Co-infection by Soil-Borne Fungal Pathogens Alters Disease Responses Among Diverse Alfalfa Varieties

Characterization and Pathogenicity of Soilborne Pathogens in Gloriosa superba: Effects of Single- and Multiple-Pathogen Coinfection on Disease Responses

Glory lily (Gloriosa superba), an ornamental climbing plant, contains the bioactive compound colchicine, attracting attention from the pharmaceutical industry. However, soilborne pathogens have emerged as a serious threat to the cultivation of glory lily, leading to substantial economic losses in the southern parts of India. Among these, the three major pathogens are Macrophomina phaseolina, Fusarium oxysporum, and Agroathelia rolfsii, causing dry root rot (also referred to as charcoal rot), wilt, and stem rot, respectively. Here, we characterized these pathogens using morphological characteristics and phylogenetic analysis of DNA sequences related to the internal transcribed spacer of ribosomal DNA, calmodulin (CAL), and translation elongation factor 1-alpha (TEF-1α). Furthermore, in the pathogenicity tests, the inoculation of M. phaseolina alone resulted in lesions measuring 7.54 ± 0.01 mm on tubers and 90% seedling mortality. This severity was comparable to the simultaneous inoculation of all three pathogens, indicating the prominence of dry root rot among soilborne diseases. This study marks the first detailed investigation of soilborne pathogens combined infection in G. superba, contributing to the understanding of fungal disease complexity in medicinal plants.

Evaluation of antifungal potentials of Albizia kalkora extract as a natural fungicide: In vitro and computational studies

The antifungal bioactivity potential of the organic extract of silk tree (Albizia kalkora) was investigated in the current study. The crude extracts of A. kalkora and methanol, n-hexane, chloroform, and ethyl acetate fractions were prepared. The antifungal activity of obtained fractions of A. kalkora was studied at different concentrations ranging from 0.39-50 µg/mL. Dimethyl sulfoxide (DMSO) was taken as a toxicity control, whereas thiophanate methyl (TM) as a positive control. All the fractions significantly reduced the FOL growth (methanolic: 9.49-94.93 %, n-hexane: 11.12-100 %, chloroform: 20.96-91.41 %, and ethyl acetate: 18.75-96.70 %). The n-hexane fraction showed 6.25 µg/mL MIC as compared to TM with 64 µg/mL MIC. The non-polar (n-hexane) fraction showed maximum antifungal bioactivity against FOL in comparison with chloroform, methanol, and ethyl acetate fractions. GC/MS analysis exhibited that the n-hexane fraction contained hexadecanoic acid, 9,12,15-octadecatrienoic acid, 9,12-octadecadienoic acid, bis(2-ethylhexyl) phthalate, methyl stearate, and [1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid. The results of in vitro antifungal inhibition were further reinforced by molecular docking analysis. Five virulence proteins of FOL i.e., pH-responsive PacC transcription factor (PACC), MeaB, TOR; target of rapamycin (FMK1), Signal transducing MAP kinase kinase (STE-STE7), and High Osmolarity Glycerol 1(HOG1) were docked with identified phytocompounds in the n-hexane fraction by GC/MS analysis. MEAB showed maximum binding affinities with zinnimide (-12.03 kcal/mol), HOG1 and FMK1with α-Tocospiro-B (-11.51 kcal/mol) and (-10.55 kcal/mol) respectively, STE-STE7 with docosanoic acid (-11.31 kcal/mol), and PACC with heptadecanoic acid (-9.88 kcal/mol) respectively with strong hydrophobic or hydrophilic interactions with active pocket residues. In conclusion, the n-hexane fraction of the A. kalkora can be used to manage FOL.

Development of a Multiplex PCR Assay for the Detection of Tomato Wilt Caused by Coinfection of Fusarium brachygibbosum, Fusarium oxysporum, and Ralstonia solanacearum Based on Comparative Genomics

