Alfalfa species Medicago sativa L. (MS) and Medicago falcata L. (MF), globally prominent perennial leguminous forages, hold substantial economic value. However, our comprehension of the molecular mechanisms governing their resistance to cold stress remains limited. To address this knowledge gap, we scrutinized and compared MS and MF cold-stress responses at the molecular level following 24 h and 120 h low-temperature exposure (4 °C). Our study revealed that MF had superior physiological resilience to cold stress compared with MS, and its morphology was healthier under cold stress, and its malondialdehyde content and superoxide dismutase activity increased, first, and then decreased, while the soluble sugar content continued to accumulate. Transcriptome analysis showed that after 120 h of exposure, there were different gene-expression patterns between MS and MF, including 1274 and 2983 genes that were continuously up-regulated, respectively, and a total of 923 genes were included, including star cold-resistant genes such as ICE1 and SIP1. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed numerous inter-species differences in sustained cold-stress responses. Notably, MS-exclusive genes included a single transcription factor (TF) gene and several genes associated with a single DNA repair-related pathway, whereas MF-exclusive genes comprised nine TF genes and genes associated with 14 pathways. Both species exhibited high-level expression of genes encoding TFs belonging to AP2-EREBP, ARR-B, and bHLH TF families, indicating their potential roles in sustaining cold resistance in alfalfa-related species. These findings provide insights into the molecular mechanisms governing cold-stress responses in MS and MF, which could inform breeding programs aimed at enhancing cold-stress resistance in alfalfa cultivars.

This study aimed to determine the distribution, stability, and soil organic carbon (SOC) of aggregates, and the contribution of soil aggregate proportion, stability index, and aggregate-associated SOC to the total SOC. Three hundred and sixty soil samples were gathered from shelterbelts and neighboring farmlands in five layers of 1 m profiles in Songnen Plain, northeastern China. The shelterbelt plantations were found to increase by 69.5% and 103.8% in >2 mm and 0.25–2 mm soil aggregates, respectively, and their R_0.25, mean weight diameter (MWD), and geometric mean diameter (GMD) were enhanced by 96.3%, 33.2%, and 40.0%, respectively, compared to those of farmlands in soil layers at 0–20 cm depth (p < 0.05). The total SOC content increased by 13.3% at 0–20 cm soil depth, and the SOC content and stock in >2 mm aggregates increased by 21.5% and 18.7% in the 20–40 cm layer (p < 0.05), respectively. The SOC content and stock in total soil had a significantly positive relationship with the proportion of >2 mm soil aggregates and a negative relationship with the value of fractal dimension (D). The enhancement in the SOC of the total soil was dependent on the increase in aggregate-associated SOC, with larger-particle aggregates having a greater contribution. Based on the study results, afforestation improved soil stability and the structure of soil aggregates, and SOC accumulation in the total soil was not only governed by SOC concentration and stock within the aggregate size class, but also the proportion of >2 mm soil aggregates and the value of the fractal dimension.

Alfalfa (Medicago sativa L.), a perennial leguminous herb, exhibits robust cold and saline-alkali tolerance. In this study, two alfalfa cultivars, LJ and 218TR, were treated with saline-alkali stress, cold stress, and combined saline-alkali-cold stress , and p henotype, physiology , key metaboli te and stress-responsive genes were analyzed . The results showed m alondialdehyde, soluble sugar, proline content, and the activities of phenylalanine ammonia-lyase (PAL), superoxide dismutase, catalase, and peroxidase initially increased under individual stresses but declined after combined stress . T he maximum photochemical efficiency of photosystem II and chlorophyll content declined under individual and combined stresses. The staining of leaves revealed that combined stress induced significantly higher cell mortality and accumulation of superoxide anio n compared to individual stresses. LJ exhibited superior resistant to saline-alkali, cold, and combined stress compared to 218TR . Metabolite analysis showed salicylic acid (SA) in two alfalfa wa s the most responsive metabolite to combined stress. The isochorismate synthase (ICS) and PAL as critical genes for SA biosynthesis were up-regulated in expression under single or combined stress, and promote d SA accumulation , thereby improving alfalfa resilience to combined saline-alkali-cold stress. This study elucidates the physiological and molecular mechanisms underlying alfalfa’s response to combined saline-alkali and cold stress, providing a theoretical basis for breeding stress-tolerant cultivars.

