Diversity and potential functional role of phyllosphere-associated actinomycetota isolated from cupuassu (Theobroma grandiflorum) leaves: implications for ecosystem dynamics and plant defense strategies.

Exploring the intricate relationships between plants and their resident microorganisms is crucial not only for developing new methods to improve disease resistance and crop yields but also for understanding their co-evolutionary dynamics. Our research delves into the role of the phyllosphere-associated microbiome, especially Actinomycetota species, in enhancing pathogen resistance in Theobroma grandiflorum, or cupuassu, an agriculturally valuable Amazonian fruit tree vulnerable to witches' broom disease caused by Moniliophthora perniciosa. While breeding resistant cupuassu genotypes is a possible solution, the capacity of the Actinomycetota phylum to produce beneficial metabolites offers an alternative approach yet to be explored in this context. Utilizing advanced long-read sequencing and metagenomic analysis, we examined Actinomycetota from the phyllosphere of a disease-resistant cupuassu genotype, identifying 11 Metagenome-Assembled Genomes across eight genera. Our comparative genomic analysis uncovered 54 Biosynthetic Gene Clusters related to antitumor, antimicrobial, and plant growth-promoting activities, alongside cutinases and type VII secretion system-associated genes. These results indicate the potential of phyllosphere-associated Actinomycetota in cupuassu for inducing resistance or antagonism against pathogens. By integrating our genomic discoveries with the existing knowledge of cupuassu's defense mechanisms, we developed a model hypothesizing the synergistic or antagonistic interactions between plant and identified Actinomycetota during plant-pathogen interactions. This model offers a framework for understanding the intricate dynamics of microbial influence on plant health. In conclusion, this study underscores the significance of the phyllosphere microbiome, particularly Actinomycetota, in the broader context of harnessing microbial interactions for plant health. These findings offer valuable insights for enhancing agricultural productivity and sustainability.

Divergence of Phyllosphere Microbial Community Assemblies and Components of Volatile Organic Compounds between the Invasive Sphagneticola trilobata, the Native Sphagneticola calendulacea and Their Hybrids, and Its Implications for Invasiveness.

Closely-related plant groups with distinct microbiomes, chemistries and ecological characteristics represent tractable models to explore mechanisms shaping species spread, competitive dynamics and community assembly at the interface of native and introduced ranges. We investigated phyllosphere microbial communities, volatile organic compound (VOC) compositions, and potential interactions among introduced S. trilobata, native S. calendulacea and their hybrid in South China. S. trilobata exhibited higher α diversity but significantly different community composition compared to the native and hybrid groups. However, S. calendulacea and the hybrid shared certain microbial taxa, suggesting potential gene flow or co-existence. The potent antimicrobial VOC profile of S. trilobata, including unique compounds like p-cymene (13.33%), likely contributes to its invasion success. The hybrid's intermediate microbial and VOC profiles suggest possible consequences for species distribution, genetic exchange, and community assembly in heterogeneous environments. This hybrid deserves further study as both an opportunity for and threat to diversity maintenance. These differentiating yet connected plant groups provide insight into ecological and evolutionary dynamics shaping microbiome structure, species co-occurrence and competitive outcomes during biological exchange and habitat transformation. An interdisciplinary approach combining chemical and microbial ecology may reveal mechanisms underlying community stability and change, informing management of species spread in a globalized world.

Structure and dynamics of microbial communities associated with the resurrection plant Boea hygrometrica in response to drought stress.

