First Report of Root Collar Canker Caused by Neoscytalidium dimidiatum on Jacaranda mimosifolia in China.

Jacaranda mimosifolia is widely cultivated as a garden ornamental tree. In July 2023, an unknown root collar canker of J. mimosifolia was discovered in green belts of Qingxiu District, Nanning, China, with a 8% incidence rate. Crowns of affected trees ranged from reddish brown leaves to deciduous or dead. Root collar tissue became necrotic matched by underbark dark brown lesions with irregular margins, and rotted at last. Six diseased plants distributed within 3000 m2 were choosed, and 24 root collar tissues were surface sterilized and placed on potato dextrose agar (PDA) plates to incubate at 28℃ for 3 to 5 days. Same colonies were consistently isolated from 18 tissues, and three isolates (M3-B1-1, M3-B1-2 and M3-B1-3) were purified for morphological and molecular determination. These isolates formed colonies with lush aerial mycelia rapidly, which covered a 90 mm plate in 72h. The colonies were initially white, then grayish-green to black. Arthrospores were colourless to light brown, short columnar, aseptate, truncate base, averaging 12.1±2.5 µm × 3.4±0.7 µm, sometimes formed arthric chains. Chlamydospores were dark brown, round or oval, aseptate, averaging 8.7±1.6 µm × 5.0±0.9 µm. Mature pycnidia and conidia produced for about 50 days on oatmeal agar medium (OMA), and conidia were colorless, oblong, aseptate, averaging 11.2±1.2 µm × 6.0±1.4 µm. These morphological characteristics were consistent with the description of Neoscytalidium dimidiatum (Penz.) Crous & Slippers (Crous et al. 2006). Genomic DNA was extracted from three isolates. The partial ITS region, TUB2 and TEF1-α genes were amplified (White et al., 1990; Glass and Donaldson 1995; Carbone and Kohn 1999). The sequences were deposited in GenBank (ITS: PP939650-PP939652; TUB2: PP942728-PP942730; TEF1-α: PP942731-PP942733). Blastn analysis revealed that ITS sequences of three isolates showed 99.8%, 100%, 100% identity (506 bp out of 507 bp, 507 bp out of 507 bp, 507 bp out of 507 bp) to N. dimidiatum C21 (KX447539), the TUB2 sequences showed 100% identity (436 bp out of 436 bp, 437 bp out of 437 bp, 437 bp out of 437 bp) to N.dimidiatum LNeo (ON099066), and the TEF1-α sequences showed 99.64% identity (276 bp out of 277 bp) to N.dimidiatum ARM230 (MK495384), respectively. Phylogenetic analysis based on concatenated ITS, TUB2 and TEF1-α sequences showed that three isolates were clustered into the same clade as N. dimidiatum. To fulfill Koch's postulates, pathogenicity of these isolates was tested on healthy two-year-old J. mimosifolia trees. Stem and root collar were wounded and placed mycelial plugs (8mm), and the inoculation sites were wrapped with parafilm or covered with nursery substrate to maintain the humidity. Four plants were inoculated with each isolate. As a control, four plants were inoculated with noncolonized PDA plugs. All treated plants were kept in a greenhouse at 28 ± 3°C and 70% relative humidity. Foliar blight and necrotic lesions around inoculation points were observed about 65 days after inoculation, and 50% of inoculated trees exhibited symptoms, whereas the control trees remained symptomless. Neoscytalidium dimidiatum was successfully reisolated from symptomatic tissue via morphological analysis. To our knowledge, this is the first report of root collar canker caused by N. dimidiatum on J. mimosifolia. Neoscytalidium dimidiatum has a wide range of hosts, including pitaya, pine, mulberry, pear, grape, locust tree (Luo et al. 2024). This finding will help in controlling of the disease epidemic.

Brown leaf spot of Jacaranda mimosifolia Caused by Colletotrichum karstii in Sichuan, China.

