Abstract
BackgroundDrought conditions adversely affect soybean growth, resulting in severe yield losses worldwide. Increasing experimental evidence indicates miRNAs are important post-transcriptional regulators of gene expression. However, the drought-responsive molecular mechanism underlying miRNA–mRNA interactions remains largely uncharacterized in soybean. Meanwhile, the miRNA-regulated drought response pathways based on multi-omics approaches remain elusive.ResultsWe combined sRNA, transcriptome and degradome sequencing to elucidate the complex regulatory mechanism mediating soybean drought resistance. One-thousand transcripts from 384 target genes of 365 miRNAs, which were enriched in the peroxisome, were validated by degradome-seq. An integrated analysis showed 42 miRNA–target pairs exhibited inversely related expression profiles. Among these pairs, a strong induction of gma-miR398c as a major gene negatively regulates multiple peroxisome-related genes (GmCSD1a/b, GmCSD2a/b/c and GmCCS). Meanwhile, we detected that alternative splicing of GmCSD1a/b might affect soybean drought tolerance by bypassing gma-miR398c regulation. Overexpressing gma-miR398c in Arabidopsis thaliana L. resulted in decreased percentage germination, increased leaf water loss, and reduced survival under water deficiency, which displayed sensitivity to drought during seed germination and seedling growth. Furthermore, overexpressing gma-miR398c in soybean decreased GmCSD1a/b, GmCSD2a/b/c and GmCCS expression, which weakened the ability to scavenge O2.−, resulting in increased relative electrolyte leakage and stomatal opening compared with knockout miR398c and wild-type soybean under drought conditions.ConclusionThe study indicates that gma-miR398c negatively regulates soybean drought tolerance, and provides novel insights useful for breeding programs to improve drought resistance by CRISPR technology.
Highlights
Drought conditions adversely affect soybean growth, resulting in severe yield losses worldwide
The study indicates that gma-miR398c negatively regulates soybean drought tolerance, and provides novel insights useful for breeding programs to improve drought resistance by CRISPR technology
Gma-miR5037c expression was all down-regulated in the leaves and roots, while gma-miR5670b expression was up-regulated in leaves and down-regulated in roots, indicating that miRNAs expression patterns need to be identified in individual tissues
Summary
Drought conditions adversely affect soybean growth, resulting in severe yield losses worldwide. Small RNAs play a prominent regulatory role influencing the adaptability to drought stress, especially microRNAs (miRNAs) via degradation or translational inhibition of their target genes [3]. Only few miRNAs in soybean, e.g. gmamiR394 and gma-miR396, by overexpressing in model plants have been verified to perform an important function in response to drought stress [6, 7]. MiR398 participates in stress resistance by regulating the expression of superoxide dismutase (SOD)-related genes in many plants, such as Arabidopsis thaliana [8], Medicago sativa [9], tomato [10], and Oryza sativa [11]. Our understanding of the roles played by miRNAs under drought stress remains limited, especially for seedlings of soybean
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