Microbial degradation is an environmentally sustainable approach to mitigate autotoxicity induced by phenolic acids in agricultural systems. However, multiple phenolic acids coexist and interact in the environment, which greatly limits the application of microbes with the capacity to degrade a single phenolic acid. Here, Rhodococcus aetherivorans RA1, a novel and highly effective bacterium capable of degrading multiple phenolic acids, was firstly isolated from the rhizosphere soil of Dioscorea spp. Within 72 h, strain RA1 degraded > 90% of the mixed substrate with a total concentration of 1200 mg/L of ferulic acid, vanillic acid, and p-hydroxybenzoic acid. Strain RA1 also exhibited a strong degrading capacity for benzoic and caffeic acid, suggesting a broad substrate range. Furthermore, it exhibited excellent adaptability, maintaining high degradation rates (37-95%) over wide ranges of salinity (0-20 g/L NaCl) and temperature (10-43 degrees C). Growth promoting assays indicated that it not only effectively alleviated the inhibitory effect of phenolic acids on the growth of Brassica rapa subsp. chinensis seeds, but also suppressed the growth of the pathogen Fusarium oxysporum by degrading phenolic acids. Whole-genome sequencing and analysis indicated that strain RA1 contains 23 phenolic acid degradation genes and a complex degradation network. This consisted of the peripheral pathways forming a multi-enzyme synergistic system and central degradation pathways composed of the protocatechuic acid 2,3-cleavage, 3,4-cleavage, and catechol pathways. Therefore, the effective degradation of phenolic acids by strain RA1 as a biological agent provides a biological resource for the application of microbes in agriculture.

Plant–metabolite–microbe interactions are crucial for crop health and quality. Yam (Dioscorea spp.) is an economically significant crop with both medicinal and edible value. However, the mechanisms by which different yam species regulate metabolite–microbiome interactions across plant compartments remain unclear. In this study, we systematically investigated microbial communities, metabolic profiles, and their potential associations in the leaves, tubers, and rhizospheres of 47 cultivars representing five commonly cultivated Dioscorea species in China. Bacterial communities were mainly shaped by deterministic processes, whereas fungal communities were governed by stochastic processes. Endophyte diversity in leaves and tubers was lower than that in the rhizosphere. We identified 33, 15, and 50 core amplicon sequence variants (ASVs) and 68, 41, and 51 biomarkers from the leaf, tuber, and rhizosphere, respectively, with bacterial biomarkers outnumbering fungal ones. LC-MS analysis identified 1526 metabolites in leaves and 580 in tubers, and revealed clear species-specific patterns. A random forest model accurately discriminated species (out-of-bag error = 0.0426) based on metabolite composition. Co-occurrence network analysis further indicated that specific core microorganisms or biomarkers were significantly and positively correlated with species-specific medicinal metabolites. This study is the first to characterize interactions among closely related Dioscorea species, their associated microbiomes, and metabolites. Our findings provide new insights into the assembly of plant-associated microbiomes, highlight key microbial taxa that may regulate the biosynthesis of functional metabolites, and offer potential targets for improving the health and quality of medicinal and edible yam crops.

To investigate the characteristics of the fungal community and potential key pathogenic fungi,ITS rDNA amplicon sequencing technology and FUNGuild analysis were used to study the fungal community composition,network characteristics and ecological function groups in rotting tubers of Dioscorea sp.Additionally,potential pathogenic fungi were isolated and identified.The results were as follows:(1)In rotting tubers of Dioscorea sp.,the dominant phylum was Ascomycota,and prevalent fungal genera included Penicillium,Colletotrichum,Fusarium,Talaromyces,Clonostachys,etc.The fungal ecological network exhibited a clear modular structure with a high ratio of positive correlation edges(99.33％),suggesting that positive cooperation was strengthen between different fungi.(2)FUNGuild analysis indicated that 10 guilds were highly correlated with yam tuber rot.Among these guilds,the relative abundances of dung saprotroph-undefined saprotroph-wood saprotroph and endophyte-plant pathogen were 33.74％and 23.64％,respectively,and the representative genera were Penicillium and Colletotrichum,respectively.Additionally,three guilds were related to both plant pathogen and wood saprotroph,and occupied 13.67％of the ecological functional groups.Moreover,Fusarium was representative genus of all three guilds.Traits analysis showed that seven genra of fungi(Penicillium,Fusarium,etc.)in the fungal community were probably invovled in yam tuber rot.(3)A total of 22 strains were isolated and belonged to 6 genera,including Fusarium(9 strains),Penicillium(5 strains)and Aspergillus(4 strains),etc.This study provides reference for understanding the pathogenesis of tuber rot in Dioscorea sp.,and for the selection of appropriate pesticides and biocontrol microbes.

