Colletotrichum Lupini Research Articles

Metabolic profiling reveals fumaric acid and GABA as possible markers of Colletotrichum lupini infection of white lupin

Anthracnose caused by Colletotrichum lupini is an essential problem limiting lupine cultivation. In this study, we analyzed metabolic profiles of two white lupin cultivars with different susceptibility to primary infection caused by two C. lupini strains isolated from a single Russian field to reveal key metabolites and metabolic pathways involved in the defense response of seedlings to the pathogen. Multivariate and hierarchical clustering analyses showed that anthracnose-resistant cultivar SN 5–19 had a more pronounced defense response against the infection than the sensitive Michurinskij cultivar. Volcano plot analysis indicated fumaric acid and GABA as potential markers of C. lupini infection. The pathway analyses revealed that the metabolic alterations are conserved across susceptible and tolerant cultivars, indicating the importance of nitrogen mobilization in response to C. lupini infections.

Attack of the clones: Population genetics reveals clonality of Colletotrichum lupini, the causal agent of lupin anthracnose.

Colletotrichum lupini, the causative agent of lupin anthracnose, affects lupin cultivation worldwide. Understanding its population structure and evolutionary potential is crucial to design successful disease management strategies. The objective of this study was to employ population genetics to investigate the diversity, evolutionary dynamics, and molecular basis of the interaction of this notorious lupin pathogen with its host. A collection of globally representative C. lupini isolates was genotyped through triple digest restriction site-associated DNA sequencing, resulting in a data set of unparalleled resolution. Phylogenetic and structural analysis could distinguish four independent lineages (I-IV). The strong population structure and high overall standardized index of association (r̅d ) indicates that C. lupini reproduces clonally. Different morphologies and virulence patterns on white lupin (Lupinus albus) and Andean lupin (Lupinus mutabilis) were observed between and within clonal lineages. Isolates belonging to lineage II were shown to have a minichromosome that was also partly present in lineage III and IV, but not in lineage I isolates. Variation in the presence of this minichromosome could imply a role in host-pathogen interaction. All four lineages were present in the South American Andes region, which is suggested to be the centre of origin of this species. Only members of lineage II have been found outside South America since the 1990s, indicating it as the current pandemic population. As a seedborne pathogen, C. lupini has mainly spread through infected but symptomless seeds, stressing the importance of phytosanitary measures to prevent future outbreaks of strains that are yet confined to South America.

CHARACTERIZATION OF WHITE LUPIN (LUPINUS ALBUS) CULTIVARS' RESPONSE TO PRIMARY INFECTION BY DIVERSE COLLETOTRICHUM LUPINI STRAINS FROM A SINGLE RUSSIAN FIELD

Anthracnose, induced by Colletotrichum lupini, significantly threatens the white lupin industry, primarily originating from infections in asymptomatic seeds. This study evaluated the aggressiveness of six C. lupini strains reisolated from symptomatic pods in the same field in 2021. The assessment targeted Russian cultivars ('Aly Parus,' 'Michurinskij,' 'SN 5-19') and the Australian cultivar 'Andromeda.' Employing a seed infection assay, seeds were directly inoculated with C. lupini mycelia, revealing morphological variations and distinct aggressiveness of the strains at different plant developmental stages. While none impeded plant emergence, four strains caused significant early mortality across all cultivars, with no discernible differences in susceptibility.

Subcuticular−Intracellular Hemibiotrophy of Colletotrichum lupini in Lupinus mutabilis

Anthracnose caused by Colletotrichum lupini is the most important disease affecting lupin cultivation worldwide. Lupinus mutabilis has been widely studied due to its high protein and oil content. However, it has proved to be sensitive to anthracnose, which limits the expansion of its cultivation. In this work, we seek to unveil the strategy that is used by C. lupini to infect and colonize L. mutabilis tissues using light and transmission electron microscopy (TEM). On petioles, pathogen penetration occurred from melanized appressoria, subcuticular intramural hyphae were seen 2 days after inoculation (dai), and the adjacent host cells remained intact. The switch to necrotrophy was observed 3 dai. At this time, the hyphae extended their colonization to the epidermal, cortex, and vascular cells. Wall degradation was more evident in the epidermal cells. TEM observations also revealed a loss of plasma membrane integrity and different levels of cytoplasm disorganization in the infected epidermal cells and in those of the first layers of the cortex. The disintegration of organelles occurred and was particularly visible in the chloroplasts. The necrotrophic phase culminated with the development of acervuli 6 dai. C. lupini used the same infection strategy on stems, but there was a delay in the penetration of host tissues and the appearance of the first symptoms.