Adzuki bean (Vigna angularis [Willd.] Ohwi & H. Ohashi) is a high-value legume crop widely cultivated globally, primarily in Asia, for its nutritional benefits and economic importance. In 2023, an epidemic outbreak of stem rot disease was observed in commercial adzuki bean fields in Shangzhi City, Heilongjiang Province, China. Through tissue isolation and fulfillment of Koch’s postulates, nine pathogenic fungal isolates were obtained from diseased stems. Morphological, molecular, and phylogenetic analyses identified Fusarium graminearum Schwabe and F. oxysporum f. sp. glycines as the causal agents, representing the first report of these fungi causing stem rot on adzuki bean in China. Pathogenicity testing of nine plant species (seven legumes and two cereals: corn and wheat) revealed that all tested crops commonly cultivated in Northeast China were susceptible to infection by F. graminearum and F. oxysporum. In vitro screening identified high sensitivity of F. graminearum to tebuconazole, with 80.0% mycelial growth inhibition at 4.3 × 10 ⁻⁴ g·ml ⁻¹ , and high sensitivity of F. oxysporum to ethylicin, with 82.7% inhibition at 8.0 × 10 ⁻⁴ g·ml ⁻¹ . This study provides a comprehensive characterization of the pathogens, defines their host range, and identifies tebuconazole and ethylicin as effective candidates for field control, offering management strategies to protect adzuki bean production in Heilongjiang Province.

Introduction: Ecological stoichiometry assessment provides insights into the dynamic interactions between the leaf–litter–humus–soil (LLHS) in different forest types. However, research on ecological stoichiometry in mixed and pure forest ecosystems is relatively weak in the karst region of southwestern China. Methods: We investigated how stand types influence the stoichiometric characteristics of carbon (C), nitrogen (N), and phosphorus (P) across the LLHS continuum. Leaf, litter, humus, and soil samples were collected from an evergreen coniferous forest ( Cryptomeria japonica var. sinensis Miquel ; CJ), a deciduous broadleaf forest ( Liquidambar formosana Hance; LF), and a mixed forest composed of both species ( C. japonica var. sinensis × L. formosana ; CJ × LF) in the fragile karst ecosystem of Southwest China. Results: The results showed that stand type had a significant effect on the concentrations of C, N, and P and on the stoichiometric ratios of all LLHS components. Compared with the two pure forests, litter in the mixed forest exhibited significantly higher C/N and C/P ratios, while N and P concentrations were significantly lower. In the broadleaf forest, leaf C/P and N/P ratios were significantly higher than those in the mixed forest and C. japonica monocultures, whereas leaf P concentrations were significantly lower than C. japonica monocultures. Compared with the mixed and broadleaf forests, humus C/N and C/P ratios showed significantly higher in the coniferous forest, while N and P concentrations and the N/P ratio were significantly lower. In the 0–20 cm soil layer, mixed forests had significantly higher C concentration, C/N ratio, and C/P ratio than the two pure forests ( p < 0.05). The P nutrient resorption efficiency of plant nutrients in the study area (40.07%–53.69%) was higher than that of N (10.43%–27.04%). Leaf C, N, P, C/N, N/P correlated positively with litter ( p < 0.01); leaf N, P, C/N, C/P correlated negatively with humus. Leaf N, C/N, C/P linked positively, leaf P negatively with soil ( p < 0.01). The explanatory power of litter, humus, and soil for leaf nutrient concentrations and stoichiometric ratios decreased in the order litter (50.8%) > humus (32.2%) > soil (1.8%). Discussion: Overall, these results indicate that the selection of stand type and dominant tree species is central to forest restoration and management in fragile karst ecosystems and plays a crucial role in maintaining the dynamic balance of C, N, and P in forest ecosystems.

Potentilla anserina L. is widely recognized for its extensive applications in traditional medicine and as a food source, harboring abundant bioactive compounds that confer significant medicinal and economic value. However, a severe disease consisting of leaf spots has adversely impacted P. anserina yield and quality in Heilongjiang Province, China. This study aims to identify the causal agent(s) of the disease, characterize the pathogen(s), and screen for effective control means. A total of 128 isolates were obtained from spotted leaves of P. anserina, with Alternaria tenuissima accounting for 68.7% and A. alternata for 32.3% of the isolates. These species were identified according to morpho-molecular characteristics and phylogenetic analyses. According to pathogenicity tests, A. alternata and A. tenuissima are both highly pathogenicity to P. anserina. In addition, all isolates were highly pathogenic to Astragalus laxmannii, Glycyrrhiza uralensis, and Trifolium pratense, moderately pathogenic to Artemisia argyi，and Beta vulgaris, and did not infect Mentha canadensis, Glycine max, Arachis hypogaea or Capsicum annuum. The isolates of A. alternata and A. tenuissima exhibited high sensitivity to benzoxystrobin and the biological control agent Paenibacillus polymyxa, with EC50 and IC50 values ranging from 0.09 to 0.57 µg/ml and 0.07 to 0.12 mg/ml, respectively. The efficacies varied between 96.1% and 97.5% at 480 μg/ml and between 95.1% and 97.1% at 240 mg/ml, respectively. According to this study, the pathogens responsible for P. anserina leaf spot in Heilongjiang, China, are A. tenuissima and A. alternata. Both showed high pathogenicity, but were effectively controlled by benzoxystrobin and Paenibacillus polymyxa, suggesting chemical treatments, intercropping and biocontrol as management strategies.