Comparative analysis of sRNAs profiles associated with the response to contrasting environments in potato

ZAVALLO D; CRESCENTE JM; ASURMENDI S; IBAÑEZ VN; MASUELLI RW; LEONE M; MARFIL CF

Congreso; II Argentine Meeting on Biology of Non-coding RNAs; 2018

Potato is the main horticultural crop worldwide and third as human food after rice and wheat.Argentina ranks the 22th in terms of production, is therefore of great interest to understand theresponse and adaptation to the environment in order to have the capacity to expand the arableareas. Wild potato species, which are adapted to diverse environments along the Andes,represents an invaluable source of heritable variability for crop improvement. These speciespresent high phenotypic plasticity and little is known about the responses to stresses orenvironmental fluctuation. During evolution, plants have acquired a series of adaptive strategiesthat allow them to survive under adverse environmental conditions. One of the central principles ofbiology is that evolutionary processes act on genetic variability in natural populations; howeverepigenetic mechanisms also play an important role in reprogramming gene expression in responseto environmental cues. Thus, epigenetic marks can serve as a priming mechanism to preparefuture generations to better withstand biotic and abiotic stresses. Epigenetic modification oftenresults in silencing gene expression in a process called RNA-directed DNA Methylation (RdDM)and one of the key components in that process involved small RNAs (sRNAs). The extent aboutthe role of sRNAs in the origin of phenotypic variation and their adaptive consequences has beenlittle explored. In this work, the Argentine wild potato species best adapted to arid regions growingin their natural habitat was used as experimental model: biological replicates (clones) of Solanumkurtzianum were in situ cultivated in the Villavicencio Natural Reserve (Mendoza) in twoexperimental gardens (EG) at contrasting elevation (i.e. 1200 m vs. 2200 m a.s.l). This altitudegradient generates differences, among others, in ultraviolet-B radiation levels (10%) and meantemperature (35%). Morphological, productivity and biochemical characters measured in leavesand tubers showed significant differences including increased leaf area, tuber number and meantuber weight in 2200 m respect to 1200 m clones. In order to assess the role of epigeneticmechanisms in the origin the documented phenotypic plasticity, a sRNA-seq experiment wasperform on leaves from clones cultivated in the two EG. Bioinformatic analysis was implemented toprofile 21 and 24nt sRNAs, the latter ones are known to be the responsible of the RdDM and twoindependent programs were used to account for the differentially accumulated sRNAs.Distributions of different features across the potato genome were performed and highlighted thosewith differentially accumulated sRNAs. Several features presented differentially accumulatedsRNAs between the two environments which they could have an impact on the epigenome and inconsequence in the transcriptome.