Pollen morphology, pollen vigor, and long-term pollen storage are critical for plant cross-breeding and genetic improvement of Exochorda racemosa. We developed a protocol for viability determination and storage of E. racemosa pollen for breeding new varieties. The medium components for E. racemosa pollen germination was optimized by using an Orthogonal Assay Test Strategy (OATS). The germination rates of E. racemosa pollen were investigated after storing at different temperatures and different storage periods. The size of E. racemosa pollen was medium with three germination ditches, and the sculptural type of pollen was striate. Red ink and 2,3,5-triphenyl tetrazolium chloride (TTC) can effectively distinguish viable pollen from the unviable pollen of E. racemosa. The most suitable medium (CK2) for E. racemosa was composed of 150 g· L^–1 sucrose, 100 mg·L^–1 boric acid, 150 mg· L^–1 Ca(NO₃)₂ and 50 mg· L^–1 GA₃. Low-temperature stress produced the greater inhibition of pollen tube growth compared with high-temperature conditions. The CK2 medium at pH 6.5 resulted in the highest pollen germination rate and most extended pollen tube length. The optimal temperature for storage of dried pollen was –80°C (P < 0.01), and the germination rate was 53.60% after storage for 390 days. Thawing in a 35°C water bath produced the best viability of E. racemosa pollen after storage at –20°C and –80°C. The short-term storage of E. racemosa fresh pollen at 4°C was better than that at –20°C and –80°C (P < 0.01). It is possible to evaluate pollen quality and store pollen grains for E. racemosa by the parameters defined in this study.

This research reports for the first time the epidermal characteristics of 10 wild tree peonies belonging to the sect. Moutan group. The leaf micromorphology of 10 wild tree peonies—P. qiui, P. decomposita, P. jishanensis, P. ostii, P. delavayi, P. lutea, P. potanini, P. rockii, P. ludlowii and P. cathayana—were investigated by light and scanning electron microscopy. The characteristics of the leaf epidermis were found to be constant at the species level, but variable among species. Patterns of anticlinal walls were slightly wavy to wavy, very wavy, and straight to curved. All studied tree peonies presented stomata only on the abaxial surfaces of the leaves. The stomatal apparatus was elliptical or rectangular. Stomatal density was highest on the abaxial surface in P. qiui (300.25 per mm²), and lowest in P. jishanensiss (198.41 per mm²). Stomatal Index was highest on the adaxial surface of P. potanini (27.30%), and lowest in P. ludlowii (18.35%). Trichomes were observed in four studied peonies, which appeared only on the abaxial surface of the leaves, and three basic types of trichomes were identified. The long conical trichomes were distinctive of P. jishanensis, and the flat-shaped trichomes were characteristic of P. qiui, P. rockii and P. cathayana, and commonly occurred in the intervenous region and leaf veins. Stomatal shape, stomatal density, anticlinal wall patterns and trichomes may be of great value and significance for the classification of wild tree peonies. The principal component analysis showed that the component 1, component 2 and component 3 were the most components and nearly 79% of the observed variation. The key to the identification of wild tree peonies based on trichomes and stomata diversity was provided.

The goal of this study was to evaluate the effect of cold cathode fluorescent lamps (CCFLs) on the growth of Gerbera jamesonii var. ‘Rui Kou’ plantlets in vitro in six different light quality ratios: 100% red CCFL (R), 80% R + 20% blue CCFL (B), 70% R + 30% B, 60% R + 40% B, 100% B and white CCFLs (W). Control radiation was provided by conventional heat-generating plant growth fluorescent lamps (PGFLs). Plantlets under CCFLs showed better plantlet height, SPAD value (i.e., leaf chlorophyll content) and root activity (as assessed by root dehydrogenase activity) than those growing under PGFLs while all other growth parameters were comparable with plants under conventional lighting systems.

The relationship between metabolite changes and biological endpoints in response to cadmium (Cd) stress remains unclear. Fountain grass has good Cd enrichment and tolerance abilities and is widely used in agriculture and landscaping. We analyzed the metabolic responses by detecting the metabolites through UPLC-MS and examined the relationships between metabolite changes and the characteristics of morphology and physiology to different Cd stress in fountain grass. Our results showed that under Cd stress, 102 differential metabolites in roots and 48 differential metabolites in leaves were detected, with 20 shared metabolites. Under Cd stress, most of the carbohydrates in leaves and roots decreased, which contributed to the lowered leaf/root length and fresh weight. In comparison, most of the differential amino acids and lipids decreased in the leaves but increased in the roots. Almost all the differential amino acids in the roots were negatively correlated with root length and root fresh weight, while they were positively correlated with malondialdehyde content. However, most of the differential amino acids in the leaves were positively correlated with leaf length and leaf fresh weight but negatively correlated with malondialdehyde content. Metabolic pathway analysis showed that Cd significantly affects seven and eight metabolic pathways in the leaves and roots, respectively, with only purine metabolism co-existing in the roots and leaves. Our study is the first statement on metabolic responses to Cd stress and the relationships between differential metabolites and biological endpoints in fountain grass. The coordination between various metabolic pathways in fountain grass enables plants to adapt to Cd stress. This study provides a comprehensive framework by explaining the metabolic plasticity and Cd tolerance mechanisms of plants.

Plant quantitative trait allelic variation stems from complex regulatory networks. Tree peony, which is native to China, is a unique woody plant with ornamental, medicinal, and oil-producing value. Paeonia ostii, as an important species of tree peony, has emerged as a novel woody oil crop in recent years. However, research on functional genes associated with yield traits in P. ostii remains relatively limited. To gain deeper insights into the genetic architecture underlying one of the three key yield components—grain weight—in this study, a genome-wide association map for 123 unrelated P. ostii was constructed by integrating short-read and long-read sequencing. From 959 screened yield-related candidate transcription factors, 57 polymorphic expressed sequence tag-simple sequence repeats (EST-SSRs) were identified. In combination with 24 previously reported polymorphic EST-SSRs linked to tree peony seed yield, 81 markers were utilized for genotyping 123 P. ostii materials. These EST-SSRs showed high genetic diversity and low linkage disequilibrium. Additionally, population structure analysis revealed two distinct subgroups within the mapping population. Furthermore, 21 EST-SSRs were significantly associated with hundred-grain weight according to mixed linear model (MLM) association analysis. These loci primarily originated from the AP2, TCP, YAB, WRKY, WD, BHLH, and MADS-box gene families, contributing to phenotypic variation at rates ranging from 9.15% to 35.94%. Through sequence alignment analysis, we determined that WRI1, ERF7, NGAL3, and YAB1 might serve as key candidate genes regulating seed weight in P. ostii, highlighting their significant research value and warranting further investigation. The findings of this study provide valuable resources for elucidating allelic variation in the quantitative traits of oil-producing woody perennials.