MAIN CONCLUSION: The resurrection plant Boea hygrometrica selectively recruits and assembles drought-specific microbial communities across the plant-soil compartments, which may benefit plant growth and fitness under extreme drought conditions. Plant-associated microbes are essential for facilitating plant growth and fitness under drought stress. The resurrection plant Boea hygrometrica in natural habitats with seasonal rainfall can survive rapid desiccation, yet their interaction with microbiomes under drought conditions remains unexplored. This study examined the bacterial and fungal microbiome structure and drought response across plant-soil compartments of B. hygrometrica by high-throughput amplicon sequencing of 16S rRNA gene and internal transcribed spacer. Our results demonstrated that the diversity, composition, and functional profile of the microbial community varied considerably across the plant-soil compartments and were strongly affected by drought stress. Bacterial and fungal diversity was significantly reduced from soil to endosphere and belowground to aboveground compartments. The compartment-specific enrichment of the dominant bacteria phylum Cyanobacteriota and genus Methylorubrum in leaf endosphere, genera Pseudonocardia in rhizosphere soil and Actinoplanes in root endosphere, and fungal phylum Ascomycota in the aboveground compartments and genera Knufia in root endosphere and Cladosporium in leaf endosphere composed part of the core microbiota with corresponding enrichment of beneficial functions for plant growth and fitness. Moreover, the recruitment of dominant microbial genera Sphingosinicella and Plectosphaerella, Ceratobasidiaceae mycorrhizal fungi, and numerous plant growth-promoting bacteria involving nutrient supply and auxin regulation was observed in desiccated B. hygrometrica plants. Our results suggest that the stable assembled drought-specific microbial community of B. hygrometrica may contribute to plant survival under extreme environments and provide valuable microbial resources for the microbe-mediated drought tolerance enhancement in crops.

Characterization of Emerging Xanthomonas campestris Isolates on the Nonnative Weed Garlic Mustard (Alliaria petiolata).

Nonnative plant infestations provide unique opportunities to investigate pathogen emergence with evolutionarily recent plant introduction events. The widespread distribution of invasive plants and their proximity to genetically related crops highlights the risks of nonnative plants acting as ancillary hosts and fostering microbial recombination and pathogen selection. Garlic mustard (Alliaria petiolata) is a widespread, nonnative cruciferous weed that grows throughout North America and along the forested edges of diverse agricultural fields. The recent identification of a novel Xanthomonas campestris pv. incanae strain isolated from a diseased A. petiolata population led to the current investigation of the distribution and diversity of X. campestris isolates from naturally infected A. petiolata. A total of 14 diseased A. petiolata sites were sampled across three states, leading to the identification of diverse X. campestris pathotypes and genotypes. Pathogenicity assays and multilocus sequence analyses identified pathogenic X. c. pv. incanae and X. c. pv. barbareae strains collected from disparate A. petiolata populations. Moreover, independently collected X. c. pv. incanae strains demonstrated a broad cruciferous host range by infecting cabbage (Brassica oleracea var. capitata), garden stock (Matthiola incana), and the cover crop yellow mustard (Guillenia flavescens). This study highlights the genetic variability and host potential of natural X. campestris populations and the potential risks to Brassica crops via widespread, dense garlic mustard reservoirs.

Development of Specific Primers for Fusarium oxysporum Formae Speciales rapae and matthiolae with an Integrated Multiplex PCR for Distinguishing Four Formae Speciales on Brassicaceae.

There are four formae speciales of Fusarium oxysporum responsible for causing yellows of Brassicaceae. Because of crossbreeding among crops, the host ranges of these formae speciales often overlap, making pathogen identification a challenging task. Among these formae speciales, F. oxysporum f. sp. rapae and F. oxysporum f. sp. matthiolae still lack specific primers for pathogen identification. To address this problem, we targeted the secreted in xylem (SIX) genes, known as specific effectors of pathogenic F. oxysporum, for primer design. Through sequence comparison with other formae speciales, we successfully designed specific primers for F. oxysporum f. sp. rapae and F. oxysporum f. sp. matthiolae on SIX14 and SIX9, respectively. Both primer pairs exhibited high specificity in detecting F. oxysporum f. sp. rapae or F. oxysporum f. sp. matthiolae, distinguishing them from 20 nontarget formae speciales of F. oxysporum, five species of phytopathogenic Fusarium, and four other common pathogenic fungi affecting cruciferous plants. Moreover, the effectiveness of these specific primers was validated by detecting the pathogens in infected plants. To further enhance the identification process of the four formae speciales, we combined the two newly designed specific primer pairs with two previously published primer pairs, enabling the establishment of a multiplex PCR method that can accurately distinguish all four formae speciales of F. oxysporum responsible for causing yellows in cruciferous plants in a single reaction.

A pair of effectors encoded on a conditionally dispensable chromosome of Fusarium oxysporum suppress host-specific immunity.