AscotraceR: An R Package Resource to Simulate the Spatiotemporal Spread of Ascochyta Blight in a Chickpea Field Over a Growing Season.

ascotraceR: An R Package Resource to Simulate the Spatiotemporal Spread of Ascochyta Blight in a Chickpea Field Over a Growing Season.

Genome-wide association study reveals white lupin candidate gene involved in anthracnose resistance

Key messageGWAS identifies candidate gene controlling resistance to anthracnose disease in white lupin.White lupin (Lupinus albus L.) is a promising grain legume to meet the growing demand for plant-based protein. Its cultivation, however, is severely threatened by anthracnose disease caused by the fungal pathogen Colletotrichum lupini. To dissect the genetic architecture for anthracnose resistance, genotyping by sequencing was performed on white lupin accessions collected from the center of domestication and traditional cultivation regions. GBS resulted in 4611 high-quality single-nucleotide polymorphisms (SNPs) for 181 accessions, which were combined with resistance data observed under controlled conditions to perform a genome-wide association study (GWAS). Obtained disease phenotypes were shown to highly correlate with overall three-year disease assessments under Swiss field conditions (r > 0.8). GWAS results identified two significant SNPs associated with anthracnose resistance on gene Lalb_Chr05_g0216161 encoding a RING zinc-finger E3 ubiquitin ligase which is potentially involved in plant immunity. Population analysis showed a remarkably fast linkage disequilibrium decay, weak population structure and grouping of commercial varieties with landraces, corresponding to the slow domestication history and scarcity of modern breeding efforts in white lupin. Together with 15 highly resistant accessions identified in the resistance assay, our findings show promise for further crop improvement. This study provides the basis for marker-assisted selection, genomic prediction and studies aimed at understanding anthracnose resistance mechanisms in white lupin and contributes to improving breeding programs worldwide.

A qPCR Assay for the Fast Detection and Quantification of Colletotrichum lupini.

White lupin (Lupinus albus) represents an important legume crop in Europe and other parts of the world due to its high protein content and potential for low-input agriculture. However, most cultivars are susceptible to anthracnose caused by Colletotrichum lupini, a seed- and air-borne fungal pathogen that causes severe yield losses. The aim of this work was to develop a C. lupini-specific quantitative real-time TaqMan PCR assay that allows for quick and reliable detection and quantification of the pathogen in infected seed and plant material. Quantification of C. lupini DNA in dry seeds allowed us to distinguish infected and certified (non-infected) seed batches with DNA loads corresponding to the disease score index and yield of the mother plants. Additionally, C. lupini DNA could be detected in infected lupin shoots and close to the infection site, thereby allowing us to study the disease cycle of this hemibiotrophic pathogen. This qPCR assay provides a useful diagnostic tool to determine anthracnose infection levels of white lupin seeds and will facilitate the use of seed health assessments as a strategy to reduce the primary infection source and spread of this disease.

Assessment of the differential gene expression in anthracnose treated seedlings of yellow lupin

Seedlings of yellow lupine treated with Colletotrichum lupini isolate were studied by the method of SRAP-analysis with the purpose to assess the differential expression of genes. As a result, the PCR fragment corresponding to tolerant seedlings was found. The genetic determinants found are likely involved in the control of the resistance (tolerance) of lupine plants to anthracnose.

Genetic diversity of Colletotrichum lupini and its virulence on white and Andean lupin

Lupin cultivation worldwide is threatened by anthracnose, a destructive disease caused by the seed- and air-borne fungal pathogen Colletotrichum lupini. In this study we explored the intraspecific diversity of 39 C. lupini isolates collected from different lupin cultivating regions around the world, and representative isolates were screened for their pathogenicity and virulence on white and Andean lupin. Multi-locus phylogeny and morphological characterizations showed intraspecific diversity to be greater than previously shown, distinguishing a total of six genetic groups and ten distinct morphotypes. Highest diversity was found across South America, indicating it as the center of origin of C. lupini. The isolates that correspond to the current pandemic belong to a genetic and morphological uniform group, were globally widespread, and showed high virulence on tested white and Andean lupin accessions. Isolates belonging to the other five genetic groups were mostly found locally and showed distinct virulence patterns. Two highly virulent strains were shown to overcome resistance of advanced white lupin breeding material. This stresses the need to be careful with international seed transports in order to prevent spread of currently confined but potentially highly virulent strains. This study improves our understanding of the diversity, phylogeography and pathogenicity of a member of one of the world’s top 10 plant pathogen genera, providing valuable information for breeding programs and future disease management.

Response to Anthracnose in a Tarwi (Lupinus mutabilis) Collection Is Influenced by Anthocyanin Pigmentation.

