Recent hybridization and allopolyploidy reprogrammedSpartinamicroRNA expression under xenobiotic induced stress

Abstract

Xenobiotic detoxification is a common trait of all living organisms, necessary for developmental plasticity and stress tolerance. The gene set involved in this biological process is dubbed the xenome (i.e. involved in drug metabolism in mammals, degradation of allelochemicals and environmental pollutants by bacteria and plant communities). Recently, we found that allopolyploidy increased tolerance to xenobiotics (phenanthrene) in Spartina. To decipher the molecular mechanisms underlying this process, we examined how interspecific hybridization and genome doubling impact miRNAs expression under xenobiotic induced stress. In this work we used a deep sequencing approach, and analyzed the parental species S. alterniflora and S. maritima, their F1 hybrid S. x townsendii and the allopolyploid S. anglica under phenanthrene exposure. We found that hybridization and genome doubling reprogrammed a myriad of miRNAs under phenanthrene-induced stress. Hence, to identify the master miRNAs involved in phenanthrene tolerance, we performed experimental functional validation of phenanthrene-responsive Spar-miRNAs using Arabidopsis T-DNA mutant lines inserted in homologous MIR genes, 39 knock out T-DNA Arabidopsis mutants, tagged in the most conserved miRNAs genes in vascular plants were screened. Development of MIR159 and MIR156 mutants was significantly affected under phenanthrene-induced stress. Subsequently, we performed in planta experimental validation to confirm the interaction between these miRNAs and their targets. These analyses suggest that MIR159 and MIR156 regulatory modules were targeted to induce the xenome relaxation and impact developmental plasticity responses in phylogenetically distant species under xenobiotic-induced stress. Graphical abstract

The miR156: A Master Regulator to Harmonize Complex Biofuel Traits in Lignocellulosic Biomass Crops

“…Furthermore, both leaves and roots were investigated, almost 57.4% to 72.4% more miR156 was expressed in salt-affected than control poplar plants. But, the expression of miR156 was higher in root as compared to leaves [77,78].…”

“…Using MIR159 and MIR156 mutants indicate the involvement of miR156-SPL-miR159 regulatory module in plants that inflicted with aromatic pollutants. The overexpression of miR156 affects SPL2 and SPL3 but not SPL13 genes, simultaneously, it also down-regulate the expression of miR159 and MYB33/62, MYB33 TFs via miR156/SPL network [78,81]. These findings are very significant because MALs would be proposed sites for farming of cellulosic biomass crops.…”

“…Therefore, various miRNAs based manipulating strategies can be applied [13,14,64] to enhance crucial genetic traits that are controlled by different miRNAs and their target genes in lignocellulosic crops. So far several conserved and novel miRNAs families are identified which are involved in the "fine-tuning" of significant feedstock traits in many bioenergy crops like switchgrass, Miscanthus species [65][66][67] Medicago sativa [68,69] S. bicolor [70,71] Brachypodium distachyon [72,73] Populus [74,75] Setaria species [76] Cordgrass, giant reed [77] Cordgrass [78], Arundo donax.L [79] Sorghastrum nutans (L.), Pennisetum [80], and other biofuel crops. However, numerous miRNAs families are identified and characterized but few of them have clearly emerged as master regulators, and thus, play a versatile role in controlling complex plant traits, for example, miR156 and miR164 (biorecalcitrance), miR159, miR172, miR395, miR444 (flower development), miR169, miR395, miR399 and miR528 (water stress) in lignocellulosic plants [8,27,45,67,[81][82][83][84][85].…”

“…The transgenic plants with hyper-accumulation of miR156 offered a substantial improvement in the form of fresh and dry biomass under the salt stress that manifestation with late flowering, improved apical dormancy, and more lateral branching and roots formations [185]. The response of salinity on the miR156/SPL module was studied in a grass halophyte (Spartina alterniflora Loisel), a model plant that shows a high level of salinity resistance [77,78]. In the same plant, the miR156 was the most abundant among the most conserved miRNA species along with miR397 that regulate abiotic stress [154,199].…”