Feed Crops Research Articles

SoyOD: An Integrated Soybean Multi-omics Database for Mining Genes and Biological Research

Abstract Soybean is a globally important crop for food, feed, oil, and nitrogen fixation. A variety of multi-omics studies has been carried out, generating datasets ranging from genotype to phenotype. In order to efficiently utilize these data for basic and applied research, a soybean multi-omics database with extensive data coverage and comprehensive data analysis tools was established. The Soybean Omics Database (SoyOD) integrates important new datasets with existing public datasets to form the most comprehensive collection of soybean multi-omics information. Compared to existing soybean databases, SoyOD incorporates an extensive collection of novel data derived from the deep-sequencing of 984 germplasms, 162 novel transcriptome datasets from seeds at different developmental stages, 53 phenotypic datasets, and more than 2500 phenotypic images. In addition, SoyOD integrates existing data resources, including 59 assembled genomes, genetic variation data from 3904 soybean accessions, 225 sets of phenotypic data, and 1097 transcriptomic sequences covering 507 different tissues and treatment conditions. Moreover, SoyOD can be used to mine candidate genes for important agronomic traits, as shown in a case study on plant height. Additionally, powerful analytical and easy-to-use toolkits enable users to easily access the available multi-omics datasets, and to rapidly search genotypic and phenotypic data in a particular germplasm. The novelty, comprehensiveness, and user-friendly features of SoyOD make it a valuable resource for soybean molecular breeding and biological research. SoyOD is publicly accessible at https://bis.zju.edu.cn/soyod.

Unravelling genetic variability for yield and contributing characteristics in green gram [vigna radiata (L.) wilczek] germplasm

Mungbean [Vigna radiata (L.) Wilczek] is an essential crop for food, feed, and income generation in rice-based farming systems across Southeast Asia and other regions. Its popularity stems from its good taste, high nutritional value, and ease of digestion, making it a promising crop for enhancing livelihoods. However, despite its significance, mungbean productivity remains low, primarily due to environmental stresses and a lack of sufficient genetic variability. This study examines the variability, heritability, phenotypic and genotypic coefficient of variation, and genetic advance among yield-contributing traits in green gram germplasm. A total of 450 germplasm lines were evaluated alongside check varieties, revealing significant variation, with the analysis of variance showing notable differences across nearly all traits. The mean sum of squares for the germplasm was highly significant for all phenotypic traits. Several traits exhibited high estimates of heritability and genetic advance, viz., the number of branches/ plants, number of clusters/ plants, number of pods/ clusters, pod length, test weight, and seed yield/plant, indicating their potential for direct selection in breeding programs. These findings suggest that additive gene effects play a dominant role in controlling these traits, with minimal environmental influence, making simple phenotypic selection an effective approach. The results provide valuable insights for advancing green gram breeding programs focused on improving yield and quality through targeted hybridization and trait selection.

Impact of urbanization and planting structure on water footprint of food, cash, and feed crops in China’s northern agro-pastoral ecotone

China, especially the northern agro-pastoral ecotone, is facing severe water scarcity, which presents a significant challenge for the agriculture sector, the largest consumer of water. This study selected Yanchi County as a typical area. First, the water footprint method is used to evaluate the water usage of food, cash, and feed crops in the region from 1990 to 2020. Then, the vector error correction model (VECM) is used to analyze the short-term effects and long-term effects of urbanization and planting structure on the water consumption of these three types of crops. The results show: 1) The total agricultural water footprint (WF) in Yanchi County, as well as the WFs of the predominantly grown food and feed crops, show an upward trend. Additionally, the proportion of blue WF is relatively high across all crop types. 2) Reducing the proportion of food crops will increase the WF of cash and feed crops, but it will not necessarily decrease the WF of food crops. 3) An increase in the level of urbanization may reduce the agricultural WF in the short term, but ultimately, it will lead to an increase in the WF. Overall, this study reveals the growing pressure on agricultural water use faced by the agro-pastoral ecotone during the processes of urbanization and planting structure transformation. It highlights the importance of developing rain-fed agriculture, seizing the technological development opportunities brought by urbanization, and reasonably adjusting the cropping structure for the sustainable use of water resources.

