Australasian Plant Disease Notes最新文献

Trachyspermum ammi is a traditional medicinal plant and is widely used for curing various diseases in humans. During a 2022 survey, yellowing symptoms associated with phytoplasma disease were observed in Bhopal. The disease was detected by direct and nested PCR using phytoplasma-specific primers in symptomatic plant leaf samples. The suspected ~ 1.2 kb amplified amplicons were sequenced and submitted in GenBank under accession number OQ216747. The phytoplasma isolate showed the highest 99.42% sequence identity and phylogenetic relationships with the 16 S ribosomal RNA gene of an isolate of aster yellows phytoplasma (‘Candidatus Phytoplasma asteris’; 16SrI group). This is the first report of ‘Ca. P. asteris’ (16SrI) associated with the yellows disease of T. ammi.

During the summers of 2022 and 2023, leaf spots suspected to be anthracnose were observed on the leaves of Rubus crataegifolius (Korean raspberry) grown in an orchard in Gimhae, South Korea. Approximately 20% of the Korean raspberry plants on the farm where the disease was discovered were confirmed to be infected. The morphological features of the fungal isolates were coincident to the descriptions of Colletotrichum gloeosporioides species complex. Phylogenetic analyses of concatenated sequences of the ITS, ACT, CAL, CHS-1, and GAPDH genes identified the causative agent as Colletotrichum aenigma. Pathogenicity tests confirmed that this fungal species is pathogenic to R. crataegifolius. To the best of our knowledge, this is the first report of C. aenigma on Korean raspberry in Korea and the world.

Lisianthus (Eustoma russellianum) is one of the emerging cut flower crops in international flower market quickly ranked in top ten cut flowers worldwide. Despite its rising popularity, studies relating to the identification and characterization of viral diseases affecting it are lacking from India. Thus, the present study was focused on identification and characterization of virus in lisianthus plants samples collected from Vensai Floritech, Narasihmanahalli village, Tubagere hobli, Doddaballapur taluk, Bengaluru rural district, Karnataka state, India exhibiting symptoms similar to begomoviruses infections. Association of the begomovirus with sample was confirmed by PCR using begomovirus specific primers which resulted in the expected amplicon (~ 1.2 kb). Further, whole-genome amplification was done by rolling circle amplification (RCA) for one representative sample (LIS-1). The amplified RCA product was cloned, sequenced and analyzed. The phylogenetic and nucleotide (nt) sequence analysis revealed that the begomovirus associated with lisianthus plants showed the maximum nt identity of 91.0% with sida yellow vein Madurai virus (SIYVMV-TN:OM141480) infecting a weed, Sida cordata, reported from Tamil Nadu, India, which is geographically close to Karnataka. Based on species demarcation criteria for begomoviruses, the collected isolate is identified as a strain of sida yellow vein Madurai virus associated with leaf curl of lisianthus from India and proposed the name “Sida yellow vein Madurai virus -[India:Karnataka:Doddaballapura:Lisianthus:2023]” and designated as SIYVMV-[IN:Kar:Dod:Lis:23]. Further, recombination analysis revealed a single intra-specific recombination event in the genomic region. Hence, this study provides a one more evidence of expanding host range for begomoviruses in India.

Eleven fruit samples from the tomato plants exhibiting different kinds of symptoms on leaves and fruits were collected from farmers fields located in two states (Karnataka and Maharashtra) of India. To confirm the identity of the pathogen, eleven tomato fruit samples were subjected DAS-ELISA, which revealed that all samples showed positive reaction to ToBRFV antibodies. Further, total RNA was isolated from infected fruits and subjected to RT-PCR assay using tomato brown rugose fruit virus (ToBRFV) coat protein gene specific primers. The resulting PCR amplicons of ~ 500 bp from eleven tomato samples were cloned, and sequenced. Sequence analysis of the CP gene from eleven isolates showed nucleotide identity of 100% with several ToBRFV isolates reported from different countries around the world. This result was further confirmed through phylogenetic analysis, wherein the eleven ToBRFV isolates are clustered closely with isolates reported from different parts of the world. To the best of our knowledge, this is the first record of ToBRFV infecting tomato in India.

In 2020, leaf spots were observed on Datura innoxia plants in Curitiba, Brazil. Alternaria alternata was identified after isolation from symptomatic leaves through morphological characterization, along with sequencing of the partial tef, gapdh, and rpb2 genes and phylogenetic analysis. Pathogenicity was proven using Koch’s Postulates. This is the first report of this species causing disease in Datura spp. worldwide.

In May 2018, symptoms of reduced growth and yellowing of Persian lime (Citrus latifolia) trees were detected in a commercial orchard located in Cotaxtla, Veracruz, Mexico. Nematodes were obtained from symptomatic trees and characterized through morphology and phylogeny, as well as pathogenicity tests. The results confirmed that Tylenchulus semipenetrans is the causal agent of the disease. To our knowledge, this is the first confirmed report of T. semipenetrans causing slow decline of Persian lime in Veracruz, Mexico.

Impatiens walleriana was introduced into Brazil and is now widely cultivated as an ornamental plant. Impatiens plants from a public garden showing leaf mosaic and colour break symptoms were submitted to total RNA extraction and high throughput sequencing. Identity of 99% with Amaranthus leaf mottle virus (AmLMV, Potyvirus) was observed. This is the first report of AmLMV in both Impatiens walleriana and the Americas.

Sixteen isolates of Fusarium fujikuroi from bakanae disease of rice in Bangladesh were examined for the presence of both mating types. Seven isolates were identified as MAT-1 and nine as MAT-2. This study suggests that there may be a chance for sexual reproduction in Bangladesh because it is the first attempt to examine the mating type of F. fujikuroi in this country.

The causal agent of rust on figs in New Zealand was determined using molecular and morphological analyses to be Phakopsora nishidana and not Cerotelium fici.