Tomato is consumed worldwide as fresh or processed food products. However, soilborne diseases of tomato plants caused by coinfection of various pathogens result in great economic losses to the tomato industry. It is difficult to accurately identify and diagnose soilborne diseases of tomato plants caused by pathogen complexes. In this study, we investigated field diseases of tomato plants by pathogen isolation and molecular identification and found that tomato wilt was caused by coinfection of Fusarium brachygibbosum, F. oxysporum, and Ralstonia solanacearum. Therefore, developing a method for simultaneous detection of DNA from F. brachygibbosum, F. oxysporum, and R. solanacearum is of great importance to efficiently and accurately monitor disease development at different growth stages of tomato plants. In this study, we performed a comparative genomic analysis of F. brachygibbosum, F. oxysporum, and R. solanacearum and determined the primer sets for simultaneous detection of DNA from these target pathogens. Then, we tested the reagent and condition parameters of multiplex PCR, including primers, dNTP and Mg2+ concentrations, and annealing temperatures, to determine the optimal parameters of a multiplex PCR system. We evaluated the specificity, sensitivity, and stability of the multiplex PCR system based on the optimized reaction conditions. The multiplex PCR system can specifically identify 13 target pathogens from 57 different fungal and bacterial pathogens, at the lower detection limit of the three target pathogens at concentrations of 100 pg/μl. In addition, we can accurately identify the three pathogens in tomato plants using the optimized multiplex PCR method. These results demonstrated that the multiplex PCR method developed in this study can simultaneously detect DNA from F. brachygibbosum, F. oxysporum, and R. solanacearum in a single PCR system to accurately identify and diagnose the pathogen causing tomato wilt.

Endophytic Streptomyces sp. NEAU-DD186 from Moss with Broad-Spectrum Antimicrobial Activity: Biocontrol Potential Against Soilborne Diseases and Bioactive Components

Soilborne diseases cause significant economic losses in agricultural production around the world. They are difficult to control because a host plant is invaded by multiple pathogens, and chemical control often does not work well. In this study, we isolated and identified an endophytic Streptomyces sp. NEAU-DD186 from moss, which showed broad-spectrum antifungal activity against 17 soilborne phytopathogenic fungi, with Bipolaris sorokiniana being the most prominent. The strain also exhibited strong antibacterial activity against soilborne phytopathogenic bacteria Ralstonia solanacearum. To evaluate its biocontrol potential, the strain was prepared into biofertilizer by solid-state fermentation. Response surface methodology was employed to optimize the fermentation conditions for maximizing spore production and revealed that the 1:1 ratio of vermicompost to wheat bran, a temperature of 28°C, and 50% water content with an inoculation amount of 15% represented the optimal parameters. Pot experiments showed that the application of biofertilizer with a spore concentration of 108 CFU/g soil could effectively suppress the occurrence of tomato bacterial wilt caused by R. solanacearum and wheat root rot caused by B. sorokiniana, and the biocontrol efficacy was 81.2 and 72.2%, respectively. Chemical analysis of strain NEAU-DD186 extracts using nuclear magnetic resonance spectrometry and mass analysis indicated that 25-O-malonylguanidylfungin A and 23-O-malonylguanidylfungin A were the main active constituents, which showed high activity against R. solanacearum (EC50 of 2.46 and 2.58 µg ml-1) and B. sorokiniana (EC50 of 3.92 and 3.95 µg ml-1). In conclusion, this study demonstrates that Streptomyces sp. NEAU-DD186 can be developed as biofertilizer to control soilborne diseases.

Phyllosphere microbial diversity and specific taxa mediate within-cultivar resistance to Phytophthora palmivora in cacao

The oomycete pathogen Phytophthora palmivora, which causes black pod rot (BPR) on cacao (Theobroma cacao L.), is responsible for devastating yield losses worldwide. Genetic variation in resistance to Phytophthora spp. is well documented among cacao cultivars, but variation has also been observed in the incidence of BPR even among trees of the same cultivar. In light of evidence that the naturally occurring phyllosphere microbiome can influence foliar disease resistance in other host-pathogen systems, it was hypothesized that differences in the phyllosphere microbiome between two field accessions of the cultivar Gainesville II 164 could be responsible for their contrasting resistance to P. palmivora. Bacterial alpha diversity was higher but fungal alpha diversity was lower in the more resistant accession MITC-331, and the accessions harbored phyllosphere microbiomes with distinct community compositions. Six bacterial and 82 fungal amplicon sequence variants (ASVs) differed in relative abundance between MITC-333 and MITC-331, including bacterial putative biocontrol agents and a high proportion of fungal pathogens, and nine fungal ASVs were correlated with increased lesion development. The roles of contrasting light availability and host mineral nutrition, particularly potassium, are also discussed. Results of this preliminary study can be used to guide research into microbiome-informed integrated pest management strategies effective against Phytophthora spp. in cacao. IMPORTANCE Up to 40% of the world's cacao is lost each year to diseases, the most devastating of which is black pod rot, caused by Phytophthora palmivora. Though disease resistance is often attributed to cacao genotypes (i.e., disease-resistant rootstocks), this study highlights the role of the microbiome in contributing to differences in resistance even among accessions of the same cacao cultivar. Future studies of plant-pathogen interactions may need to account for variation in the host microbiome, and optimizing the cacao phyllosphere microbiome could be a promising new direction for P. palmivora resistance research.