Saline-alkali stress (SAS) significantly impairs crop growth, yield and quality, while allantoin plays a crucial role in enhancing plant tolerance to this stress. Yam (Dioscorea opposita Thunb.) has substantial nutritional and medicinal value. However, the regulatory mechanism of allantoin in regulating yam growth and nutritional quality under SAS remains largely unclear. In this study, we found that SAS severely inhibited the growth and root development of yam bulbil seedlings. Specifically, in leaves, the contents of osmotic regulators (e.g., proline, soluble sugar) and malondialdehyde (MDA), along with the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were significantly increased. Additionally, leaf Na+ content was increased, K+ content was decreased, and the Na+/K+ ratio was significantly elevated. Meanwhile, the contents of allantoin, diosgenin, and polysaccharides in tubers were significantly increased. Overexpression of the allantoin synthase gene DoAS in Arabidopsis thaliana further enhanced its tolerance to SAS. Furthermore, compared with the SAS-only group, allantoin treatment significantly improved yam seedling growth, reduced leaf proline and MDA contents, enhanced SOD and POD activities, decreased the Na+/K+ ratio, increased tuber yield and contents of major active components, and lowered tuber Na+ content. Taken together, allantoin significantly improves ionic balance and antioxidant capacity in yam bulbil seedlings under SAS, thereby promoting seedling growth and nutrient accumulation in tubers. This study thus highlights the critical role of allantoin in regulating the growth and nutrient accumulation in tuber crops under SAS.

Yam (Dioscorea spp.) is an important crop cultivated worldwide with significant economic value. However, Pratylenchus coffeae is one of the most prevalent pathogenic nematodes causing yam root lesion disease, primarily spreading through seed yams (top tuber portions) or soil. Ensuring that quality of seed yams and cultivated soil free from pathogenic nematodes is crucial for yam production, and an efficient detection method for P. coffeae is essential, especially under field conditions. From November 2022 to November 2024, a simple, rapid, and efficient molecular identification method was developed for P. coffeae detection in yam tissues without requiring expensive laboratory equipment or specialized personnel. The entire detection process was completed in 65 min, including crude nematode DNA extraction (10 min), recombinase polymerase amplification (RPA) (30 min), and CRISPR/Cas12a-based detection (25 min). Compared with PCR and qPCR assays, the proposed diagnostic method demonstrated high sensitivity, with detection as low as 4 copies/mu L per reaction, and exhibited high specificity for P. coffeae without cross-reactivity with other common plant-parasitic nematodes. The detection results obtained using RPA-CRISPR/Cas12a were highly consistent with those of conventional PCR assays conducted on 18 seed yams, indicating the method's high applicability and accuracy for field detection. In conclusion, RPA-CRISPR/Cas12a holds great potential as a reliable and rapid diagnostic tool for detecting P. coffeae infections, particularly for seed yam quality control in field conditions where complex equipment is unavailable.

Yam (Dioscorea opposita Thunb.) is an important crop that is highly valuable as both food and medicine in China. However, fungal diseases pose a significant threat to the safety and reliability of its production. In this study, a strain designated 23HNTG4-2 was isolated and shown to play predominant role in the occurrence of leaf spot disease on D. opposita. Its pathogenicity was determined based on Koch's postulates. Further analysis based on a multigene phylogenetic tree identified the 23HNTG4-2 as Alternaria alternata. Considering that the traditional methods for detecting pathogens are often time-consuming, we developed a platform based on RPA-CRISPR/ Cas12a to detect A. alternata. Our research revealed that the CRISPR RNA (crRNA) that contained two bases (Al-crRNA3) of the protospacer adjacent motif (PAM) site exhibited a maximum fluorescence value (1.37 +/- 0.052) during the CRISPR/Cas12a reaction. Compared with PCR and qPCR assays, this platform was much more sensitive (3 x 101 copies/mu L) and enhanced the reliability of the detection results. The platform can be utilized in field tests without the need for intricate instruments. In summary, we verified that A. alternata produces necrotic spots on the yam leaves and provided an RPA-CRISPR/Cas12a detection platform, which is suitable for field tests owing to significant advances in sensitivity and specificity, visible results, and its lack of reliance on complicated instruments.

