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SUMMARY: Drought is a detrimental environmental factor that restricts plant growth and threatens food security throughout the world. WRKY transcription factors play vital roles in abiotic stress response. However, the roles of IIe subgroup members from WRKY transcription factor family in soluble sugar mediated drought response are largely elusive. In this study, we identified a drought‐responsive IIe subgroup WRKY transcription factor, PoWRKY69, from Paeonia ostii. PoWRKY69 functioned as a positive regulator in response to drought stress with nucleus expression and transcriptional activation activity. Silencing of PoWRKY69 increased plants sensitivity to drought stress, whereas conversely, overexpression of PoWRKY69 enhanced drought tolerance in plants. As revealed by yeast one‐hybrid, electrophoretic mobility shift assay, and luciferase reporter assays, PoWRKY69 could directly bind to the W‐box element of fructose‐1,6‐bisphosphate aldolase 5 (PoFBA5) promoter, contributing to a cascade regulatory network to activate PoFBA5 expression. Furthermore, virus‐induced gene silencing and overexpression assays demonstrated that PoFBA5 functioned positively in response to drought stress by accumulating fructose to alleviate membrane lipid peroxidation and activate antioxidant defense system, these changes resulted in reactive oxygen species scavenging. According to yeast two‐hybrid, bimolecular fluorescence complementation, and firefly luciferase complementation imaging assays, valine‐glutamine 11 (PoVQ11) physically interacted with PoWRKY69 and led to an enhanced activation of PoWRKY69 on PoFBA5 promoter activity. This study broadens our understanding of WRKY69‐VQ11 module regulated fructose accumulation in response to drought stress and provides feasible molecular measures to create novel drought‐tolerant germplasm of P. ostii. Significance Statement: This manuscript identified a novel WRKY69‐VQ11 module that regulated fructose accumulation in response to drought stress, which provides feasible molecular measures to create novel drought‐tolerant germplasm of Paeonia ostii. [ABSTRACT FROM AUTHOR]

Stem strength plays a crucial role in the growth and development of plants, as well as in their flowering and fruiting. It not only impacts the lodging resistance of crops, but also influences the ornamental value of ornamental plants. Stem development is closely linked to stem strength; however, the roles of the SPL transcription factors in the stem development of herbaceous peony (Paeonia lactiflora Pall.) are not yet fully elucidated. In this study, we obtained and cloned the full-length sequence of PlSPL14, encoding 1085 amino acids. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression level of PlSPL14 gradually increased with the stem development of P. lactiflora and was significantly expressed in vascular bundles. Subsequently, utilizing the techniques of virus-induced gene silencing (VIGS) and heterologous overexpression in tobacco (Nicotiana tabacum L.), it was determined that PlSPL14-silenced P. lactiflora had a thinner xylem thickness, a decreased stem diameter, and weakened stem strength, while PlSPL14-overexpressing tobacco resulted in a thicker xylem thickness, an increased stem diameter, and enhanced stem strength. Further screening of the interacting proteins of PlSPL14 using a yeast two-hybrid (Y2H) assay revealed an interactive relationship between PlSPL14 and PlSLR1 protein, which acts as a negative regulator of gibberellin (GA). Additionally, the expression level of PlSLR1 gradually decreased during the stem development of P. lactiflora. The above results suggest that PlSPL14 may play a positive regulatory role in stem development and act in the xylem, making it a potential candidate gene for enhancing stem straightness in plants. [ABSTRACT FROM AUTHOR]