Jacaranda mimosifolia D. Don is widely cultivated in southwest China (Yunnan, Sichuan, and other regions). It is widely applied in papermaking, medicine, environmental monitoring, timber, urban and rural afforestation, and soil and water conservation. In October 2020, a new brown leaf spot disease of J. mimosifolia was discovered in Xichang City (27°49' to 27°56'N, 102°16' to 102°11'E), with approximately 66.23% disease incidence. Firstly, the typical symptoms showed deep yellow necrotic lesions in the center or on the margin of the leaves. Gradually, the necrotic lesions expanded and developed into brown spots. Under humid conditions, the edges of necrotic lesions turned dark brown progressively. Finally, the leaves withered, died, and fell off. Infected tissues from ten samples were cut into small pieces of 2.5 × 2.5 mm. The surfaces of infected tissues were sterilized for 30 s in 3% sodium hypochlorite, 60 s in 75% ethanol, and rinsed three times in sterile water. They were then blot-dried with autoclaved paper towels and cultured on potato dextrose agar (PDA) at 25℃ for 3 to 8 days. After culturing for 8 days at 25℃ and 12 h/12 h light/dark on PDA, the colony diameter reached 78.2 to 82.7 mm. The colonies were light orange, turned pale pink with light orange beneath. The conidia were single-celled, aseptate, cylindrical, smooth-walled, straight, hyaline with both ends bluntly rounded, measuring 12.3 to 16.8 × 4.3 to 5.6 µm (n = 100; average=14.5 × 5.1µm). These morphological characteristics were consistent with the description of C. karstii (Zhao et al. 2021). For molecular identification, the genomic DNA of the representative isolate JM202010 was extracted using a fungal genomic DNA extraction kit (Solarbio, Beijing). The internal transcribed spacer (ITS) [ITS1/ITS4 (White et al., 1990)], calmodulin (CAL) [CL1C/CL2C (Weir et al., 2012)], actin (ACT) [ACT512F/ACT-783R (Carbone & Kohn, 1999)], chitin synthase (CHS-1) [CHS-79F/CHS-345R (Carbone & Kohn, 1999)], ß-tubulin (TUB2) [BT2A/BT2B (O'Donnell et al., 1997)], and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) [GDF/GDR (Templeton et al. 1992)] were amplified. Sequences were deposited in GenBank (ITS: OL454787, CAL: OL518966, ACT: OL518967, CHS-1: OL518968, TUB2: OL518969, and GAPDH: OL518970). BLAST results indicated that the ITS, CAL, ACT, CHS-1, TUB2 and GAPDH sequences showed >99% identity with Colletotrichum karstii sequences at NCBI (GenBank MW494453.1, MW495036.1, MG387951.1, MW495038.1, MW495042.1, and MG602034.1). The conidial suspension (1 × 106 conidia/ml) was sprayed on the leaves of 4-year-old J. mimosifolia plants (10 plants) and inoculated for pathogenicity test. Fifteen leaves of each plant (10 pots in total) were inoculated with spore suspensions on both sides of the leaves. An equal number of control leaves was sprayed with sterilized distilled water as a control. Finally, all pots were kept in a greenhouse at 26°C under a 16 h/8 h photoperiod and 60 to 68% relative humidity. The inoculated plants showed symptoms similar to those of the original diseased plants, but the controls remained asymptomatic. Colletotrichum karstii was re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated thrice, which showed similar results, confirming Koch's postulates. To our knowledge, this is the first report of brown leaf spot on J. mimosifolia caused by C. karstii in China. C. karstii was previously reported as the causal agent of anthracnose on Fatsia japonica (Xu et al. 2020) and Nandina domestica (Li et al. 2017) in China. This finding provides an important basis for further research on the control of this disease.

Antibacterial and Antibiofilm Activity of Chemically and Biologically Synthesized Silver Nanoparticles.

Bacterial biofilms are a significant problem in the food industry, as they are difficult to eradicate and represent a threat to consumer health. Currently, nanoparticles as an alternative to traditional chemical disinfectants have garnered much attention due to their broad-spectrum antibacterial activity and low toxicity. In this study, silver nanoparticles (AgNPs) were synthesized by a biological method using a Jacaranda mimosifolia flower aqueous extract and by a chemical method, and the factors affecting both syntheses were optimized. The nanoparticles were characterized by Ultraviolet-visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), Dynamic light scattering (DLS), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) with a spherical and uniform shape. The antibacterial and antibiofilm formation activity was carried out on bacterial species of Pseudomonas aeruginosa and Staphylococcus aureus with the capacity to form biofilm. The minimum inhibitory concentration was 117.5 µg/mL for the chemical and 5.3 µg/mL for the biological nanoparticles. Both types of nanoparticles showed antibiofilm activity in the qualitative Congo red test and in the quantitative microplate test. Antibiofilm activity tests on fresh lettuce showed that biological nanoparticles decreased the population of S. aureus and P. aeruginosa by 0.63 and 2.38 logarithms, respectively, while chemical nanoparticles had little microbial reduction. In conclusion, the biologically synthesized nanoparticles showed greater antibiofilm activity. Therefore, these results suggest their potential application in the formulation of sanitizing products for the food and healthcare industries.

