Temporal responses of conserved miRNAs to drought and their associations with drought tolerance and productivity in rice.

BACKGROUND

Plant miRNAs play crucial roles in responses to drought and developmental processes. It is essential to understand the association of miRNAs with drought-tolerance (DT), as well as their impacts on growth, development, and reproduction (GDP). This will facilitate our utilization of rice miRNAs in breeding.

RESULTS

In this study, we investigated the time course of miRNA responses to a long-term drought among six rice genotypes by high-throughput sequencing. In total, 354 conserved miRNAs were drought responsive, representing obvious genotype- and stage-dependent patterns. The drought-responsive miRNAs (DRMs) formed complex regulatory network via their coexpression and direct/indirect impacts on the rice transcriptome. Based on correlation analyses, 211 DRMs were predicted to be associated with DT and/or GDP. Noticeably, 14.2% DRMs were inversely correlated with DT and GDP. In addition, 9 pairs of mature miRNAs, each derived from the same pre-miRNAs, were predicted to have opposite roles in regulating DT and GDP. This suggests a potential yield penalty if an inappropriate miRNA/pre-miRNA is utilized. miRNAs have profound impacts on the rice transcriptome reflected by great number of correlated drought-responsive genes. By regulating these genes, a miRNA could activate diverse biological processes and metabolic pathways to adapt to drought and have an influence on its GDP.

CONCLUSION

Based on the temporal pattern of miRNAs in response to drought, we have described the complex network between DRMs. Potential associations of DRMs with DT and/or GDP were disclosed. This knowledge provides valuable information for a better understanding in the roles of miRNAs play in rice DT and/or GDP, which can facilitate our utilization of miRNA in breeding.