IntroductionIncreasing the research on the development and utilization of unconventional feed resources is one of the effective ways for the sustainable development of herbivorous animal husbandry. China is one of the countries most severely impacted by the invasion of the alien plant Solanum rostratum Dunal (S. rostratum), but this resource has not been used effectively.MethodsThe aim of this study was to investigate the effects of Lactobacillus plantarum and cellulase on the fermentation quality and microbial community in mixed silage of S. rostratum and alfalfa. Treatments were a control treatment with no additive (CK), Lactobacillus plantarum (LP), cellulase (CE), and Lactobacillus plantarum in combination with cellulase (L+C), all of which were stored at ambient temperature for 7, 15, 30, and 60 days.ResultsThe results showed that the mixture could retain dry matter (DM), crude protein (CP), and water soluble carbohydrates (WSC) content, increase lactic acid (LA) content, decrease pH and alkaloid content, and improve fermentation quality during silage. The use of additives increased the abundance of Lactobacillus and Weissella, which was related to the improvement of the quality of mixed silage and the degradation of total alkaloids. Differential microbial functions were mainly carbohydrate metabolism, biosynthesis of secondary metabolites and carbon metabolism.ConclusionThe application of additives and mixed silage provides a new idea for the feed utilization of S. rostratum.

Microbial activity in stored native grass hay may induce quality deterioration and alter flavor profiles, resulting in significant economic losses and forage safety risks. This study elucidated the association between microbial communities, nutritive qualities, and volatile components during native grass hay storage. High-throughput sequencing was conducted for determining the microbial composition of stored native grass hay. Headspace solid-phase microextraction-gas chromatography-mass spectrometry was performed for identifying volatile compounds in native grass hay. This study also assessed the correlation of volatile compounds with the hay microbiome. According to the obtained results, the water-soluble carbohydrate and crude protein content of native grass hay significantly decreased by 14.37% and 25.24%, respectively, after 360 days of storage (P < 0.01). From the 112 volatile compounds identified in native grass hay, hydrocarbons and alcohols were the major contributors to the volatile profile characteristics of native grass hay during storage, while ketones, heterocyclic compounds, and aromatic compounds were the minor constituents. Forty-nine potential spoilage markers were screened based on OPLS-DA and VIP values. The dominant fungi at the phylum level were Ascomycota and Basidiomycota. Alternaria and Kabatiella were the main fungal genera during the storage of native hay. Correlation analysis showed that 3 key volatile compounds (eucalyptol, geranyl acetone, and dihydroactinidiolide) exhibited a high association with quality loss and Aspergillus of native grass hay. The present findings could improve our knowledge about how storage affects microbial communities and volatile components in native grass hay.

Grassland which covers 40% of terrestrial land is an important ecosystem having a multitude of functions, which has suffered various degrees of degradation with the interaction between global climate change and unreasonable human utilization (e.g., grazing and reclamation). Improved understanding of soil and microbial community diversity during meadow steppe degradation is crucial for predicting degradation mechanisms and restoration strategies. Here, we used Illumina sequencing technology to investigate the patterns of soil microbial community structure and the driving factors of its change across different degradation degrees of meadow steppe [i.e., non-degraded grasslands (NDG), lightly degraded grasslands (LDG), moderately degraded grasslands (MDG), and severely degraded grasslands (SDG)] south of the Greater Khingan Mountains. Our results showed a significant variation in soil properties, enzyme activity, and soil metal elements across the degraded meadows. Soil available phosphorus (AP), urease (UE), and cellulase (CL) in soils increased with the intensity of grassland degradation. Grassland degradation significantly decreased soil bacterial and fungal richness. In addition, grassland degradation significantly increased the relative abundance of Firmicutes (from 1.65% to 5.38%) and Myxococcota (from 2.13% to 3.13%). Degradation considerably increased the relative abundance of Ascomycota (from 66.54% to 75.05%), but decreased Basidiomycota (from 18.33% to 9.92%). The relative abundance of nitrogen fixation and cellulolysis decreased significantly due to grassland degradation. For fungal functional guilds, the relative abundance of pathotrophs increased while saprotrophs decreased significantly with increasing severity of degradation. Total nitrogen (TP), AP, available potassium (AK), manganese (Mn), lead (Pb), UE, sucrase (SC), and alcalase protease (ALPT) were the main drivers of soil bacterial community composition, while TP, AP, AK, Pb, UE, and SC were the main drivers of soil fungal community composition in the degraded grassland. Our findings demonstrated that severe grassland degradation has an enormous effect on soil microbial communities and soil physicochemical dynamics. These findings improve our theoretical understanding of the interactions between soil microbial populations and soil environmental variables in degraded grassland.