Many plant pathogenic fungi contain conditionally dispensable (CD) chromosomes that are associated with virulence, but not growth in vitro. Virulence-associated CD chromosomes carry genes encoding effectors and/or host-specific toxin biosynthesis enzymes that may contribute to determining host specificity. Fusarium oxysporum causes devastating diseases of more than 100 plant species. Among a large number of host-specific forms, F. oxysporum f. sp. conglutinans (Focn) can infect Brassicaceae plants including Arabidopsis (Arabidopsis thaliana) and cabbage. Here we show that Focn has multiple CD chromosomes. We identified specific CD chromosomes that are required for virulence on Arabidopsis, cabbage, or both, and describe a pair of effectors encoded on one of the CD chromosomes that is required for suppression of Arabidopsis-specific phytoalexin-based immunity. The effector pair is highly conserved in F. oxysporum isolates capable of infecting Arabidopsis, but not of other plants. This study provides insight into how host specificity of F. oxysporum may be determined by a pair of effector genes on a transmissible CD chromosome.

Multiple Colletotrichum species commonly exhibit focal effector accumulation in a biotrophic interface at the primary invasion sites in their host plants.

Fungal plant pathogens deploy a suite of secreted proteins, called effectors, to facilitate successful infection. Several fungal pathogens have been reported to secrete and accumulate their effector proteins in the host-pathogen interfacial spaces. Previously, we reported that the strain 104-T of the cucurbit anthracnose pathogen Colletotrichum orbiculare secretes and accumulates mCherry-tagged effectors along with the formation of ring-shaped fluorescence signals beneath the appressoria. However, it was unclear whether these effector accumulation patterns occur in other C. orbiculare isolates and other species belonging to the Colletotrichum genus. Here, we investigated the effector localization during host infection of C. orbiculare MAFF306589, C. trifolii MAFF305078, which infects alfalfa, and C. higginsianum MAFF305635, which infects Brassicaceae plants. We generated effector-reporter lines of each species, which constitutively expressed mCherry-tagged CoDN3 effector (CoDN3:mCherry). Immunoblotting analysis of the liquid culture fluids of the generated lines detected CoDN3:mCherry, which confirmed secretion of CoDN3:mCherry by fungal cells. Via inoculation assays in the corresponding host plants, we detected ring-shaped CoDN3:mCherry fluorescence around the appressorial invasion sites in all tested reporter lines. These results suggest that pathogens in the Colletotrichum genus have evolutionarily conserved the trait of effector secretion in the infection stage irrespective of differences in their hosts.

Metapopulation Structure Predicts Population Dynamics in the Cakile maritima-Alternaria brassicicola Host-Pathogen Interaction.

AbstractIn symbiotic interactions, spatiotemporal variation in the distribution or population dynamics of one species represents spatial and temporal heterogeneity of the landscape for the other. Such interdependent demographic dynamics result in situations where the relative importance of biotic and abiotic factors in determining ecological processes is complicated to decipher. Using a detailed survey of three metapopulations of the succulent plant Cakile maritima and the necrotrophic fungus Alternaria brassicicola located along the southeastern Australian coast, we developed a series of statistical analyses-namely, synchrony analysis, patch occupancy dynamics, and a spatially explicit metapopulation model-to understand how habitat quality, weather conditions, dispersal, and spatial structure determine metapopulation dynamics. Climatic conditions are important drivers, likely explaining the high synchrony among populations. Host availability, landscape features facilitating dispersal, and habitat conditions also impact the occurrence and spread of disease. Overall, we show that the collection of extensive data on host and pathogen population dynamics, in combination with spatially explicit epidemiological modeling, makes it possible to accurately predict disease dynamics-even when there is extreme variability in host population dynamics. Finally, we discuss the importance of genetic information for predicting demographic dynamics in this pathosystem.

Commercial wash of leafy vegetables do not significantly decrease bacterial load but leads to shifts in bacterial species composition.

Production of leafy vegetables for the "Ready-to-eat"-market has vastly increased the last 20 years, and consumption of these minimally processed vegetables has led to outbreaks of food-borne diseases. Contamination of leafy vegetables can occur throughout the production chain, and therefore washing of the produce has become a standard in commercial processing. This study explores the bacterial communities of spinach (Spinacia oleracea) and rocket (Diplotaxis tenuifolia) in a commercial setting in order to identify potential contamination events, and to investigate effects on bacterial load by commercial processing. Samples were taken in field, after washing of the produce and at the end of shelf-life. This study found that the bacterial community composition and diversity changed significantly from the first harvest to the end of shelf-life, where the core microbiome from the first to the last sampling constituted <2% of all OTUs. While washing of the produce had no reducing effect on bacterial load compared to unwashed, washing led to a change in species composition. As the leaves entered the cold chain after harvest, a rise was seen in the relative abundance of spoilage bacteria. E. coli was detected after the washing indicating issues of cross-contamination in the wash water.