Chromosomal-Level Reference Genome of the Neotropical Tree Jacaranda mimosifolia D. Don.

Jacaranda mimosifolia D. Don is a deciduous tree widely cultivated in the tropics and subtropics of the world. It is famous for its beautiful blue flowers and pinnate compound leaves. In addition, this tree has great potential in environmental monitoring, soil quality improvement, and medicinal applications. However, a genome resource for J. mimosifolia has not been reported to date. In this study, we constructed a chromosome-level genome assembly of J. mimosifolia using PacBio sequencing, Illumina sequencing, and Hi-C technology. The final genome assembly was ∼707.32 Mb in size, 688.76 Mb (97.36%) of which could be grouped into 18 pseudochromosomes, with contig and scaffold N50 values of 16.77 and 39.98 Mb, respectively. A total of 30,507 protein-coding genes were predicted, 95.17% of which could be functionally annotated. Phylogenetic analysis among 12 plant species confirmed the close genetic relationship between J. mimosifolia and Handroanthus impetiginosus. Gene family clustering revealed 481 unique, 103 significantly expanded, and 16 significantly contracted gene families in the J. mimosifolia genome. This chromosome-level genome assembly of J. mimosifolia will provide a valuable genomic resource for elucidating the genetic bases of the morphological characteristics, adaption evolution, and active compounds biosynthesis of J. mimosifolia.

Jacaranda flower (Jacaranda mimosifolia) as an alternative for antioxidant and antimicrobial use.

Antimicrobial resistance to antibiotics is a serious health problem worldwide, for this reason, the search for natural agents with antimicrobial power against pathogenic microorganisms is of current importance. The objective of this work was to evaluate the antioxidant capacity (ABTS+ and DPPH), antimicrobial activity, and polyphenol compounds of methanolic and aqueous extracts of Jacaranda mimosifolia flowers. The antimicrobial activity against Bacillus cereus ATCC 10876, Bacillus subtilis ATCC 6633, Enterococcus faecalis ATCC 51299, Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19115, Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium ATCC 14028, Staphylococcus aureus ATCC 25923, and Streptococcus mutans ATCC 25175, was determined using the Kirby Bauer technique. The results of polyphenolic compounds showed a high amount of total flavonoids in the methanolic and aqueous extracts (503.3 ± 86.5 and 245. 7 ± 27.8 mg Rutin Equivalents/g DW, respectively). Quercetin, gallic acid, caffeic acid, and rutin were identified by the HPLC-DAD technique, while in the GC-MS analysis, esters, fatty acids, organic compounds, as well as monosaccharides were identified. Higher antioxidant capacity was detected by the ABTS technique (94.9% and 62.6%) compared to DPPH values (52.5% and 52.7 %) for methanolic and aqueous extracts, respectively. The methanolic extract showed a greater inhibitory effect on gram-positive bacteria, with a predominant higher inhibition percentage on Listeria monocytogenes and Streptococcus mutans (86% for both). In conclusion, Jacaranda flower extracts could be a natural antimicrobial and antioxidant alternative due to the considerable amount of polyphenolic compounds, and serve as a sustainable alternative for the isolation of active ingredients that could help in agriculture, aquaculture, livestock, pharmaceutics, and other industrial sectors, to remediate problems such as oxidative stress and antimicrobial abuse.

Complete plastome sequence of Jacaranda mimosifolia D. Don (Bignoniaceae): a beautiful landscaping tree species.

Jacaranda mimosifolia is a deciduous arbor with blue flowers native to Brazil, Bolivia, and Argentina in South America. After introduction from South America, it was widely cultivated as a garden ornamental plant in South China. The complete chloroplast (cp) genome sequence of this ornamental species is reported in this study, based on high-throughput sequencing (Illumina). The complete cp genome is 153,514 bp in length, containing a pair of inverted repeat regions (IRs) of 25,408 bp, a large single-copy (LSC) region of 84,755 bp, and a small single-copy (SSC) region of 17,943 bp. The cp genome contains 130 genes, consisting of 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The overall A/T content in the cp genome of J. mimosifolia is 61.70%. The phylogenetic analyses indicate that there is a close relationship between J. mimosifolia and Tecomaria capensis. The complete cp sequence of J. mimosifolia will provide a useful resource for the development and utilization of this species as well as for the phylogenetic studies in Bignoniaceae.