Soil salinization is a major global problem and an important environmental factor threatening crop production. Yam (Dioscorea opposita Thunb.) is the fourth important root and tuber crop and is known for its substantial vegetable and medicinal properties. Anthocyanins serving a pivotal function in plant resistance to saline-alkali stress, but the regulatory mechanism of yam anthocyanins under saline-alkali stress is not fully understood. Here, the mechanism underlying salt-alkali resistance in high-anthocyanin purple yam was investigated. The root morphological, anthocyanin content, leaf anatomical structure, malondialdehyde content, antioxidant enzyme activity and the RNA-seq were investigated after yam seedlings exposure to saline-alkali stress treatments. Saline-alkali stress could markedly inhibit the growth of yam bulbil seedlings and induce the production of purple plants. The thickness of the upper epidermis and spongy tissue, and the malondialdehyde content of the purple leaces were significantly lower than those of the green ones, while the thickness of lower epidermis was significantly increased. Meanwhile, compared with the purple seedlings, the enzymatic activities of superoxide dismutase, peroxidase and catalase in the the green plants were significantly increased. Furthermore, RNA-seq of purple and green yam seedlings subjected to saline-alkali stress identified substantial differences in differentially expressed genes, which were predominantly enriched in metabolic pathways or factors influencing anthocyanin synthesis. Saline-alkali stress resulted in an increase in anthocyanin content and modifications in leaf morphology, thereby enhancing the stress resistance of yam. These data provided a basis for further exploration of the role of anthocyanins in saline-alkali stress in tuber crops.

Plant endophytic bacteria play crucial roles in the prevention and control of crop diseases. Yam (Dioscorea opposita), an important tuber and root crop, is renowned for its rich vegetable and medicinal values. However, the black-spot disease is relatively prevalent during its cultivation process, and there are no reports on using endophytes to control this disease. In this study, an endophytic bacterium that strongly antagonized Alternaria alternata, the pathogen causing yam black-spot disease, was isolated from ‘Tiegun’ yam leaves, and it was identified as a strain of Bacillus and named E-Do8. Further investigations revealed that the E-Do8 fermentation broth could significantly inhibit the spore germination and mycelial growth of A. alternata, and the mycelia showed uneven thickness, swelling, and irregular entanglement. Moreover, the ability of A. alternata to penetrate cellophane was weakened when cultured with the E-Do8 fermentation broth, which could also significantly inhibit the pathogenicity of A. alternata. In addition, the UHPLC-Orbitrap Exploris 240 system was employed to analyze the active ingredients in the E-Do8 fermentation broth that inhibit A. alternata, and it was found that E-Do8 only produced surfactin-type compounds, C14-surfactin and surfactin. This study provided a theoretical foundation for the employment of Dioscorea endophytes in controlling its diseases.

Yam (Dioscorea polystachya Turcz.) is an asexually reproduced food and traditional Chinese medicinal crop with extensive genomic variability. However, the detailed characterization of genetic diversity among different yam germplasm samples is still insufficient. This study evaluated the genetic divergence and genetic structure of 113 D. polystachya accessions collected from 17 provinces in China based on 50 distinctness, uniformity, and stability (DUS) traits and 19 simple sequence repeat (SSR) markers. All the selected varieties were categorized into three groups based on morphological characteristics and further validated by principal component analysis. Furthermore, 14 core traits, including 6 leaf traits, 4 tuber traits, 3 bulbil traits, and 1 stem trait, were selected to increase field inspection efficiency. SSR fingerprinting, utilizing 19 highly polymorphic markers, successfully distinguished all 113 yam varieties, revealing relatively high levels of genetic variation. Interestingly, the optimal genetic structure defined three groups, whereas a finer-scale model consistently classified the varieties into five groups, corroborating the genotypic cluster analysis. Furthermore, this study preliminarily identified 10 groups of potential heterotypic synonyms and 13 groups of potential homonyms among the yam accessions. These results demonstrate that the 19 selected SSR markers, in conjunction with DUS traits, can effectively discriminate the 113 D. polystachya varieties. Our findings provide critical insights for the conservation of pure breeds and the utilization of Dioscorea germplasm resources.