Managing forage for grain: Strategies and mechanisms for enhancing forage production to ensure feed grain security 1

The “Greater Food” approach has replaced the older “taking grain production as a top priority” approach. The importance of feed and forage as the material basis for guaranteeing high-quality development of the livestock industry has gradually become prominent. However, owing to the tradition of “both human staple food and animal feed relying on grain production” in China and the decoupling of feed crop planting and livestock farming, the risk of feed grain security has increased, especially as it relates to the supply of high-quality protein feed ingredients from abroad, which is facing a bottleneck. To ensure food security, effective domestic agricultural production should be adopted. Nevertheless, guaranteeing the supply of high-quality protein feed through domestic soybean production is difficult because of limited arable land; furthermore, pressure on the staple food supply is still extreme. In this article, the historical and realistic implications for the security risks of feed grain in China are analyzed. Proposals are made to separate staple food grains for humans from the feed grain supply for animals and to develop high-quality forage to reduce feed grain use. High-quality forage can be supplied via intercropping with grain crops in arable land and reseeding perennial legumes or grasses into natural grasslands. However, “managing forage for grain” needs to be supported via technical paths and policies as the forage industry develops to effectively increase the capacity to ensure feed grain security.

Assessment of Lepidopteran Pest Dynamics in Maize: Dominance of Spodoptera frugiperda and Implications for Targeted Management in Himachal Pradesh, India

Maize (Zea mays L.) plays a crucial role in the agricultural economy of India, particularly in Himachal Pradesh, where it serves as a vital crop for food, feed, and fodder. This study assessed the distribution, and relative abundance of lepidopteran pests infesting maize during the kharif, 2022-23 across two agro-climatic zones of Himachal Pradesh. Surveys identified five key lepidopteran pests: Spodoptera frugiperda, Chilo partellus, Mythimna separata, Agrotis ipsilon, and Euproctis spp. Among all, S. frugiperda is the only pest occurring among the major three crop stages of maize. The findings revealed that S. frugiperda was the most dominant pest, with relative abundance values of 19.57 per cent in Zone I and 18.94 per cent in Zone II during the seedling stage, increasing to 30.87 per cent and 30.40 per cent during the vegetative stage, respectively. In contrast, other pests like C. partellus, M. separata, A. ipsilon, and Euproctis spp. exhibited variable distribution patterns, with some showing limited occurrence. In conclusion, this study underscores the necessity for targeted pest management strategies to address dominant and subdominant lepidopteran pests in maize cultivation in Himachal Pradesh. The results offer valuable insights that can inform focused pest control efforts, with the potential to significantly enhance sustainable maize production, crop resilience and overall productivity in the region.

Dynamics of fermentation quality, bacterial communities, and fermentation weight loss during fermentation of sweet sorghum silage

BackgroundSweet sorghum is used mainly as an energy crop and feed crop in arid and semiarid regions, and ensiling is a satisfactory method for preserving high-quality sweet sorghum. The aim of this study was to reveal the dynamics of the fermentation quality, bacterial communities, and fermentation weight loss (FWL) of sweet sorghum silage during fermentation.MethodsSweet sorghum was harvested at the first inflorescence spikelet stage and ensiled without (CK) or with lactic acid bacterial (LAB) additives (L). After ensiling, samples were collected on days 0, 1, 3, 5, 15, 40, and 100 to assess the fermentation quality, bacterial communities, and FWL.ResultsFor CK and L, on day 1, the pH was 5.77 and 5.57, respectively, and the lactic acid (LA) was 1.30 and 2.81 g/kg dry matter (DM), respectively. Compared with CK, L had a lower pH and higher LA from days 1 to 5 (P < 0.05), a lower FWL from days 5 to 100 (P < 0.05), and a greater abundance of Lactiplantibacillus from days 1 to 15 (P < 0.05). The main bacterial genera were Leuconostoc and Weissella in CK and Lactiplantibacillus, Leuconostoc, and Weissella in L on day 1; Lactiplantibacillus in all silages from days 3 to 40; and Lactiplantibacillus and Lentilactobacillus in all silages on day 100.ConclusionsSweet sorghum silage fermented relatively slowly during the first day. Moreover, inoculation with LAB accelerated fermentation and optimized bacterial communities during the initial fermentation phase. Inoculation with LAB also reduced the silage FWL, and the LAB succession relay occurred in the silage throughout the fermentation process.

