Isolation, molecular characterization and first report of Dothiorella gregaria associated with fruit rot of walnuts of Jammu and Kashmir, India

Walnuts are known for their high levels of antioxidants, which are linked to various health benefits. However, challenges related to distribution and storage, as well as the risk of fungal infections, can affect the quality of walnut kernels. Fungal pathogens from the Botryosphaeriaceae family, including Dothiorella species and Diplodia species, can damage fruit and reduce its antioxidant content. To comprehend the cause of fruit rot in walnuts, Dothiorella gregaria isolates were studied using polyphasic methods, including multiple gene sequences and morphological identification, as well as analysis of polyphenol content and pathogenicity. The walnuts kernels purchased from market places of Jammu and Kashmir (J&K), India were observed to be affected by Dothiorella gregaria species causing the quality detoriation and decrease in polyphenol content thus undeniably with decreased antioxidant properties. D. gregaria Infected walnut kernels were having some brown and black spots and some were having white mycelial growth and however, most samples were asymptomatic. Pathogenicity testing revealed that the pathogen was able to develop all the symptoms under experimental conditions and the reisolated pathogen was morphologically similar to D. gregaria. The samples infected with this pathogen showed considerable decrease in polyphenol content, 10.9 ± 2.66 mgGAE/g (mean ± standard deviation) thus decreased antioxidant quality as compared to the samples which showed zero incidence of this pathogen, 52.50 ± 4.27 mgGAE/g (mean ± standard deviation). Furthermore, the pathogen was studied using polyphasic approach involving morphological, molecular and phylogenetic analysis. Combined nucleotide dataset of nuclear ribosomal ITS and tef1-α revealed that Dothiorella gregaria (NY6) formed a clade with Dothiorlla iberica (MAEC33), Dothiorella sarmentorium (MAEC28) and Dothiorella iberica (CAA905) strains with 83% bootstrap support. Besides, we observed six nucleotide changes, four were insertions or deletions and two were substitutions in the 502-bp region of the ITS rRNA gene when we compared our isolate to the most equivalent sequences submitted to NCBI GenBank. This is the first report of Dothiorella gregaria affecting walnuts purchased from various markets in J&K, India, causing fruit rot in walnuts after harvest. Given that local farmers store and export walnuts, it could pose an emerging threat to their livelihood. Thus, creating post-harvesting interventions for D. gregaria and knowing more about the fruit rot in walnuts can be benefited from morphological and molecular identification using several gene loci, genetic variability in the ITS rRNA gene, and total phenol analysis.

Study on pathogenicity and characterization of disease causing fungal community associated with cultured fish of Kashmir valley, India

Cultured fisheries of developing countries are continously challenged by a number of pathogenic microbes. Among microbial diseases, fungal and fungal like pathogen outbreaks lead to negative social and economic impacts on stakeholders. The cultured fisheries of Kashmir valley are also facing challenge from fungal pathogens, leading to tremendous socio-economic lossess to the fish farmer community hence, yearns to boost the sector with efficient management strategy. Our study was aimed at investigating the diversity of fungal communities infecting cultured rainbow trout and carp fish species. We employed classical microbiology, macro and micro morphological characteristics, and molecular analysis (multilocus typing) for fungal identification. Also histopathological approach was used to examine the pathogenicity patterns of diverse fungal groups. The study revealed that the infection in fish was predisposed to both superficial as well as visceral organs. However, skin, gills and head were predominantly infected compared to internal organs. The microbiological investigation of infected fish by culture dependent approach helped us to obtain the total of 250 fungal isolates. Out of these isolates, 21 different species were identified belonging to three diverse fungal groups which mostly included 14 species among Ascomycetes, 03 species of Oomycetes and 04 species of Zygomycetes. The majority of fungi which were infectious to cultured fish of valley are biotrophic or opportunistic soil fungi, and some of them being exclusive pathogens of fish.