Melanose disease is one the most widely distributed and economically important fungal diseases of citrus worldwide. The causative agent is the filamentous fungus Diaporthe citri Wolf (syn. Phomopsis citri H.S. Fawc.). Here, we report the genome assemblies of three strains of D. citri, namely strains ZJUD2, ZJUD14 and Q7, which were generated using a combination of PacBio Sequel long-read and Illumina paired-end sequencing data. The assembled genomes of D. citri ranged from 52.06 Mb to 63.61 Mb in genome size, containing 15,977 ~ 16,622 protein-coding genes. We also sequenced and annotated the genome sequences of two Citrus-related Diaporthe species, D. citriasiana and D. citrichinensis. In addition, a database for citrus-related Diaporthe genomes was established to provide a public platform to access genome sequences, genome annotation and comparative genomics data of these Diaporthe species. The described genome sequences and the citrus-related Diaporthe genomes database provide a useful resource for the study of fungal biology, pathogen-host interaction, molecular diagnostic marker development, and population genomic analyses of Diaporthe species. The database will be updated regularly when the genomes of newly isolated Diaporthe species are sequenced. The citrus-related Diaporthe genomes database is freely available for non-profit use at http://www.zjudata.com/blast/diaporthe.php.

A simple, rapid and feasible method is developed for direct and simultaneous determination of phenol (Ph), hydroquinone (HQ) and 4-nitrophenol (4-NP) on unmodified boron-doped diamond (BDD) electrode. Results showed that the oxidative peaks of these three phenolic compounds can be completely separated on BDD electrode in acidic conditions by using electrochemical cyclic voltammetry technique. The peak potential separations are all higher than 0.35 V. Moreover, BDD electrode is extremely easy to be refreshed to obtain current values with good reproducibility, even if it is passivated by phenolic compounds with different adsorption characteristics. All the above features are on account of the outstanding electrochemical characteristics of BDD electrode, and lead to the advantage and feasibility for simultaneous determination of three phenolic compounds without any other separation operation. For each tested phenolic compound, the concentration range with linearity is in two or three orders of magnitude in the presence of other coexisting phenolic compounds with the concentrations more than 1000 times higher than that of the tested component. The present method is also shown to be promising for the determination of phenolic contaminants in the real wastewater samples.

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Citrus target spot, caused by Pseudofabraea citricarpa (Zhu et al.) Chen, Verkley & Crous, was a recently reported disease on satsuma mandarin and kumquat in Chenggu (Shaanxi province, China). In January 2019, target spot-like disease was also observed on ‘Eureka’ lemon and ‘Beijing’ lemon in Wanzhou (Chongqing province), satsuma in Yichang (Hubei province), and ‘Ponkan’ in Jishou (Hunan province). The identity of the causative agent was conducted and confirmed as P. citricarpa based on symptoms, fungal morphology, and multigene phylogenetic analysis, as well as pathogenicity tests. Investigations revealed that P. citricarpa can also infect ‘Tarocco’ blood orange and ‘Newhall’ navel orange. It can not only infect leaves and shoots but also can infect fruits. These results suggest that P. citricarpa could potentially spread to other citrus-growing regions in China.

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