根际土壤微生物群落对外来入侵植物形成反馈是其成功入侵的重要原因之一.采用单因素完全随机试验设计,以入侵植物长刺蒺藜草根际土壤、本土植物狗尾草根际土壤及无植物种植土壤为对象,通过高通量测序技术研究三者的土壤微生物群落结构组成及其差异,并探讨其入侵机制.结果表明,与本土植物狗尾草根际土壤微生物群落相比,入侵植物长刺蒺藜草根际土壤细菌群落的多样性降低,根际土壤真菌群落的多样性提高;入侵植物长刺蒺藜草根际土壤主要细菌门为变形菌门(Proteobacteria)和放线菌门(Actinobacteria);LEfSe多级物种差异分析表明,蓝细菌(Cyanobacteria)和Methylomirabilota是长刺蒺藜草根际土壤的优势细菌.FAPROTAX功能预测结果显示,入侵植物长刺蒺藜草根际土壤细菌在光合营养作用、光能自养作用、氧性光能自养、蓝细菌等方面的功能类群均有较高的丰度.变形菌门(Proteobacteria)、鞘脂单胞菌属(Sphingomonas)、蓝细菌(Cyanobacteria)和Methylomirabilota是驱动长刺蒺藜草成功入侵的优势细菌.

Smooth bromegrass (Bromus inermis Leyss.) is an excellent forage species widely distributed in Gansu, Qinghai, Inner Mongolia, and other provinces of China (Gong et al. 2019). In July 2021, typical leaf spot symptoms were observed on the leaves of smooth bromegrass plants in Ewenki Banner of Hulun Buir, China (49°5'8″N, 119°44'28″E, alt. 622.5 m). Approximately 90% of plants were affected, with symptoms apparent throughout the plant but mainly concentrated on the lower middle leaves. We collected 11 plants to identify the causal pathogen of leaf spot on smooth bromegrass. Samples (5×5 mm) of symptomatic leaves were excised and surface-sanitized with 75% ethanol for 3 min, rinsed three times with sterile distilled water, and incubated on water agar (WA) at 25℃ for three days. The lumps were cut along the edges and transplanted to potato dextrose agar (PDA) for subculture. After two purification cultures, ten strains, termed HE2 to HE11, were collected. The front side of the colony morphology was cottony or woolly, the center was greyish-green, circled with greyish-white color, with reddish pigmentation on the reverse. The conidia were globose or subglobose, yellow-brown or dark brown, with surface verrucae, and 23.89±3.76×20.28±3.23 μm (n = 50) in size. The morphological characteristics of the mycelia and conidia of the strains mtched those of Epicoccum nigrum (El-Sayed et al. 2020). The primers ITS1/ITS4 (White et al. 1991), LROR/LR7 (Rehner and Samuels 1994), 5F2/7cR (Sung et al. 2007), and TUB2Fd/TUB4Rd (Woudenberg et al. 2009) were used to amplify and sequence four phylogenic loci (ITS, LSU, RPB2 and β-tubulin), respectively. The sequences of ten strains have been deposited in GenBank, and the detailed accession numbers were shown in Table S1. BLAST analysis of these sequences showed 99-100%, 96-98%, 97-99% and 99-100% homology with the E. nigrum strain in the ITS, LSU, RPB2 and TUB sequenced regions, respectively. The sequences of ten test strains and other Epicoccum spp. strains obtained from GenBank were aligned by ClustalW by MEGA (version 11.0) software. After a series of alignment, cutting and splicing, the phylogenetic tree was constructed by the neighbor-joining method with 1000 bootstrap replicates based on the ITS, LSU, RPB2, and TUB sequences. The test strains were clustered together with E. nigrum, with branch support rate of 100%. Combined with morphological and molecular biological characteristics, ten strains were identified as E. nigrum. For the pathogenicity test, the seeds of smooth bromegrass were soaked for four days and then sown into six pots (10 cm diameter × 15 cm height) and kept in a greenhouse under a 16-h photoperiod with temperatures of 20-25°C and 60% relative humidity. Microconidia of the strain produced on wheat bran medium after 10 days were washed with sterile deionized water, filtered through three layers of sterile cheese cloth, quantified, and the concentration adjusted to 1 × 106 microconidia/ml with a hemocytometer. When the plants had grown to a height of about 20 cm, the leaves of plants in three pots were sprayed with the spore suspension, 10 mL per pot, while the remaining three pots were inoculated with sterile water and served as controls (LeBoldus and Jared 2010). The inoculated plants were cultured in an artificial climate box under a 16-h photoperiod with temperatures of 24°C and 60% relative humidity. Brown spots were apparent on the leaves of the treated plants after five days, whereas the leaves of the controls remained healthy. The same E. nigum strain were re-isolated from the inoculated plants and identified by the morphological and molecular techniques described above. To our knowledge, this is the first report of leaf spot disease caused by E. nigrum on smooth bromegrass in China, as well as in the world. Infection with this pathogen could reduce the yield and quality of smooth bromegrass production. For this reason, strategies for the management and control of this disease should be developed and implemented.

