Rhabdoviruses in Rice and Maize

Rhabdoviruses and Their Vectors in Rice and Maize

• Two unique rhabdoviruses infect rice and cause yield losses: rice stripe mosaic virus (RSMV) and rice yellow stunt virus (RYSV)
• RSMV, an emerging pathogen, was first detected in 2015 in southern China and is transmitted by the zigzag leafhopper
• RSMV isolates are highly conserved, with over 99% nucleotide sequence identity at the whole genome level
• RYSV, causing rice yellow stunt disease, was first observed in China in 1957 and is transmitted by the green rice leafhopper Nephotettix spp.
• Maize is infected by several rhabdoviruses, including maize yellow striate virus (MYSV) from Argentina, and maize mosaic virus (MMV) and maize Iranian mosaic virus (MIMV)
• MYSV and BYSMV are transmitted by the planthopper Delphacodes kuscheli and the small brown planthopper, respectively
• MMV is transmitted by the Delphacid planthopper, while MIMV is transmitted by L. striatellus
• Maize fine streak virus (MFSV) is transmitted by the leafhopper vector Graminella nigrifrons and has been proposed as the sole member of the proposed new genus Gammanucleorhabdovirus
• In comparative studies, localization of most MMV proteins was conserved in both insect and plant cells, but MMV P3 did not have a similar localization pattern in insect cells
• Predicted receptor molecules in the vector midgut that specifically interact with viral surface G proteins have not been identified so far
• In P. maidis exposed to MMV, 144 genes were differentially expressed, compared to almost 600 in G. nigrifrons exposed to MFSV, with 25 shared responsive transcripts, some related to transposable elements and innate immunity
• Long-term non-pathogenic infections of vectors result in higher vector capacity over the life-span of the vector, making the insect a more efficient vector of the virus