Yam (Dioscorea spp.) is used not only as food in the world but also as an important traditional medicinal herb in East Asia. However, its yield and quality are severely affected by leaf spot disease. Isolating and identifying the novel pathogens will be very helpful for controlling yam leaf spot disease. In 2023, leaf spot disease occurred in about 40

Yam is an important medicinal and edible dual-purpose plant with high economic value. However, nematode damage severely affects its yield and quality. One of the major effects of nematode infestations is the secondary infection of pathogenic bacteria or fungi through entry wounds made by the nematodes. Understanding the response of the symbiotic microbial community of yam plants to nematodes is crucial for controlling such a disease. In this study, we investigated the rhizosphere and how endophytic microbiomes shift after nematode infection during the tuber expansion stage in the Dioscorea opposita Thunb. cultivar Tiegun. Our results revealed that soil depth affected the abundance of nematodes, and the relative number of Meloidogyne incognita was higher in the diseased soil at a depth of 16 to 40 cm than those at a depth of 0 to 15 and 41 to 70 cm. The abundance of and interactions among soil microbiota members were significantly correlated with root-knot nematode (RKN) parasitism at various soil depths. However, the comparison of the microbial α-diversity and composition between healthy and diseased rhizosphere soil showed no difference. Compared with healthy soils, the co-occurrence networks of M. incognita-infested soils included a higher ratio of positive correlations linked to plant health. In addition, we detected a higher abundance of certain taxonomic groups belonging to Chitinophagaceae and Xanthobacteraceae in the rhizosphere of RKN-infested plants. The nematodes, besides causing direct damage to plants, also possess the ability to act synergistically with other pathogens, especially Ramicandelaber and Fusarium, leading to the development of disease complexes. In contrast to soil samples, RKN parasitism specifically had a significant effect on the composition and assembly of the root endophytic microbiota. The RKN colonization impacted a wide variety of endophytic microbiomes, including Pseudomonas, Sphingomonas, Rhizobium, Neocosmospora, and Fusarium. This study revealed the relationship between RKN disease and changes in the rhizosphere and endophytic microbial community, which may provide novel insights that help improve biological management of yam RKNs.

Dioscorea opposita Thunb. cv. Tiegun yam is an important dual-purpose medicinal and edible plant that has significant economic value in China. Understanding the assembly and function of rhizosphere and endospheric microbial communities will provide new avenues to elucidate the pathogenesis and mechanisms of serious continuous cropping obstacles (CCO) in yam, as well as to develop relevant plant probiotics. However, very few studies have focused on the dynamic changes of the microbial community along with the growth stages of such root and tuber plants. In this study, we investigated temporal changes in the structure and functions of endophytic and rhizosphere communities in field yam production. Molecular analysis results showed that the Shannon abundance in the rhizosphere community increased from the seedling to the mature stages, which contrasted with the trend of the endophytic community, and the microbial community was the most complex during the expansion stage of the underground tuber. As the growth cycle was extended, the rhizospheric genera Pseudomonas , Pseudeurotium , and Alternaria , and the endophytic genera Bacillus , Delftia , and Cladosporium increased rapidly. In contrast, rhizospheric Bacillus , Mortierella , and Talaromyces and the endophytic Enterobacter , Pantoea , and Fusarium decreased significantly. Bacillus , Enterobacter, and Pantoea bacterial strains and Fusarium , Talaromyces , and Trichoderma fungal strains were isolated from the yam rhizosphere and endospheric environments. These microorganisms represented the dominant genera at different growth stages of yam. In vitro functional assays indicated that Bacillus , Pseudomonas , and Enterobacter were capable of phosphate dissolution, indole compounds production, and resistance to pathogens. The strains represented by Bacillus , Pseudomonas , and Enterobacter accounted for 54.33 %, 32.28 %, and 33.07 % of the isolated strains, respectively. Thus, these findings suggest that supplementing necessary microorganisms according to the characteristics of the microbial community at different growth stages is a potential strategy for improving the health and quality of yam.

