Constitutive Expression of miR408 Improves Biomass and Seed Yield in Arabidopsis

Abstract

miR408 is highly conserved among different plant species and targets transcripts encoding copper-binding proteins. The function of miR408 in reproductive development remains largely unclear despite it being known to play important roles during vegetative development in Arabidopsis. Here, we show that transgenic Arabidopsis plants overexpressing MIR408 have altered morphology including significantly increased leaf area, petiole length, plant height, flower size, and silique length, resulting in enhanced biomass and seed yield. The increase in plant size was primarily due to cell expansion rather than cell proliferation, and was consistent with higher levels of myosin gene expression and gibberellic acid (GA) measured in transgenic plants. In addition, photosynthetic rate was significantly increased in the MIR408-overexpressing plants, as manifested by higher levels of chloroplastic copper content and plastocyanin (PC) expression. In contrast, overexpression of miR408-regulated targets, Plantacyanin and Laccase 13, resulted in reduced biomass production and seed yield. RNA-sequencing revealed that genes involved in primary metabolism and stress response were preferentially enriched in the genes upregulated in MIR408-overexpressing plants. These results indicate that miR408 plays an important role in regulating biomass and seed yield and that MIR408 may be a potential candidate gene involved in the domestication of agricultural crops.

Global identification and characterization of miRNA family members responsive to potassium deprivation in wheat (Triticum aestivum L.)

“…miR408 regulates both growth and stress responses in plant species. For example, transgenic Arabidopsis lines overexpressing miR408 showed altered morphology and significantly increased leaf area, petiole length, plant height, flower size, pod length, and seed yields 57 . In rice, posttranscriptional modification of the target OsUCL8 by miR408 improves cellular Cu homeostasis, plastocyanin function, photosynthesis, and yield formation capacity 57 .…”

“…For example, transgenic Arabidopsis lines overexpressing miR408 showed altered morphology and significantly increased leaf area, petiole length, plant height, flower size, pod length, and seed yields 57 . In rice, posttranscriptional modification of the target OsUCL8 by miR408 improves cellular Cu homeostasis, plastocyanin function, photosynthesis, and yield formation capacity 57 . Expression of miR408 in chickpea plants enhanced their drought tolerance, improved their phenotype, and increased plant biomass under water deficit 38 .…”

Genome-wide identification of miRNAs and their targets during early somatic embryogenesis in Dimocarpus longan Lour.

“…dlo-miR397a, dlo-miR408-3p and dlo-miR166a-3p might participate in the development of early SE via the lignin metabolism pathway. miR397, miR408 and miR166 are conserved miRNAs in plants, which have been reported to participate in lignin and xylem synthesis [51][52][53] . Laccase and HD-Zip have also been widely studied [54][55][56] .…”

Biotechnological strategies for improved photosynthesis in a future of elevated atmospheric CO2

“…Since PC is the only soluble constituent of the photosynthetic electron transport chain, it would be expected that its accumulation could be modulated to a substantial degree, and its overexpression could, therefore, provide a means for enhancing this process. Indeed, the overexpression of microRNA408 (miR408), which is highly conserved in plants and typically up-regulated in response to abiotic stress (Trindade et al 2010;Li et al 2011), in Arabidopsis, tobacco and rice resulted in increased copper content within chloroplasts, augmented levels of PC, enhancements in net photosynthetic rates and light saturation points, as well as increased biomass production and seed size (Zhang et al 2017;Pan et al 2018b;Song et al 2018). In rice, significant improvements in grain yield were also noted in field conditions (Pan et al 2018b).…”