Black Stem Research Articles

First Report of Fusarium fujikuroi Causing Black Stem Rot of Zanthoxylum bungeanum in China.

Chinese prickly ash (Zanthoxylum bungeanum Maxim.), native to China, is an important tree species for soil and water conservation, barren mountain afforestation, and garden greening. Its fruit is commonly used for seasoning and medicine. In August 2016, black stem rot of Z. bungeanum was first observed in Hanyuan County, Ya'an City. In June 2019, the symptoms were observed on > 60% of 10,000 plants in Hanyuan County. At its early stage, the bark was wet and rotten, slightly concave, and accompanied by gummosis. The lesions were dark brown and long oval, peeling off the rotten bark covered with white hyphae. At the later stage, the lesions shrunk and cracked, with many orange-red particles (conidia) and dense black particles (ascospores). Larger lesions often caused large-scale bark necrosis. After the lesions girdled the trunk, the plants rapidly died. A total of 36 isolates were isolated from 320 infested tissue fragments (5 × 5 mm) that were surface sterilized for 60 s in 3% sodium hypochlorite, and 60 s in 75% ethanol, rinsed three times in sterilized water, placed onto potato dextrose agar (PDA) amended with streptomycin sulfate (50 µg/ml), and incubated in the dark at 25°C. Among them, 28 exhibited morphological characteristics described as Fusarium fujikuroi Nirenberg. On PDA, the fungus produced white to grey orange, circular colonies. On carnation leaf agar (CLA), the microconidia were club shaped with a flattened base and 0 to 1 septum, 5 to 15 × 2 to 4 μm in size, whereas macroconidia were relatively slender, medium length with no significant curvature, and had a tapered apical cell and a poorly developed, notched basal cell, 3 to 5 septa, 20 to 50 × 3 to 5 μm in size. For molecular identification, DNA was extracted from a representative isolate using a fungus genomic DNA extraction kit (Solarbio, Beijing). PCRs were performed with primers EF1f/EF2r for translation elongation factor 1α (EF-1α) region, and primers 5f2/7cr for RNA polymerase II genes (RPB2) region. PCRs were amplified and their products (GenBank accession nos. MT448248 and MT448247) were sequenced and blasted, showing 99 to 100% sequence homology with known F. fujikuroi isolates (GenBank accession nos. MN102101.1 and MN193888.1). To conduct pathogenicity test, twigs of 42 three-year-old potted Z. bungeanum plants were superficially wounded with a needle on the cortex, and each twig was inoculated by dropping a 100 µl conidial suspension (1×106 conidia/ml) of the fungus onto its wound surface. The inoculated areas were bandaged with gauze moistened with sterilized water. The wounded wigs that were inoculated with sterilized water served as the controls. Treated plants were maintained in a greenhouse with temperature ranging from 22 to 29°C and RH from 70% to 80%. One month later, 100% of inoculated plants showed the symptoms similar to those observed in the field, with the size of lesions ranging from 0.5 to 1.0 cm2. The fungus was re-isolated from the branch cortexes and confirmed morphologically and molecularly. To our knowledge, this is the first report of F. fujikuroi as a causal agent of black stem rot disease on Z. bungeanum in China. These results will help correctly identify this disease and develop proper strategies to manage the disease.

Identification, Pathogenicity, and Fungicide Sensitivity of Ascochyta caulina (Teleomorph: Neocamarosporium calvescens) Associated with Black Stem on Quinoa in China.

Quinoa black stem is a new disease that affects the stems of quinoa plants and is more likely to develop under cool conditions (15 to 25°C, RH = 55 ± 2%). The typical symptoms include the formation of black necrotic lesions on the stem, which can completely wrap around the stem, causing lodging and blanking (development of 'empty' and sterile grain on the panicle). Furthermore, the pycnidia form small round protrusions on the surface of the lesions. Phylogenetic analysis revealed that representative isolates LMHS-3 and LMHS-5 were closely related to Ascochyta caulina (teleomorph: Neocamarosporium calvescens). Comprehensive morphological and molecular characterizations confirmed A. caulina as the pathogen that caused quinoa black stem. A. caulina mainly infected quinoa stems and could produce many pycnidia, but it rarely infected quinoa leaves. Pathogenicity testing showed that the most suitable temperature for the onset of quinoa black stem was from 15 to 25°C. When the temperature was increased above 30°C, the conidial germination of A. caulina became malformed, and when the temperature was decreased below 5°C, mycelium growth of A. caulina became extremely slow; thus, both extreme high and low temperatures affected the pathogenicity of A. caulina. Mancozeb and azoxystrobin fungicides were revealed to have had the strongest inhibitory effects on the conidial germination of A. caulina, and in some cases caused malformations in conidial germination. Tebuconazole and difenoconazole had the strongest inhibitory effects on A. caulina mycelial growth and less on the effects on the conidial germination. The results of the present study provide a basis for the recognition and management of quinoa black stem.