Background and Aims The tree peony (Paeonia suffruticosa Andr.) has been widely cultivated as a field plant, and petal blotch is one of its important traits, which not only promotes proliferation but also confers high ornamental value. However, the regulatory network controlling blotch formation remains elusive owing to the functional differences and limited conservation of transcriptional regulators in dicots. Methods We performed phylogenetic analysis to identify MYB44-like transcription factors in P. suffruticosa blotched cultivar 'High noon' petals. A candidate MYB44-like transcription factor, PsMYB44, was analysed via expression pattern analysis, subcellular localization, target gene identification, gene silencing in P. suffruticosa petals and heterologous overexpression in tobacco. Key Results A blotch formation-related MYB44-like transcription factor, PsMYB44, was cloned. The C-terminal of the PsMYB44 amino acid sequence had a complete C2 motif that affects anthocyanin biosynthesis, and PsMYB44 was clustered in the MYB44-like transcriptional repressor branch. PsMYB44 was located in the nucleus, and its spatial and temporal expression patterns were negatively correlated with blotch formation. Furthermore, a yeast one-hybrid assay showed that PsMYB44 could target the promoter of the late anthocyanin biosynthesis-related dihydroflavonol-4-reductase (DFR) gene, and a dual-luciferase assay demonstrated that PsMYB44 could repress PsDFR promoter activity. On the one hand, overexpression of PsMYB44 significantly faded the red colour of tobacco flowers and decreased the anthocyanin content by 42.3 % by downregulating the expression level of the tobacco NtDFR gene. On the other hand, PsMYB44 -silenced P. suffruticosa petals had a redder blotch colour, which was attributed to the fact that silencing PsMYB44 redirected metabolic flux to the anthocyanin biosynthesis branch, thereby promoting more anthocyanin accumulation in the petal base. Conclusion These results demonstrated that PsMYB44 negatively regulated the biosynthesis of anthocyanin by directly binding to the PsDFR promoter and subsequently inhibiting blotch formation, which helped to elucidate the molecular regulatory network of anthocyanin-mediated blotch formation in plants. [ABSTRACT FROM AUTHOR]

Oil bodies (OBs) are organelles of lipid storage in plants. In order to clarify the properties of OBs development in herbaceous peony (Paeonia lactiflora Pall.) seeds, this research had studied anatomical structures, particle size, zeta potential, the stability of OBs and characteristics of oleosin gene (OLE). It showed that OB particle size increased gradually during seed development, OBs accumulated in the endosperm cells, and their zeta potential firstly decreased and then increased. Temperature had not affected the stability of OBs, they could be maintained stably under the conditions of neutral and alkaline pH and less than 50 mM NaCl. Subsequently, P. lactiflora OLE was isolated, it had 824 bp in full-length and a 435-bp open reading frame encoding 144 amino acids with isoelectric point 9.40, which had three transmembrane domain and did not has a signal peptide, and belonged to the stable protein. Alpha helix was the main part of the secondary structure, no glycosylation site and 14 potential phosphorylation sites were found. Additionally, the express level of OLE initially increased and then decreased, and reached the highest on 60 days after flowering. These results could contribute to understand the properties of OBs development and characteristics of OLE in P. lactiflora seeds. [ABSTRACT FROM AUTHOR]

Herbaceous peony ( Paeonia lactiflora Pall.) seed oil (HPSO) was extracted from seeds by ultrasonic-assisted extraction (UAE). Changes in the oil yield, fatty acid (FA) composition, retinol and tocopherol (α-, γ-, and δ-tocopherol) contents of HPSO at the different developmental stages and in tested cultivars were examined, and the microscopic structure of HPSO droplets was also observed. The results showed that the HPSO yield increased with the seed development and reached its maximum level at the mature stage with values from 29.04 to 34.98% for different cultivars. The unsaturated fatty acid (UFA) contents were between 88.36 to 94.58%. Among the UFAs, the contents of oleic acid (27.19-45.06%), linoleic acid (20.59-37.59%), and α-linolenic acid (13.59-30.87%) were relatively high. The average γ-tocopherol content was 337.47 ± 57.42 µg/g, accounting for approximately 92.97% of the total tocopherol content. Transmission electron microscopy (TEM) observations of the HPSO microscopic structures indicated that the quantity and size of the oil bodies increased with the development of endosperm cells in P. lactiflora. This report was the first to study the HPSO, and the results will provide theoretical guidance for the exploitation and utilization of P. lactiflora resources. The content of UFA (A) was more than 90% in HPSO, and the content of γ-tocopherol was 353.67 ± 0.22 µg/g, accounting for about 93% of total tocopherols content (B). [ABSTRACT FROM AUTHOR]