Distribution and molecular characterization of Maize rayado fino virus presents in maize commercial fields in the state of Paraná, Brazil

Diseases and pests have major impact in corn production in several regions around the world and are among the main problems for the crop. Corn stripe virus, caused by the Maize rayado Fino virus (MRFV) which is transmitted by the leafhopper Dalbulus maidis (Hemiptera: Cicadellidae), is one of the most important diseases for corn crops in the state of Paraná, Brazil. The virus is part of the corn stunt complex (CEM), along with the diseases associated with the phytoplasma ‘Candidatus Phytoplasma asteris’ and the spiroplasma Spiroplasma kunkelii. The objectives of this study were to determine the occurrence of corn streak virus and characterize the molecular diversity of MRFV present in corn plants in the state of Paraná, Brazil. The evaluations were carried out on corn plants symptomatic for the corn stunt complex (CEM) monitored and selected in commercial crops in municipalities distributed around different regions of the State. A total of 216 samples were collected in 98 different municipalities from January 2021 to December 2022. Plants with symptoms of diseases characteristic of CEM were initially identified by visual diagnosis in the field, and symptomatic leaves were collected and sent to the IDR Virology Laboratory -Paraná, in Londrina, PR. Detection of the MRFV virus was performed by RT-PCR and the molecular characterization by genomic sequencing. The occurrence of corn stripe disease caused by MRFV was confirmed for 65 plant samples from different municipalities in the state of Paraná. Genomic analysis carried out by sequencing the viral coat protein gene revealed 98% similarity among the MRFV isolates present in different regions of the state of Paraná, Brazil.