Salicylic acid perturbs small RNA-gibberellin regulatory network in immune response of potato to Potato virus Y infection and renders plants tolerant to the pathogen

18 Potato virus Y is the most economically important potato viral pathogen. We aimed at 19 unraveling the roles of small RNAs (sRNAs) in the complex immune signaling network 20 controlling the establishment of tolerant response of potato cv. Désirée to the virus. We 21 constructed a sRNA regulatory network connecting sRNAs and their targets to link sRNA 22 level responses to physiological processes. We discovered an interesting novel sRNAs23 gibberellin regulatory circuit being activated as early as 3 days post inoculation, before viral 24 multiplication can be detected. Increased levels of miR167 and phasiRNA931 were reflected 25 in decreased levels of transcripts involved in gibberellin biosynthesis. Moreover, decreased 26 concentration of gibberellin confirmed this regulation. The functional relation between lower 27 activity of gibberellin signaling and reduced disease severity was previously confirmed in 28 Arabidopsis-virus interaction using knockout mutants. We additionally showed that this 29 regulation is salicylic acid dependent as the response of sRNA network was attenuated in 30 salicylic acid-depleted transgenic counterpart NahG-Désirée expressing severe disease 31 not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission. The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/130757 doi: bioRxiv preprint first posted online Apr. 26, 2017;