Endophytic Streptomyces sp. NEAU-ZSY13 from the leaf of Perilla frutescens, as a promising broad-spectrum biocontrol agent against soil-borne diseases

Soil-borne diseases cause significant economic losses in global agricultural production. These diseases are challenging to control due to the invasion of multiple pathogens into host plants, and traditional chemical control methods often yield unsatisfactory results. In this study, we isolated and identified an endophytic Streptomyces, designated as NEAU-ZSY13, from the leaf of Perilla frutescens. This isolate exhibited broad-spectrum antifungal activity against 17 soil-borne phytopathogenic fungi, with Bipolaris sorokiniana being the most prominent. Additionally, it displayed strong antibacterial activity against the soil-borne phytopathogenic bacterium Ralstonia solanacearum. To assess its biocontrol potential, the isolate was utilized to produce a biofertilizer through solid-state fermentation. The fermentation conditions were optimized using response surface methodology to maximize the spore production. The results revealed that more abundant spores were produced with a 1:2 ratio of vermicompost to wheat bran, 60% water content, 20% inoculation amount and 28°C. Subsequent pot experiments demonstrated that the application of the biofertilizer with a spore concentration of 108 CFU/g soil effectively suppressed the occurrence of tomato bacterial wilt caused by R. solanacearum and wheat root rot caused by B. sorokiniana, with biocontrol efficacies of 72.2 and 78.3%, respectively. Chemical analysis of NEAU-ZSY13 extracts, using nuclear magnetic resonance spectrometry and mass analysis, identified niphimycin C and niphimycin A as the primary active constituents. These compounds exhibited high activity against R. solanacearum (EC50 of 3.6 and 2.4 μg mL-1) and B. sorokiniana (EC50 of 3.9 and 3.4 μg mL-1). In conclusion, this study demonstrates the potential of Streptomyces sp. NEAU-ZSY13 as a biofertilizer for the control of soil-borne diseases.

Impact of Fusarium Infection on Potato Quality, Starch Digestibility, In Vitro Glycemic Response, and Resistant Starch Content

Potato dry rot disease caused by multiple Fusarium species is a major global concern in potato production. In this investigation, the tubers of cultivars Kufri Jyoti and Kufri Frysona were artificially inoculated with an individual or combined inoculum of Fusarium sambucinum and Fusarium solani. Fusarium sambucinum caused a significantly higher lesion development (p < 0.01) than Fusarium solani, irrespective of cultivars. The combined inoculum of both the Fusarium species caused significantly higher rot development (p < 0.005) in inoculated tubers. Analyses of starch and amylose content revealed that individual or mixed infection of fungi caused a significant reduction (p < 0.005) in these parameters compared to healthy tubers. The increased starch digestibility due to fungal infection caused a higher glycemic index and glycemic load. The resistant starch also deteriorated in the infected potato tubers as compared to the control. Kufri Jyoti showed a higher starch and amylose content reduction in response to the treatments compared to Kufri Frysona. The correlation analysis demonstrated a negative correlation in lesion diameter and rot volume with starch and amylose content (p < -0.80). However, the glycemic index and resistant starch were positively correlated with lesion development. Altogether, these findings highlight the progressive deterioration of quality parameters, which will be a critical concern for processing industry stakeholders and consumers.

Surfactin and Spo0A-Dependent Antagonism by Bacillus subtilis Strain UD1022 against Medicago sativa Phytopathogens

Plant growth-promoting rhizobacteria (PGPR) such as the root colonizers Bacillus spp. may be ideal alternatives to chemical crop treatments. This work sought to extend the application of the broadly active PGPR UD1022 to Medicago sativa (alfalfa). Alfalfa is susceptible to many phytopathogens resulting in losses of crop yield and nutrient value. UD1022 was cocultured with four alfalfa pathogen strains to test antagonism. We found UD1022 to be directly antagonistic toward Collectotrichum trifolii, Ascochyta medicaginicola (formerly Phoma medicaginis), and Phytophthora medicaginis, and not toward Fusarium oxysporum f. sp. medicaginis. Using mutant UD1022 strains lacking genes in the nonribosomal peptide (NRP) and biofilm pathways, we tested antagonism against A. medicaginicola StC 306-5 and P. medicaginis A2A1. The NRP surfactin may have a role in the antagonism toward the ascomycete StC 306-5. Antagonism toward A2A1 may be influenced by B. subtilis biofilm pathway components. The B. subtilis central regulator of both surfactin and biofilm pathways Spo0A was required for the antagonism of both phytopathogens. The results of this study indicate that the PGPR UD1022 would be a good candidate for further investigations into its antagonistic activities against C. trifolii, A. medicaginicola, and P. medicaginis in plant and field studies.

