Soybean Stem Research Articles

Experimental modelling for phenotyping soybean host reaction to Aphelenchoides besseyi

Summary The nematode causing the green stem and foliar retention syndrome of soybean, Aphelenchoides besseyi, is a concern to Brazilian growers, especially in warm and humid climates, where losses can reach 60% of the yields. Management options have not yet been studied properly, but apparently genetic variability is found in soybean genotypes in the resistance to this nematode. However, the correct phenotyping of soybean genotypes is compromised by the scarcity of studies of this pathosystem. Therefore, the objective of this study was to evaluate the inoculum densities of A. besseyi and the plant ages at inoculation to obtain the correct phenotyping of soybean genotypes. Experiments were conducted under glasshouse conditions with the soybean ‘Elite’, using a completely randomised design and a factorial scheme (five nematode population densities: 150, 300, 600, 1200 and 2400 nematodes plant−1, and three plant ages at inoculation: 7, 12 and 17 days after planting). Evaluations were performed 35 days after inoculation, extracting nematodes from soil, roots and shoot parts of plants to obtain the final population of the nematodes of each replicate. The inoculum of 150-300 A. besseyi specimens per plant is the most suitable to assess the reaction of soybean genotypes to this nematode as it resulted in the greatest reproduction factors. Population densities higher than 1500 nematodes per plant could lead to misclassification of the host reaction because of the inconsistent reproduction factors obtained.

Shade-Tolerant Soybean Reduces Yield Loss by Regulating Its Canopy Structure and Stem Characteristics in the Maize-Soybean Strip Intercropping System.

The shading of maize is an important factor, which leads to lodging and yield loss of soybean in the maize–soybean strip intercropping system, especially in areas with low solar radiation. This study was designed to explore how shade-tolerant soybean reduces yield loss by regulating its canopy structure and stem characteristics in the maize–soybean strip intercropping system. The soybean cultivars Tianlong No.1 (TL-1, representative of shade-tolerant plants) and Chuandou-16 (CD-16, representative of shade-intolerant plants) were grown in monocropping and intercropping systems from 2020 to 2021 in Chongzhou, Sichuan, China. Regardless of shade-intolerant or shade-tolerant soybean, the canopy and stem of soybean in strip intercropping were weaker than those of the corresponding monoculture. But compared with shade-intolerant soybean, the shade-tolerant soybean slightly changed its spatial structure of canopy and stem morphology and physiology in maize–soybean strip intercropping system, especially in the later growth stages. On the one hand, the canopy of shade-tolerant soybean showed relatively high transmission coefficient (TC) and relatively low leaf area index (LAI) and mean leaf angle (MLA). On the other hand, the stem of shade-tolerant soybean was obviously stronger than that of shade-intolerant soybean in terms of external morphology, internal structure, and physiological characteristics. Additionally, compared with shade-intolerant soybean, shade-tolerant soybean showed higher APnWP (the average net photosynthetic rate of the whole plant) and seed yield in the strip intercropping. The results showed that shade-tolerant soybean increased light energy capture and photosynthesis in the different canopy levels to promote the morphological and physiological development of the stem and ultimately reduce the yield loss of the strip intercropping system. However, the molecular mechanism of low radiation regulating soybean canopy structure (LAI, TC, and MLA) needs further in-depth research to provide theoretical guidance for cultivating plants with ideal canopy shape that can adapt to changing light environment in intercropping system.

Experimental investigation on biomass gasification mechanism in supercritical water for poly-generation of hydrogen-rich gas and biochar

Supercritical water gasification (SCWG) technology can realize efficient utilization of biomass. But the gasification mechanism of real biomass is relatively complicated, and complete gasification only can be realized at a relatively high temperature. Identifying reaction mechanism and realize resource utilization of biomass via SCWG technology at a more moderate condition is necessary for industrialization of this technology. In this paper, biomass gasification experiment was conducted, and the gasification mechanism was analyzed. Experiment in quartz tube reactor showed that gasification efficiency and hydrogen yield increased with time and temperature, which reached 90% 14.95 mol/kg at temperature of 700℃, reaction time of 30 min. Carbon distribution study showed that more than 90% carbon was distributed in gas and biochar, proving that SCWG could realize cogeneration of hydrogen and biochar. Thus, experiment was conducted in batch tank reactor to obtain enough liquid and solid products for further study. Reaction mechanism study showed that soybean stem was decomposed to cellulose, hemicellulose, and lignin; then cellulose and hemicellulose were converted to small molecule sugar, which can be further converted to gas; as for lignin, it was decomposed to its monomers first, then it went through de-methoxy reactions and formed gases and phenol; phenol was difficult to be decomposed and could form biochar easily. Study of pore structure evolution of biochar showed that gasification in SCW could produce abundant pore structure, and with gasification proceeding, content of pores increased greatly. Pore size of biochar obtained from gasification of 15 min mainly focused on 6.5 nm and 16 nm. More mesopore were formed at the higher temperature and the diameter of macropore size increased with temperature due to the release of volatiles.

