The adventitious rooting−related oxygenase (ARRO−1) gene is specifically expressed in the early rooting stage and is considered a molecular marker of rooting. In this study, a PsARRO−1 gene (GenBank accession number KJ620008) was identified from a pre−constructed transcriptome database of root development of Paeonia suffruticosa under sandy loam cultivation. The expression was verified by RT−qPCR, and it was found that the expression trend was consistent with the expression in the transcriptome database. The PsARRO−1 gene was specifically highly expressed during the root primordium germination phase. In addition, the RT−qPCR analysis indicated that the expression of PsARRO−1 in roots was significantly higher than in stems and leaves, its peak expression in vitro was 5 days earlier than in soil, and its expression was higher than that of tree peony in soil. Subcellular localization analysis showed that PsARRO−1 was localized in the plasma membrane. Moreover, the transient silent expression of the PsARRO−1 gene was found in the roots of peony seedlings grown using VIGS technology. The root activity was significantly reduced after transient silencing of the expression of the PsARRO−1 gene. These results indicate that PsARRO−1 has a positive regulatory effect on tree peony root development.

Relatively poor in vitro rooting has limited the large-scale commercial production of tree peony. In this study, on the basis of transcriptome sequencing, differentially expressed genes and the associated metabolic pathways were identified in tree peony roots at different stages of root formation under sandy loam cultivation. A total of 31.63 Gb raw data were generated and 120,188 unigenes (mean length of 911.98 bp) were annotated according to six databases (NR, NT, GO, KEGG, COG, and Swiss-Prot). Analyses of the ungerminated root primordium period, induced root primordium period, and root formation period detected 8,232, 6,907, and 10,687 differentially expressed genes related to 133, 132, and 133 metabolic pathways, respectively. Two significantly differentially expressed genes (Unigene13430_All and CL10096.Contig1_All) were associated with the auxin pathway. The full-length Unigene13430_All coding sequence (843 bp) encoded 280 amino acids, whereas the full-length CL10096.Contig1_All coding sequence (1,470 bp) encoded 489 amino acids. Unigene13430_All and CL10096.Con-tig1_All were identified as IAA gene family members and were respectively named PsIAA27 and PsARF19. The qRT-PCR analysis and functional verification indicated that the expressions of PsARF19 and PsIAA27 in tree peony seedlings, cuttings and grafted seedlings were significant different. PsARF19 promoted root development, it might be a regulatory gene related to the formation of tree peony roots, while PsIAA27 inhibited lateral root development, and it might be involved in controlling auxin sensitivity during root formation. The results of this study may form the basis of future investigations on the mechanism mediating peony root formation. The transcriptome data will be an excellent resource for researchers interested in characterizing the rooting-related tree peony genes.

Spathiphyllum floribundum is an important indoor flower species. Thus, optimizing its growth by regulating the light quality under indoor low-light conditions may be critical for generating high-quality flowers. In this study, the effects of the following six light-quality treatments on peroxidase and superoxide dismutase activities in two S. floribundum cultivars (‘Sweet Chico’ and ‘Queen’) were analyzed: monochromatic light comprising 100% red (R, 657 nm) or 100% blue (B, 450 nm) light, a combination of R and B lights [80% R + 20% B (8:2), 70% R + 30% B (7:3), and 60% R + 40% B (6:4)], and white light. The light treatments were performed using light-emitting diodes. The light intensity and photoperiod were set to 45±2 µmol·m-2·s-1 and 14 h·d-1, respectively. The results of this study revealed that an appropriate R:B light ratio may lead to increased pigment contents, thereby increasing the synthesis and accumulation of photosynthetic products, which will result in increased stress resistance and enhanced growth. These findings provide the basis for future investigations on the growth and production of S. floribundum and other indoor ornamental plants.

Tree peony (Paeonia ostii) is an ornamental flowering plant that is generally recalcitrant to establishment of a mature somatic embryo regeneration system in vitro. Glucose-6-phosphate translocator (GPT) plays an important regulatory role in embryogenesis of plants. In this study, PoGPT1 was cloned, and a bioinformatic analysis and functional verification of the gene were performed. The results showed that PoGPT1 encoded a polypeptide of 392 amino acids, which was a basic non-secreted hydrophobic transmembrane protein, and was mainly localized in the plastids. PoGPT1 was highly expressed in tree peony leaves, and its transcript abundance increased with the progression of zygotic embryo development. Overexpression of PoGPT1 caused up-regulation of leafy cotyledon 1 (PoLEC1), somatic embryogenesis receptor-like kinase (PoSERK), and agamous-like15 (PoAGL15) in tree peony callus. In addition, PoGPT1 overexpression promoted the increase in indole-3-acetic acid (IAA), 5-deoxystrigol (5DS), and brassinolide (BL) contents, especially of IAA, but reduced the contents of abscisic acid (ABA), 6-benzyladenosine (BARP), and 1-aminocyclopropanecarboxylic acid (ACC). The present research showed that PoGPT1 synergistically regulated the contents of endogenous hormones and expression levels of embryogenesis-related genes to promote the embryonic development of tree peony. The results provide theoretical and technical support for the establishment of a tree peony embryogenic callus formation and subsequent research on somatic embryogenesis.

Light-emitting diodes (LEDs) can be programmed to provide specialized light sources and spectra for plant growth. UV-A (397.6 nm), blue (460.6 nm), green (520.7 nm), and red (661.9 nm) LED light sources were used to study the effects of different monochromatic lights on the growth, antioxidant system, and photosynthetic characteristics of Spathiphyllum floribundum ‘Tian Jiao’ (a shade-loving species) and Chrysanthemum morifolium ‘Huang Xiu Qiu’ (a sun-loving species). This research revealed that green and blue light could enhance the morphological indicators, Chl a/b, photosynthetic electron transfer chain performance, and photosystem activity of S. floribundum, blue and red light could enhance the solution protein, Chl a, and photosynthetic electron transfer chain performance of C. morifolium, red and UV-A light viewed the highest SOD and CAT activities of S. floribundum (275.56 U·min·g−1; 148.33 U·min·g−1) and C. morifolium (587.03 U·min·g−1; 98.33 U·min·g−1), respectively. Blue and green light were more suitable for the growth and development of the shade-loving plant S. floribundum, while red and blue light were more suitable for the sun-loving plant C. morifolium. UV-A light could be used for their stress research. The research revealed the different adaptation mechanism of different plants to light environmental conditions.