Stage and tissue-specific modulation of ten conserved miRNAs and their targets during somatic embryogenesis of Valencia sweet orange

Abstract

Somatic embryogenesis (SE) is a remarkable process of plant somatic cells developing into an embryo capable of forming a complete plant. MiRNAs play important roles in plant development by regulating expression of their target genes, but its function in SE has rarely been studied. Herein, ten conserved miRNAs with critical functions in plant development are detected by stem-loop qRT-PCR in the SE system of Valencia sweet orange. Sixteen unigenes from citrus are predicted to be targeted by six of the miRNAs. Cleavage sites on 15 of these target mRNAs are mapped by 5'RACE, of which ten are reported in this study. Transcript abundances of the 16 target unigenes are detected by qRT-PCR during SE process. Stage and tissue-specific expressions of miRNAs and their targets suggest their possible modulation on SE of citrus callus: miR156, 168 and 171 exert regulatory function during somatic embryo induction process; miR159, 164, 390 and 397 are related to globular-shaped embryo formation; miR166, 167 and 398 are required for cotyledon-shaped embryo morphogenesis; in addition, target genes of miR164, 166 and 397 are associated with SE disability of nonembryogenic callus. Exploration of miRNA-mediated modulation on SE is expected to provide new insights into plant cell totipotency, as well as how to maintain and enhance the embryogenic capacity of somatic cells.

AGING GENE PATHWAY OF MICRORNAS 156/157 AND 172 IS ALTERED IN JUVENILE AND ADULT PLANTS FROM IN VITRO PROPAGATED Prunus sp.

“…Additionally, there is evidence about the role of miR156 in redifferentiation during the induction of organogenesis (Liu et al, 2014) and somatic embryo induction (Wu et al, 2011). Moreover, it is well documented that prolonged cultivation of plant cells in vitro induces single nucleotide substitutions and increases the global DNA methylation level in a time-dependent fashion, which is associated with aging in plants (Dubrovina and Kiselev, 2016).…”

The pivotal role of small non-coding RNAs in the regulation of seed development

“…It is likely that in addition to SPL TFs, other potential targets of miR156 related to its role in somatic embryogenesis remain to be identified and validated (Mahdavi-Darvari et al 2015). Also miR397 has been associated both to the globular-shaped embryo formation and somatic embryogenesis incapacity of non-embryogenic callus in sweet orange (Wu et al 2011). As suggested by Luo et al (2006), the strong expression of miR397 in pro-embryogenic cells results in downregulation of laccase genes.…”

“…While the artificial environment in which somatic embryos develop certainly has an effect on gene regulation, this experimental system may still add useful contributions to the dissection of sRNA roles in zygotic embryo/seed development. For instance, there are evidences that support the relevance of miR156 in somatic embryogenesis across different plant species such as rice (Luo et al 2006) and sweet orange (Wu et al 2011) where it seems to be especially relevant during the somatic embryogenesis induction process, or in cotton where it showed a gradual increase during somatic embryo development, reaching a high level of expression in the cotyledon-stage somatic embryo (Yang et al 2013). It is likely that in addition to SPL TFs, other potential targets of miR156 related to its role in somatic embryogenesis remain to be identified and validated (Mahdavi-Darvari et al 2015).…”

Functional analysis of an iaaM gene in parthenocarpic fruit development in transgenic Physalis pubescens L. plants

“…A recent study on somatic embryogenesis of different plants and crops demonstrated the significance of optimization of sterilization and regeneration protocols for each individual cultivar, as well as the necessity of developing an effective regeneration system for each individual variety prior to the development of transformation systems (Dai et al 2011;Wu et al 2011). However, there were few regeneration systems reported previously for species belonging to the genus Physalis, such as P. minima, P. ixocarpa and P. philadelphica (Escobar-Guzmán et al 2009;Steffen et al 1986), and there was almost no research related to transformation.…”