To investigate the amelioration of salt-induced damage on Paeonia ostii ‘Fengdan’ by exogenous silicon, we analyzed the photosynthetic and physiological characteristics of 1.5-year-old ‘Fengdan’ seedlings under NaCl stress by applying exogenous silicon (0, 0.75, and 1.5 mmol/L). Our results showed that the contents of the photosynthetic pigments chlorophyll a, chlorophyll b, and carotene, the transpiration rate, stomatal conductance, and intercellular CO₂ were significantly enhanced under salt stress when silicon treatment was applied, implying that the net photosynthetic rate was greatly improved. In addition, the plant height, stem thickness, and above-ground dry biomass of tree peony seedlings were effectively increased under salt stress with low-concentration silicon (0.75 mmol/L) treatment, along with osmotic substance (SS, SP, and Pro) content, total polyamine (TP) contents, and the activities of antioxidant-related enzymes (SOD, POD, and CAT) and polyamine-related synthetases (ADC, ODC, and SAMDC). In the low-concentration silicon treatment, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and superoxide anions (O₂⁻) were transformed quickly, which eventually reduced cell oxidative damage and improved seedling tolerance. This is an important finding in the understanding of how exogenous low-concentration silicon can alleviate salt-induced damage and promote the growth of tree peony seedlings, thus providing a new perspective on tree peony cultivation.

Low temperature is the most common abiotic stress factor in peanut cultivation. Chitooligosaccharide (COS) plays an important role in the low-temperature resistance in plants, however, the role of COS in regulating the cold tolerance in peanuts is not clear. This research investigated the effects of exogenous COS on peanut seedlings in response to low temperatures. The results showed that exogenous COS can significantly alleviate the cooling symptoms of seedlings by reducing the content of malondialdehyde (MDA) and reactive oxygen species (ROS) under simulated low-temperature conditions (8 °C). These reductions may be related to the elevation of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenoloxidase (PPO) activities and the increased contents of osmotic substances such as soluble sugars (SS), soluble protein (SP), proline (Pro), and total phenols (TP) compared with those in untreated seedlings. Meanwhile, the contents of chlorophyll a and b in a peanut leaf also increased, as well as the net photosynthetic rate (Pn), resulted in an increased plant height, a heavier fresh weight, and an increased dry weight. Notably, the treatment of 100 mg·L⁻¹ COS had maximum gain effects compared with those of other treatments. In summary, this study revealed the usage of COS for chilling stress alleviation, and 100 mg L⁻¹ foliar spraying is recommended.

Tree peony (Paoenia ostii) is a famous Chinese traditional flower well-known in many countries of the world. However, the short and concentrated flowering period of tree peony greatly affects the ornamental and economic value of the flowers. Exogenous brassinosteroid (BR) treatment can delay the flowering period of ostii T. Hong et J. X. Zhang var. lishizhenenii B. A. Shen for 3 days, but the underlying regulatory mechanism remains elusive. Here, full-length transcriptome and transcriptome sequencing were used to mine key genes related to BR-induced delayed flowering in tree peony. The transcriptome sequencing of the petals yielded 21.27 G clean data and 62,229 isoforms. Among them, 58,218 isoforms were annotated in NR, NT, SwissProt, KEGG, KOG, InterPro and GO databases. GO and KEGG analyses showed that 2460 DEGs were related to delayed flowering in response to BR. Additionally, a total of seven genes affecting flowering were annotated from 11 isoforms, which responded to BR through three pathways to delay the flowering of P. ostii var. lishizhenii. BR treatment increased the expression of BRASSINOSTEROID-SIGNALING KINASE3 (BSK3), potentially by promoting BRI1 ASSOCIATED KINASE RECEPTOR 1 (BAK1). Moreover, BR treatment suppressed the expression of SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE 1 (SPL1), possibly to inhibit the expressions of downstream WRKY genes and APETALA 2 (AP2). Meanwhile, BR treatment promoted the expression of DELLA, which might inhibit the expressions of CONSTANS (CO) and SPL. These results suggest a theoretical basis for further analyses of the molecular mechanism of flowering regulation in tree peony.

Tree peony (Paeonia section Moutan DC.) is a traditional ornamental flower of China, which has thousands of varieties with different flower colors and types after a long history of natural selection and artificial breeding. However, tree peony is a perennial woody plant with a long breeding, and there are still significant challenges to accelerate the process of genetic improvement of important ornamental traits. In this study, a total of sixteen primer pairs with high polymorphism and good universality were selected from the initial pool of 115 SSR markers. The SSR marker set was derived from published papers on the genetic linkage map and association analysis of tree peony. Furthermore, we conducted a genetic diversity and population structure analysis on 322 tree peony cultivars using molecular markers with functional. These SSRs amplified a total of 391 alleles, the average number of different alleles was 5.113 alleles across all loci. The average Shannon’s information index, gene diversity and polymorphism information content were 0.842, 0.532, and 0.503 over all loci, respectively. Population genetic diversity analysis indicated that the average expected heterozygosity of the total population was larger than the observed heterozygosity, showing the presence of a certain degree of heterozygous deletion phenomenon. The Japan varieties had the richest diversity with the highest H (0.508) and PIC (0.479) values. The Zhongyuan varieties showed the greatest variation may be related to its longstanding cultivation history. Moreover, the STRUCTURE and principal coordinate analyses indicated that 322 tree peony individuals from five populations were grouped into two clusters. An analysis of molecular variance demonstrated significant genetic diversity among different populations. This research may contribute to the sustainable management, conservation, and utilization of tree peony resources.

Wheat grain protein content (GPC), quantified as the mass proportion of protein relative to the total dry grain weight, is a key indicator for wheat quality evaluation. Based on space–air–ground collaborative observations, this study screened GPC-sensitive spectral parameters and multi-stage and multi-scale remote-sensing GPC estimation models. Results showed that the optimal feature set derived from unmanned aerial vehicle (UAV) imagery consisted of four vegetation indices (VIs) and three optimized texture indices (TIs). The Random Forest-based Soil–Plant Analysis Development (SPAD) model for field plots achieved the highest accuracy at the anthesis stage, with a coefficient of determination (R²) of 0.91 and a root mean square error (RMSE) of 1.77. Cross-year validation gave a correlation coefficient of 0.80 and RMSE of 3.83. Data analysis indicated that GPC of mature wheat had an extremely significant correlation with SPAD values across various growth stages, higher than leaf area index (LAI). We thus established a quantitative GPC estimation framework with UAV-derived SPAD as an intermediate variable, which kept stable R² (0.60) and RMSE (1.1%) except during grain-filling. On this basis, UAV-retrieved GPC data were scaled up to 10 m. Eight optimal parameters were selected from Sentinel-2 satellite data, and the regional-scale GPC estimation model was developed via the partial least squares regression (PLSR) algorithm. Compared with the model established directly using ground measured data without scale conversion, the scale-up model increased R² by 8.9% and reduced RMSE by 40%, improving the model inversion accuracy. The proposed regional-scale GPC remote-sensing estimation model effectively solves the scale mismatch between ground observation and satellite data, and provides technical support for field and regional wheat quality remote-sensing estimation.