Delineating the Tissue-Mediated Drought Stress Governed Tuning of Conserved miR408 and Its Targets in Rice

Abstract

MicroRNAs act as the cardinal post-transcriptional monitors of gene regulatory networks sculpturing the developmental plasticity and stress responses in plants. Single miRNA target several genes and how the transcriptional regulation of miRNA impacts its pool of targets in different tissues and stress conditions is still elusive. The present study investigated the highly conserved and evolving MIR408 family comprehensively by redefining its evolutionary conservation and diversification in plants followed by detailed functional analysis in rice. MIR408 family comprises three dominant mature forms (21 nt) including a distinct monocot variant. Plant MIR408 family can be divided into six groups. miR408 majorly cleave genes belonging to blue copper protein in addition to several other species-specific targets in plants. Screening of 4726 rice accessions identified 22 sequence variants in 1 Kb upstream (15) and MIR408 region leading to the identification of 8 haplotypes (3: Japonica-specific and 5: Indica-specific). miR408-3p follows flag leaf preferential and drought upregulated expression profile in flag leaf and roots of N22 which seems to be regulated by differential fraction of mCs in the precursor region. The active pool of miR408 regulated targets under control and drought conditions is impacted by the tissue type. Comparative expression analysis of miR408/target module under different sets of conditions features 83 targets exhibiting antagonistic expression in rice. Twelve high confidence targets including 4 plantacyanins (OsUCL6, 7, 9 and 30), pirin, OsLPR1, OsCHUP1, OsDOF12, OsBGLU1, glycine rich cell wall, deoxyuridine 5-triphosphate nucleotidohydrolaseand OsERF7 with antagonistic expression under most conditions. Further, over-expression of osa-MIR408 in drought sensitive rice cultivar leads to the massive enhancement of vegetative growth in rice with improved ETR and Y(II) and enhanced the dehydration stress tolerance at seedling stage.

Drought-responsive miRNAs in plants: a review

“…In chickpea, increased drought tolerance was achieved by overexpression of miR408 [80], which in turn is known as environmental regulator in a variety of stresses such as dehydration [87,90,32], and mechanical stress [91], and reactive oxygen species [92]. In line with this study, recently Balyan et al [99] found that overexpression of miR408 in drought-sensitive rice enhances photosynthetic parameters such as electron transport rate (ETR) and effective photochemical quantum yield of photosystem II (Y(II)) and water scarcity tolerance. Additionally, the function of miR408 in drought-stress tolerance has been recently validated in cowpea seedlings, where overexpression of miR408 result in enhanced drought and salinity tolerance in transgenic lines compared to the wild type [100].…”

Integration of mRNA and miRNA analysis reveals the differentially regulatory network in two different Camellia oleifera cultivars under drought stress

“…miR408 is a multistress-responsive miRNA that observed to be differentially regulated in plants such as Arabidopsis (Song et al, 2017), Triticum (Feng et al, 2013), Oryza (Balyan et al, 2022), Chickpea (Hajyzadeh et al, 2015), and Vigna unguiculata (Mishra et al, 2021). Previous studies showed that overexpression of miR408, by downregulation of the direct target genes, obviously promotes photosynthetic activity, biomass, and seed yield (Song et al, 2017;Pan et al, 2018), as well as tolerance to drought stress (Hang et al, 2021).…”