Abstract
Mediator complex is a multiprotein complex that regulates RNA polymerase II-mediated transcription. Moreover, it functions in several signaling pathways, including those involved in response to biotic and abiotic stresses. We used virus-induced gene silencing (VIGS) to study the functions of two genes, namely OsMED16 and OsMED25 in response to biotic and abiotic stresses in rice. Both genes were differentially induced by Magnaporthe grisea (M. grisea), the causative agent of blast disease, hormone treatment, and abiotic stress. We found that both BMV: OsMED16- and BMV: OsMED25-infiltrated seedlings reduced the resistance to M. grisea by regulating the accumulation of H2O2 and expression of defense-related genes. Furthermore, BMV: OsMED16-infiltrated seedlings decreased the tolerance to cold by increasing the malondialdehyde (MDA) content and reducing the expression of cold-responsive genes.
Highlights
Mediator complex, a multiprotein complex, was first discovered in yeast as a cofactor of RNA polymerase II that participates in RNA polymerase II-mediated transcription (Conaway and Conaway, 2011)
Phylogenetic tree analysis revealed that OsMED16 and OsMED25 showed more than 40% of sequence identity to Arabidopsis AtMED16 and AtMED25 which were already reported to have functions in response to biotic and abiotic stresses (Figure 1)
The expression of OsMED16 and OsMED25 was induced by the inoculation of rice plants with M. grisea, hormone treatment, and abiotic stresses (Figures 2, 3)
Summary
A multiprotein complex, was first discovered in yeast as a cofactor of RNA polymerase II that participates in RNA polymerase II-mediated transcription (Conaway and Conaway, 2011). Bioinformatics analysis and wet experiments revealed it to be a conserved multiprotein complex containing approximately 20 to 30 subunits. The mediator complex is not stationary and uses isomerism to transfer numerous signals (Conaway and Conaway, 2011). Mediator complex was first purified from plants in 2007 (Backstrom et al, 2007). The sequences of its subunits in plants are considerably different from those in other eukaryotic organisms; their secondary structure is similar. Out of the 27 subunits present in the Arabidopsis mediator complex, 21 are conserved across eukaryotic organisms, whereas the remaining six are specific to plants (Backstrom et al, 2007; Kidd et al, 2011; Mathur et al, 2011). The mediator complex functions in several signaling pathways involved in development, response to biotic and abiotic stresses, and cellular movement (Samanta and Thakur, 2015; Malik et al, 2017; Chong et al, 2020a,b; Crawford et al, 2020)
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