Maize streak Reunion virus (MSRV) is a member of the Mastrevirus genus in the family Geminiviridae. Of the diverse and increasing number of mastrevirus species found so far, only Wheat dwarf virus and Sweetpotato symptomless virus 1 have been discovered in China. Recently, a novel, unbiased approach based on deep sequencing of small interfering RNAs followed by de novo assembly of siRNA, has greatly offered opportunities for plant virus identification.
Image of a mastrevirus from Ed Rybicki
This is quite a big deal: there are very few cereal-infecting geminiviruses described from Eurasia, let alone symptomatic maize-infecting mastreviruses whose closest relatives come from Isle de la Reunion in the South Indian Ocean and Nigeria.
Mastreviruses are not seed-transmitted, so how did it get there? What is transmitting it? Is it possibly the elusive Bajra streak virus from India, that was described but never sequenced?
The authors say, in their conclusion:
“To date, other than MSV, MSRV is the only mastrevirus species that has ever been sampled from maize having maize streak disease symptoms. Interestingly, MSRV was also detected from wild grasses such as Setaria barbata and Rottboellia sp. in Nigeria, suggesting expanded host and geographical ranges for this virus . This first report of MSRV isolates in China reveals that this virus is likely to possess a far greater diversity and distribution than has been appreciated. Because 10 of 22 samples from Yunnan Province, China, were infected with MSRV-YN, for an infection rate of 45.5 %, further work on epidemics of MSRV-YN in China is needed.”
Absolutely! Maize streak, whether caused by MSV or potentially by MRSV, can be a devastating disease – and if this is expanding out of endeminicty in grasses thanks to leafhopper population expansion, or climate change, things could get interesting int hat part of the world.