The interplay between miR156/SPL13 and DFR/WD40-1 regulate drought tolerance in alfalfa

Citation

Feyissa, B.A., Arshad, M., Gruber, M.Y., Kohalmi, S.E., Hannoufa, A. (2019). The interplay between miR156/SPL13 and DFR/WD40-1 regulate drought tolerance in alfalfa. BMC Plant Biology, [online] 19(1), http://dx.doi.org/10.1186/s12870-019-2059-5

Plain language summary

In the current study, the role of miR156 and its mode of action in regulating drought tolerance was investigated. Hence, alfalfa plants with increased levels of miR156 and altered miR156-regulated downstream genes (such as SPL13) were used to assess parameters linked to abiotic stress. The physiological and molecular responses revealed the positive role of miR156 in drought stress tolerance. Upon drought stress, low to moderate level miR156 having alfalfa plants maintain plant water status and physiological activity by increasing responsible genes and stress-reducing metabolites. Knowledge gained on the role of miR156 and its target SPL genes in response to drought can be utilized in developing tools for alfalfa breeding and a resource for scientific knowledge.

Abstract

Background: Developing Medicago sativa L. (alfalfa) cultivars tolerant to drought is critical for the crop's sustainable production. miR156 regulates various plant biological functions by silencing SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. Results: To understand the mechanism of miR156-modulated drought stress tolerance in alfalfa we used genotypes with altered expression levels of miR156, miR156-regulated SPL13, and DIHYDROFLAVONOL-4-REDUCTASE (DFR) regulating WD40-1. Previously we reported the involvement of miR156 in drought tolerance, but the mechanism and downstream genes involved in this process were not fully studied. Here we illustrate the interplay between miR156/SPL13 and WD40-1/DFR to regulate drought stress by coordinating gene expression with metabolite and physiological strategies. Low to moderate levels of miR156 overexpression suppressed SPL13 and increased WD40-1 to fine-tune DFR expression for enhanced anthocyanin biosynthesis. This, in combination with other accumulated stress mitigating metabolites and physiological responses, improved drought tolerance. We also demonstrated that SPL13 binds in vivo to the DFR promoter to regulate its expression. Conclusions: Taken together, our results reveal that moderate relative miR156 transcript levels are sufficient to enhance drought resilience in alfalfa by silencing SPL13 and increasing WD40-1 expression, whereas higher miR156 overexpression results in drought susceptibility.

Publication date

2019-10-21