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Rice-paper plant, Tetrapanax papyrifer is a woody plant native to Taiwan and widely distributed in western Japan. Due to its low commercial value, little is known about its interactions with microorganisms. Here, we isolated Neofusicoccum parvum, a known causal agent of grape stem rot and mango stem-end rot, from leaf blight on T. papyrifer. Compared to mango isolate, N. parvum from rice-paper plant showed comparable virulence on grape stem and mango fruit. N. parvum strains exhibited pathogenicity on a variety of common weeds, which may act as disease reservoirs and boost N. parvum prevalence in commercially grown mango and grape. [ABSTRACT FROM AUTHOR]

In March 2016, grey mould disease was observed on mango (Mangifera indica) in Okinawa Prefecture, Japan. During the flowering period, the disease caused a brown coloration of the petals and peduncles accompanied by white aerial mycelium. As the disease symptoms progressed, the rot of panicle parts was accompanied by grey mould, resulting in fruit set failure. A fungus was isolated from the discoloured inflorescence into pure culture. Based on morphology and analyses of glyceraldehyde-3-phosphate dehydrogenase (g3pdh), heat-shock protein 60 (hsp60) and DNA-dependent RNA polymerase subunit II (rpb2) DNA sequences the fungus was identified as Botrytis cinerea. In an inoculation test, the isolate reproduced the symptoms observed on mango petals and peduncles and was reisolated from the flowers. This is the first report of B. cinerea as the causal agent of grey mould (haiirokabi-byo in Japanese) on floral tissue of mango in Japan. [ABSTRACT FROM AUTHOR]

Since 2002, papaya black rot has been spreading over several islands of Okinawa Prefecture. The pathogen of the disease was identified as Erwinia sp., genetically close to E. mallotivora and E. papayae. In terms of the disease transmission, it is probably carried by the wind or rain. In order to devise a prevention strategy for the disease, in vitro pesticides susceptibility of the pathogen and tests with papaya pot seedlings were conducted. A minimum inhibitory concentration assay demonstrated that copper (II) hydroxide, basic copper sulfate, and captan present in the papaya-registered pesticides inhibited the growth of the pathogen on nutrient agar plates. In addition, mancozeb that is non-papaya-registered pesticide also showed an inhibitory effect on the pathogen. Thus, there is a high possibility that even the existing papaya-registered or non-papaya-registered pesticides can prevent papaya black rot. In the test with papaya pot seedlings, copper (II) hydroxide exerted a relatively lower pesticide effect; however, captan exhibited a pesticide effect, although it is one of the fungicides not registered for use in the treatment of bacterial diseases of plants in Japan till date. Indeed, based on the result of the present study, the official registration of legal expansion for use of captan to control papaya black rot was approved in Japan on December 22, 2021. [ABSTRACT FROM AUTHOR]

Foot rot, also known as stem rot or tuber-root rot syndrome, on sweet potato occurs in sweet potato fields in Okinawa, Japan. Isolates of one fungal species that was consistently isolated from affected sweet potato produced pycnidia having alpha and gamma conidia. The same symptoms as those in the field were produced in vitro after inoculation of test plants with a representative isolate. Based on morphological and molecular phylogenetic evidence, we identified the fungus as Diaporthe destruens. This is the first report of the occurrence of foot rot on sweet potato caused by D. destruens in Japan. [ABSTRACT FROM AUTHOR]

Since 2002, papaya black rot has been spreading over several islands of Okinawa Prefecture, Japan. To devise a prevention strategy for the disease, microbiological research on the pathogen was conducted. Twelve strains were isolated from papaya infected with black rot showing symptoms such as water‐soaked lesions on stems and petioles, black spots on fruits, and rotted leaves turning yellow with necrotic spots. Through Koch's postulates, we confirmed that the isolated strains caused papaya black rot. Bacteriological assays showed that the strains have characteristics different from the type strains of Erwinia mallotivora, E. papayae, and E. psidii. Moreover, 16S rDNA sequence similarity searches showed that the isolated strains had less than 98.6% similarity with type strains. Additionally, phylogenetic analysis of 16S rDNA sequences suggested that the isolated strains were possibly a novel species belonging to the genus Erwinia, as the strains formed an independent cluster and had low sequence similarity with the type strains. Earlier studies indicated that papaya black rot is caused by E. cypripedii. Therefore, we propose to add the Erwinia sp. isolated in this study to the list of papaya black rot pathogens. [ABSTRACT FROM AUTHOR]

Powdery mildew disease was found on mango (Mangifera indica) in Okinawa Prefecture, Japan, in April 2013. During and after flowering, infected panicles, leaves, and young fruits became coated with a whitish powdery fungus. Fungal growth was usually severe on panicles, then plants became brown and defoliated. The fungal sample collected from conidia on diseased panicles was identified as Erysiphe quercicola based on morphology and rDNA-ITS sequence analysis. Inoculation with the isolate reproduced the symptoms on mango leaves and the fungus was reisolated from the inoculated leaves. In addition, the fungus infected Japanese oak (Quercus crispula), konara oak (Q. serrata), and ubame oak (Q. phillyraeoides). This is the first report of powdery mildew (udonko-byo in Japanese) on mango caused by E. quercicola in Japan. [ABSTRACT FROM AUTHOR]

