Maize dwarf mosaic virus: a new causal agent inducing disease in rice plants of the fields of Kurdistan Region of Iraq

Rice ( Oryza sativa ) is one of the cereal crops that has great importance worldwide, especially in various regions of Asia. There are several viruses that are considered the most serious threat to rice productivity. Despite the worldwide identification of many viruses that cause dramatic reductions in rice yield, there might be many other viral agents that infect rice but have not been identified yet. In this study, we aimed to determine whether maize dwarf mosaic virus (MDMV) could infect rice plants under the field conditions of the Kurdistan region of Iraq. The leaves and seeds of rice plants that were likely to be infected with the virus were collected randomly in each survey at different locations in the rice fields in Akre, Bedole, Rovia, Sheladze, Deralok, and Zakho during different periods of July and September for each growing season of 2020 and 2021. The collected samples were tested for the incidence of MDMV using RT-PCR. The results showed that the collected samples from the fields located in Akre, Bedole, and Rovia were infected by MDMV. The amplified fragments were cloned, sequenced, and compared with those available at the GenBank. The seeds of the infected rice plants were MDMV-free. The incidence of MDMV in symptomatic rice plants was confirmed by RT-PCR, mechanical transmission, and aphid transmission. To the best of our knowledge, this is the first report that demonstrates that MDMV has the capability to infect rice plants naturally and, therefore, rice is considered a new natural host of MDMV.