listed in a table of recommended names along with the required action. If priority is not accorded to sexually typified generic names after 2017, only four names would require formal protection: Chaetosphaerellaover Oedemium, Diatrypeover Libertella, Microdochiumover Monographella, and Phaeoacremoniumover Romelliaand Togninia.Concerning species in the recommended genera, one replacement name (Xylaria benjaminiinom. nov.) is introduced, and the following new combinations are made: Arthrinium sinense, Chloridium caesium, C. chloroconium, C. gonytrichii, Corollospora marina, C. parvula, C. ramulosa, Juncigena fruticosae, Melanospora simplex, Seimatosporium massarina, Sporoschisma daemonoropis, S. taitense, Torpedospora mangrovei, Xylaria penicilliopsis, and X. termiticolacombs. nov.

Genes encoding the cellobiohydrolase enzyme (CBHI), designated as cbhI, were isolated from the basidiomycetes Auricularia fuscosuccinea, Pleurotus giganteus, P. eryngii, P. ostreatus, and P. sajor-caju. Initially, the fungal genomic DNA was extracted using a modified cetyltrimethyl ammonium bromide (CTAB) protocol and used as a DNA template. The cbhIgenes were then amplified and cloned using the pGEM-T Easy Vector Systems. The sizes of these PCR amplicons were between 700~800 bp. The DNA sequences obtained were similar showing high identity to the cbhIgene family. These cbhIgenes were partial consisting of three coding regions and two introns. The deduced amino acid sequences exhibited significant similarity to those of fungal CBHI enzymes belonging to glycosyl hydrolase family 7.