RNA Silencing Is Resistant to Low-Temperature in Grapevine

Abstract

RNA silencing is a natural defence mechanism against viruses in plants, and transgenes expressing viral RNA-derived sequences were previously shown to confer silencing-based enhanced resistance against the cognate virus in several species. However, RNA silencing was shown to dysfunction at low temperatures in several species, questioning the relevance of this strategy in perennial plants such as grapevines, which are often exposed to low temperatures during the winter season. Here, we show that inverted-repeat (IR) constructs trigger a highly efficient silencing reaction in all somatic tissues in grapevines. Similarly to other plant species, IR-derived siRNAs trigger production of secondary transitive siRNAs. However, and in sharp contrast to other species tested to date where RNA silencing is hindered at low temperature, this process remained active in grapevine cultivated at 4°C. Consistently, siRNA levels remained steady in grapevines cultivated between 26°C and 4°C, whereas they are severely decreased in Arabidopsis grown at 15°C and almost undetectable at 4°C. Altogether, these results demonstrate that RNA silencing operates in grapevine in a conserved manner but is resistant to far lower temperatures than ever described in other species.

DNA methylation in Arabidopsis has a genetic basis and shows evidence of local adaptation

“…Furthermore, while CHH methylation varied with temperature at both DCL3- and CMT2-dependent DMRs ( Figure 5 ), DCL3-dependent DMRs were much more strongly associated with previously identified temperature DMRs (4703 out of 10,138 DCL3-dependent DMRs, or 46%, overlapped temperature-sensitive DMRs, whereas the corresponding numbers for CMT2-dependent DMRs were 2299 out of 33,422, or 7%; Fisher's exact p-value < 2.2e-16), suggesting that much of the temperature variation in CHH methylation is due to components of the RdDM pathway. This result is consistent with previous findings showing that RNA silencing is less active at lower temperatures ( Romon et al, 2013 ).

10.7554/eLife.05255.010 Figure 5.

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Transient expression assays in grapevine: a step towards genetic improvement

“…Recently, Romon et al . () observed that the RNA silencing machinery of grapevine is resistant to low temperatures, contrary to that of herbaceous species such as N. benthamiana or A. thaliana . The RNAi strategy is therefore relevant for conferring virus resistance in this perennial crop which is often subjected to low temperatures.…”

“…As shown by transient expression in N. benthamiana, amiRNA constructs based on grapevine miRNA precursors can also efficiently target grapevine viral sequences (Roumi et al, 2012). Recently, Romon et al (2013) observed that the RNA silencing machinery of grapevine is resistant to low temperatures, contrary to that of herbaceous species such as N. benthamiana or A. thaliana.…”

Linking the knowledge and reasoning of dissenting actors fosters a bottom-up design of agroecological viticulture

“…4), still following the same research action method. The biologists, who studied vine health in laboratories (Romon et al 2013), started addressing the issue in a more holistic way. In collaboration with the group, the project deals with the vineyards in their environment.…”