Genome-wide identification and characterization of NAC transcription factor family members in Trifolium pratense and expression analysis under lead stress.

BACKGROUND: The NAC TF family is widely involved in plant responses to various types of stress. Red clover (Trifolium pratense) is a high-quality legume, and the study of NAC genes in red clover has not been comprehensive. The aim of this study was to analyze the NAC gene family of red clover at the whole-genome level and explore its potential role in the Pb stress response. RESULTS: In this study, 72 TpNAC genes were identified from red clover; collinearity analysis showed that there were 5 pairs of large fragment replicators of TpNAC genes, and red clover was found to be closely related to Medicago truncatula. Interestingly, the TpNAC genes have more homologs in Arabidopsis thaliana than in soybean (Glycine max). There are many elements in the TpNAC genes promoters that respond to stress. Gene expression analysis showed that all the TpNAC genes responded to Pb stress. qRT-PCR showed that the expression levels of TpNAC29 and TpNAC42 were significantly decreased after Pb stress. Protein interaction network analysis showed that 21 TpNACs and 23 other genes participated in the interaction. In addition, the TpNAC proteins had three possible 3D structures, and the secondary structure of these proteins were mainly of other types. These results indicated that most TpNAC members were involved in the regulation of Pb stress in red clover. CONCLUSION: These results suggest that most TpNAC members are involved in the regulation of Pb stress in red clover. TpNAC members play an important role in the response of red clover to Pb stress.

First Report of Anthracnose Leaf Spot Caused by Colletotrichum americae-borealis on Potentilla anserina in China.

Potentilla anserina L. has an abundance of bioactive compounds and is widely recognized for its diverse applications in traditional medicine and as a food. In August 2023, typical symptoms of anthracnose were observed in 80% of P. anserina plants in Harbin, China. Symptoms, characterized by reddish-brown spots, tend to occur more frequently on leaves closer to the ground. They initially appeared as oval or irregular circles, measuring 1 to 3 mm in diameter, and later merged into larger patches surrounded by chlorotic areas on the leaves. Twenty leaves exhibiting characteristic symptoms were sampled. Each leaf was sectioned into 5×5 mm pieces at the interface between the diseased and healthy tissues. The sections were disinfected sequentially with 75% ethanol for 30 s, followed by 1% NaClO for 2 min, rinsed three times in sterilized distilled water. Post air-drying, samples were cultured on potato dextrose agar (PDA) plates and incubated at 26°C in the dark for 5 d, yielding nine morphologically similar single-spore isolates (JTC1 to JTC9). The colonies initially displayed gray aerial mycelia, becoming pale brown, accompanied by numerous black microsclerotia. The acervuli appeared black, protruded from the surface of the medium, and were adorned with dark brown setae. Setae (n=50) ranged from 58.4 to 188.2 µm in length, appearing dark brown to black, with smooth walls, rounded tips, swollen bases, and containing 1 to 4 septa. The conidia were hyaline, aseptate, cylindrical to spindle-shaped, with blunt and rounded ends, measuring 13.7 to 18.3 µm in length and 3.4 to 4.3 µm in width (n=50). Morphological analysis indicated a close affinity with Colletotrichum americae-borealis (Damm et al. 2014). For molecular identification, genomic DNA was extracted from three representative isolates (JTC1, JTC2, and JTC3).The ITS, HIS3，GAPDH, and ACT genes were amplified and sequenced using the primers described previously by Damm et al. (2014). The sequences were submitted to GenBank (ITS: PP338190 to PP338192; HIS3: PP355770 to PP355772; GAPDH: PP355773 to PP355775; ACT: PP355776 to PP355778). BLAST analysis showed 99 to 100% identity with C. americae-borealis type strain CBS 136232 (GenBank accessions: KM105224, KM105364, KM105579, and, KM105434, respectively). Multigene phylogenetic analysis positioned the three isolates close to C. americae-borealis. Pathogenicity tests were performed twice on 6-week-old P. anserina seedlings (cv. Qinghai Juema 1) in a greenhouse. A conidial suspension of the JTC1 isolate (1×105 conidia/ml) was sprayed applied to ten pots, each containing two seedlings, and the plants in the control pots were sprayed with sterile distilled water. Two weeks after inoculation under greenhouse conditions (26/22°C day/night temperature, 12-hour photoperiod, 90% relative humidity), the inoculated seedlings exhibited brown spots and necrotic lesions similar to those observed in the field, C. americae-borealis was successfully reisolated from these symptomatic tissues. To the best of our knowledge, this is the first report of C. americae-borealis causing leaf spot on P. anserina in China. Anthracnose caused by C. americae-borealis is associated with leaf spot disease in oats (Wang et al. 2022), alfalfa (Li et al. 2021), and licorice (Lyu et al.2020). However, C. americae-borealis poses a significant threat to P. anserina in China as well, highlighting the urgent need to develop effective disease management strategies.