Chemical and magnetic analyses on tree bark as an effective tool for biomonitoring: A case study in Lisbon (Portugal).

Tree bark has proven to be a reliable tool for biomonitoring deposition of metals from the atmosphere. The aim of the present study was to test if bark magnetic properties can be used as a proxy of the overall metal loads of a tree bark, meaning that this approach can be used to discriminate different effects of pollution on different types of urban site. In this study, the concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, P, Pb, V and Zn were measured by ICP-OES in bark samples of Jacaranda mimosifolia, collected along roads and in urban green spaces in the city of Lisbon (Portugal). Magnetic analyses were also performed on the same bark samples, measuring Isothermal Remanent Magnetization (IRM), Saturation Isothermal Remanent Magnetization (SIRM) and Magnetic Susceptibility (χ). The results confirmed that magnetic analyses can be used as a proxy of the overall load of trace elements in tree bark, and could be used to distinguish different types of urban sites regarding atmospheric pollution. Together with trace element analyses, magnetic analyses could thus be used as a tool to provide high-resolution data on urban air quality and to follow up the success of mitigation actions aiming at decreasing the pollutant load in urban environments.

Biosynthesis of ZnO nanoparticles using Jacaranda mimosifolia flowers extract: Synergistic antibacterial activity and molecular simulated facet specific adsorption studies.

The naturally occurring biomolecules present in the plant extracts have been identified to play an active role in the single step formation of nanoparticles with varied morphologies and sizes which is greener and environmentally benign. In the present work, spherical zinc oxide nanoparticles (ZnO NPs) of 2-4nm size were synthesized using aqueous extract of fallen Jacaranda mimosifolia flowers (JMFs), treated as waste. The microwave assisted synthesis was completed successfully within 5min. Thereafter, phase identification, morphology and optical band gap of the synthesized ZnO NPs were done using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and UV-Visible spectroscopy techniques. The composition of JMFs extract was analyzed by gas chromatography-mass spectrometry (GC-MS) and the ZnO NPs confirmation was further explored with fourier transform infrared spectroscopy (FTIR). The GC-MS results confirmed the presence of oleic acid which has high propensity of acting as a reducing and capping agent. The UV-Visible data suggested an optical band gap of 4.03eV for ZnO NPs indicating their small size due to quantum confinement. Further, facet specific adsorption of oleic acid on the surface of ZnO NPs was studied computationally to find out the impact of biomolecules in defining the shape and size of NPs. The viability of gram negative Escherichia coli and gram positive Enterococcus faecium bacteria was found to be 48% and 43%, respectively at high concentration of NPs.

Effects of arbuscular mycorrhizal inoculation and fertilization on mycorrhizal Statute of Jacaranda mimosifolia D.Don cultivated in nurseries.

The effects of fertilization and the nature of the inoculum as well as the variation of the dose intake of the latter on the level of Jacaranda mimosifolia D.Don mycorhization were tested. Young plants were treated with two inoculums presenting different origins, compositions and modes of application: one is a commercial product containing Glomus irregulare, and the other is a composite indigenous inoculum resulting from trapping five species of genus Glomus and also from multiplication on mycotrophic plants: leek (Allium porrum L.) and vetch (Vicia sativa L.). For each inoculum, two doses were tested and for each dose of inoculum, four levels of fertilization based on a complete commercial fertilizer (Osmocote) were tested: 0 g/plant, 2 g/plant, 4 g/plant, and 6g/plant. Three repetitions were performed for each combination treatment of inoculum/fertilizer. One-year-old young Jacaranda plants, being about 40 cm high, were cultured under greenhouse in 10/12 cm caliber pots. After six months, all the inoculated plants were mycorrhized. According to endomycorrhizal structures found on their roots, plants receiving doses of composite indigenous inoculum reached a more advanced stage of mycorrhization than those treated with the commercial inoculum. The existence of an interaction effect between the inoculum dose and the level of fertilization on Jacaranda mycorhization rate was excluded. These two parameters of variation were studied as simple effects. The increase in commercial inoculum dose had a significant positive influence on the level of Jacaranda plants mycorrhization (P=0.05). The rate of mycorrhization jumped from 12.69% to 21.92%. Nonetheless, for plants receiving increasing doses of composite indigenous inoculum, the level of mycorrhization has varied randomly. In both instances of inoculum treatments, increasing the dose of fertilizer significantly inhibited endomycorrhizal colonization of Jacaranda roots (P=0.01). Thus, the rate of root colonization decreased from 47.43% to 2.41% for plants receiving the composite indigenous inoculums. It decreased from 32.35% to 3.95% for those treated with the commercial inoculum. Mycorrhization had a positive effect on root dry biomass of Jacaranda, as in the case of unfertilize ave the highest rates of colonization.