Identification of Candidate Genes for Soybean Storability via GWAS and WGCNA Approaches

Soybean (Glycine max (L.) Merr.) is an important crop for both food and feed, playing a significant role in agricultural production and the human diet. During long-term storage, soybean seeds often exhibit reduced quality, decreased germination, and lower seedling vigor, ultimately leading to significant yield reductions in soybean crops. Seed storage tolerance is a complex quantitative trait controlled by multiple genes and is also influenced by environmental factors during seed formation, harvest, and storage. This study aimed to evaluate soybean germplasms for their storage tolerance, identify quantitative trait nucleotides (QTNs) associated with seed storage tolerance traits, and screen for candidate genes. The storage tolerance of 168 soybean germplasms was evaluated, and 23,156 high-quality single nucleotide polymorphism (SNP) markers were screened and analyzed through a genome-wide association study (GWAS). Ultimately, 14 QTNs were identified as being associated with seed storage tolerance and were distributed across the eight chromosomes of soybean, with five QTNs (rs25887810, rs27941858, rs33981296, rs44713950, and rs18610980) being newly reported loci in this study. In the linkage disequilibrium regions of these SNPs, 256 genes were identified. By combining GWAS and weighted gene co-expression network analysis (WGCNA), eight hub genes (Glyma.03G058300, Glyma.04G1921100, Glyma.04G192600, Glyma.04G192900, Glyma.07G002000, Glyma.08G329400, Glyma.16G074600, Glyma.16G091400) were jointly identified. Through the analysis of expression patterns, two candidate genes (Glyma.03G058300, Glyma.16G074600) potentially involved in seed storage tolerance were ultimately identified. Additionally, haplotype analysis revealed that natural variations in Glyma.03G058300 could affect seed storage tolerance. The findings of this research provide a theoretical foundation for understanding the regulatory mechanism underlying soybean storage.

Thermal Stress as a Critical Factor in the Viability and Duration of Spittlebug Eggs

The spittlebug Mahanarva spectabilis (Distant, 1909) (Hemiptera: Cercopidae) is an important pest that causes significant losses in the production of forage crops for cattle feed. Information on the thermal requirements of this insect during the egg stage is crucial in assessing the interaction between insects and forage. The aim of this research was to evaluate the effects of constant and oscillating (diurnal/nocturnal) temperatures on the viability of M. spectabilis eggs and the duration of the egg stage. Temperatures of 20 °C to 30 °C were ideal for the development of this insect pest, resulting in greater viability and faster development of the embryos. In addition, it should be noted that a variation of up to 8 days is feasible for synchronizing the phenological stages of the forage plants and the eggs to be laid on these plants when subjected to 30 °C (16.6 days) or 20 °C (25.7 days) without significantly altering the viability of the eggs. Notably, a temperature oscillation of 25 °C during the day and 15 °C at night increased the viability of the eggs after exiting diapause. These results are essential for the rearing of M. spectabilis in the laboratory, allowing for the supply of eggs for experiments and contributing to advances in studies aimed at developing effective integrated management strategies for this pest.

Feeding global aquaculture.

The growth of animal aquaculture requires ever more feed. Yet, fish and crustacean farming is argued to be sustainable because wild fish use is low and has improved over time. Here, accounting for trimmings and by-products from wild fish in aquaculture feed, and using four different sources of industry-reported feed composition data, we find ratios of fish inputs to farmed outputs of 0.36 to 1.15-27 to 307% higher than a previous estimate of 0.28. Furthermore, a metric that incorporates wild fish mortality during capture and excludes unfed systems raises the wild fish mortality-to-farmed fish output ratio to 0.57 to 1.78. We also evaluate terrestrial ingredients in aquaculture feeds. Widely cited estimates of declines in wild fish use from 1997 to 2017 entailed a trade-off of more than fivefold increase in feed crops over the same period. Our assessment challenges the sustainability of fed aquaculture and its role in food security.