First report of tobacco bacterial hollow stalk caused by Dickeya chrysanthemi (syn. Erwinia chrysanthemi) in Nanping, China.

Tobacco, Nicotiana tabacum L., family Solanaceae, is grown for its leaves (mature period). It originated in the Mesoamericas but today is cultivated globally. China produces about one-third of the world´s supply of tobacco leaves and is the largest tobacco producer in the world (Hu et al. 2007). In the early summer of 2019, after tobacco has been topped, typical tobacco hollow stalk disease symptoms were observed in two to five percent of the fields in Shaowu and Jianyang counties of Nanping, Fujian province, China. Symptoms consisted of lesions extending from the point of topping downward, resulting in a black hollow stem (harvest period). The symptoms were similar to tobacco hollow stalk disease caused by Pectobacterium species. Four infected stems of different tobacco plants were collected from Nanping (N 27°37'48″, E 118°2'24″) for isolation. Small sections from the stems were surface sterilized with 1% sodium hypochlorite for 3 min, rinsed three times in sterile distilled water (SDW), then macerated in 400 μl of SDW. The suspensions were then streaked on Nutrient agar (NA) and incubated at 28°C in darkness. After 2 days, two predominant isolates that produced circular, convex, small (< 1 mm) colonies without pigmentation, were purified. The BIOLOG GEN III Microplates system was then used to identify the putative pathogenic bacteria based on the results of the biochemical assays read by the plate reader and its associated software and database. After culturing for 48 and 60 h,BIOLOG analysis identified the two isolates as Dickeya chrysanthemi (SIM=0.516, DIST=7.224 and SIM=0.589, DIST=5.984). To confirm its identification, the 16S rDNA gene from strain NPEc1 was amplified with the general primer 27F/1492R (Frank et al. 2008), A BLASTn search in GenBank of this sequence (1,465 bp, Accession No. MN640862) showed over 99% identity to the 16S rDNA of D. chrysanthemi (CP 001655). Partial sequences of housekeeping gene DNA polymerase III, subunits gamma and tau (dnaX), and the recombinase A (recA) gene were also analyzed according to Racix et al. (2014). The 511-bp dnaX sequence (MT597420) and 736-bp recA sequence (MT597421) respectively matched 98.22% and 96.19% with D. chrysanthemi (syn. Erwinia chrysanthemi) strain CFBP 2048 (JX434939) and ICMP 5703 (DQ859873). For pathogenicity testig, six tobacco seedlings of the 45-day-old cultivar Yunyan 87 were planted in nutriculture at room temperature. After three days, approximately 20 μl of each bacterial suspension (107 CFU/ml) of isolates NPEc1 and NPEc2 was injected into the leaf axils of six tobacco stems. As a control, similar seedlings were inoculated with SDW. Twelve hours after inoculation, symptoms of water-soaked decay appeared in the injected leaf axils. After 2 days, these symptoms developed into a severe rot similar to that of naturally infected plants. In contrast, the controls were symptomless. The bacterium was isolated from the rotten tissues and demonstrated a similar identity to the inoculants by the Biolog automated microbial identification system comparison, thus fulfilling Koch's postulates. The inoculation was repeated twice. On the basis of morphological, Biolog Gen III, molecular characteristics and pathogenicity, the causal agent of a hollow stalk rot on tobacco at Nanping, was identified as D. chrysanthemi. Previously, this pathogen was reported on tobacco in Cuba by Pérez (1981) and more recently isolated from poinsettia stems in China (Rungnapha et al. 2008). To our knowledge, this is the first report of Dickeya chrysanthemi causing a hollow stalk disease of toacco in China. Reference cultures have been deposited in CGMCC (NO. MT211276). Further spread of the pathogen may pose a threat to tobacco production in Nanping and other regions in China.