In July 2013, a severe postharvest rot of mango fruits (cv. Lippens), with symptoms identical to stem-end rot caused by Lasiodiplodia theobromae or Neofusicoccum parvum, was found in Okinawa Prefecture, Japan. From affected fruit, Diaporthe species were consistently isolated. The isolates reproduced the original symptoms in healthy mango fruits after inoculation and were re-isolated from the inoculated fruits. Based on morphology and a phylogenetic analysis of rDNA-ITS, CAL, H3, EF1-α, and TUB, the isolates were classified into two Diaporthe species (Clade I and Clade II). In terms of susceptibility to procymidone, a registered fungicide against mango stem-end rot in Japan, the two Diaporthe species were less sensitive than previously reported mango stem-end rot pathogens and had MIC and EC50 values higher than the standard concentration applied. [ABSTRACT FROM AUTHOR]

Anthracnose of jaboticaba (Myrciaria cauliflora) was found in Okinawa Prefecture in 2013. The fungus isolated from diseased leaves was identified as Colletotrichum tropicale based on morphological characteristics and molecular analyses of the rDNA-ITS, TUB2, CAL, GAPDH, and GS regions. Inoculation tests using the isolated fungus confirmed that C. tropicale was the causal agent of the disease. This is the first report of anthracnose disease (tanso-byo) on jaboticaba caused by C. tropicale in Japan. [ABSTRACT FROM AUTHOR]

Viruses assumed to belong to a new Potyvirus were detected in passionfruit plants with foliar mosaic, leaf curl and fruit malformation that were collected from Akita City, Akita Prefecture in 2013, Nago City, Okinawa Prefecture in 2014, and Satsuma Town and Yoron Island, Kagoshima Prefecture in 2015. The isolates of this virus species were not detected by ELISA and RT-PCR targeting East Asian Passiflora virus (EAPV)-AO (Amami Oshima strain), which induces woodiness disease of passionfruit in Japan. The isolates were designated PV-AK (Akita), PV-OK (Okinawa), PV-YO (Yoron), and PV-SA (Satsuma). In a host-range test of 13 cultivars of French bean, four were systemically infected with the PV isolates and two with EAPV-AO. Cowpea cv. Kurodane sanjaku was systemically infected with PV isolates and induced mosaic symptoms on non-inoculated leaves distant from the inoculated leaves but was immune to EAPV-AO. The complete genomic sequences of the PV isolates consisted of 9973 nucleotides (nt) excluding the poly(A) tail, and encoded 3217 amino acids of polyprotein, flanked by 129–130 nt of the 5′-noncoding region and 193 nt of the 3′-noncoding region. Whole-genome nucleotide and amino acid sequences indicated that they belong to identical species. The potyvirus with the highest whole-genome nucleotide identity to the PV isolates is watermelon mosaic virus, which shares 68.1% identity, versus 65.3% for EAPV-AO. On the basis of ICTV-naming regulations, these PV isolates belong to a new species in the Potyvirus genus, but are distantly related to EAPV. Here, we propose East Asian Passiflora distortion virus as the new species name. [ABSTRACT FROM AUTHOR]

A panicle blight with sclerotia was found on mango ( Mangifera indica L.) in Okinawa Prefecture, Japan, in March 2016. Water-soaked lesions with white mycelia developed on panicles in the flowering stage; softening and decay of panicles was followed by formation of sclerotia. The fungus isolated from these sclerotia was identified as Sclerotinia sclerotiorum based on morphology and analysis of rDNA-ITS sequences. The isolate reproduced the symptoms on mango panicles in an inoculation test and was reisolated from flower stalks. This is the first report of sclerotinia rot (kinkaku-byo in Japanese) on mango caused by S. sclerotiorum in Japan. [ABSTRACT FROM AUTHOR]

A new antifungal compound, (3S)-4,6-dihydro-8-methoxy-3,5-dimethyl-6-oxo-3H-2-benzopyran (4), was isolated from Penicillium expansum. During the isolation procedure 4 was determined to be unstable and readily reacted with methanol, ethanol, and water, forming three new isochromans, (1S,3S)-6-hydroxy-1,8-dimethoxy-3,5-dimethylisochroman (1), 1-ethoxy-6-hydroxy-8-methoxy-3,5-dimethylisochroman (2), and 1,6-dihydroxy-8-methoxy-3,5-dimethylisochroman (3), respectively. (3S)-6-Hydroxy-8-methoxy-3,5-dimethylisochroman (5) was reisolated from P. expansum. In fungicide disk assays, compounds 1, 2, and 4 inhibited the mycelial growth of Lasiodiplodia theobromae at 100 microg/mL by 76%, 74%, and 69%, respectively.