Effects of a Microbial Restoration Substrate on Plant Growth and Rhizosphere Microbial Community in a Continuous Cropping Poplar

In poplar cultivation, continuous cropping obstacles affect wood yield and soil-borne diseases, primarily due to structural changes in microbes and fungus infection. The bacterium Bacillus cereus BJS-1-3 has strong antagonistic properties against pathogens that were isolated from the rhizosphere soil of poplars. Poplar rhizospheres were investigated for the effects of Bacillus cereus BJS-1-3 on microbial communities. Three successive generations of soil were used to replant poplar seedlings. BJS-1-3 inoculated poplars were larger, had higher plant height and breast height diameter, and had a greater number of total and culturable bacteria than non-inoculated controls. B. cereus BJS-1-3 inoculated poplar rhizospheres were sequenced, utilizing the Illumina MiSeq platform to analyze changes in diversity and structure. The fungi abundance and diversity in the BJS-1-3 rhizosphere were significantly lower than in the control rhizosphere. In comparison to the control group, Bacillus sp. constituted 2.87% and 2.38% of the total bacterial community, while Rhizoctonia sp. constituted 2.06% and 6.00% of the total fungal community. Among the potential benefits of B. cereus BJS-1-3 in poplar cultivation is that it enhances rhizosphere microbial community structure and facilitates the growth of trees.

Divergent Outcomes of Direct Conspecific Pathogen Strain Interaction and Plant Co-Infection Suggest Consequences for Disease Dynamics

Plant diseases are often caused by co-infections of multiple pathogens with the potential to aggravate disease severity. In genetically diverse pathogen species, co-infections can also be caused by multiple strains of the same species. However, the outcome of such mixed infections by different conspecific genotypes is poorly understood. The interaction among pathogen strains with complex lifestyles outside and inside of the host are likely shaped by diverse traits, including metabolic capacity and the ability to overcome host immune responses. To disentangle competitive outcomes among pathogen strains, we investigated the fungal wheat pathogen Zymoseptoria tritici. The pathogen infects wheat leaves in complex strain assemblies, and highly diverse populations persist between growing seasons. We investigated a set of 14 genetically different strains collected from the same field to assess both competitive outcomes under culture conditions and on the host. Growth kinetics of cocultured strains (~100 pairs) significantly deviated from single strain expectations, indicating competitive exclusion depending on the strain genotype. We found similarly complex outcomes of lesion development on plant leaves following co-infections by the same pairs of strains. While some pairings suppressed overall damage to the host, other combinations exceeded expectations of lesion development based on single strain outcomes. Strain competition outcomes in the absence of the host were poor predictors of outcomes on the host, suggesting that the interaction with the plant immune system adds significant complexity. Intraspecific co-infection dynamics likely make important contributions to disease outcomes in the wild. IMPORTANCE Plants are often attacked by a multitude of pathogens simultaneously, and different species can facilitate or constrain the colonization by others. To what extent simultaneous colonization by different strains of the same species matters, remains unclear. We focused on intra-specific interactions between strains of the major fungal wheat pathogen Zymoseptoria tritici. The pathogen persists in the environment before infecting plant leaves early in the growing season. Leaves are typically colonized by a multitude of strains. Strains cultured in pairs without host were growing differently compared to strains cultured alone. Wheat leaves infected either with single or pairs of strains, we found also highly variable outcomes. Interactions between strains outside of the host were only poorly explaining how strains would interact when on the host, suggesting that pathogen strains engage in complex interactions dependent on the environment. Better understanding within-species interactions will improve our ability to manage crop infections.