Dioscorea opposita cultivar Tiegun is an economically important crop with high nutritional and medicinal value. Plants can activate complex and diverse defense mechanisms after infection by pathogenic fungi. Moreover, endophytic fungi can also trigger the plant immune system to resist pathogen invasion. However, the study of the effects of endophytic fungi on plant infection lags far behind that of pathogenic fungi, and the underlying mechanism is not fully understood. Here, the black spot pathogen Alternaria alternata and the endophytic fungus Penicillium halotolerans of Tiegun were identified and used to infect calli. The results showed that A. alternata could cause more severe membrane lipid peroxidation, whereas P. halotolerans could rapidly increase the activity of the plant antioxidant enzymes superoxide dismutase, peroxidase, and catalase; thus, the degree of damage to the callus caused by P. halotolerans was weaker than that caused by A. alternata. RNA sequencing analysis revealed that various plant defense pathways, such as phenylpropanoid biosynthesis, flavonoid biosynthesis, plant hormone signal transduction, and the mitogen-activated protein kinase signaling pathway, play important roles in triggering the plant immune response during fungal infection. Furthermore, the tryptophan metabolism, betalain biosynthesis, fatty acid degradation, flavonoid biosynthesis, tyrosine metabolism, and isoquinoline alkaloid biosynthesis pathways may accelerate the infection of pathogenic fungi, and the ribosome biogenesis pathway in eukaryotes may retard the damage caused by endophytic fungi. This study lays a foundation for exploring the infection mechanism of yam pathogens and endophytic fungi and provides insight for effective fungal disease control in agriculture.

Common lambsquarters (Chenopodium album Linn.) is one of the most problematic weeds associated with crops worldwide due to its fast-growing, high fecundity, and wide tolerance to various conditions. Meanwhile, C. album is also an herbaceous vegetable plant, and the leaves and young shoots of this plant are considered nutritious in the human diet (Aman et al. 2016). In September 2023, C. album plants exhibiting yellowing, stunted growth, and extensive galled root symptoms were collected from a yam field in Fengqiu (34°54'24"N; 114°34'57"E), Henan Province, China. At the selected sampling site, we randomly selected 100 C. album plants, and the disease incidence was 73% on a 0.67-ha field. A RKN species belonging to the genus Meloidogyne was found, comprising an average of 550 second-stage juveniles (J2s) from 100 g of the 10 to 30 cm soil layer. The J2s were isolated from fresh soil with a Baermann funnel. C. album roots were thoroughly washed with tap water and dissected. Nematodes at different stages were collected and morphologically identified. Females and egg masses were obtained by dissecting galls. Females were white with a protruding neck, globular to pear-shaped. The perineal patterns of females predominantly exhibited a pronounced dorsal arch, characterized by either a square or trapezoid shape, lacking obvious lateral lines. Males isolated from root galls were vermiform, annulated, and showed a trapezoidal labial region, including a high head cap that was concaved at the center of the top end in lateral view. J2s were distinguished by the conspicuous, round stylet knobs, and they had wrinkled tails with a hyaline region and an obtuse tip. Morphological measurements are described in the supplementary material. All features were consistent with the morphological characteristics of Meloidogyne incognita (Eisenback and Hirschmann 1981). Identification was accomplished with subsequent species-specific PCR and sequencing analysis. The genomic DNA of 10 individual females was extracted, and the molecular identification was carried out with M. incognita-specific primers Mi-F/Mi-R, and Inc-K14-F/Inc-K14-R (Meng et al. 2004; Randig et al. 2002). PCR amplification generated 955 and 399 bp fragments for the analyzed samples, respectively, and the amplicons were confirmed by sequence analyses. The sequences were deposited in GenBank under accession number PP836070 and PP836071. BLASTn searches showed 100% identity with available GenBank M. incognita sequences (accession no. MK410954, OQ427638). To verify reproduction on C. album, 10 healthy plants (30 days old) grown in pots with sterilized soil were inoculated with 1,000 M. incognita J2s under greenhouse conditions (light/dark: 16 h/8 h, temperature: 25-28°C). Five uninoculated plants were used as negative control. Two months after inoculation, stunted growth and root-galling symptoms were observed similar to those in field, whereas control plants remained symptomless. Many root galls and egg masses were observed in all inoculated plants. The root galling index (scale of 0 to 10; Poudyal et al. 2005) was ~7 and nematode reproduction factor (final population density/initial population density) was 5.3. The morphological features of the nematodes reisolated from root tissue closely match the description of M. incognita, fulfilling Koch's postulates. The pathogenicity test was carried out twice with similar results. M. incognita is an emerging disease of economic importance in many crop plants worldwide, and may cause serious economic losses (Phani et al. 2021). This widely distributed C. album plant is likely a reservoir for the pathogen and serves as an alternate host for nematodes. The findings are significant for the integrated management practices of RKNs, particularly for crops that are infested with C. album. To our knowledge, this is the first report of the nematode parasitizing C. album in China. The development of effective short- and long-term control procedures is urgently needed for managing M. incognita.

