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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #307166
Title: Dynamics of small RNAs of virus and host origin from wheat streak mosaic virus and/or triticum mosaic virus infected susceptible and temperature-sensitive resistant wheat cultivars

Author
item Tatineni, Satyanarayana - Ts
item RIETHOVEN, JEAN-JACK - University Of Nebraska
item Graybosch, Robert
item French, Roy
item MITRA, AMITAVA - University Of Nebraska

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2014
Publication Date: 11/3/2014
Citation: Tatineni, S., Riethoven, J., Graybosch, R.A., French, R.C., Mitra, A. 2014. Dynamics of small RNAs of virus and host origin from wheat streak mosaic virus and/or triticum mosaic virus infected susceptible and temperature-sensitive resistant wheat cultivars. PLoS One 9(11):e111577. doi:10.1371/journal.pone.0111577.

Interpretive Summary: Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) are economically important viruses negatively impacting wheat production in the Great Plains region. Co-infection of wheat by WSMV and TriMV causes increased virus titers and disease severity and is common in growers’ fields because both viruses are transmitted by a common vector the wheat curl mite. In this study, we examined how co-infection of wheat by WSMV and TriMV induced more severe disease than single infections, by examining accumulation of virus- and host-specific small RNAs from WSMV and/or TriMV-infected susceptible (‘Arapahoe’) and temperature-sensitive resistant (‘Mace’) wheat cultivars. We found that virus-specific small RNAs accumulated similarly or more in doubly infected wheat cultivars than in singly infected plants, indicating that suppression of host defense mechanisms by the two viruses is not responsible for synergistic interaction of unrelated viruses. The presence of the virus-specific small RNAs indicates the host defense mechanism still functions, but somehow is overwhelmed by the viruses. Additionally, virus infections caused a shift in the profile of host small RNAs, suggesting that viral infections did alter the host defense mechanisms. Virus-specific small RNAs accumulated predominantly in Arapahoe at 27ºC and 18ºC and Mace at 27ºC but not at 18ºC; further demonstrating that Mace is resistant to both WSMV and TriMV at 18ºC.

Technical Abstract: Co-infection of wheat (Triticum aestivum L.) by Wheat streak mosaic virus (WSMV, a Tritimovirus) and Triticum mosaic virus (TriMV, a Poacevirus) of the family Potyviridae causes synergistic interaction. In this study, the effects of the synergistic interaction between WSMV and TriMV on endogenous and virus-specific small interfering RNAs (vsiRNAs) were examined in susceptible (‘Arapahoe’) and temperature-sensitive resistant (‘Mace’) wheat cultivars at 27ºC and 18ºC. Single- and double-infections in wheat caused a shift in the profile of endogenous small RNAs from 24 nt being the most predominant in healthy plants to 21 nt in infected wheat. Massive amounts of 21 and 22 nt vsiRNAs accumulated in singly and doubly infected Arapahoe at both temperatures and in Mace at 27ºC but not at 18ºC. The plus- and minus-sense vsiRNAs were distributed throughout the genomic RNAs in Arapahoe at both temperature regimens and in Mace at 27ºC, although some regions served as hot-spots spawning an excessive number of vsiRNAs. The vsiRNA peaks were conserved among wheat cultivars, suggesting that the Dicer-like enzymes in susceptible and resistant cultivars similarly accessed the genomic RNAs of WSMV or TriMV. Our data suggest that virus synergism and RNA silencing are unrelated because a large amount of vsiRNAs accumulated in doubly infected wheat despite the presence of two RNA silencing suppressor proteins. The high-resolution map of endogenous and vsiRNAs from WSMV- and/or TriMV-infected wheat cultivars may form a foundation for understanding the virus-host interactions, the effect of synergistic interactions on host defense, and virus resistance mechanisms in wheat.