Líquenes como bioindicadores de contaminación aérea en el corredor metropolitano de la ciudad de Guatemala / Lichens as bioindicators of air pollution in the metropolitan corridor Guatemala City

El incremento en las sustancias tóxicas a la atmósfera en la ciudad de Guatemala ha generado un empeoramiento paulatino de la calidad del aire. Por lo tanto, es necesaria la incorporación de un sistema de monitoreo que sea económico y que permita determinar las áreas de la ciudad con altos índices de contaminación aérea, para posteriormente tomar medidas adecuadas para su mitigación. En este sentido, el presente estudio categorizó los niveles de contaminación aérea por medio del Índice de Pureza Atmosférica (IPA), complementado con coberturas de cada especie, el Factor de Clasificación Ambiental (ECF) y el cambio en la diversidad de líquenes en árboles de jacaranda en 32 puntos del corredor metropolitano en la ciudad de Guatemala. Los resultados reportan 16 familias, 23 géneros y 65 especies de líquenes, de las cuales 26 son nuevos registros para el país y 5 para la ciudad. Los valores de IPA variaron de 4.5 a 25.5 indicando homogeneidad en los índices de contaminación aérea a lo largo del corredor metropolitano. En los puntos P5 Instituto Normal para Señoritas Centro América (INCA) y P13 (Parroquia Santa Marta) se obtuvieron los menores valores de IPA por lo que son los puntos con mayor grado de contaminación aérea; y los puntos P28 (Universidad Francisco Marroquín) y P21 (Avenida las Américas 1) obtuvieron los mayores siendo las áreas menos contaminadas. La incorporación del valor de cobertura al IPA, permite categorizar las áreas a una escala más fina, dándole mayor peso a especies toxitolerantes y toxisensibles. Estos resultados evidencian que los líquenes pueden complementar mediciones físicoquímicas de contaminación aérea, especialmente en puntos en donde no se cuenta con equipo para ello y pueden indicar lugares con problemas ambientales que necesiten investigación instrumental, como los puntos P5 y P13. Así mismo, se proponen 10 especies foliosas de líquenes para ser utilizadas como indicadoras de contaminación aérea en futuras investigaciones. Palabras clave: Líquenes, Índice de Pureza Atmonsférica, Factor de Clasificación Ambiental, bioindicador,

The increase of toxic substances into the atmosphere in Guatemala City has led to a progressive deterioration of the air quality. Therefore, it is necessary to incorporate an economic monitoring system that is able to identify the areas of the city with the highest levels of air pollution, and after that, be able to take the appropriate mitigation measures according to it. In this regard, this study categorized the levels of air pollution through the Index of Atmospheric Purity (IAP) complemented with coverage of each specie, the Environmental Classification Factor (ECF) and the change in diversity of lichens on Jacaranda trees in 32 points of metropolitan corridor of Guatemala City. The result reports 16 families, 23 genera and 65 species of lichens, whose 26 are new records for the country, and 5 for the city. IAP rate varied from 4.5 to 25.5, indicating that the metropolitan corridor is homogeneous regarding to high levels of air pollution. In points P5 (INCA) and P13 (Parish Church Parroquia Santa Marta) the lower rate of IAP were found, meaning that these are the points with the higher degree of air pollution; and points P28 (Marroquín University) and P21 (Avenida las Americas 1) obtained the highest degree, being the least polluted areas. The incorporation of the value of coverage to the IAP allows categorizing areas at a finer scale, giving more importance to toxitolerant and toxisensitive species. These results demonstrate that lichens can complement physical-chemical measurements of air pollution, especially in places where there is no equipment for it and it and therefore could indicate places with environmental problems that may need instrumental research, such as points P5 and P13. Furthermore, 10 micro lichen species are proposed to be used as air pollution indicators in future researches.