Background The bacterial genus Bacillus , an important group of bacteria which can suppress phytopathogens, has been widely used in agriculture. However, different species of Bacillus often displayed significant differences in probiotic efficiency and mechanism, suggesting that it is very necessary to investigate the biocontrol potential of new Bacillus isolates, especially from under-evaluated Bacillus spp. Rehmannia glutinosa ( R. glutinosa ), an important traditional Chinese medicinal herb, is affected by a serious root-rot disease caused by the fungus Fusarium solani ( F. solani ) . Biocontrol agents against this root-rot disease in R. glutinosa have yet to be developed. This study explored, for the first time, the activity and biocontrol mechanism of a new Bacillus isolate, Bacillus tequilensis A13, in antagonizing F. solani . Results B. tequilensis A13 displayed a strong inhibitory activity (73.49% ± 1.33%) against F. solani growth in vitro and was able to survive and multiply in the sterilized soil. The results from liquid chromatography electrospray ionization tandem mass spectrometry (LC–MS/MS) and Gene Ontology (GO) analyses indicated that B. tequilensis A13 cell-free supernatant contained six antifungal compounds, eight antifungal compound synthases, and several functional proteins involved in the processes of plant stress resistance, etc. Finally, the joint application of complex fertilizer together with B. tequilensis A13 significantly reduced the incidence of R. glutinosa root rot in the field. Conclusion B. tequilensis A13 strongly inhibited F. solani growth by producing antifungal compounds and proteins associated with plant stress resistance/tolerance, and proved to be a promising candidate biocontrol agent against R. glutinosa root-rot disease. Graphical Abstract

