Reduced ascorbic acid (AsA) can be converted into oxidized state by ascorbate oxidase (AO). In present study, AO gene was down-regulated by RNA interference in tomato via Agrobacterium-mediated transformation. The existence of the RNA interference T-DNA in transformed plants and their progenies were confirmed by polymerase chain reaction amplification and Southern blotting. AO expression levels in transgenic lines were monitored by semi-quantitative reverse transcriptase-polymerase chain reaction. The decreased AO enzyme activity and significantly improved AsA content in tomato fruit were observed to be correlated with AO gene suppression. Transgenic plants with AO suppression and AsA improvement exhibited higher photosynthesis capacity than untransformed control under drought stress. This report demonstrates the AsA oxidation pathway by RNA interference, and provides a feasible approach to improve AsA content in horticultural plants by regulating genes related to AsA metabolism.
Background: Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) is a rapid and sensitive approach to identify miRNA and protein-coding gene expression in plants. However, because of the specially designated reverse transcription and shorter PCR products, very few reference genes have been identified for the quantitative analysis of miRNA expression in plants, and different internal reference genes are needed to normalize the expression of miRNAs and mRNA genes respectively. Therefore, it is particularly important to select the suitable common reference genes for normalization of quantitative PCR of miRNA and mRNA. Results: In this study, a modified reverse transcription PCR protocol was adopted for selecting and validating universal internal reference genes of mRNAs and miRNAs. Eight commonly used reference genes, four stably expressed novel genes in Populus tremula, three small noncoding RNAs and three conserved miRNAs were selected as candidate genes, and the stability of their expression was examined across a set of 38 tissue samples from four developmental stages of poplar clone 84K (Populus alba × Populus glandulosa). The expression stability of these candidate genes was evaluated systematically by four algorithms: geNorm, NormFinder, Bestkeeper and DeltaCt. The results showed that Eukaryotic initiation factor 4A III (EIF4A) and U6-2 were suitable for samples of the callus stage; U6-1 and U6-2 were best for the seedling stage; Protein phosphatase 2A-2 (PP2A-2) and U6-1 were best for the plant stage; and Protein phosphatase 2A-2 (PP2A-2) and Oligouridylate binding protein 1B (UBP) were the best reference genes in the adventitious root (AR) regeneration stage. Conclusions: The purpose of this study was to identify the most appropriate reference genes for qRT-PCR of miRNAs and mRNAs in different tissues at several developmental stages in poplar. U6-1, EIF4A and PP2A-2 were the three most appropriate reference genes for qRT-PCR normalization of miRNAs and mRNAs during the plant regeneration process, and PP2A-2 and UBP represent the best reference genes in the AR regeneration stage of poplar. This work will benefit future studies of expression and function analysis of miRNAs and their target genes in poplar.
Adventitious roots occur naturally in many species and can also be induced from explants of some tree species including Populus, providing an important means of clonal propagation. Auxin has been identified as playing a crucial role in adventitious root formation, but the associated molecular regulatory mechanisms need to be elucidated. In this study, we examined the role of PagFBL1, the hybrid poplar (Populus alba × P. glandulosa clone 84K) homolog of Arabidopsis auxin receptor TIR1, in adventitious root formation in poplar. Similar to the distribution pattern of auxin during initiation of adventitious roots, PagFBL1 expression was concentrated in the cambium and secondary phloem in stems during adventitious root induction and initiation phases, but decreased in emerging adventitious root primordia. Overexpressing PagFBL1 stimulated adventitious root formation and increased root biomass, while knock-down of PagFBL1 transcript levels delayed adventitious root formation and decreased root biomass. Transcriptome analyses of PagFBL1 overexpressing lines indicated that an extensive remodelling of gene expression was stimulated by auxin signalling pathway during early adventitious root formation. In addition, PagIAA28 was identified as downstream targets of PagFBL1. We propose that the PagFBL1-PagIAA28 module promotes adventitious rooting and could be targeted to improve Populus propagation by cuttings.
The plant hormone auxin is a central regulator of plant growth. TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB) is a component of the E3 ubiquitin ligase complex SCFTIR1/AFB and acts as an auxin co-receptor for nuclear auxin signaling. The SCFTIR1/AFB-proteasome machinery plays a central regulatory role in development-related gene transcription. Populus trichocarpa, as a model tree, has a unique fast-growth trait to which auxin signaling may contribute. However, no systematic analyses of the genome organization, gene structure, and expression of TIR1-like genes have been undertaken in this woody model plant. In this study, we identified a total of eight TIR1 genes in the Populus genome that are phylogenetically clustered into four subgroups, PtrFBL1/PtrFBL2, PtrFBL3/PtrFBL4, PtrFBL5/PtrFBL6, and PtrFBL7/PtrFBL8, representing four paralogous pairs. In addition, the gene structure and motif composition were relatively conserved in each paralogous pair and all of the PtrFBL members were localized in the nucleus. Different sets of PtrFBLs were strongly expressed in the leaves, stems, roots, cambial zones, and immature xylem of Populus. Interestingly, PtrFBL1 and 7 were expressed mainly in vascular and cambial tissues, respectively, indicating their potential but different roles in wood formation. Furthermore, Populus FBLs responded differentially upon exposure to various stresses. Finally, over-expression studies indicated a role of FBL1 in poplar stem growth and response to drought stress. Collectively, these observations lay the foundation for further investigations into the potential roles of PtrFBL genes in tree growth and development.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.