Phytophthora sojae Pathotype Distribution and Fungicide Sensitivity in Michigan.

Identifying the pathotype structure of a Phytophthora sojae population is crucial for the effective management of Phytophthora stem and root rot of soybean (PRR). P. sojae has been successfully managed with major resistance genes, partial resistance, and fungicide seed treatments. However, prolonged use of resistance genes or fungicides can cause pathogen populations to adapt over time, rendering resistance genes or fungicides ineffective. A statewide survey was conducted to characterize this pathotype structure and fungicide sensitivity of P. sojae within Michigan. Soil samples were collected from 69 fields with a history of PRR and fields having consistent plant stand establishment issues. Eighty-three isolates of P. sojae were obtained, and hypocotyl inoculations were performed on 14 differential soybean cultivars, all of which carry a single Rps gene or no resistance gene. The survey identified a loss of effectiveness of Rps genes 1b, 1k, 3b, and 6, compared with a previous survey conducted in Michigan from 1993 to 1997. Three effective resistance genes were identified for P. sojae management in Michigan; Rps 3a, 3c, and 4. Additionally, the effective concentration of common seed treatment fungicides to inhibit mycelial growth by 50% (EC50) was determined. No P. sojae isolates were insensitive to the tested chemistries with mean EC50 values of 2.60 × 10-2 μg/ml for ethaboxam, 3.03 × 10-2 μg/ml for mefenoxam, 2.88 × 10-4 μg/ml for oxathiapiprolin, and 5.08 × 10-2 μg/ml for pyraclostrobin. Results suggest that while there has been a significant shift in Rps gene effectiveness, seed treatments are still effective for early season management of this disease.

First Report of Pod and Stem Blight and Seed Decay Caused by Diaporthe longicolla on Soybean in Western Canada

In Oct. 2019, soybean plants (Glycine max) (cv. 24-10RY, R7 growth stage) with dry rot, necrosis, reddish-brown lesions, and small black fruiting bodies in linear rows were collected from fields in Manitoba (Carman, St. Adolph, Dauphin), Canada. The pods and seeds were shrivelled, small and some seeds were covered with whitish mycelium. Symptoms began as brown lesions, which darkened, elongated, causing wilt of the above stems then plant death. Microscopy showed that the fruiting bodies were pycnidia. Symptomatic stems were cut into 1-2 cm pieces and seeds surface-sterilized in 0.5% NaOCl, rinsed twice in sterilized H2O, air-dried on sterilized filter paper, and plated on PDA medium amended with 100 mg/L streptomycin sulfate at room temperature with 12-h fluorescent light/12-h dark for 3 days. The emerging hyphae were transferred using the hyphal tip method to new PDA petri dishes and incubated for 21 days (room T°). Mycelia of 20 isolates were dense, white and floccose with occasional green-yellow areas. Black stromata in concentric patterns or scattered as large masses were visible on the cultures' back. Pycnidia formed solely or aggregated after 4-5 weeks of incubation on PDA. Alpha conidia emanated from pycnidia in creamy-to-yellowish drops and were hyaline, non-septate, ellipsoid to fusiform, and biguttulate. The average length and width of Alpha conidia were 5.5 μm and 1.5 μm, respectively (n = 30). No perithecia were seen. The cultures' morphology was consistent with Phomopsis longicolla's description (Hobbs et al., 1985). Seven isolates were selected for molecular characterization to confirm their identity by amplifying the ITS region with universal primers ITS4/ITS5 (White et al. 1990). All PCR amplicons were analyzed by electrophoresis through 1.5 % agarose gels and the size of PCR amplicons estimated using 1-kb plus DNA ladder (Thermo Fisher Sci., ON, Canada). PCR amplicons (~650 bp) were purified and sequenced in two directions by Psomagen Inc. (Rockville, MD, USA). ITS sequences were identical for all isolates, and GenBank searches (BLASTn: Altschul et al. 1990) confirmed species identity. ITS sequences (accessions MW466183-MW466189) were deposited in GenBank and matched the type sequence of Diaporthe longicolla strain ATCC 60325 (accession NR_144924) from G. max in USA with identities = 473/475 (99.6%) and gaps = 0/475 (0%). To confirm the pathogenicity of the seven isolates, the stems of V4-stage (four open trifolilates) soybean plants (cv. 24-10RY) were excised using a sterile scalpel. Mycelial plugs (9 mm in diameter) from 1-week-old culture of each isolate were placed over the wounded stems (Abdelmagid et al., 2019). Sterile PDA plugs were used on control plants. Six plants were used per isolate and control. Plugs of both treatments were wrapped with parafilm to avoid drying. The plants were incubated in a humidity chamber for 4 days and then in a greenhouse at 24:16°C day/night, 13:11-h light/dark cycle, and 70-80% relative humidity, and were irrigated as needed. Symptoms similar to those observed in the field were seen on the stems and seeds of all artificially-infected plants approx. 8 weeks after inoculation. Pods and seeds of inoculated plants were shrivelled and small. No symptoms were observed on control plants. Diaporthe longicolla was re-isolated only from the diseased plants and seeds. To our knowledge, this is the first report following Koch's postulates to identify the causal pathogen of soybean pod and stem blight and seed decay in Western Canada. This will be instrumental in determining the causes of stem decay and contribute in properly dealing with soybean seed issues in Western Canada in the future.