A robust method for mapping soybean by phenological aligning of Sentinel-2 time series

Soybean is an important crop for food and animal feed. Production and area both continue to increase and expand into new areas and countries. Spatially explicit information on soybean cultivation is essential to crop monitoring, production estimation, and national accounting systems. However, its cultivation in diverse climate conditions, landscapes, and agricultural systems poses challenges to accurately map soybean across different regions and years. We propose an innovative soybean mapping method combining phenological alignment with machine learning (named here RF-DTW), which can be applied to diverse geographies and years by aligning phenological shifts and using distinctive features from Sentinel-2 time-series. The method first uses the dynamic time warping (DTW) algorithm to align the growing season between pixels across different sites. Then, based on the harmonized time-series, a set of distinctive features was identified and used to build random forest (RF) models to classify soybean across ten globally distributed sites and multiple years. Results show that the green chlorophyll vegetation index (GCVI), greenness and water content composite index (GWCCI), normalized difference senescent vegetation index (NDSVI), red edge position (REP), and short-wave infrared bands are important inputs for distinguishing soybean from other crops. Spectral-phenological features, particularly the curve slope metrics of GCVI and GWCCI during the peak to late growing season, rank as the most important features for mapping soybean. RF-DTW demonstrates good generalizability across ten study sites, achieving an overall accuracy (OA) of 0.92 and an F1-score of 0.84. F1-scores for eight out of ten sites ranged between 0.82 and 0.98, outperforming a benchmark method, although they were lower (F1-score < 0.60) for the two sites in Sub-Saharan Africa. Additionally, RF-DTW performs robustly when transferred to untrained regions and years, with most cases showing an F1-score higher than 0.70. Our proposed method, as a combination of phenological alignment and machine learning, can be used to map soybean accurately and efficiently across different regions and years, to provide crucial information for understanding the rapid dynamics of soybean cultivation and its global-scale impacts.

EVALUATION OF COMMERCIAL AND COLLECTION VARIETIES OF BARLEY FOR RESISTANCE TO MAJOR FUNGAL DISEASES IN FIELD CONDITIONS

Barley is an important grain feed crop. A significant amount of it is also used for the production of cereals and beer. Barley ranks fourth in the world in terms of sown area (about million hectares) and grain harvest. The volume of barley crops in the Republic of Kazakhstan is reaching 2 million hectare. In 2021-2023 on the experimental field of the Kazakh Research Institute of Agriculture and Plant Growing conducted a field assessment of the resistance of 216 varieties of winter and spring domestic barley origin to the most common fungal diseases in Kazakhstan Over three years of field research, it was possible to obtain objective data on the reaction to infection with a pathogen. Based on the results of phytopathological assessment, sources of resistance to major fungal diseases were selected among barley varieties. We divided the studied varieties into groups based on the degree of resistance (susceptibility) to the causative agents of fungal diseases, highly resistant (damage rate 0%) not detected, resistant: were discovered 59 varieties of winter and spring barley resistant to fungal diseases.

BIOLOGICAL AND ECOLOGICAL STATE OF COMMON SMUT (USTILAGO ZEAE) IN CORN SILAGE FIELDS IN THE KYZYLORDA REGION AND MEASURES TO COMBAT IT

Corn, as one of the most important grain feed crops, is of great importance in increasing gross grain yields. Corn smut (Ustilago zeae) can also cause large economic losses in susceptible sweet corn hybrids. Protection against this pathogen is mainly based on prevention. To date, many corn smut control methods have been recommended or evaluated, including crop rotation, sanitation, seed treatments, fertility modification, and biological control. Despite these frequently cited control strategies, host resistance appears to be the only effective control method for common smut in areas where Ustilago zeae is common. The purpose of the study is to study the resistance to smut against a natural infectious background of samples from a collection of corn from breeding nurseries in Kazakhstan. Based on the results of a study of the resistance of a corn collection to bladder smut against a natural infectious background, varieties were identified on whose plants symptoms of the disease were not detected: Altay 250 MV, Budan 237 MV, Tatty-2012 and Tayelsizdik-20 SV. The identified samples also had high productivity and grain yield. A high level of heritability (Hb2 – 0.85) of the disease susceptibility index among the studied samples was revealed.

