Periapical lesion-derived decellularized extracellular matrix as a potential solution for regenerative endodontics.

Pulp regeneration remains a crucial target in the preservation of natural dentition. Using decellularized extracellular matrix is an appropriate approach to mimic natural microenvironment and facilitate tissue regeneration. In this study, we attempted to obtain decellularized extracellular matrix from periapical lesion (PL-dECM) and evaluate its bioactive effects. The decellularization process yielded translucent and viscous PL-dECM, meeting the standard requirements for decellularization efficiency. Proteomic sequencing revealed that the PL-dECM retained essential extracellular matrix components and numerous bioactive factors. The PL-dECM conditioned medium could enhance the proliferation and migration ability of periapical lesion-derived stem cells (PLDSCs) in a dose-dependent manner. Culturing PLDSCs on PL-dECM slices improved odontogenic/angiogenic ability compared to the type I collagen group. In vivo, the PL-dECM demonstrated a sustained supportive effect on PLDSCs and promoted odontogenic/angiogenic differentiation. Both in vitro and in vivo studies illustrated that PL-dECM served as an effective scaffold for pulp tissue engineering, providing valuable insights into PLDSCs differentiation. These findings pave avenues for the clinical application of dECM's in situ transplantation for regenerative endodontics.

Proteomic analysis of leaves and roots during drought stress and recovery in Setaria italica L.

Drought is a major environmental factor that limits agricultural crop productivity and threatens food security. Foxtail millet is a model crop with excellent abiotic stress tolerance and is consequently an important subject for obtaining a better understanding of the molecular mechanisms underlying plant responses to drought and recovery. Here the physiological and proteomic responses of foxtail millet (cultivar Yugu1) leaves and roots to drought treatments and recovery were evaluated. Drought-treated foxtail millet exhibited increased relative electrolyte leakage and decreased relative water content and chlorophyll content compared to control and rewatering plants. A global analysis of protein profiles was evaluated for drought-treated and recovery treatment leaves and roots. We also identified differentially abundant proteins in drought and recovery groups, enabling comparisons between leaf and root tissue responses to the conditions. The principal component analysis suggested a clear distinction between leaf and root proteomes for the drought-treated and recovery treatment plants. Gene Ontology enrichment and co-expression analyses indicated that the biological responses of leaves differed from those in roots after drought and drought recovery. These results provide new insights and data resources to investigate the molecular basis of tissue-specific functional responses of foxtail millet during drought and recovery, thereby significantly informing crop breeding.

Effects of salt stress on seed germination and respiratory metabolism in different Flueggea suffruticosa genotypes.

The selection and utilization of ornamental plants that are highly tolerant to salt are helpful for landscape construction and the ecological protection of coastal and arid areas. To evaluate salt tolerance, one of the most used methods is the observation of seed germination under salt stress. Therefore, this work aimed to evaluate the influence of different concentrations of NaCl in water absorption, germination, and respiratory metabolism in seeds of different Flueggea suffruticosa genotypes. P2 and P27, salt-sensitive and salt-tolerant line s of F. suffruticosa, were chosen for treatment with 0, 40, 80, 120, 160, 200, and 240 mM NaCl. F. suffruticosa under salt stress exhibited inhibition of seed germination. The seeds of F. suffruticosa have different times for the physiological phases of water absorption with different NaCl concentrations. Salt stress retarded the seed water absorption process, and it depended on seed genotypes for F. suffruticosa. Soluble sugars accumulated in both P2 and P27 under salt stress. Meanwhile, the activities of hexokinase, 6-phosphofructokinase, pyruvate kinase, pyruvate dehydrogenase, citrate synthase, and glucose-6-phosphate dehydrogenase were overall increased in P27 after salt treatment, which caused increases in pyruvic acid and citric acid. The citrate synthase and glucose-6-phosphate dehydrogenase activities decreased in P2. These results suggest that the respiratory metabolism of salt-tolerant F. suffruticosa was enhanced, compared with the salt-sensitive line, to ameliorate the repression of seed germination under salt stress. The different changes in respiratory metabolism could influence the degree of salt tolerance.

First Report of Leaf Blight Caused by Alternaria tenuissima on Senna nomame in China.

