Identification the Pathogens Causing Rot Disease in Pomegranate (Punica granatum L.) in China and the Antifungal Activity of Aqueous Garlic Extract

Outbreak of Alternaria Black Spot of Pomegranate (Punica granatum L.) in Italy as a Consequence of Unusual Climatic Conditions

Alternaria black spot of pomegranate (Punica granatum) was reported for the first time in Italy. In spring 2023, an outbreak of this disease was noticed in commercial pomegranate 'Wonderful' orchards of the municipality of Misterbianco (Sicily), following an unusually rainy period. A total of 30 randomly selected Alternaria isolates recovered from typical necrotic spots of leaves and fruits were characterized. Based on the colony morphology on solid agar media (PDA and MEA), isolates were separated into three distinct morphotypes (1, 2, and 3). The first two morphotypes comprised only isolates from fruits, while morphotype 3 comprised only isolates from leaves. Multigene phylogenetic analysis of four DNA regions, including internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and a SCAR marker (OPA10-2), identified the isolates of morphotypes 1 and 2 as Alternaria alternata and morphotype 3 isolates as A. arborescens. In pathogenicity tests on unwounded leaves and fruit, the isolates of all three morphotypes produced symptoms on the leaves of three pomegranate cultivars, 'Acco', 'Wonderful', and 'Etna'. The symptoms on 'Acco' leaves were the least severe. Conversely, the fruits of 'Acco' were the most susceptible. The isolates of morphotypes 2 and 3 were not pathogenic on the fruits of 'Wonderful' and 'Etna'. This is the first report of Alternaria black spot in Italy and of A. arborescens associated with Alternaria black spot of pomegranate worldwide.

Identification of Fungal Pathogens to Control Postharvest Passion Fruit (Passiflora edulis) Decays and Multi-Omics Comparative Pathway Analysis Reveals Purple Is More Resistant to Pathogens than a Yellow Cultivar

Production of passion fruit (Passiflora edulis) is restricted by postharvest decay, which limits the storage period. We isolated, identified, and characterized fungal pathogens causing decay in two passion fruit cultivars during two fruit seasons in China. Morphological characteristics and nucleotide sequences of ITS-rDNA regions identified eighteen isolates, which were pathogenic on yellow and purple fruit. Fusarium kyushuense, Fusarium concentricum, Colletotrichum truncatum, and Alternaria alternata were the most aggressive species. Visible inspections and comparative analysis of the disease incidences demonstrated that wounded and non-wounded yellow fruit were more susceptible to the pathogens than the purple fruit. Purple cultivar showed higher expression levels of defense-related genes through expression and metabolic profiling, as well as significantly higher levels of their biosynthesis pathways. We also found fungi with potential beneficial features for the quality of fruits. Our transcriptomic and metabolomics data provide a basis to identify potential targets to improve the pathogen resistance of the susceptible yellow cultivar. The identified fungi and affected features of the fruit of both cultivars provide important information for the control of pathogens in passion fruit industry and postharvest storage.

Terroir Is the Main Driver of the Epiphytic Bacterial and Fungal Communities of Mango Carposphere in Reunion Island

The diversity of both bacterial and fungal communities associated with mango surface was explored using a metabarcoding approach targeting fungal ITS2 and bacterial 16S (V3-V4) genomic regions. Fruits were collected in Reunion Island from two different orchards according to a sampling method which allowed the effect of several pre-harvest factors such as geographical location (terroir), cultivars, fruit parts, tree position in the plot, fruit position on the tree (orientation and height), as well as the harvest date to be investigated. A total of 4,266,546 fungal and 2,049,919 bacterial reads were recovered then respectively assigned to 3,153 fungal and 24,087 to bacterial amplicon sequence variants (ASVs). Alpha and beta diversity, as well as differential abundance analyses revealed variations in both bacterial and fungal communities detected on mango surfaces depended upon the studied factor. Results indicated that Burkholderiaceae (58.8%), Enterobacteriaceae (5.2%), Pseudomonadaceae (4.8%), Sphingomonadaceae (4.1%), Beijerinckiaceae (3.5%), and Microbacteriaceae (3.1%) were the dominant bacterial families across all samples. The majority of fungal sequences were assigned to Mycosphaerellaceae (34.5%), Cladosporiaceae (23.21%), Aureobasidiaceae (13.09%), Pleosporaceae (6.92%), Trichosphaeriaceae (5.17%), and Microstromatales_fam_Incertae_sedis (4.67%). For each studied location, mango fruit from each cultivar shared a core microbiome, and fruits of the same cultivar harvested in two different locations shared about 80% fungal and bacterial family taxa. The various factors tested in this study affected bacterial and fungal taxa differently, suggesting that some taxa could act as geographical (terroir) markers and in some cases as cultivar fingerprints. The ranking of the factors investigated in the present study showed that in decreasing order of importance: the plot (terroir), cultivar, fruit parts, harvest date and the position of the fruits are respectively the most impacting factors of the microbial flora, when compared to the orientation and the fruit position (height) on the tree. Overall, these findings provided insights on both bacterial and fungal diversity associated with the mango surface, their patterns from intra-fruit scale to local scale and the potential parameters shaping the mango microbiota.