Carbon assimilation and dry matter partitioning in soybean ameliorates with the integration of nano-black carbon, along with beneficial microbes and phosphorus fertilization

The immobility of phosphorus (P) and its precipitation in the soil is a major fact and remains in place where P fertilizer applied. Without organic amendments and beneficial microbes, P availability is limited in the current season crop. To increase crop productivity and P availability, field experiments were conducted at Agriculture Research Institute Mingora Swat (ARI) for two consecutive years in the summer season (2016 and 2017). The main objective of this research work was to evaluate the impact of peach based residues (partially decomposed, compost, and Nano-black carbon), three P levels (50, 75, 100 kg P ha−1), and two beneficial microbes, [phosphate solubilizing bacteria (PSB) and fungi (Trichoderma)] on soybean. Experimental outcomes revealed dry matter partitioning and dry weight in soybean stem, leaves, and pods amplified with peach organic amendments and carbon sequestration in soil. Dry weight and partitioning in leaf, stem, pods, and total plant considerably improved with combined application of peach Nano-black carbon, soil application of Trichoderma, and 100 kg P ha−1 in both stages combine over the two years. It is suggested to enhance P availability in soil, Nano-black carbon and soil application of Trichoderma might be effective with 100 kg P ha−1 for optimum plant growth, yield, and yield contributing traits.

Santino’s growth chamber: A chamber for studies with Aphelenchoides besseyi on plants

The soybean green stem and foliar retention syndrome (GFSR) [1], caused by Aphelenchoides besseyi, is reported in Brazilian fields located at the States of Mato Grosso, Pará, Amapá, Tocantins, and Maranhão, which correspond to warm climates with well-defined rainfall patterns when the air humidity is high during several consecutive days. Studies showed that the infection of plants by A. besseyi occurs in regions with a high frequency of rains and under temperatures higher than 28 °C, when the nematode founds adequate conditions to migrate from soil to shoot parts of plants to initiate its parasitism [2]. One of the challenges was the difficulty in simulating the natural conditions for the disease development, which needs luminosity, high temperatures, and moisture. These conditions can be reproduced using modern growth chambers, but these equipment are onerous and scarce in most Brazilian research centers. So, for the studies with A. besseyi and different plant hosts, it is difficult to reproduce the environmental conditions similar to those found in the field where this nematode is reported, especially under the operational and economic points of view. Considering these environmental conditions and the necessity in conducting studies under controlled environments with this pathossystem aiming a detailed investigation about the symptoms and the nematode parasitism, but also to isolate the effects due to exclusively the nematode parasitism instead of other effects that occur under field conditions, especially in crops like soybean, common bean, and cotton [1–4], the objective of this project was to develop a growth chamber for the cultivation of these plants under controlled environmental, simulating the necessary conditions for the GFSR development. For this, we used an environmental chamber [5] as the base to our project, where we could find the important aspects that need to be adjusted to suit our purpose.•We developed a plant growth chamber to be used under greenhouse conditions for the studies with Aphelenchoides besseyi and different host plants.•The soybean green stem and foliar retention syndrome (GFSR) needs specific environmental conditions of humidity and temperature for the development of the characteristic symptoms and for the nematode multiplication in the parasitized plants.•This method simulates adequately the environmental conditions found in the field, since the chamber is installed inside a greenhouse, assuring the reliable observation of the plant behavior in relation to the pathogen and allowing the conduction of experiments of this nature in regions different from those where the disease naturally occurs.

