Search Results (7)

Hydrogen peroxide (H₂O₂) is a prevalent reactive oxygen species (ROS) found in cells and takes a central role in plant development and stress adaptation. The root apical meristem (RAM) has evolved strong plasticity to adapt to complex and changing environmental conditions. Recent advances have made great progress in explaining the mechanism of key factors, such as auxin, WUSCHEL-RELATED HOMEOBOX 5 (WOX5), PLETHORA (PLT), SHORTROOT (SHR), and SCARECROW (SCR), in the regulation of RAM activity maintenance. H₂O₂ functions as an emerging signaling molecule to control the quiescent center (QC) specification and stem cell niche (SCN) activity. Auxin is a key signal for the regulation of RAM maintenance, which largely depends on the formation of auxin regional gradients. H₂O₂ regulates the auxin gradients by the modulation of intercellular transport. H₂O₂ also modulates the expression of WOX5, PLTs, SHR, and SCR to maintain RAM activity. The present review is dedicated to summarizing the key factors in the regulation of RAM activity and discussing the signaling transduction of H₂O₂ in the maintenance of RAM activity. H₂O₂ is a significant signal for plant development and environmental adaptation. Full article

INDETERMINATE DOMAIN (IDD) proteins are plant-specific transcription factors that interact with GRAS proteins, such as DELLA and SHORT ROOT (SHR), to regulate target genes. The combination of IDD and DELLA proteins regulates genes involved in gibberellic acid (GA) synthesis and GA signaling, whereas the combination of IDD with the complex of SHR and SCARECROW, another GRAS protein, regulates genes involved in root tissue formation. Previous bioinformatic research identified seven IDDs, two DELLA, and two SHR genes in Physcomitrium patens, a model organism for non-vascular plants (bryophytes), which lack a GA signaling pathway and roots. In this study, DNA-binding properties and protein–protein interaction of IDDs from P. patens (PpIDD) were analyzed. Our results showed that the DNA-binding properties of PpIDDs were largely conserved between moss and seed plants. Four PpIDDs showed interaction with Arabidopsis DELLA (AtDELLA) proteins but not with PpDELLAs, and one PpIDD showed interaction with PpSHR but not with AtSHR. Moreover, AtIDD10 (JACKDAW) interacted with PpSHR but not with PpDELLAs. Our results indicate that DELLA proteins have modified their structure to interact with IDD proteins during evolution from moss lineage to seed plants, whereas the interaction of IDD and SHR was already present in moss lineage. Full article

BIG, a regulator of polar auxin transport, is necessary to regulate the growth and development of Arabidopsis. Although mutations in the BIG gene cause severe root developmental defects, the exact mechanism remains unclear. Here, we report that disruption of the BIG gene resulted in decreased quiescent center (QC) activity and columella cell numbers, which was accompanied by the downregulation of WUSCHEL-RELATED HOMEOBOX5 (WOX5) gene expression. BIG affected auxin distribution by regulating the expression of PIN-FORMED proteins (PINs), but the root morphological defects of big mutants could not be rescued solely by increasing auxin transport. Although the loss of BIG gene function resulted in decreased expression of the PLT1 and PLT2 genes, genetic interaction assays indicate that this is not the main reason for the root morphological defects of big mutants. Furthermore, genetic interaction assays suggest that BIG affects the stem cell niche (SCN) activity through the SCRSCARECROW (SCR)/SHORT ROOT (SHR) pathway and BIG disruption reduces the expression of SCR and SHR genes. In conclusion, our findings reveal that the BIG gene maintains root meristem activity and SCN integrity mainly through the SCR/SHR pathway. Full article

INDETERMINATE DOMAIN (IDD) family proteins are plant-specific transcription factors. Some Arabidopsis IDD (AtIDD) proteins regulate the expression of SCARECROW (SCR) by interacting with GRAS family transcription factors SHORT-ROOT (SHR) and SCR, which are involved in root tissue formation. Some AtIDD proteins regulate genes involved in the synthesis (GA3ox1) or signaling (SCL3) of gibberellic acid (GA) by interacting with DELLA proteins, a subfamily of the GRAS family. We analyzed the DNA binding properties and protein–protein interactions of select AtIDD proteins. We also investigated the transcriptional activity of the combination of AtIDD and GRAS proteins (AtIDD proteins combined with SHR and SCR or with REPRESSOR of ga1-3 (RGA)) on the promoters of SCR, SCL3, and GA3ox1 by conducting a transient assay using Arabidopsis culture cells. Our results showed that the SCR promoter could be activated by the IDD and RGA complexes and that the SCL3 and GA3ox1 promoters could be activated by the IDD, SHR, and SCR complexes, indicating the possibility that these complexes regulate and consequently coordinate the expression of genes involved in GA synthesis (GA3ox1), GA signaling (SCL3), and root formation (SCR). Full article

