Cu-miRNA stress relievers

Abstract

Many LACs are regulated by copper-miRNAs (Cu-miRNAs), which target genes encoding copper-containing proteins. LACs are required for lignification and flavonoid synthesis in plants and have been associated with plant development and stress tolerance. So, the researchers investigated the effects on stress tolerance of manipulating Cu-miRNAs. Specifically, they chose three Cu-miRNAs (miR397, miR408 and miR528), as these three collectively target 18 out of the 28 LAC family genes in rice. Simultaneously overexpressing the three Cu-miRNAs in rice (3miR-OE) caused extensive silencing of LACs, reducing both laccase activity and lignin content, whereas knocking out the three miRNAs generated the opposite phenotype.

The transcriptome of 3miR-OE plants showed changes in the expression of genes encoding laccases, peroxidases, and elements of the phenylpropanoid metabolic and flavonoid biosynthetic pathways. The metabolome of 3miR-OE plants showed a reduction in products of the lignin pathway but dramatically increased flavonoid metabolites. So, overexpressing the three miRNAs diverts metabolism from lignin synthesis to flavonoid accumulation in rice.