Conventional and Molecular Improvement of Maize for Drought Tolerance: Research Review

Maize (Zea mays L.) is an important staple crop for food, feed, and industry globally. Despite the importance of maize as a principal food crop in developing countries, drought is a major constraint that affects maize production, particularly in Sub-Saharan Africa, where maize is grown under rainfed conditions. Plant breeders have been striving to improve and develop drought-tolerant crops. Nevertheless, these efforts still cannot meet the demand for food security due to fast population growth and climatic change. Conventional maize breeding for drought tolerance follows a diverse approach that includes recurrent selection, backcrossing, pedigree breeding, and subsequently evaluating inbred lines and hybrids at optimum conditions, a managed screening site, and random stress across multiple environments. Molecular markers were used to select donor parents with drought-adaptive alleles and then integrated into elite maize lines to create a new population of drought-tolerant inbred lines.

Measurement of maize stalk shear moduli.

Maize is the most grown feed crop in the United States. Due to wind storms and other factors, 5% of maize falls over annually. The longitudinal shear modulus of maize stalk tissues is currently unreported and may have a significant influence on stalk failure. To better understand the causes of this phenomenon, maize stalk material properties need to be measured so that they can be used as material constants in computational models that provide detailed analysis of maize stalk failure. This study reports longitudinal shear modulus of maize stalk tissue through repeated torsion testing of dry and fully mature maize stalks. Measurements were focused on the two tissues found in maize stalks: the hard outer rind and the soft inner pith. Uncertainty analysis and comparison of multiple methodologies indicated that all measurements are subject to low error and bias. The results of this study will allow researchers to better understand maize stalk failure modes through computational modeling. This will allow researchers to prevent annual maize loss through later studies. This study also provides a methodology that could be used or adapted in the measurement of tissues from other plants such as sorghum, sugarcane, etc.

Bioethanol production from groundnut shell using microorganisms derived from sugarcane root soil

Bioethanol is a form of renewable energy that can be produced from fuel or energy crops. Ethanol is produced by the fermentation of sugars present in agricultural feed stocks and crop residues. This study investigates the use of agro wastes like groundnut shells for ethanol production. Initially, the groundnut shells were washed, dried and grinded into powder. Then it was subjected to ethanol production using yeast. After 20 days of incubation the ethanol was estimated using potassium dichromate method. The maximum ethanol yield (1.55%) was obtained when 1% yeast was used. To increase the efficiency of ethanol production, the cellulolytic bacteria was isolated from the cow dung dumped soil site. The 10 bacterial isolates were screened for cellulase enzyme production. Among them one bacterium showed maximum decolourization of congored which was subjected for enzyme production in nutrient broth. The organism showed maximum enzyme activity of 558.12 U/ml. The isolated cellulolytic bacteria were identified as Bacillus anthracis using 16s rDNA sequencing. Ethanol production from the groundnut shells was again carried out with various concentration of crude cellulase enzyme isolated from the bacteria. The estimation result showed 3.8% of ethanol as maximum. Then the ethanol was condensed using a rotary evaporator and when again estimated, showed 7.3% of ethanol. Finally, the presence of ethanol was confirmed by iodoform test. Thus, groundnut shells can efficiently be used for the production of ethanol, which can be used as a high potential fuel source for transportation in the future.

Thermodynamic Sustainability Assessment of Turkish Cash and Feed Crops: Evaluations and Recommendations