Phytosulfokine-α (PSK-α) is a newly discovered short peptide that acts as a phytohormone in various plants. Previous studies have shown that PSK-α is critical for many biological processes in plants, such as cell division and differentiation, somatic embryogenesis, pollen germination and plant resistance. In this study, we cloned two PSK homolog genes from Cunninghamia lanceolata (Lamb.) Hook (Chinese fir), ClPSK1 and ClPSK2, and characterized their function in root development. Quantitative RT-PCR analyses showed that both ClPSK1 and ClPSK2 were expressed in vegetative organs, mainly in roots. Transgenic Arabidopsis plants overexpressing ClPSK1 or ClPSK2 showed a higher frequency of adventitious root formation and increased root length. The expression of genes in Arabidopsis that are involved in stem cell activity (PLT1, PLT2 and WOX5), radial organization of the root (SHR and SCR) and cell cycle (CYCB1;1, CYCD4;1, CDKB1;1 and RBR) were significantly up-regulated, which may contribute to the elongation of the primary root and the formation of adventitious root in transgenic lines. Our results suggest that ClPSKs play an important role during root growth and development. Full article

The normalization of data by choosing suitable reference genes is fundamental for obtaining accurate and reliable results in quantitative real-time polymerase chain reaction (qPCR) analyses. In this study, the expression stability of 12 candidate reference genes of Pinus massoniana under different abiotic stresses was evaluated using four statistical algorithms: geNorm, NormFinder, BestKeeper, and RefFinder. The results indicate that the following genes could be used as reference genes under different treatments: Actin 2 (ACT2) and F-box family gene (F-box) for salinity treatment, cyclophilin (CYP) and alpha-tubulin (TUA) for ABA treatment, actin 7 (ACT7) and CYP for drought treatment, actin 1 (ACT1) and ACT7 for cold treatment, ACT1 and CYP for heat treatment, and TUA and ACT2 for the “Total” group. To validate the suitability of the selected reference genes in this study, the Short-Root protein (SHR), Alpha-pinene synthase (APS), and Pyrabactin resistance-like protein (PYL) gene expression patterns were analyzed. The expression patterns had significant biases when the most unstable reference genes were used for normalization, compared with when the optimum reference gene or gene combinations were used for normalization. These results will be beneficial for further studies on gene transcription in early-stage, unlignified seedlings of P. massoniana. Full article

Among the GRAS family of transcription factors, SHORT ROOT (SHR) and SCARECROW (SCR) are key regulators of the formation of root tissues. In this study, we isolated and characterized two genes encoding SHR proteins and one gene encoding an SCR protein: ThSHR1 (Accession Number MF045148), ThSHR2 (Accession Number MF045149) and ThSCR (Accession Number MF045152) in the adventitious roots of Taxodium hybrid ‘Zhongshanshan’. Gene structure analysis indicated that ThSHR1, ThSHR2 and ThSCR are all intron free. Multiple protein sequence alignments showed that each of the corresponding proteins, ThSHR1, ThSHR2 and ThSCR, contained five well-conserved domains: leucine heptad repeat I (LHRI), the VHIID motif, leucine heptad repeat II (LHR II), the PFYRE motif, and the SAW motif. The phylogenetic analysis indicated that ThSCR was positioned in the SCR clade with the SCR proteins from eight other species, while ThSHR1 and ThSHR2 were positioned in the SHR clade with the SHR proteins from six other species. Temporal expression patterns of these genes were profiled during the process of adventitious root development on stem cuttings. Whereas expression of both ThSHR2 and ThSCR increased up to primary root formation before declining, that of ThSHR1 increased steadily throughout adventitious root formation. Subcellular localization studies in transgenic poplar protoplasts revealed that ThSHR1, ThSHR2 and ThSCR were localized in the nucleus. Collectively, these results suggest that the three genes encode Taxodium GRAS family transcription factors, and the findings contribute to improving our understanding of the expression and function of SHR and SCR during adventitious root production, which may then be manipulated to achieve high rates of asexual propagation of valuable tree species. Full article