Proteome of the fungus Phoma macdonaldii, the causal agent of black stem of sunflower

Phoma macdonaldii causes black stem of sunflower, which severely affects sunflower yield and quality. There is currently little molecular information available for this pathogenic fungus. In this study, a global proteomic analysis of P. macdonaldii was performed to determine the biological characteristics and pathogenicity of this pathogen. A total of 1498 proteins were identified by LC-MS/MS in all biological replicates. Among the identified proteins, 1420 proteins were classified into the three main GO categories (biological process, cellular component, and molecular function) while 806 proteins were annotated into the five major KEGG database (metabolism, genetic information processing, environmental information processing, cellular processes, and organismal systems). The regulated expression levels of eight genes encoding selected identified proteins were investigated to assess their potential effects on fungal development and pathogenesis. To the best of our knowledge, this is the first study to characterize the proteome of the necrotrophic fungus P. macdonaldii. The presented results provide novel insights into the development and pathogenesis of P. macdonaldii and possibly other Phoma species. SignificanceBlack stem of sunflower is a devastating disease caused by the necrotrophic fungus Phoma macdonaldii. Relatively little is known regarding the molecular characteristics of this pathogen, and no proteomic investigation has been reported. Thus, we conducted a global proteomic analysis of P. macdonaldii. Many proteins were found to be differentially regulated during fungal development and pathogenesis, suggesting they may be important for these two processes. This is the first proteomic study of P. macdonaldii, and the data presented herein will be useful for elucidating the molecular characteristics of this fungus as well as other Phoma species.

Diversity and pathogenicity of Botryosphaeriaceae species associated with black root rot and stem cutting dry rot in Manihot esculenta in Brazil

Cassava is a starch-rich, high-calorie tuberous root used as human and animal food, as well as an input material in various industries. Black root rot (BRR) and stem cutting dry rot (SCDR) are cassava diseases that compromise product quality and can greatly reduce crop yields. Consequently, the aim of this study was to identify Botryosphaeriaceae species associated with both diseases in areas of the northeast of Brazil and in areas of the Minas Gerais State in the southeast of the country and infer a correlation between them. Fungal species were identified by morphology combined with phylogenetic analyses of partial sequences of translation elongation factor 1 alpha (tef1-α), internal transcribed spacer (ITS) and RNA polymerase subunit II (rpb2). Five species were identified as being associated with both BRR and SCDR (Lasiodiplodia euphorbicola, L. hormozganensis, L. parva, L. theobromae, and Neoscytalidium dimidiatum), while five others were associated only with SCDR (L. brasiliense, L. caatinguensis, L. iraniensis, L. laeliocattleyae, and L. pseudotheobromae). All species identified in this survey were able to induce disease in cassava roots and seedlings. In decreasing order, the most frequently isolated species were L. theobromae, N. dimidiatum, and L. euphorbicola. This is the first report of L. brasiliense, L. caatinguensis, L. hormozganensis, L. iraniensis, L. laeliocattleyae, and L. parva associated with cassava diseases worldwide.

Real-time PCR quantification of Rhizoctonia solani AG-3 from soil samples

Rhizoctonia solani anastomosis group 3 (AG-3) causes several diseases of potato, including black scurf and stem canker, affecting potato production in the Skagit Valley, Washington, and around the world. Primers for a SYBR-Green II-based real-time polymerase chain reaction (qPCR) assay were designed from sequences of the nuclear internal transcribed spacer (ITS) regions of fungal isolates of potato and onion from the Pacific Northwest, USA. The primers preferentially amplified R. solani AG-3 DNA, compared to DNA from R. solani AG-4, AG-5 and AG-8. In silico analysis of primer-template duplex stability indicated that the assay also will detect R. solani AG-3 isolates from pea and onion in Washington State and from diverse crop species around the world, but not R. solani AG-9 and AG-2-1. The assay was used to quantify R. solani AG-3 populations in pathogen-infested field soils after temporary flooding rotation, a practice found to be effective for reducing Sclerotinia sclerotiorum and R. solani AG-3 in potatoes in growth chamber studies. Population densities of the pathogen were not significantly reduced in saturated (flooded) soils relative to fallow. However, the qPCR approach was more sensitive and quantitative than the toothpick baiting method for diagnosis of these soil samples. Accurate detection and quantification of R. solani AG-3 in soil will facilitate the development of integrated management plans for Rhizoctonia diseases of potato.