Dioscorea opposita is an annual twining plant in China that is used for consumption and medicinal purposes. The planting area of D. opposita is near 500,000 hectares in China, mainly in Shangdong, Hebei, Henan, Jiangxi and Yunnan provinces. In August 2021, we observed that some D. opposita plants grew poorly with smaller and chlorotic leaves in Changyuan (35°8'12"N; 114°43'52"E), Henan Province, China. Galls with hook-shaped roots and tuber damage were also observed, typical of root-knot nematode. Thirty tubers were randomly collected and 60% were infested with root-knot nematodes. During a disease survey in Changyuan, the incidences of root-knot nematode damage were 31.5%, 21%, and 18% in three fields (0.33, 0.67, and 4 ha, respectively) at harvest. The average tuber length of infected plants was decreased by 65.8%, and the average weight was decreased by 70.1% compared to the healthy plants. Males, females, second-stage juveniles (J2s), and eggs were extracted from individual diseased tubers from the three fields for morphological identification. Females were white, pear-shaped with a projecting neck. Males showed a trapezoidal labial region with prominent stylet knobs, including a high head cap which had a stepped outline and was centrally concave in lateral view. Morphological measurements are described in the supplementary material. All data and descriptions conformed to the morphological characteristics of Meloidogyne incognita. Genomic DNA was extracted from J2s (n=9) using PCR lysis buffer, and used for PCR amplification of the sequence characterized amplified region (SCAR) markers specific for M. incognita. Two pairs of the SCAR primers, Mi-F/Mi-R, and Inc-K14-F/Inc-K14-R, were used to diagnose whether these nematodes from D. opposita were M. incognita (Meng et al. 2004; Randig et al. 2002). The PCR produced expected amplification products of 955 and 399 bp, confirming the nematode to be M. incognita. Primers specific for M. arenaria (Far/Rar) and M. javanica (Fjav/Rjav) were used but failed to amplify fragments (Randig et al. 2002; Zijlstra et al. 2000). The obtained PCR fragments were sequenced and deposited in GenBank (accession no. OQ420602.1, OQ427638.1). They showed 99.9 and 100% identity to the available GenBank M. incognita sequence (accession no. MK410954.1, ON861825.1), respectively. A pathogenicity test was conducted in greenhouse conditions. Bulbils of D. opposita were sown in the pots filled with 2,000 ml of autoclaved soil mixture (loamy soil/sand, 1:1). One month later, 15 seedlings (five to six leaf stage) were inoculated with 1,000 M. incognita J2s individually. Five plants without nematode inoculation were used as the control. Two months after inoculation, all of the inoculated roots had galling symptoms similar to those observed in the field, and 100% of root system tissues had galls. The root gall index was ~6 according to a 0 to 10 RKN damage rating scale (Poudyal et al. 2005). No symptoms were found on the control plants. The nematodes were reisolated from root tissue and identified. M. incognita has a broad host range in many species of economic importance including Salvia miltiorrhiza (Wen et al. 2023), Ipomoea batatas (Maleita et al. 2022), and Zea mays (López-Robles et al. 2013). So far, M. incognita has been reported in D. alata and D. rotundata in Africa (Onkendi et al. 2014). To our best knowledge, this is the first record of M. incognita on D. opposita in Henan Province, China. With the increased planting area of D. opposita in China, root-knot nematodes are becoming more serious and reducing tuber production, with yield losses more than 60%. This identification is a preliminary step in developing effective disease management schemes. Declaration of interest The authors declare no conflict of interest. Funding This work was financially supported by the Key Scientific Research Projects of Higher Education Institutions of Henan Province (21A180013), China Agriculture Research System (CARS-21), The Zhongyuan high level talents special support plan-Science and Technology Innovation Leading Talents (224200510011) and Science and Technology Research Project of Henan Province (222102310211). References López-Robles, J., et al. 2013. Plant Dis. 97:694. https://doi.org/10.1094/PDIS-07-12-0674-PDN. Maleita, C., et al. 2022. Plant Dis. 106:2536. https://doi.org/10.1094/PDIS-12-21-2680-PDN. Meng, Q. P., et al. 2004. Acta Phytopathol. Sinica 34:204. https://doi.org/10.13926/j.cnki.apps.2004.03.003. Onkendi, E. M., et al. 2014. Plant Pathol. 63:727. https://doi.org/10.1111/ppa.12202. Poudyal, D. S., et al. 2005. Australas. Plant Pathol. 34:181. https://doi.org/10.1071/AP05011. Randig, O., et al. 2002. Genome 45:862. https://doi.org/10.1139/g02-054. Wen, Y., et al. 2023. Plant Dis. Accepted. https://doi.org/10.1094/PDIS-05-22-0997-PDN. Zijlstra, C., et al. 2000. Nematology 2:847. https://doi.org/10.1163/156854100750112798.

BBX proteins play important roles in all of the major light-regulated developmental processes. However, no systematic analysis of BBX gene family regarding the regulation of photoperiodic microtuber formation has been previously performed in yam. In this study, a systematic analysis on the BBX gene family was conducted in three yam species, with the results, indicating that this gene plays a role in regulating photoperiodic microtuber formation. These analyses included identification the BBX gene family in three yam species, their evolutionary relationships, conserved domains, motifs, gene structure, cis-acting elements, and expressional patterns. Based on these analyses, DoBBX2/DoCOL5 and DoBBX8/DoCOL8 showing the most opposite pattern of expression during microtuber formation were selected as candidate genes for further investigation. Gene expression analysis showed DoBBX2/DoCOL5 and DoBBX8/DoCOL8 were highest expressed in leaves and exhibited photoperiod responsive expression patterns. Besides, the overexpression of DoBBX2/DoCOL5 and DoBBX8/DoCOL8 in potato accelerated tuber formation under short-day (SD) conditions, whereas only the overexpression of DoBBX8/DoCOL8 enhanced the accelerating effect of dark conditions on tuber induction. Tuber number was increased in DoBBX8/DoCOL8 overexpressing plants under dark, as well as in DoBBX2/DoCOL5 overexpressing plants under SD. Overall, the data generated in this study may form the basis of future functional characterizations of BBX genes in yam, especially regarding their regulation of microtuber formation via the photoperiodic response pathway.

Chrysanthemum morifolium cv. ‘Huaibai’ is a well-known medicinal chrysanthemum. However, ‘Huaibai’ plants are susceptible to severe diseases due to long-term asexual reproduction, moreover, slender stems make ‘Huaibai’ prone to lodging, which can seriously affect the yield and medicinal quality. In this study, autodecaploid plants were induced from pentaploid ‘Huaibai’ (2n = 5x = 45) by 0.05