ABSTRACTThis work analyzes the sustainability status of cash crops (rice, wheat, and sunflower) and feed crops (silage and clover) cultivation in Turkey through thermodynamic sustainability assessment technique, emergy analysis (EA). EA offers insights into agricultural system's dependence on external resources, environmental loading, and renewability by classifying the resources that drive agricultural production as renewable, nonrenewable, and purchased. Data belonging to 17 agricultural systems evaluated in this work are gathered through survey method by interviewing the farmers. EA results reveal that production of cash crops is essentially unsustainable due to high dependence on externally purchased inputs fertilizer, diesel, and nonrenewable input water. Of cash crops, rice production has the lowest system renewability and the highest environmental loading. In feed crops, silage production is mainly unsustainable and clover production is in transition state in terms of sustainability. Feed crop production creates less environmental loading than cash crop production mainly due to being partially integrated with husbandry. Coinciding with this, the level of organic fertilization is found to be the determining factor in the sustainability status of the feed crop systems. Transforming these systems to sustainable ones requires increasing system's self‐sufficiency through enhanced circularity (increased nutrient recycling) and functioning of natural processes. Consequently, we recommend growing crops in polycultures rather than monocultures to benefit from sister plant and predator–prey relations, integrating crop production with animal rearing (natural fertilization) and utilizing waste‐origin bioenergy. For resource efficiency, we suggest adopting methods such as drip irrigation and utilization of biodegradable polymer‐coated fertilizer grains to prevent fertilizer runoffs.

Understanding the chemical language mediating maize immunity and environmental adaptation.

Diverse networks of specialized metabolites promote plant fitness by mediating beneficial and antagonistic environmental interactions. In maize (Zea mays), constitutive and dynamically formed cocktails of terpenoids, benzoxazinoids, oxylipins, and phenylpropanoids contribute to plant defense and ecological adaptation. Recent research has highlighted the multifunctional nature of many specialized metabolites, serving not only as elaborate chemical defenses that safeguard against biotic and abiotic stress but also as regulators in adaptive developmental processes and microbiome interactions. Great strides have also been made in identifying the modular pathway networks that drive maize chemical diversity. Translating this knowledge into strategies for enhancing stress resilience traits has the potential to address climate-driven yield losses in one of the world's major food, feed, and bioenergy crops.

Integration of Conventional Breeding and Molecular Tools for Drought Tolerance in Maize: Review

Maize is an important staple crop for food, feed and industry globally. Despite the importance of maize as a principal food crop in developing country, drought is a major constraint that affects maize production, particularly in Sub-Saharan Africa where maize is grown under rainfed condition. Plant breeder has been striving to improve and develop drought tolerance crops. Nevertheless, these efforts still cannot meet the demand of food security due to fast population growth and climatic change. Secondary traits with associated to grain yield, advanced phenotyping, marker assisted selection/QTL, genomic wide association study and genomic selection methods are more expected to help for improvement of drought tolerance in maize. This article discussed the most secondary traits used for selection, plant physiological traits and crossing among drought tolerance elite lines and evaluation their segregants as well as hybrids performance under stress and optimum conditions. Emphasis also given to molecular dissection of drought tolerance complex trats using GWAS and /or gene discovery at hotspot regions for secondary traits, marker-assisted backcrossing and genome selection have been highlighted for increasing genetic gain in grain yield and predicating the breeding value for selection. Thus, further improvement is essential integration of conventional breeding and genomic tools for development of resilience maize varieties for drought tolerance in maize.

Occurrence of Maize Leaf Spot Disease Caused by Leptosphaerulina australis in Yunnan, China.