First report of Phytophthora black pod disease of cocoa spread by Iridomyrmex cordatus in Sulawesi: A dilemma about predatory insect for cocoa pest control

While implementing biological control agent driven from predatory insect to retain an ecological population balance of main cocoa pest, has become popular in environment, the unforeseen consequence of this technique is due to uncontrolled insect behaviour, a potential spread of a major cocoa disease-Phytophthora black pod and stem cancer, caused by a superior oomycete Phytophthora palmivora species and this attempt poses a difficult dilemma. This paper will investigate potential risk of insect ant species and explain its behaviour in transmitting cocoa disease to new trees before suggestion way to diminish negative impact and to improve a specific and selective management of cocoa pests and diseases.

Variability in content of hydrophilic extractives and individual phenolic compounds in black locust stem

The main goal of this study was to investigate the amounts of hydrophilic extractives in bark and wood samples of black locust stem (Robinia pseudoacacia L.). Six adult trees were included in the present investigation. Samples were taken from each felled trunk at four different heights. Material was extracted with a mixture of acetone and water, and the hydrophilic extractives were, then, qualitatively and quantitatively analysed. The highest contents of hydrophilic extractives, total phenols, dihydrorobinetin and robinetin were measured in wound-wood and heartwood. The concentrations of extractives were highest in the outermost samples of heartwood. Knotwood of black locust contained less dihydrorobinetin than heartwood. Significantly less hydrophilic compounds were extracted from bark and sapwood samples. This study shows that heartwood of black locust can be considered a source of value-adding compounds. The investigation showed significant variability in the content of extractives in radial direction and less pronounced axial variability within the black locust stems.

Effect of secondary metabolites of Trichoderma spp. in inhibiting Phytophthora palmivora growth in cacao (Theobroma cacao L.)

Secondary metabolites are organic compounds produced by microorganisms or plants which are not directly involved to development and reproduction. The secondary metabolites produced by Trichoderma spp. are antibiotic compounds, enzymes, toxins, and hormones that inhibit the growth of plant pathogens. Phytophthora palmivora is a pathogen that causes black pod, leaf blight, and stem canker in cacao, which potentially reduce production up to 40%. This study was aimed to determine the inhibitory effect of Trichoderma spp. secondary metabolites against P. palmivora. Isolates of Trichoderma spp., i.e. T. virens LP1, T. hamatum LP2, T. amazonicum LP3, T. atroviride JB2, and T. viride PRD were cultured on vegetative and generative medium, then their secondary metabolites was extracted using butanol and ethyl acetate. Analysis of the extracts of secondary metabolite was performed using HPLC to determine their chromatogram profile. The secondary metabolites obtained were tested against P. palmivora using poisoned-medium method and cacao seedlings. In vitro inhibition activity, disease severity, and growth of cacao seedlings were observed. The results showed that extraction of the secondary metabolite using butanol produces more metabolites than those using ethyl acetate. Secondary metabolites of T. virens LP1 and T. amazonicum LP3, significantly inhibited P. palmivora growth up to 90.98%. In general, secondary metabolites of Trichoderma spp. can suppress P. palmivora infection (60.02%–70.00%) in cacao seedlings.

Occurrence of black stem on Helianthus annuus caused by Phoma macdonaldii and resistant evaluation of different sunflower varieties

The first reported case of Phoma macdonaldii Boerema that caused sunflower black stem disease in China was from Xinjiang Uygur Autonomous Region in 2008. Black spindle lesions were observed on sunflower stems in the fields of Inner Mongolia region in China. The causal agents were isolated from the infected stems. Cultures on potato dextrose agar (PDA) plates were whitish with black particles underneath. Dark and pear-like pycnidia with yellowish or dirty whitish exudates were also observed on the surface of the cultures. The cultures produce primarily non-septate conidia. The cultures could infect sunflowers stems by artificial inoculation and developed symptoms consistent with those in the field. Morphological characteristics and molecular identification indicated the isolated causal agents were P. macdonaldii. Phylogenetic analysis based on ITS1, 5.8 s RNA and ITS2 region confirmed the identification. Disease resistance assessments were performed on twenty sunflower varieties and the results suggested that the resistance of seven sunflower varieties to P. macdonaldii was above the average; SC89 and Longkuiza1 were susceptible to P. macdonaldii.