Secondary Metabolites Produced by Xylaria necrophora Are Responsible for Foliar Symptoms Associated with Taproot Decline of Soybean

Taproot decline (TRD) of soybean ( Glycine max [L] Merr.) is an emerging disease caused by Xylaria necrophora and currently observed in the southern United States. X. necrophora infects soybean roots, causing necrosis and foliar interveinal chlorosis followed by necrosis. The most recent estimates of yield losses associated with this disease (0.57 to 1.18 million bushels) highlight its potential to become a major problem for producers in the region. The mechanism by which X. necrophora affects soybean foliage remains unknown, but a plausible explanation is that phytotoxic secondary metabolites (SMs) are produced by X. necrophora in the roots. To test this hypothesis, cell-free culture filtrates (CFCFs) from three X. necrophora strains and one putative Colletotrichum siamense isolate were used to challenge soybean stem cuttings to determine if foliar symptoms of TRD are caused by SMs, tolerance to SMs among potentially resistant soybean cultivars identified in greenhouse and field experiments, and specificity of SMs across plant species (cotton, peanut, tomato, and soybean). Measurements of chlorophyll content and root length were obtained at 7 and 14 days of exposure. Lower chlorophyll content and shorter roots were observed on all soybean cultivars treated with CFCFs of pathogenic isolates, and no effects on other plant species were observed, suggesting that X. necrophora produces SMs that are detrimental to soybean exclusively and resistance upon direct exposure to SMs does not exist. These results suggest that soybean-specific SMs are produced by X. necrophora in the roots, causing the interveinal chlorosis and subsequent necrosis observed on plants affected by TRD.

TECHNOLOGY AND AGROECOLOGICAL STABILITY OF RAPID VARIETIES OF SOYBEAN

According to the duration of the growing season, early maturing and ultra early maturing varieties of soybeans develop within 83-85 days. As of 2021, 17 early-maturing and ultra-early-maturing soybean varieties were entered into the State Register of Plant Varieties of Ukraine. Most of these varieties have a growing season of 85 days, and only the Diona varieties have 83 days and Arnika - 84 days. The height of plants of early maturing soybean varieties varies widely - 58-110 cm. The highest are Arrata plants - 110 cm, Rogiznyanka and Rozhdestvenskaya - 81 cm each, OAC Avatar and Diona - 80 cm each. Height of attachment of the lower beans in early maturing soybean varieties is 10-16 cm from the soil surface. Above, the lower beans are attached in soybean varieties OAC Brook - 16 cm, Rogiznyanka - 15 cm, Kobza and OAC Avatar - 14 cm each. The highest resistance to lodging, which determines the completeness of mowing and selection of the soybean stem mass, had plants of the varieties Aventurin, OAC Lakeview, Geba and Berkana - 9.0 points each, OAC Avatar Rogiznyanka - 8.9 points each. All early ripening varieties of soybeans are highly resistant to seed shedding - 7.0-9.0 points. The most drought-resistant varieties are OAC Lakeview, Geba, Berkana - 9.0 points each. Soybean varieties Aventurine, Kobza, Diona, Arrata, Rogiznyanka, Arnika are resistant to diseases - 9.0 points each. The seed yield of early maturing soybean varieties is 2.00-3.25 t/ha. The highest yields were noted for the Diona varieties - 3.25 t/ha, Arrata - 3.0 t/ha. The least productive varieties are Rogiznyanka - 2.00 t/ha, OAC Brook - 2.03 t/ha, Kobza - 2.14 t/ha. Soybean varieties had a high protein content in seeds: Berkana - 43.4%, Raduga - 42.3%, Dove and Melody - 42.1% each. The lowest protein content was in the varieties Arrata - 38.0%, Legend, Diona - 38.5% each, Kobza - 39.1%. The fat content in the seeds of soybean varieties Heba - 22.0%, OAC Lakeview - 21.7% and Golubka - 21.6% was the highest, and in Krasavitsa varieties - 19.3%, Arnika - 20.5% and Melodiya - 20.6% - the smallest.

First report of Diaporthe ueckerae causing stem canker on soybean (Glycine max L.) in Colombia.

