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bioRxiv · 10.1101/2021.10.06.463290

In planta dynamics, transport-biases and endogenous functions of mobile siRNAs in Arabidopsis

Brosnan, C. A.·Devers, E. A.·Sarazin, A.·Lim, P.·Lehesranta, S.·Helariutta, Y.·Voinnet, O.
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Abstract

O_LIIn RNA interference (RNAi), small-interfering (si)RNAs processed from double-stranded RNA guide ARGONAUTE(AGO) proteins to silence sequence-complementary RNA/DNA. Plant RNAi can propagate locally and systemically, but despite recent mechanistic advances, basic questions/hurdles remain unaddressed. For instance, RNAi is inferred to diffuse through plasmodesmata, yet how its dynamics in planta compares with that of established symplastic-diffusion markers remains unknown. Also unknown is why select siRNA species, or size-classes thereof, are recovered in RNAi-recipient tissues, yet only under some experimental settings. Finally, RNAi shootward movement in micro-grafted Arabidopsis - necessary to study its presumptive transgenerational effects- has not been achieved thus far and endogenous functions of mobile RNAi remain scarcely documented. C_LIO_LIFocusing on non-amplified RNAi in Arabidopsis, we show here that (i) transgenic RNAi-movement, although symplasmic, only partially recapitulates the diffusion pattern of free GFP in planta, (ii) the presence/absence of specific AGOs in incipient/traversed/recipient tissues likely explains the apparent siRNA-selectivity observed during vascular movement, (iii) stress application allows endo-siRNA translocation against the shoot-to-root phloem flow, and (iv) mobile endo-siRNAs generated from a single inverted-repeat(IR) locus, have the potential to regulate hundreds of transcripts. C_LIO_LIOur results close important knowledge-gaps, rationalize previously-noted inconsistencies between mobile RNAi settings, and provide a framework for functional endo-siRNA studies. C_LI

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Brosnan, C. A., Devers, E. A., Sarazin, A., Lim, P., Lehesranta, S., Helariutta, Y., Voinnet, O.. 2021-10-06. In planta dynamics, transport-biases and endogenous functions of mobile siRNAs in Arabidopsis. https://doi.org/10.1101/2021.10.06.463290

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