Effect of Trichoderma spp. and potassium fertilizer on Phytophthora palmivora infection in cacao seedlings

Phytophthora palmivora is a pathogen that causes black pod, leaf blight, and stem cancer on cacao, that cause yield loss up to 40%. Control of P. palmivora is intended to make plants healthy, by using Trichoderma spp. and potassium fertilizer. The study was aimed to determine the effect of Trichoderma spp. and potassium fertilizer application against P. palmivora infection in cacao seedlings. The study used a randomized block design consisting of 13 treatments with 5 replications. The treatments were Trichoderma spp. (T. atroviride JB2, T. amazonicum LP3, T. hamatum LP2), and potassium fertilizers dosages (1, 2 and 3 g), chemical fungicides (mancozeb) for comparison, and control. Cacao seedlings were treated with Trichoderma spp. and potassium fertilizer, then the plants were inoculated with P. palmivora. Observations were on attack symptoms, incubation period, disease severity, growth of cacao seedlings, and lignin content. The results showed that the application of Trichoderma spp. and potassium fertilizer prolonged the incubation period and reduced the number of leaves spots (48.95–75.37%). T. amazonicum + 3 g of potassium fertilizer and T. hamatum + 2 g of potassium fertilizer suppressed the number of spots up to 75.37% and 71.36% respectively, higher than chemical fungicides that were 70.86%.

Characterization of blackleg and soft rot from potato in northern Thailand

AbstractBlackleg and soft rot of potato cause economic loss through reduced yield and quality. The causal agents of bacterial blackleg and soft rot of potato were identified based on biological data and sequence analyses of the 16S rDNA gene. Between 2016 and 2018, diseased potato stems and tubers were collected in Chai Prakan District, Chiang Mai Province, and Chiang Khum District, Pa Yao Province. The symptoms included black stem lesions, soft rot on tubers, wilting, break down of the stem vascular ring and foliar yellowing. Of 13 bacterial isolates, five were identified asPectobacterium carotovorumsubsp.brasiliense, four‐Dickeya dadantii, two‐Pseudomonas putidaand two‐Bacillus altitudinis. Pathogenicity tests ofP. carotovorumsubsp.brasilienseandD. dadantiiresulted in lower leaves turning yellow and wilting followed by blackleg symptoms on lower stems and maceration of tuber tissue. Symptoms caused byP. putidawere yellowing and wilting of leaves.B. altitudiniscaused yellowing of the lower leaves and wilting followed by drying of leaf tissue. This is a first report of these bacterial pathogens causing blackleg and soft rot of potato in Thailand.

Infestation and Damage Caused by Wheat Stem Sawflies (Hymenoptera: Cephidae) to Some Wheat Cultivars in Southeast Anatolia Region, Turkey

The European wheat stem sawfly, Cephus pygmeus (Linnaeus, 1767) and the black grain stem sawfly, Trachelus tabidus (Fabricius, 1775) are important and common pests in wheat growing areas of Turkey. These sawfly species continue to be a threat to wheat production in the southeast Anatolia Region of the country. This study was conducted to determine larval infestation rates and yield losses caused by these sawfly species in common wheat cultivars grown in the southeast Anatolia Region. Durum and bread wheat fields were surveyed to record larval infestation and damage caused by these sawfly species in four provinces (Adiyaman, Diyarbakir, Mardin and Sanliurfa) of the region. A total 100 wheat fields were randomly selected and stem samples were taken from each field during the harvest period. Spike length, mean number of grains, grain weight and 1000-grain weight were recorded from 100 infested and healthy spikes and crop losses were calculated for 16 wheat cultivars.The surveyed provinces significantly differed in infestation rates, with the highest infestation level recorded for Diyarbakir province with a mean of 17.4% (range 2.1- 54.3%), while the minimum infestation was determined in Adiyaman province with a mean of 5.3% (range 1.4-17.3%). Durum and bread wheat cultivars had negligible effects on larval infestation. Spike length of infested wheat plants was reduced by 0.9-14.4% and the mean number of grains and grain weight were reduced by 0.5-19.7% and 7.2-28.5%, respectively. The loss in 1000-grain weight was 8.9% in bread wheat cultivars, while the loss was 7.9% in durum wheat cultivars. It was concluded that the loss in 1000-grain weight reached 10.9%. Therefore, appropriate control measures should be taken against stem sawflies in high-infestation locations.