In October 2018, soybean plants displaying elongated black to reddish-brown lesions on stems were observed in a field planted to the cv. BRS Serena in the locality of Puerto López (Meta, Colombia), with 20% incidence of diseased plants. Symptomatic stems were collected from five plants, and small pieces (∼5 mm2) were surface sterilized, plated on potato dextrose agar (PDA) and incubated for 2 weeks at 25°C in darkness. Three fungal isolates with similar morphology were obtained, i.e., by subculturing single hyphal tips, and their colonies on PDA were grayish-white, fluffy, with aerial mycelium, dark colored substrate mycelium, and produced circular black stroma. Pycnidia were globose, black, occurred as clusters, embedded in tissue, erumpent at maturity, with an elongated neck, and often had yellowish conidial cirrus extruding from the ostiole. Alpha conidia were observed for all isolates after 30 days growth on sterile soybean stem pieces (5 cm) on water agar, under 25ºC and 12 h light/12h darkness photoperiod. Alpha conidia (n = 50) measured 6.0 - 7.0 µm (6.4 ± 0.4 µm) × 2.0 - 3.0 µm (2.5± 0.4 µm), were aseptate, hyaline, smooth, ellipsoidal, often biguttulate, with subtruncate base. Beta conidia were not observed. Observed morphological characteristics of these isolates were similar to those reported in Diaporthe spp. by Udayanga et al. (2015). DNA from each fungal isolate was used to sequence the internal transcribed spacer region (ITS), and the translation elongation factor 1-α (TEF1) gene, using the primer pairs ITS5/ITS4 (White et al. 1990) and EF1-728F/EF1- 986R (Carbone & Kohn, 1999), respectively. Results from an NCBI-BLASTn, revealed that the ITS sequences of the three isolates (GenBank accessions MW566593 to MW566595) had 98% (581/584 bp) identity with D. miriciae strain BRIP 54736j (NR_147535.1), whereas the TEF1 sequences (GenBank accessions MW597410 to MW597412) had 97 to 100% (330-339/339 bp) identity with D. ueckerae strain FAU656 (KJ590747). The species Diaporthe miriciae R.G. Shivas, S.M. Thomps. & Y.P. Tan, and Diaporthe ueckerae Udayanga & Castl. are synonymous, with the latter taking the nomenclature priority (Gao et al. 2016). According to a multilocus phylogenetic analysis, by maximum likelihood, the three isolates clustered together in a clade with reference type strains of D. ueckerae (Udayanga et al. 2015). Soybean plants cv. BRS Serena (growth stages V3 to V4) were used to verify the pathogenicity of each isolate using a toothpick inoculation method (Mena et al. 2020). A single toothpick colonized by D. ueckerae was inserted directly into the stem of each plant (10 plants per isolate) approximately 1 cm below the first trifoliate node. Noncolonized sterile toothpicks, inserted in 10 soybean plants served as the non-inoculated control. Plants were arbitrarily distributed inside a glasshouse, and incubated at high relative humidity (>90% HR). After 15 days, inoculated plants showed elongated reddish-brown necrosis at the inoculated sites, that were similar to symptoms observed in the field. Non-inoculated control plants were asymptomatic. Fungal cultures recovered from symptomatic stems were morphologically identical to the original isolates. This is the first report of soybean stem canker caused by D. ueckerae in Colombia. Due to the economic importance of this disease elsewhere (Backman et al. 1985; Mena et al. 2020), further research on disease management strategies to mitigate potential crop losses is warranted.

Interaction of Phytophthora sojae Effector Avr1b With E3 Ubiquitin Ligase GmPUB1 Is Required for Recognition by Soybeans Carrying Phytophthora Resistance Rps1-b and Rps1-k Genes.

Phytophthora sojae is an oomycete that causes stem and root rot disease in soybean. P. sojae delivers many RxLR effector proteins, including Avr1b, into host cells to promote infection. We show here that Avr1b interacts with the soybean U-box protein, GmPUB1-1, in yeast two-hybrid, pull down, and bimolecular fluorescence complementation (BIFC) assays. GmPUB1-1, and a homeologous copy GmPUB1-2, are induced by infection and encode 403 amino acid proteins with U-Box domains at their N-termini. Non-synonymous mutations in the Avr1b C-terminus that abolish suppression of cell death also abolished the interaction of Avr1b with GmPUB1-1, while deletion of the GmPUB1-1 C-terminus, but not the U box, abolished the interaction. BIFC experiments suggested that the GmPUB1-1-Avr1b complex is targeted to the nucleus. In vitro ubiquitination assays demonstrated that GmPUB1-1 possesses E3 ligase activity. Silencing of the GmPUB1 genes in soybean cotyledons resulted in loss of recognition of Avr1b by gene products encoded by Rps1-b and Rps1-k. The recognition of Avr1k (which did not interact with GmPUB1-1) by Rps1-k plants was not, however, affected following GmPUB1-1 silencing. Furthermore, over-expression of GmPUB1-1 in particle bombardment experiments triggered cell death suggesting that GmPUB1 may be a positive regulator of effector-triggered immunity. In a yeast two-hybrid system, GmPUB1-1 also interacted with a number of other RxLR effectors including Avr1d, while Avr1b and Avr1d interacted with a number of other infection-induced GmPUB proteins, suggesting that the pathogen uses a multiplex of interactions of RxLR effectors with GmPUB proteins to modulate host immunity.