Evaluation of physiological and molecular effect of variable virulence of Alternaria brassicae isolates in Brassica juncea, Sinapis alba and Camelina sativa.

Brassica genus comprises many prominent species valuable for human nutrition including vegetable crops and oilseed. Production of B. juncea is challenged by many abiotic and biotic stresses, Alternaria blight caused by a necrotrophic fungal pathogen Alternaria brassicae is one of the most prominent diseases of cruciferous crops including B. juncea. However, some closely related wild species like Sinapis alba and Camelina sativa exhibit a variable level of resistance towards the pathogen. Apart from the host resistance, intra-specific pathogen variability also influences disease severity to a larger extent. In this study, we identified and isolated two strains of A. brassicae viz ABS1 and ABS2 exhibiting morphological and pathological variability. These isolates were further used to artificially inoculate B. juncea and two of its wild relatives under in-vitro as well as in-vivo conditions to inspect their pathogenicity in a susceptible, a moderately resistant and a highly resistant host. virulent isolate (ABS2) was able to readily establish infection in all the three species whereas the less virulent isolate (ABS1) readily infected susceptible species B. juncea but delayed and mild infection was noticed in tolerant hosts. Variable physiological and molecular host response towards the differential level of virulence of pathogen were established with many confirmatory experiments like DAB staining study, Disease severity index and microscopic analysis. Real-time PCR results confirm that these two isolates induce a variable level of induction in genes PR1 and PDF1.2 within 48 h of the artificial inoculation in B. juncea and its wild relatives.

Interactions of Bunias orientalis plant chemotypes and fungal pathogens with different host specificity in vivo and in vitro.

Within several plant species, a high variation in the composition of particular defence metabolites can be found, forming distinct chemotypes. Such chemotypes show different effects on specialist and generalist plant enemies, whereby studies examining interactions with pathogens are underrepresented. We aimed to determine factors mediating the interaction of two chemotypes of Bunias orientalis (Brassicaceae) with two plant pathogenic fungal species of different host range, Alternaria brassicae (narrow host range = specialist) and Botrytis cinerea (broad host-range = generalist) using a combination of controlled bioassays. We found that the specialist, but not the generalist, was sensitive to differences between plant chemotypes in vivo and in vitro. The specialist fungus was more virulent (measured as leaf water loss) on one chemotype in vivo without differing in biomass produced during infection, while extracts from the same chemotype caused strong growth inhibition in that species in vitro. Furthermore, fractions of extracts from B. orientalis had divergent in vitro effects on the specialist versus the generalist, supporting presumed adaptations to certain compound classes. This study underlines the necessity to combine various experimental approaches to elucidate the complex interplay between plants and different pathogens.

Cercospora beticola: The intoxicating lifestyle of the leaf spot pathogen of sugar beet.

Cercospora leaf spot, caused by the fungal pathogen Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discusses C. beticola genetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur between C. beticola and its sugar beet host. We highlight the known virulence arsenal of C. beticola as well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management of C. beticola infections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen. TAXONOMY: Cercospora beticola Sacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, Genus Cercospora. HOST RANGE: Well-known pathogen of sugar beet (Beta vulgaris subsp. vulgaris) and most species of the Beta genus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g., Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g., Malva), Plumbaginaceae (e.g., Limonium), and Polygonaceae (e.g., broad-leaved dock) families. DISEASE SYMPTOMS: Leaves infected with C. beticola exhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan-brown to reddish-purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore-bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses. MANAGEMENT: Application of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high-yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease. USEFUL WEBSITE: https://www.ncbi.nlm.nih.gov/genome/11237?genome_assembly_id=352037.

Labeling of dsRNA for Fungal Uptake Detection Analysis.