Deprogramming Deficit: A Narrative of a Developing Black Critical STEM Education Researcher

Deprogramming Deficit: A Narrative of a Developing Black Critical STEM Education Researcher

Exploring Identity-Safety Cues and Allyship Among Black Women Students in STEM Environments

Black women are underrepresented in science, technology, engineering, and math (STEM) and report feeling unwelcome in STEM. A successful scientist exemplar or role model may signal to Black women they are valued in STEM environments. We investigated who acts as an identity-safety cue for Black women. In Study 1, Black women students who learned about a Black man or a Black woman professor in a hypothetical School of Science and Engineering reported greater anticipated belonging and trust, relative to those learning about a White man or a White woman professor. In Study 2, we recruited Black women STEM majors from a predominantly White institution and a women-only historically Black college. We examined how both groups identified role models in STEM and assessed how perceptions that role models were allies related to belonging in the institution and belonging in STEM. Across both educational environments, having Black women and Black men role models, and perceiving role models who lacked a common racial identity as allies, positively related to belonging in the institution. We encourage the use of Black exemplars and role models, as well as allies, in interventions geared toward increasing belonging among Black women in STEM. Additional online materials for this article are available on PWQ’s website at http://journals.sagepub.com/doi/suppl/10.1177/0361684319830926 and a podcast for instructors who want to use this article for teaching is available on PWQ's website at http://journals.sagepub.com/page/pwq/suppl/index

Unique gene Pmhyp controlling melanization of pycnidia in Phoma medicaginis

Phoma medicaginis (syn. Ascochyta medicaginicola Qchen & L. Cai) causes spring black stem and leaf spot of alfalfa and the model legume Medicago truncatula. Phoma medicaginis produces uninucleate conidia in melanized pycnidia and is genetically tractable through Agrobacterium tumefaciens-mediated transformation (ATMT), which can result in insertional mutants. One T-DNA-tagged mutant, P1A17 produced conidia in non-melanized (hyaline) pycnidia. Pycnidial melanization recovered if the mutant was supplemented with melanin precursors or allowed to age. DNA sequences flanking the insertion did not predict any disrupted open reading frames (ORF) unless a Coccidioides prediction algorithm was used. Pmhyp gene was expressed in the wild type, but not the mutant, and has not been annotated in any genomes, to date. Expression of two conserved genes flanking the T-DNA disrupted Pmhyp was unchanged from the wild type. Knockout of Pmhyp strain displayed same cultural phenotype (non-melanized pycnidia). Complementation of Pmhyp strains with wild type PmHYP partially recovered pycnidial melanization. Both knockout and complementation transformants were confirmed using RT-PCR and southern blot analysis. Taken together, PmHYP appears to be a novel regulator of pycnidium specific melanization.

Delignification and hydrolyzation of mycorrhizal black locust biomass pretreated with aqueous ammonia

Arbuscular mycorrhizae (AM) fungi can increase the biomass of host plants that are used as biofuel feedstock. However, little is known about the effects of AM fungi during aqueous ammonia pretreatment of biomass to remove lignin or on the enzymatic hydrolysis of cellulose. The analysis of mycorrhizal colonization (Rhizophagus irregularis or Glomus versiforme) on stems of black locust (Robinia pseudoacacia) plants in their first and second year of growth revealed that the presence of AM fungi and the growth time significantly influenced the lignin and cellulose content of untreated black locust but had no effect on the content of stems pretreated with aqueous ammonia. The presence of AM fungi and/or the growth time also affected the black locust stem structure and the chemical structure of lignin. Hydrolysis of mycorrhizal and non-mycorrhizal biomass produced similar glucose yields (except for the second-year R. irregularis biomass, which produced significantly less glucose than the other treatments). The results suggest that mycorrhizal black locust biomass is a suitable substrate for biofuel production.

Time-course metabolic profiling in alfalfa leaves under Phoma medicaginis infection.