First report of soybean stem blight caused by Diaporthe phaseolorum in Sichuan province, China.

In September 2020, a disease resembling stem blight on soybean was found in Chengdu city, Sichuan province, southwestern of China. Symptoms began as a brown lesion on the stems, usually at the nodes, then lesions expanded, darkened, and even girdled the stems, causing wilt of the above stems (Figure 1A). In three 0.33-ha fields, a total of 300 soybean plants (20 plants/site × 5 sites/filed × 3 fields) were investigated, and 3% of the plants showed the disease symptoms. The symptoms were consistent with those previously reported for stem canker and stem blight on soybean caused by Diaporthe complex (Cui et al. 2009; Mena et al. 2019; Santos et al. 2011). The tissues of symptomatic soybean stems were rinsed by water, disinfected by submerging them in 75% ethanol for 30 s and in 2% sodium hypochlorite solution for 2 min, then followed by washing with sterile distilled water. Small diseased tissue fragments were placed on selective potato dextrose agar (PDA) containing rifampicin and ampicillin (both 50 mg/μl). Plates were sealed and incubated at 26°C for two days. Developing mycelia of isolates were transferred to fresh PDA and purified by single hyphal tip. For the five obtained isolates (Figure 1B), five markers, including the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA, parts of the translation elongation factor 1-α (TEF1), part of the histone H3 (HIS) gene, the calmodulin gene (CAL), and the beta-tubulin gene (TUB), were amplified using the established primers ITS4/ITS5 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), CYLH3F (Crous et al. 2006) and H3-1b (Glass and Donaldson 1995), CAL228F/CAL737R (Carbone and Kohn 1999), and Bt-2a/Bt-2b (Glass and Donaldson 1995), respectively, and sequenced (GenBank IDs: MW595761-MW595780 and MW624472-MW624476). Phylogenetic trees were constructed based on concatenated sequences of the five markers using the maximum-likelihood (ML) method in MEGA-5.2.2. Based the results of morphological (Figure 1C-E) and phylogenetic analysis (Figure 2), the five isolates were all identified as D. phaseolorum. Pathogenicity tests for the isolates were conducted on 7-day-old soybean seedlings (cv. Shangdou 1310) using a hypocotyl slit inoculation method. At the stem 2-cm below cotyledon, a 6-mm long slit was cut with a sterile scalpel, and placed inside with a 3 mm × 3 mm PDA plug with or without mycelia of pathogen. Ten plants were assayed for each treatment, and the plants were maintained in greenhouse at 26°C, with humidity higher than 90% for the first two days. The assay was repeated at least three times. Typical brown lesions on the stems were observed four days after inoculation (Figure 1F), even 20% treated plants died. The D. phaseolorum was reisolated from these stem lesions. No disease symptom was observed on control plants (Figure 1G). Thus D. phaseolorum was the pathogen causing the soybean stem blight in field. To our knowledge, this is the first report of D. phaseolorum causing this disease in Sichuan province, China. The result may provide useful information for soybean disease control in this region of China. The authors declare no conflict of interest. Funding: China Agriculture Research System (CARS-004-PS14).

Genome Sequence Resource of Phomopsis longicolla YC2-1, a Fungal Pathogen Causing Phomopsis Stem Blight in Soybean.

Diaporthe-Phomopsis disease complex causes considerable yield losses in soybean production worldwide. As one of the major pathogens, Phomopsis longicolla T. W. Hobbs (syn. Diaporthe longicolla) is not only the primary agent of Phomopsis seed decay but is also one of the agents of Phomopsis pod and stem blight and Phomopsis stem canker. We performed both PacBio long-read sequencing and Illumina short-read sequencing and obtained a genome assembly for the strain P. longicolla YC2-1, which was isolated from soybean stem with Phomopsis stem blight disease. The 63.1 Mb genome assembly contains 87 scaffolds, with a minimum, maximum, and N50 scaffold length of 20 kb, 4.6 Mb, and 1.5 Mb respectively, and a total of 17,407 protein-coding genes. The high-quality data expand the genomic resource of P. longicolla species and will provide a solid foundation for a better understanding of their genetic diversity and pathogenic mechanisms.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Production of briquettes from Indonesia agricultural biomass waste by using pyrolysis process and comparing the characteristics

