552 / 2019-03-15 21:01:32

MicroRNAs constitute a crucial regulatory layer in crosstalk of plant responses to biotic and abiotic stress

Signal crosstalk,Transcription factors (TFs),miRNAs,Biotic and abiotic stress

Environmental Interactions > Environmental Interactions

In nature plants are often simultaneously challenged by different stress factors. The abiotic stress UV-B irradiation induces the production of UV-protective flavonols, but their accumulation is attenuated by biotic stress, e.g. by treatment with pathogen elicitors (flg22). This suppression has been shown to occur via suppression of flavonol pathway genes (FPGs) enabling the plant to direct its secondary metabolism to a more efficient pathogen defense response. Recently, we employed Arabidopsis plants to unravel the molecular mechanism underlying this signal crosstalk. As a result, we found that this crosstalk mainly relies on an antagonistic regulation of several MYB transcription factors (TFs) including MYB11, MYB12, MYB111 and MYB75 by UV-B and flg22, respectively. This is consistent with the previous results from the cell culture system with exception for MYB4, which role in the crosstalk could not be clearly defined. As miRNAs mainly target TFs, we thus investigated the role of miRNAs in this crosstalk. We found that the miR828 and miR858 both act as master regulators in this crosstalk by directly interfering the MYBs. Furthermore, the expression of miR828 and miR858 was found to be reciprocally regulated by UV-B und flg22 treatments, respectively and in a UVR8- and FLS2-receptor dependent manner. Following this, we conclude that miRNAs constitute a crucial regulatory layer in crosstalk of plant responses to biotic and abiotic stress. A functional model is postulated.