Lepidopteran insects mainly rely on sex pheromones to complete sexual communications. Pheromone receptors (PRs) are expressed on the olfactory receptor neurons (ORNs) of the sensilla trichodea and play an essential role in sexual communication. Despite extensive investigations into the mechanisms of peripheral recognition of sex pheromones in Lepidoptera, knowledge about these mechanisms in L. sticticalis remains limited. In this study, five candidate LstiPRs were analyzed in a phylogenetic tree with those of other Lepidopteran insects. Electroantennography (EAG) assays showed that the major sex pheromone component E11-14:OAc elicited a stronger antennal response than other compounds in male moths. Moreover, two types of neurons in sensilla trichodea were classified by single sensillum recordings, of which the “a” neuron specifically responded to E11-14:OAc. Five candidate PRs were functionally assayed by the heterologous expression system of Xenopus oocytes, and LstiPR2 responded to the major sex pheromone E11-14:OAc. Our findings suggest that LstiPR2 is a PR sensitive to L. sticticalis’s major sex pheromone compound, E11-14:OAc. Furthermore, this study offers valuable insights into the sexual communication behavior of L. sticticalis, forming a foundation for further analysis of the species’ central nervous system.

草地是我国生态系统的重要组成部分,更是我国畜牧业发展的重要物质基础.外来生物入侵迫使我国脆弱的草地生态系统雪上加霜,严重威胁生态安全、生物安全和畜牧业高质量发展.本文全面总结了我国草地外来入侵生物的物种组成、来源及其危害,系统分析了重要外来生物的入侵扩散机制和防控现状.根据文献统计,我国草地外来入侵生物共有176种,包括入侵植物145种,入侵动物25种,入侵微生物6种,它们主要来源于北美洲.大量外来生物入侵直接影响了草地物种多样性,破坏了草地生态系统的结构和功能,严重威胁人畜健康和社会经济可持续发展.草地外来生物成功入侵与其自身的生物学生态学特性、与本地种的相互作用和环境条件的可入侵性密切相关,虽然目前利用化学防治、生物防治和生态控制等技术可以进行有效防治,但防控的实效性、可持续性差,建议建立基于智能识别与监测预警,集成应急阻截和持续减灾等关键技术的系统解决方案,实现外来入侵物种早发现、早治理,为快速抑制扩散蔓延和区域持续减灾提供科技支撑.