Indonesia biomass waste is a potential feedstock as a source of renewable energy since it can be converted into carcoal briquettes. However, the production of the briquettes using pyrolysis process using the agricultural waste was lacking. In this research, briquette was made from palm shells, corncob and soybean stem wood due to its high availability and have high cellulose content. The purpose of this research was to produce briquettes from three kind of raw materials by employing pyrolysis process and compared the characteristics. The briquette was made from different type of raw materials (palm shells, corncob and soybean stem) and the concentration of binder : 3-7 %. Pyrolysis was done at 500 °C, and 100 kg / cm2 of pressing pressure. Results showed that, the best charcoal briquette was achieved from palm shells by using 5% binder, which resulted 4,1% moisture content, 3.4% ash content, 15% volatile matter content, 77.5% carbon content, 7075 cal/g calorific value and 1.4 kg/cm2 compresive strength. It is found that the concentration of binder and raw material influenced the quality of the briquettes. In overall, the production of the briquettes by employing pyrolysis method could meet the standard.

Effect of Ti treatments on growth, photosynthesis, phosphorus uptake and yield of soybean (Glycine max L.) in maize-soybean relay strip intercropping

Shade is the main growth and yield limiting factor for soybean seedlings in maize-soybean relay strip intercropping. Therefore, a field experiment was conducted to investigate the effect of titanium (Ti) foliar application on soybean under a maize-soybean relay strip intercropping system. In this study, the soybean plants were sprayed with Ti treatments (T0S = 0, T1S = 125, T2S = 250, T3S = 500 and T4S = 1000 mg L−1) under maize-soybean relay strip intercropping. The results have indicated that under intercropping environment, Ti application significantly affected the growth of the plants. The soybean plants supplied with Ti treatment (T1S) significantly improved soybean diameter and stem strength at both V5 and R5 stages. Ti application resulted in a significant increase in SPAD values in T1S (i.e. 31.69 % and 21.21 %) and T2S (i.e. 21.55 % and 22.19 %) in comparison to control at both V5 and R5 stage, respectively. Furthermore, foliar application of Ti (T1S) significantly increased photosynthetic rate by 33.15 % and 22.80 % at both V5 and R5 stages. The stomatal conductance (Gs) increased significantly in T1S (44.39 %) and T2S (31.30 %) at the V5 stage and in T1S (29.85 %) at the R5 stage, respectively in comparison to control leading to increase root and shoot biomass in both V5 and R5 stages except for treatment T4S. Analysis of stem anatomical structure, stem strength (lodging resistance), and phosphorus content revealed that foliar application of Ti not only improved the shade tolerance but also increased yield (16–17 %) of soybean under maize-soybean relay strip intercropping. Conclusively, foliar application of Ti could be helpful in mitigating the shade stress and increasing soybean yield under the strip intercropping system.

QTL mapping of the genetic basis of stem diameter in soybean.

QTL mapping of stem diameter was carried out in three RIL populations using a high-density genetic map, and candidate genes related to stem diameter were predicted. Stem diameter is an important agronomic trait affecting soybean lodging and productivity. However, this trait is underexploited, and the underlying genetic mechanism in soybean remains unclear. In this study, three recombinant inbred line (RIL) populations, including 156 F10 lines from Nannong 94-156 × Bogao (N × B), 127 F9 lines from Dongnong 50 × Williams 82 (D × W), and 146 F9 lines from Suinong 14 × Enrei (S × E), were used to identify QTLs for soybean stem diameter across multiple environments. Phenotype analysis revealed that stem diameter exhibited strong positive correlations with plant height and 100-seed weight, two of the most important yield components. A total of 12 QTLs for stem diameter were identified on eight chromosomes across three RIL populations and five environments. The most influential QTL that was stably identified across all the populations and environments, q11, explained 12.58-26.63% of the phenotypic variation. Detection of several environment-specific QTLs, including q14, q16, and q20, suggests that environments may also have important effects in shaping the natural variation in soybean stem diameter. Furthermore, we predicted candidate genes underlying the QTLs and found that several promising candidate genes may be responsible for the variation in stem diameter in soybean. Overall, the markers/genes linked closely or underlying the major QTLs may be used for marker-assisted selection of soybean varieties to enhance lodging resistance and even yield. Our results lay the foundation for the fine mapping of stem development-related genes to reveal the molecular mechanisms.

