The dissertation is devoted to the detection and study of viruses that infect gladiolus in Ukraine. The spread of cucumber mosaic and bean yellow mosaic viruses on gladiolus plants in different regions of Ukraine was established, biological and molecular properties of detected isolates were studied, phylogenetic analysis of their sequences was performed and strain affiliation of gladiolus viral isolates was established.
Despite the circulation of CMV and BYMV on some agricultural plants in Ukraine, the study of the prevalence and detailed analysis of bean yellow mosaic virus and cucumber mosaic virus in gladiolus plantings in Ukraine has not been conducted before. The aim of the dissertation was to study gladiolus for virus infection, their identification and the study of biological and molecular properties of the identified isolates.
In the course of work on the dissertation the analysis of BYMV and CMV presence in private gladiolus plantings in different regions of Ukraine was performed using visual, serological and molecular research methods and the genetic diversity of Ukrainian gladiolus isolates of BYMV and CMV was analyzed. Samples of 21 varieties of gladiolus of domestic and foreign selection, which were collected in the period from 2019 to 2021 were used in the study. The most common symptom of viral infection was streaked mosaic on gladiolus leaves, which was observed in all studied regions, namely - in Kyiv, Poltava, Sumy, Lviv, Zhytomyr, Kherson regions.
According to the results of the analysis, the infectious nature of the detected symptoms on gladioli was established. The presence of viruses in gladiolus samples was proved by DAS-ELISA and RT-PCR. Bean yellow mosaic virus was detected in Kyiv, Poltava, Sumy, Lviv, Kherson regions, while cucumber mosaic virus was detected in Kyiv, Poltava, Zhytomyr, Lviv, Kherson regions. For the first time in Ukraine, the fact of infection of gladiolus with both BYMV + CMV was established in Kyiv, Poltava and Kherson regions.
Varietal peculiarities of gladiolus symptom manifestations have been established, and varieties that are insensitive to BYMV, CMV and therefore may be of potential interest for selection and creation of new gladiolus varieties have been selected.
The study of the morphology of viral particles in the juice of gladioli with symptoms of streaked mosaic revealed filamentous virions 720-750 nm long and about 11-13 nm in diameter, which is characteristic of BYMV. Another group of viral particles icosahedral, about 30 nm in diameter with an electronically dense center, which is characteristic of CMV.
The narrow specificity of BYMV and CMV gladiolus isolates was confirmed during testing on plant species sensitive to the studied viruses.
For the first time, the sequences of the capsid protein (CP) gene region of nine Ukrainian gladiolus isolates of cucumber mosaic virus with a size of 443 nt and eight isolates of bean yellow mosaic virus with a size of 578 nt were obtained.
Seven isolates were found to belong to the phylogenetic group Monocot and have a capsid protein gene region identity with isolates of this group of 94.8%-99.4% by nucleotide sequence (nt) and 95.3%-100% by amino acid (aa). The BYMV-Gl-FHL-20 isolate is clustered with the General phylogenetic group, having an identity with its representatives of 92.0%-99.6% by nt and 93.2%-100% by aa sequence.
For the first time in Ukraine, the CP gene sequences of gladiolus CMV isolates were analyzed. Seven of the studied isolates were found to belong to the phylogenetic subgroup IA and have an identity with the isolates of this group of 94.8% - 99.4% by nt and 83.0% - 100% by aa sequence. The CMV-G1-SkvP-20 isolate belongs to the phylogenetic subgroup IB, having identity with the isolates of this subgroup of 95.8% - 100% by nt and 96.0% - 100% by aa sequence. Isolate CMV-Gl-Zt-20, isolated from the Peter Pierce variety in the Zhytomyr region, belongs to subgroup II (identity with isolates of this subgroup 97.8% - 99.3% by nt and 95.8% - 99.2% by aa sequence).
Infection with both BYMV + CMV viruses was detected in three varieties of gladiolus: Lehendy Kiyeva, Pam’yat, Victoria Skvyrska, which was confirmed by DAS-ELISA and RT-PCR.
The above thesis is not only theoretical but also practical. Thus, varietal specificity to the manifestation of CMV, BYMV infection has been established.
It has been confirmed that during the vegetative reproduction of gladioli happens a transmission of viral infection from the mother plant, which is a factor in the spread of viruses to new areas. The path of vector transmission of CMV by aphids that transmitted the virus from vegetable crops. Thus, possible ways of infection with the studied gladiolus viruses and their potential role as reservoir plants for viral infection in the agrocenosis have been established.
