Species composition of fungi of the genus Fusarium link on garlic plants in Moscow region

Garlic ( Allium sativum L.) cultivation is restrained by the lack of seed propagation and high sensitivity to pathogenic fungi, bacteria, viruses and nematodes. Currently, Fusarium dry rot caused by soil fungi of the genus Fusarium is the most harmful disease of the crop. For the first time, in a multidisciplinary study, we have quantified the ratio of the main Fusarium dry rot pathogens affecting garlic in the Moscow region. Data shows the percentage of occurrence of key pathogens, high harmfulness and a dominant position of dry rot of the species F. proliferatum in the complex of pathogens. The work aimed to investigate the species composition of plant pathogenic fungi of the genus Fusarium on a garlic ( Allium sativum L.) crop in the Moscow region. Diseased bulbs ( n = 1108) of winter garlic cv. Gladiator were collected during 2019 to 2021 (All-Russian Research Institute of Vegetable Growing) and divided into sample sets based on the same symptoms of bulbs and cloves damage. Two hundred garlic cloves from each sample were surface sterilized by common methods and used to isolate pathogens. Scrapings from damaged clove tissues were placed on Czapek’s medium in sterile Petri dishes and incubated for 12 days at 25 °C. The colonies were subcultured until monospore cultures were obtained. The isolates were identified using taxonomic keys. The frequency of occurrence of pathogens was calculated. Analysis of the marker sequences of the TEF1a gene (translation elongation factor 1 alpha) (~ 550 bp) and MCM7 (gene encoding minichromosome maintenance protein 7) (~ 650 bp) was performed to confirm the taxonomic identification of the isolates. Molecular identification of the isolates was performed by quantitative PCR using species-specific primers for F. proliferatum . NCBI’s BLAST algorithm (https://blast.ncbi.nlm.nih.gov/Blast.cgi) was used to analyse the nucleotide sequences of the TEF1a and MCM7 genes. Seven genera of fungi, the Fusarium , Penicillium , Botrytis , Embellisia , Aspergillus , Alternaria , and Sclerotium were isolated from the garlic bulbs with varying degrees of occurrence. Among these pathogens, the genus Fusarium prevailed with a frequency of more than 44 %. Of six identified species, the F. proliferatum , F. oxysporum , F. poae , F. verticilloides , F. culmorum and F. acuminatum , the F. proliferatum predominated at a frequency of 61.4-75.6 %. Sequencing of DNA markers confirmed identification of the F. proliferatum isolates. The similarity to the sequences deposited in the NCBI database was 99-100 % for TEF1a gene (reference sequence numbers MN158137, KP267240, MN012923, KT224299) and 98-99 % for MCM7 gene (reference sequence numbers XM031230017, XM0311M36726). qPCR analysis using specific primers also confirmed these results. Our findings add on the available data on the prevalence and dynamics of changes in the species composition of fungi of the genus Fusarium in the Moscow region. The data are also practically important for the development of more effective methods to prevent and control Fusarium diseases of garlic.