GmBTB/POZ promotes the ubiquitination and degradation of LHP1 to regulate the response of soybean to Phytophthora sojae

Phytophthora sojae is a pathogen that causes stem and root rot in soybean (Glycine max [L.] Merr.). We previously demonstrated that GmBTB/POZ, a BTB/POZ domain-containing nuclear protein, enhances resistance to P. sojae in soybean, via a process that depends on salicylic acid (SA). Here, we demonstrate that GmBTB/POZ associates directly with soybean LIKE HETEROCHROMATIN PROTEIN1 (GmLHP1) in vitro and in vivo and promotes its ubiquitination and degradation. Both overexpression and RNA interference analysis of transgenic lines demonstrate that GmLHP1 negatively regulates the response of soybean to P. sojae by reducing SA levels and repressing GmPR1 expression. The WRKY transcription factor gene, GmWRKY40, a SA-induced gene in the SA signaling pathway, is targeted by GmLHP1, which represses its expression via at least two mechanisms (directly binding to its promoter and impairing SA accumulation). Furthermore, the nuclear localization of GmLHP1 is required for the GmLHP1-mediated negative regulation of immunity, SA levels and the suppression of GmWRKY40 expression. Finally, GmBTB/POZ releases GmLHP1-regulated GmWRKY40 suppression and increases resistance to P. sojae in GmLHP1-OE hairy roots. These findings uncover a regulatory mechanism by which GmBTB/POZ-GmLHP1 modulates resistance to P. sojae in soybean, likely by regulating the expression of downstream target gene GmWRKY40.

Efficient Agrobacterium tumefaciens-mediated transformation system of Diaporthe caulivora

This is the first report describing the genetic transformation of Diaporthe caulivora, the soybean stem canker fungus. A simple and 100% efficient protocol of Agrobacterium tumefaciens-mediated transformation used mycelium as starting material and the hygromycin B resistance and green fluorescent protein (GFP) as a selection and reporter agents, respectively. All transgenic isolates were mitotically stable in two independent experiments and polymerase chain reaction with hygromycin B resistance primers confirmed successful T-DNA integration into the fungal genome. Plant-fungus interaction studies, including pathogenicity, latency, and endophytism, as well as further studies of random and targeted mutagenesis will be possible with GFP-expressing isolates of D. caulivora and other species in the Diaporthe / Phomopsis complex.

Aphelenchoides besseyi Parasitizing Common Bean in Brazil.

Aphelenchoides besseyi is the causal agent of soybean green stem and foliar retention syndrome known as "Soja Louca II." This nematode has recently been reported parasitizing cotton in Brazil. In Costa Rica, it causes the symptoms known as "amachamiento" and false angular spots in common bean (Phaseolus vulgaris). Due to the great importance of beans to Brazilian agriculture, the objective of this research was to study the pathogenicity of A. besseyi in common bean under greenhouse conditions, including its endoparasitic relationships by staining root and shoot system tissues with fuchsin acid. In addition, A. besseyi was collected and quantified from shoot systems 30 days after inoculation by washing the tissue in water and blender centrifugal flotation. We observed the symptoms of amachamiento, leaf and vein deformation in the expanded trifoliate leaves, and also leaves with necrotic, brown to reddish and angular lesions, characteristics from false angular spot, and deformed stems characterized by enlargement of nodes, retortions, and necrotic lesions. High numbers of nematodes were found inside common bean plants. This is the first report of the pathogenicity and symptoms caused by A. besseyi in common bean in Brazil. These findings are important for development of management strategies to avoid losses on bean cropped in infested areas.

Effects of Biostimulants on Primary and Secondary Substance Contents in Lettuce Plants

Lettuce (Lactuca sativa L.) is not only easy to grow, but it is also common in diets around the world. This study was conducted to determine the impact of Chinese chive (Allium tuberosum Rottler), soybean (Glycine max L.) leaf, and soybean stem extracts on lettuce plants’ secondary substances, minerals, amino acids, and free sugars. This study was carried out in order to better understand which types of plant extract applications are most effective in increasing lettuce plants’ nutritional value. While not all applications produced an increased nutritional value in the lettuce plants, we found that soybean leaf extract treatments increased the Mg and Ca contents and Chinese chive treatments increased the Fe contents in the lettuce plants. Additionally, glucose and maltose contents in lettuce plants were higher after treatments of Chinese chive and soybean leaf extracts. Finally, all selected extracts increased the total and free amino acid levels in our test plants.