The Multiple Promoting Effects of Suaeda glauca Root Exudates on the Growth of Alfalfa under NaCl Stress.

Under abiotic stress, plant root exudates can improve plant growth performance. However, studies on the effect of root exudates on the stress resistance of another plant are insufficient. In this study, root exudates (REs) were extracted from Suaeda glauca to explore their effect on alfalfa seedlings under salt stress. The results showed that the plant height and fresh weight of alfalfa significantly increased by 47.72% and 53.39% after 7 days of RE treatment at a 0.4% NaCl concentration. Under 1.2% salt stress, REs reduced the Malondialdehyde content in alfalfa by 30.14% and increased the activity of its antioxidant enzymes (peroxidase and catalase) and the content of its osmotic regulators (soluble sugar and proline) by 60.68%, 52%, 45.67%, and 38.67%, respectively. Soil enzyme activity and the abundance of soil-beneficial bacteria were increased by REs. Spearman analysis showed that urease and neutral phosphatase were related to the richness of beneficial bacteria. Redundancy analysis confirmed that urease affected the composition of the soil bacterial community. The partial least squares structural equation model (PLS-SEM) revealed that REs had a direct positive effect on alfalfa growth under salt stress by regulating the plant's injury and antioxidant systems, and the soil bacterial community had an indirect positive effect on alfalfa growth through soil enzyme activity.

Effects of the fermentation quality and microbial community of waxy maize mixed with fodder soybean silage.

Waxy maize (Zea mays L. sinensis Kulesh) is highly regarded for its high nutritional content and unique taste. Although the stalks and leaves contain high carbohydrate levels after ear harvesting, inadequate crude protein (CP) limits the utilization and promotion of waxy maize silage in animal husbandry. In this study, waxy maize and fodder soybeans were mixed for sowing in different proportions [1:0 (CK), 1:1 (A1), 1:2 (A2), 1:3 (A3), and 1:4 (A4)] to investigate the effects of different mixing ratios on the growth of the waxy maize, the chemical indices, fermentation quality, and the microbial community of the mixed silage after ear harvesting. The mixed planting of waxy maize and fodder soybeans in different proportions had no effect on the yield and quality of the waxy maize ears and increased the aboveground biomass after ear harvesting. After ear harvesting, the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents significantly decreased, and the CP content and relative feeding value (RFV) gradually increased in the mixed silage. The pH of the treatments was lower than 4.2 except for A4, and the lowest ammonia nitrogen (AN) concentration was observed in A3. With increasing proportions of fodder soybeans, the abundance of beneficial bacteria increased and that of harmful bacteria decreased; Firmicutes and Lactobacillus were the dominant phylum and genus, respectively, and both increased gradually. Redundancy analysis (RDA) revealed that the fermentation indices affecting the microbial community composition in the silage were inconsistent among the different mixed sowing combinations. The Mantel test showed that the composition of the microbial communities in the treatments was significantly correlated with the ADF, water-soluble carbohydrate (WSC), and propionic acid (PA) contents. Comprehensive analysis revealed that the optimal mixed sowing ratio of waxy maize to fodder soybeans was 1:3, and waxy maize and fodder soybeans silage can increase the utilization of aboveground biomass and improve the fermentation quality and feeding quality of silage by changing the microbial community. These findings lay a certain theoretical foundation for improving the utilization of waxy maize.

Mechanism of action, benefits, and research gap in fermented soybean meal utilization as a high-quality protein source for livestock and poultry.

Animal nutritionists have incessantly worked towards providing livestock with high-quality plant protein feed resources. Soybean meal (SBM) has been an essential and predominantly adopted vegetable protein source in livestock feeding for a long time; however, several SBM antinutrients could potentially impair the animal's performance and growth, limiting its use. Several processing methods have been employed to remove SBM antinutrients, including fermentation with fungal or bacterial microorganisms. According to the literature, fermentation, a traditional food processing method, could improve SBM's nutritional and functional properties, making it more suitable and beneficial to livestock. The current interest in health-promoting functional feed, which can enhance the growth of animals, improve their immune system, and promote physiological benefits more than conventional feed, coupled with the ban on the use of antimicrobial growth promoters, has caused a renewed interest in the use of fermented SBM (FSBM) in livestock diets. This review details the mechanism of SBM fermentation and its impacts on animal health and discusses the recent trend in the application and emerging advantages to livestock while shedding light on the research gap that needs to be critically addressed in future studies. FSBM appears to be a multifunctional high-quality plant protein source for animals. Besides removing soybean antinutrients, beneficial bioactive peptides and digestive enzymes are produced during fermentation, providing probiotics, antioxidants, and immunomodulatory effects. Critical aspects regarding FSBM feeding to animals remain uncharted, such as the duration of fermentation, the influence of feeding on digestive tissue development, choice of microbial strain, and possible environmental impact.