Double-stranded RNA (dsRNA) plays an essential role in many biological processes and has a great potential for agronomic applications in disease and pest control. A simple and effective method to monitor dsRNA uptake by fungi is crucial for the use of dsRNA as alternative fungicide. The protocol reported in this chapter describes an efficient method to detect and localize labeled dsRNA in fungal hyphae. We use the fungal Verticillium longisporum, a fungal plant pathogen that commonly infects rapeseed and other Brassica species, to explain the procedure, though we have validated the method in a broad spectrum of fungi. Hereafter we elucidate step-by-step the production, fluorescence labeling, as well as detection of dsRNA via fluorescence microscopy in fungal mycelium.

Sesterterpenes and macrolide derivatives from the endophytic fungus Aplosporella javeedii.

Five sesterterpenes (1-5) including two new compounds (1 and 2), as well as a new (6) and a known macrolide (7) were isolated from the endophytic fungus Aplosporella javeedii. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and HRMS data as well as by comparison with the literature. Compound 4 and its acetyl derivatives 4a, 4b, 4c which were prepared by acetylation of 4 exhibited moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 6.2 to 12.8 µM, respectively. Moreover, 4a and 4c exhibited also cytotoxicity against human leukemia (Jurkat J16) and lymphoma (Ramos) cell lines. Compound 7 showed strong cytotoxicity against the L5178Y cell line, as well as against human Jurkat J16 and Ramos cells with IC50 values of 0.4, 5.8, and 4.4 µM, respectively. Mechanistic studies indicated that 7 induces apoptotic cell death. In addition, compounds 3, 4 and 7 showed low antibacterial activities against Mycobacterium tuberculosis H37Rv and compound 6 against Staphylococcus aureus, respectively, with MICs of 100 µM. Preliminary structure-activity relationships are discussed.

Occurrence and diversity of ciliated protozoa in the most commonly consumed leafy greens in Brazil: a qualitative study / Ocorrência e diversidade de protozoários ciliados nos vegetais folhosos mais consumidos no Brasil: um estudo qualitativo

Ciliated protozoa are an ubiquitous group of eukaryotes that have been poorly reported on leafy greens. The present study aimed to verify the occurrence and diversity of ciliated protozoa in the leaves and roots of three of the most commonly consumed leafy greens in Brazil – lettuce, rocket and coriander. The vegetable samples were washed by manual agitation (3 minutes) in two different media (mineral water and Page ́s Amoeba Saline solution). After washing, the contents were incubated in Petri dishes and aliquots were removed for microscopic identification and in vivo observation. A total of 21 ciliated protozoa species were found, most of which were bacterivorous. Leafy greens have commonly been associated with foodborne outbreaks and ciliated protozoa, which although they are not a Public Health concern, can act as “Trojan Horses” harboring bacteria, viruses and other protozoa cysts and oocysts and can suggest a new route towards microbiological quality related to the food chain. This is the first report of ciliated protozoa on leafy greens consumed in Brazil.

Os protozoários ciliados constituem um grupo onipresente de eucariotos pouco relatados em vegetais folhosos. O presente estudo teve como objetivo verificar a ocorrência e a diversidade de protozoários ciliados nas folhas e raízes de três dos vegetais folhosos mais consumidos no Brasil - alface, rúcula e coentro. As amostras de vegetais foram lavadas por agitação manual (3 minutos) em dois meios diferentes (água mineral e Solução Salina para Ameba). Após a lavagem, o conteúdo foi incubado em placas de Petri e alíquotas foram retiradas para identificação microscópica e observação in vivo dos organismos. Um total de 21 espécies de protozoários ciliados foi encontrado, a maioria das quais era bacterívora. Tais hortaliças têm sido comumente associadas a surtos transmitidos por alimentos e os protozoários ciliados que, embora não sejam um problema de saúde pública, podem atuar como “Cavalos de Tróia” ao abrigar bactérias, vírus além de cistos e oocistos de protozoários o que pode sugerir uma nova rota para a avaliação da qualidade microbiológica relacionada à cadeia alimentar. Este é o primeiro relato de protozoários ciliados em folhas verdes consumidas no Brasil.

A combined transcriptional, biochemical and histopathological study unravels the complexity of Alternaria resistance and susceptibility in Brassica coenospecies.