Screening of Alfalfa Varieties Resistant to Phytophthora cactorum and Related Resistance Mechanism

Alfalfa is one of the most important legume forages in the world. Root rot caused by soil-borne pathogens severely restricts the production of alfalfa. The knowledge of the interaction between alfalfa and root rot-pathogens is still lacking in China. Phytophthora cactorum was isolated from symptomatic seedlings of an alfalfa field in Nanjing with high levels of damping-off. We observed the different infection stages of P. cactorum on alfalfa, and found that the purified P. cactorum strain was aggressive in causing alfalfa seed and root rot. The infecting hyphae penetrated the epidermal cells and wrapped around the alfalfa roots within 48 h. By evaluating the resistance of 37 alfalfa cultivars from different countries to P. cactorum, we found Weston is a resistant variety, while Longdong is a susceptible variety. We further compared the activities of various enzymes in the plant antioxidant enzyme system between Weston and Longdong during P. cactorum infection, as well as gene expression associated with plant hormone biosynthesis and response pathways. The results showed that the disease-resistant variety Weston has stronger antioxidant enzyme activity and high levels of SA-responsive PR genes, when compared to the susceptible variety Longdong. These findings highlighted the process of interaction between P. cactorum and alfalfa, as well as the mechanism of alfalfa resistance to P. cactorum, which provides an important foundation for breeding resistant alfalfa varieties, as well as managing Phytophthora-caused alfalfa root rot.

Root rot a silent alfalfa killer in China: Distribution, fungal, and oomycete pathogens, impact of climatic factors and its management

Alfalfa plays a significant role in the pasture ecosystems of China's north, northeast, and northwest regions. It is an excellent forage for livestock, improves soil structure, prevents soil erosion, and has ecological benefits. Presently root rot is a significant threat to the alfalfa productivity because of the survival of the pathogens as soil-borne and because of lack of microbial competition in the impoverished nutrient-deficient soils and resistant cultivars. Furthermore, these regions' extreme ecological and environmental conditions predispose alfalfa to root rot. Moisture and temperature, in particular, have a considerable impact on the severity of root rot. Pathogens such as Fusarium spp. and Rhizoctonia solani are predominant, frequently isolated, and of major concern. These pathogens work together as disease complexes, so finding a host genotype resistant to disease complexes is challenging. Approaches to root rot control in these regions include mostly fungicides treatments and cultural practices and very few reports on the usage of biological control agents. As seed treatment, fungicides such as carbendazim are frequently used to combat root rot; however, resistance to fungicides has arisen. However, breeding and transgenic approaches could be more efficient and sustainable long-term control strategies, especially if resistance to disease complexes may be identified. Yet, research in China is mainly limited to field investigation of root rot and disease resistance evaluation. In this review, we describe climatic conditions of pastoral regions and the role of alfalfa therein and challenges of root rot, the distribution of root rot in the world and China, and the impact of root rot pathogens on alfalfa in particular R. solani and Fusarium spp., effects of environmental factors on root rot and summarize to date disease management approach.

Research Progress and Prospect of Alfalfa Resistance to Pathogens and Pests

Alfalfa is one of the most important legume forages in the world and contributes greatly to the improvement of ecosystems, nutrition, and food security. Diseases caused by pathogens and pests severely restrict the production of alfalfa. Breeding resistant varieties is the most economical and effective strategy for the control of alfalfa diseases and pests, and the key to breeding resistant varieties is to identify important resistance genes. Plant innate immunity is the theoretical basis for identifying resistant genes and breeding resistant varieties. In recent years, the framework of plant immunity theory has been gradually formed and improved, and considerable progress has been made in the identification of alfalfa resistance genes and the revelation of the related mechanisms. In this review, we summarize the basic theory of plant immunity and identify alfalfa resistance genes to different pathogens and insects and resistance mechanisms. The current situation, problems, and future prospects of alfalfa resistance research are also discussed. Breeding resistant cultivars with effective resistance genes, together with other novel plant protection technologies, will greatly improve alfalfa production.

Co-infection of Fusarium aglaonematis sp. nov. and Fusarium elaeidis Causing Stem Rot in Aglaonema modestum in China