Information on disease process and pathogenicity mechanisms is important for understanding plant disease. Spring black stem and leaf spot caused by the necrotrophic pathogen Phoma medicaginis var. medicaginis Malbr. & Roum causes large losses to alfalfa. However, till now, little is known about alfalfa-P. medicagnis interactions and the pathogenicity mechanisms of the pathogen. Here, alfalfa inoculated with P. medicaginis was subjected to GC-MS based metabolic profiling. The metabolic response in P. medicaginis-inoculated and mock-inoculated alfalfa leaves was assessed at 2, 4, 6, 8, 12, 16, 20, 24, 26 and 28 days post inoculation. In total, 101 peaks were detected in the control and inoculated groups, from which 70 metabolites were tentatively identified. Using multivariate analysis, 16 significantly regulated compounds, including amino acids, nitrogen-containing compounds and organic acids, polyols, fatty acids, and sugars were tentatively identified (Variable importance values, VIP>1.0 and p <0.05). Among these metabolites, the levels of malate, 5-oxoproline, palmitic acid and stearic acid were increased significantly in P. medicaginis-infected alfalfa leaves compared to the controls. In contrast, the levels ofγ-aminobutyric acid and 2-pyrrolidinone were significantly decreased in infected leaves compared to the controls. Further metabolic pathway analysis of the 16 significantly regulated compounds demonstrated that glycolysis, the tricarboxylic acid cycle, and β-oxidation of fatty acids were significantly induced in the alfalfa leaves at later stages of P. medicaginis infection. The strong induction of tricarboxylic acid cycle pathways at later infection stages caused by the pathogen may induce senescence in the alfalfa leaves, leading to plant death. However, intermediate metabolites of these metabolic pathways, and inositol phosphate, glutathione, the metabolic pathways of some amino acids accumulated rapidly and strongly at early stages of infection, which may enhance the ability of alfalfa to resist necrotrophic P. medicaginis disease. Understanding metabolic pathways is essential for understanding pathogenesis.

“Black Genius, Asian Fail”: The Detriment of Stereotype Lift and Stereotype Threat in High-Achieving Asian and Black STEM Students

Asians are typically situated at the top of the STEM educational and career hierarchy and enjoy a host of material benefits as a result. Thus, their STEM lives are often considered problem-free. This article describes the role of race-based stereotypes in shaping the experiences of high-achieving Black and Asian STEM college students. Their experiences exposed the insidious presence of anti-Black and pro-Asian sentiment, operationalized through the frameworks of stereotype threat and stereotype lift. Stereotype threat and stereotype lift situate the racialized experiences of Black and Asian students as opposites, thereby ignoring their shared marginalization and responses to being stereotyped. I argue that both racial groups endure emotional distress because each group responds to its marginalization with an unrelenting motivation to succeed that imposes significant costs. I aim to demonstrate that Black and Asian college students are burdened with being stereotyped and judged unfairly, enduring sometimes debilitating consequences even while they are praised for fulfilling or defying stereotypes. Discussion includes coalition building among racial groups of color in STEM, serving in part to co-construct racialized psycho-social coping skills, and a strategy for more equitable material outcomes for Black STEMers.

Physicochemical, Antioxidant and Microbial Properties of Fresh Black Stem Sugarcane Juice with Addition of Calamansi Juice

This study was designed to determine the physicochemical, antioxidant and microbial properties of fresh sugarcane juice with calamansi juice addition. The sugarcane that was used in the experiments was the black cane variety (Saccharum officinarum). Sugarcane pressed with and without their peel was juiced and added with calamansi juice before analysis was carried out. Standard method was used to analyse physicochemical properties such as pH, total soluble solids, acidity and colour of sugarcane juice. Total phenolic content (TPC), DPPH and FRAP assay were conducted for antioxidant properties. Total plate count and yeast and mould count were carried out for the microbiological analyses. Two way analysis of variance (ANOVA) shows significant (p 0.05) difference shown for pH, acidity and total soluble solids of sugarcane juice pressed with and without peel. Sugarcane juice pressed with peel produced higher antioxidant value compared to sugarcane pressed without peel. However, sugarcane juice pressed without peeled showed a lower microbial count compared to sugarcane juice pressed with peel. The addition of calamansi juice proved to have significant (p<0.05) effect on colour, antioxidant and microbial count of the sugarcane juices.