Alternaria blight is one of the most devastating diseases of rapeseed-mustard caused by a necrotrophic fungus Alternaria brassicae. Lack of satisfactory resistance resource in Brassica is still a main obstruction for developing resistance against Alternaria. In this study, we have selected Brassica juncea, Sinapis alba and Camelina sativa to understand and unravel the mechanism of disease resistance against Alternaria. Histopathological studies showed early onset of necrosis in B. juncea (1 dpi) and delayed in S. alba (2 dpi) and C. sativa (3 dpi) respectively. Early and enhanced production of hydrogen peroxide (H2O2) was observed in C. sativa and S. alba (6 hpi) when compared to B. juncea (12 hpi). An increase in catalase activity was observed in both C. sativa (36 % at 6 hpi) and S. alba (15 % at 12 hpi), whereas it significantly decreased in B. juncea at 6 hpi (23 %), 12 hpi (30 %) and 24 hpi (8 %). Gene expression analysis showed induction of PR-3 and PR-12 genes only in C. sativa and S. alba when compared to B. juncea suggesting their vital role for Alternaria resistance. In contrast, SA marker genes were significantly expressed in B. juncea only which provides evidence of hormonal cross talk in B. juncea during Alternaria infection thereby increasing its susceptibility.

Genome Sequence of Fusarium oxysporum f. sp. matthiolae, a Brassicaceae Pathogen.

The filamentous fungus Fusarium oxysporum is a soilborne pathogen of many cultivated species and an opportunistic pathogen of humans. F. oxysporum f. sp. matthiolae is one of three formae speciales that are pathogenic to crucifers, including Arabidopsis thaliana, a premier model for plant molecular biology and genetics. Here, we report a genome assembly of F. oxysporum f. sp. matthiolae strain PHW726, generated using a combination of PacBio and Illumina sequencing technologies. The genome assembly presented here should facilitate in-depth investigation of F. oxysporum-Arabidopsis interactions and shed light on the genetics of fungal pathogenesis and plant immunity.

The Brassicaceae-specific secreted peptides, STMPs, function in plant growth and pathogen defense.

Low molecular weight secreted peptides have recently been shown to affect multiple aspects of plant growth, development, and defense responses. Here, we performed stepwise BLAST filtering to identify unannotated peptides from the Arabidopsis thaliana protein database and uncovered a novel secreted peptide family, secreted transmembrane peptides (STMPs). These low molecular weight peptides, which consist of an N-terminal signal peptide and a transmembrane domain, were primarily localized to extracellular compartments but were also detected in the endomembrane system of the secretory pathway, including the endoplasmic reticulum and Golgi. Comprehensive bioinformatics analysis identified 10 STMP family members that are specific to the Brassicaceae family. Brassicaceae plants showed dramatically inhibited root growth upon exposure to chemically synthesized STMP1 and STMP2. Arabidopsis overexpressing STMP1, 2, 4, 6, or 10 exhibited severely arrested growth, suggesting that STMPs are involved in regulating plant growth and development. In addition, in vitro bioassays demonstrated that STMP1, STMP2, and STMP10 have antibacterial effects against Pseudomonas syringae pv. tomato DC3000, Ralstonia solanacearum, Bacillus subtilis, and Agrobacterium tumefaciens, demonstrating that STMPs are antimicrobial peptides. These findings suggest that STMP family members play important roles in various developmental events and pathogen defense responses in Brassicaceae plants.

Genome-wide identification and characterization of Chitinase gene family in Brassica juncea and Camelina sativa in response to Alternaria brassicae.

Chitinases belong to the group of Pathogenesis-related (PR) proteins that provides protection against fungal pathogens. This study presents the, genome-wide identification and characterization of chitinase gene family in two important oilseed crops B. juncea and C. sativa belonging to family Brassicaceae. We have identified 47 and 79 chitinase genes in the genomes of B. juncea and C. sativa, respectively. Phylogenetic analysis of chitinases in both the species revealed four distinct sub-groups, representing different classes of chitinases (I-V). Microscopic and biochemical study reveals the role of reactive oxygen species (ROS) scavenging enzymes in disease resistance of B. juncea and C. sativa. Furthermore, qRT-PCR analysis showed that expression of chitinases in both B. juncea and C. sativa was significantly induced after Alternaria brassicae infection. However, the fold change in chitinase gene expression was considerably higher in C. sativa compared to B. juncea, which further proves their role in C. sativa disease resistance to A. brassicae. This study provides comprehensive analysis on chitinase gene family in B. juncea and C. sativa and in future may serve as a potential candidate for improving disease resistance in B. juncea through transgenic approach.