Senna nomame (Makino) T. C. Chen is an annual plant in the Fabaceae. This plant can be used in a tonic, as a diuretic, and for the prevention of obesity due to the presence of anthraquinones, flavonoids, and lipase inhibitors isolated from the aerial parts and seeds (Hatano et al. 1997). In June to September 2019, a severe foliar blight was observed on the leaves of 1-year-old S. nomame landrace plants in Qinglong (40.41°N, 118.95°E) in Qinhuangdao City, Hebei Province, China. The incidence of leaf blight was as high as 67% in the fields (n≥3). Symptoms began with small, brown spots at the margins and tips of leaves, with gray or yellowish-brown spots in the center of leaves. The spots gradually expanded to irregular large yellowish-brown lesions, and the leaves gradually withered. The pathogen was isolated from 20 leaves with typical symptoms from 10 individual plants. Leaf pieces (2 to 4 mm2) were excised from the junction of diseased and healthy tissues, disinfected in 75% ethanol for 15 s, rinsed in sterile distilled water, and placed on potato dextrose agar (PDA) plates. Colonies of 69% of the isolated fungi had round margins, and the olive-green fluffy aerial mycelia began to sporulate after 3 days at 28°C. On potato carrot agar (PCA), pure cultures formed yellowish brown mycelium with a light-colored, taupe-white center. Conidiophores were brown, simple or branched, and produced numerous conidia in short chains of three to six conidia. The conidia (n=50) were inverted pear-shaped or orbicular-ovate, light brown to brown, with a cylindrical short beak at the tip, and 19.9 to 30.4 µm (mean 25.4±3.6 µm) × 10.4 to 17.1 µm (mean 13.4±1.9 µm), with two to four transverse septa and zero to three longitudinal septa. The fungal isolates U-2, U-2-1, and U-2-2 were further characterized by sequencing of the rDNA ITS (MN712241, MZ781312, MZ781313), actin (ACT) (MN752246, MZ593671, MZ593672), calmodulin (CAL) (ON811636 to ON811638), ATPase (ON872785 to ON872787), and Alt a 1 (ON792172 to ON792174) genes using ITS1/ITS4, ACT-512F/ACT-738R, CALDF1/CALDR1, ATPDF1/ATPDR1, and Alt-for/Alt-rev primers for PCR amplification, respectively (Yang et al. 2009; Elfar et al. 2018). The sequences of the amplicons showed 99% to 100% identity with Alternaria tenuissima isolates: ITS (569/570 bp; MK560480 ), ACT (243/243 bp; MK593135), Alt a 1 (509/512 bp; MK593137), CAL (717/721 bp; MG925128), ATPase (1196/1197 bp; MG740623). Therefore, based on morphological characteristics and DNA sequence data, the isolates were identified as A. tenuissima. For pathogenicity tests, leaves on 10 healthy 1-year-old potted S. nomame plants were inoculated by wounding with a sterile needle and sprayed with a conidial suspension (2×105 spores/mL). Sterile water was used as the control. Inoculated plants were incubated in a greenhouse at 28°C with a 12 h photoperiod (75% to 80% relative humidity). The pathogenicity test was repeated three times. Lesions were observed on inoculated plants seven to nine days after inoculation, but no lesions were observed on control plants. A. tenuissima was successfully re-isolated from the symptomatic leaves and identified by morphology and sequencing of PCR amplicons. A. tenuissima has caused brown leaf spot on kiwifruit (Li et al. 2019) in China and pigeonpea (Sharma et al. 2012) in India. To our knowledge, this is the first report of A. tenuissima causing leaf blight on S. nomame in China. This new finding is essential in the diagnosis and management in field production.

Effects of nicosulfuron on plant growth and sugar metabolism in sweet maize (Zea mays L.).

The sulfonylurea herbicide nicosulfuron is efficient, harmless and selective at low doses and has been widely used in maize cultivation. In this study, a pair of corn sister lines, HK301 (nicosulfuron-tolerence, NT) and HK320 (nicosulfuron-sensitive, NS), was chosen to study the effect of nicosulfuron on plant growth and sugar metabolism in sweet maize (Zea mays L.) seedlings. All the experimental samples were subjected to treatment with water or 80 mg kg-1 of nicosulfuron when the sweet maize seedlings grew to the four-leaf stage. Nicosulfuron significantly inhibited the growth of NS line. The content of sucrose and the activities of sucrose phosphate synthase and sucrose synthase in the two inbred lines increased differentially under nicosulfuron stress compared with the respective control treatment. After nicosulfuron treatment, the activities of hexokinase and 6-phosphofructokinase and the contents of pyruvic acid and citric acid in NS line decreased significantly compared with those of NT line, while the content of sucrose and activities of sucrose phosphate synthase and sucrose synthase increased significantly. The disruption of sugar metabolism in NS line led to a lower supply of energy for growth. This study showed that the glycolysis pathway and the tricarboxylic acid cycle were enhanced in nicosulfuron-tolerant line under nicosulfuron stress in enhancing the adaptability of sweet maize.

Responses of photosynthesis, antioxidant enzymes, and related gene expression to nicosulfuron stress in sweet maize (Zea mays L.).

Weed control in maize (Zea mays L.) crops is usually undertaken using the postemergence herbicide nicosulfuron. The toxicity of nicosulfuron on maize, especially sweet maize, has been widely reported. In order to examine the effect of nicosulfuron on seedling photosynthetic characteristics, chlorophyll fluorescence, reactive oxygen species production, antioxidant enzyme activities, and gene expressions on sweet maize, nicosulfuron-tolerant "HK310" and nicosulfuron-sensitive "HK320" were studied. All experiment samples were subjected to a water or 80 mg kg-1 of nicosulfuron treatment when sweet maize seedlings grow to the stage of four leaves. After treatment with nicosulfuron, results for HK301 were significantly higher than those for HK320 for net photosynthetic rate, transpiration rate, stomatal conductance, leaf maximum photochemical efficiency of PSII, photochemical quenching of chlorophyll fluorescence, and the electron transport rate. These results were contrary to nonphotochemical quenching and intercellular CO2 concentration. As exposure time increased, associated effects also increased. Both O2·- and H2O2 detoxification is modulated by antioxidant enzymes. Compared to HK301, SOD, POD, and CAT activities of HK320 were significantly reduced as exposure time increase. Compared to HK320, the gene expression for the majority of SOD genes, except for SOD2, increased due to inducement by nicosulfuron, and it significantly upregulated the gene expression of CAT in HK301. Results from this study indicate that plants can improve photosynthesis, scavenging capabilities of ROS, and protective mechanisms to alleviate phytotoxic effect of nicosulfuron. Future research is needed to further elucidate the important role antioxidant systems and gene regulation play in herbicide detoxification in sweet maize.