Maize (Zea mays) is vital as a staple food and livestock feed crop. Yunnan is one of the main maize-producing provinces in China (National Bureau of Statistics, 2022). While corn production in Yunnan is lower than the national average, the development of drought-tolerant varieties has contributed to improving productivity. In August 2021, a new leaf spot disease on maize was observed in Lancang, Yunnan (22°26'38.11"N to 22°48'38.68"N, 99°48'15.13"E to 99°59'20.03"E), causing serious damages to maize production with incidence up to 76.19 %. Initially, small light yellow lesions were seen scattered on diseased maize leaves, round or polygon, measuring 0.3 to 2.0 cm in diameter. In the intermediate phase, these lesions sank, ruptured, and turned white with dark brown borders. In severe cases, they merged into large irregular patches, reaching up to 10 cm, leading to complete leaf necrosis. Small black ascomata were seen on the lesions. Tissue sections reveal perithecium embedded in leaves, measuring 94~145 μm in diameter. Symptomatic tissues were sterilized in 1.5% NaClO for 60s, and washed twice withsterile purified water, then plated on potato dextrose agar (PDA) at 25℃, 90% relative humidity (RH), and a 12-hour light cycle. 6 isolates were obtained from 2 diseased maize cultivars. In 20 days, the colony reached the edge of the PDA plate, the center darkening from white, featuring white aerial mycelium on top and black on the reverse side. Brown ascomata, solitary or clustered, measured 80.1~176.7 × 55.57~138.9 μm. The ellipsoid to oblong ascospores were 17.9~39.7 × 10.9~14.1 μm, and the bitunicate, thick-walled asci were 90.1~133.3 × 26.6~33.5 μm. The genomic DNA was extracted using the Chelex-100 method (Möller et al. 1992). For molecular identification, the ITS, LSU, and β-tubulin (Tub2) genes were amplified using primer pairs ITS1/ITS4 (White et al. 1990), LR0R/LR5 (Vilgalys et al. 1990) and Btub2Fd/Btub4Rd (Woudenberg et al. 2009), respectively. Sequencing was performed by Sangon Biotech (Shanghai) Co., Ltd. The sequenced loci (GenBank accession nos.: LSU, OL687348-53; ITS, OL617009-10, and OL664058-61; Tub2, OL741678-83) of the isolates exhibited 100%/ 99%/ 100% similarities with L. australis genes: LSU, MH868885; ITS, KF381084; Tub2, GU237541, respectively. Using MEGA 11.0, phylogenetic trees were constructed using the maximum-likelihood algorithm on concatenated sequences of LSU, ITS, and Tub2 for isolates LCMB1 to 6. The isolates clustered with two L. australis strains with 100 % bootstrap support (1,000 replicates). The results were consistent with the Bayesian Inference tree. The pathogenicity test used strain LCMB4 on six healthy maize plants during the heading period under natural conditions. Three leaves pre-plant were wounded with sterile sandpaper and sprayed with conidial suspension (106 spores ml-1, diluted in sterilized water) in the greenhouse at 28℃, 90% RH, and a 12-hour light cycle, with sterilized distilled water used for control. Inoculated leaves developed symptoms consistent with the described after 10 days, while control leaves remained symptomless. The same pathogen was re-isolated from the infected leaves, fulfilling Koch's postulates. Previously, L. australis has been isolated from turfgrass (Mitkowski et al. 2004), Alfalfa (Zhang et al. 2021), soil (Li et al. 2018), and Paris polyphylla var. chinensis (Fu et al. 2019), but not from maize. This is the first report of L. australis causing leaf spot on maize globally.

Study on the metabolic changes and regulatory mechanism of Aspergillus flavus conidia germination.

Aspergillus flavus conidia are widespread in air; they attach to food and feed crops and secrete aflatoxins, which results in serious contamination. Germination of A. flavus conidia is the most critical step in contamination of food by A. flavus. This study aims to gain an insight into A. flavus conidia through dormancy to germination to provide a theoretical basis for inhibition of A. flavus conidia germination. The morphological changes and regulation mechanism of A. flavus conidia germination at 0, 4, 8, and 12 hours were observed. Transcriptomic and metabolomic analyses showed that conidia became active from dormancy (0 hour) to the initial stage of germination (4 hours), cellular respiration and energy metabolism increased, and amino acids and lipids were synthesized rapidly. The number of differentially expressed genes and differential metabolites was highest at this stage. Besides, we found that conidia germination had selectivity for different carbon and nitrogen sources. Compared with monosaccharides, disaccharides, as the only carbon source, significantly promoted the germination of conidia. Moreover, MepA, one of genes in the ammonium transporter family was studied. The gene deletion mutant ΔMepA had a significant growth defect, and the expression of MeaA was significantly upregulated in ΔMepA compared with the wild-type, indicating that both MepA and MeaA played an important role in transporting ammonium ions.IMPORTANCEThis is the first study to use combined transcriptomic and metabolomics analyses to explore the biological changes during germination of Aspergillus flavus conidia. The biological process with the highest changes occurred in 0-4 hours at the initial stage of germination. Compared with polysaccharides, monosaccharides significantly increased the size of conidia, while significantly decreasing the germination rate of conidia. Both MeaA and MepA were involved in ammonia transport and metabolism during conidia germination.