Aglaonema modestum (A. modestum) (Araceae) is an evergreen herbage, which is intensively grown as an ornamental plant in South China. A new disease was observed in A. modestum from 2020 to 2021 in Guangdong province, China. The disease symptoms associated with plants were initial leaf wilt, stem rot, and resulting plant death, leading to severe economic losses. In total, six Fusarium isolates were obtained from diseased plants. The putative pathogen was identified using both morphological characteristics and molecular phylogenetic analysis of calmodulin A (cmdA), RNA polymerase largest subunit 1 (rpb1), RNA polymerase II (rpb2), translation elongation factor-1α (tef1-α), and beta-tubulin (β-tubulin) sequences. Two Fusarium species were identified, namely, one new species, Fusarium aglaonematis (F. aglaonematis) belonging to Fusarium fujikuroi species complex. In addition, Fusarium elaeidis (F. elaeidis) belonging to the Fusarium oxysporum (F. oxysporum) species complex was also identified. Pathogenicity assays were conducted by inoculating each species into potted A. modestum plants and co-inoculating two species. The results showed that two Fusarium species could infect plants independently and can infect them together. Co-infection of these two species enhanced the disease severity of A. modestum. Compared to single inoculation of F. elaeidis, severity was higher and disease development was quicker when plants were only inoculated with F. aglaonematis. In addition, these two Fusarium species could infect Aglaonema plants without wounds, while inoculation with a physical injury increased disease severity. This is the first report of co-infection by F. aglaonematis and F. elaeidis causing stem rot on A. modestum worldwide. This study will be an addition to the knowledge of Fusarium diseases in ornamental plants. These results will provide a baseline to identify and control diseases associated with A. modestum.

First report of Alfalfa root rot caused by Fusarium commune in China

Alfalfa (Medicago sativa) is the most important perennial forage legume worldwide, with high yields and nutrient quality. Diseases are significant threats to alfalfa and cause substantial yield losses (Fang et al. 2021). In March 2022, a disease with symptoms similar to fusarium wilt was observed in an alfalfa (cultivar Aurora) field in Baima teaching and research base (119°18'07″E, 31°61'47″N) in Nanjing, China. Reddish-brown discoloration of the roots, stele, basal stems and the withering symptoms on the aerial portions are the specific symptoms of fusarium wilt. The disease incidence varied from 3 to 6% in around 0.3 hectares of alfalfa fields surveyed. Fresh tissues from symptomatic alfalfa were cut into pieces (3-5 mm) and surface sterilized with 75% ethanol for 30 seconds, followed by 1% sodium hypochlorite (NaClO) for 120 seconds, and three rinses with sterile distilled water. Tissue pieces were placed on selective potato dextrose agar (PDA) containing 50 mg/L rifampicin and ampicillin. Plates were sealed and incubated at 25°C for 48 to 72 hours. Over 70 tissue fragments plated, 20 isolates from different fragments showed similar colonies. These isolates were purified by single spore isolation and grown on PDA and mung bean medium for morphology identification, molecular identification and pathogenicity test. The colony showed white to pink, abundant, densely aerial mycelium, while its backside was light violet. Macroconidia were hyaline, falcate with septa, and ranged in size from 25.5 to 61.5 × 3.8 to 6.2 μm (n=50). Microconidia were non-septate, hyaline, oval, straight to slightly curved, and were 5.6 to 10.7 × 2.4 to 3.2 μm (n=50). Spherical chlamydospores were 10.6 ± 1.3 μm in size. The rDNA internal transcribed spacers (ITS), RNA polymerase II subunit 2 (RPB2) and translation elongation factor 1-α (TEF) genes were amplified and sequenced (White et al. 1990; Carbone et al. 1999; Wang et al. 2019). Blast analysis showed 99.41% to 100% identity to F. commune sequences in the GenBank database (KU341324.1, MN892350.1, MH341219.1). The pathogenicity test was conducted using the dipping method in roots. Fresh F. commune hyphae were cut into 3 x 3mm agar plugs from a 7 cm PDA plate and inoculated in 200 mL mung bean medium on a shaker at 160 rpm, 25°C for 5 days. Spores were filtered through a cheese cloth, adjusted to 1 × 106 spores/mL with distilled water and used immediately. Roots in two-week-old alfalfa seedlings were soaked in spore suspension for 30 mins before being transplanted to sterile vermiculate with four repeats, while those in sterile water were used as non-inoculated control. The plants were placed in the green house at 25°C with 16 h of light and 8 h of darkness. The symptoms were observed two weeks following the inoculation. 30% of the seedlings withered, and reddish-brown discoloration symptoms were visible on the roots and stem of the unwithered plant. F. commune was isolated from these lesions again, and no disease symptoms were observed in the control plant. F. commune has been reported to cause root and stem rot in many plants worldwide, including tobacco (Zhong et al. 2021), maize (Mezzalama et al. 2021; Xi et al. 2019), soybean (Detranaltes et al. 2022) and sugarcane (Wang et al. 2018). Our results show that F. commune was the causative agent of alfalfa root rot. To our knowledge, this is the first report of F. commune causing root rot in alfalfa. The finding provides insights for disease diagnosis of alfalfa root rot disease and management in the region.