Anthracnose, caused by Colletotrichum lupini, is a major limiting factor for lupin production. Tarwi or Andean Lupin (Lupinus mutabilis) is generally regarded as susceptible to anthracnose, but the high protein and oil content of its seeds raise interest in promoting its cultivation in Europe. In this study we evaluated the response to anthracnose of 10 tarwi accessions contrasting in anthocyanin pigmentation, by comparison to white lupin (Lupinus albus), using a contemporary Portuguese fungal isolate. A severity rating scale was optimized, including weighted parameters considering the type of symptoms and organs affected. All tarwi accessions were classified as susceptible, exhibiting sporulating necroses on the main stem from seven days after inoculation. Anthracnose severity was lower on anthocyanin-rich tarwi plants, with accession LM34 standing out as the less susceptible. Accession I82 better combines anthracnose response and yield. In global terms, disease severity was lower on white lupin than on tarwi. Although based on a limited collection, the results of the study show the existence of genetic variability among L. mutabilis towards anthracnose response relatable with anthocyanin pigmentation, providing insights for more detailed and thorough characterization of tarwi resistance to anthracnose.

Secondary metabolites produced by Colletotrichum lupini, the causal agent of anthachnose of lupin (Lupinus spp.)

ABSTRACT Colletotrichum lupini is the causal agent of lupin (Lupinus albus L.) anthracnose, a destructive seed-borne disease affecting stems and pods. Despite that several biological studies have been carried out on this pathogen, the production of secondary metabolites has not yet been investigated. Thus, a strain of C. lupini, obtained from symptomatic stems of L. albus, has been grown in vitro to evaluate its ability to produce bioactive compounds. From its culture filtrates, a 3-substituted indolinone, named lupindolinone, and a 5,6-disubstituted tetrahydro-α-pyrone, named lupinlactone, were isolated together with the known (3R)-mevalonolactone and tyrosol. Lupindolinone and lupinlactone were characterized as 3-ethylindolin-2-one and 5-hydroxy-6-methyltetrahydropyran-2-one by spectroscopic methods (essentially nuclear magnetic resonance [NMR] and high-resolution electrospray ionization mass spectrometry [HR ESI-MS]). The R absolute configuration (AC) at C-5 of lupinlactone was determined by applying the modified Mosher’s method. Thus, considering its relative stereochemistry assigned by NMR spectroscopy, the AC of lupinlactone could be formulated as 5R,6S. Lupindolinone was isolated as racemic mixture as shown by investigation using chiroptical methods. The metabolites were assayed in different biological tests and proved to have some activities at the used concentration.

Phylogenetic Diversity and Effect of Temperature on Pathogenicity of Colletotrichum lupini.

Although lupin anthracnose caused by Colletotrichum lupini is a significant threat for spring and winter lupin crops, it has been poorly studied so far. This study aimed at characterizing the (i) phylogenetic, (ii) morphological, and (iii) physiological diversity of collected isolates from anthracnose-affected lupins. The genetic identification of representative isolates (n = 71) revealed that they were all C. lupini species, further confirming that lupin anthracnose is caused by this species. However, multilocus sequencing on these isolates and 16 additional reference strains of C. lupini revealed a separation into two distinct genetic groups, both of them characterized by a very low genetic diversity. The diversity of morphological characteristics of a selected subset of C. lupini isolates was further evaluated. To the best of our knowledge, microsclerotia production observed for some isolates has never been reported so far within the Colletotrichum acutatum species complex. Finally, the modeling of growth responses of a subset of C. lupini strains revealed the capacity of some strains to grow in vitro at 5°C. This ability was also evidenced in planta, because C. lupini DNA was detectable in plants from 14 days postinoculation at 5°C onward, whereas symptoms began to appear a week later, although at a very low level. Since lupin crops are planted during winter or early spring, growth studies in vitro and in planta demonstrated the capability of the species to grow at temperatures ranging from 5 to 30°C, with an optimum close to 25°C. In this study, C. lupini-specific primers were also designed for real-time quantitative PCR on fungal DNA and allowed the detection of C. lupini in asymptomatic field samples. These results open perspectives to detect earlier and limit the development of this pathogen in lupin crops.

Molecular Detection of the Seed-Borne Pathogen Colletotrichum lupini Targeting the Hyper-Variable IGS Region of the Ribosomal Cluster.

Lupins anthracnose is a destructive seed and airborne disease caused by Colletotrichum lupini, affecting stems and pods. Primary seed infections as low as 0.01–0.1% can cause very severe yield losses. One of the most effective management strategies is the development of a robust and sensitive seed detection assay to screen seed lots before planting. PCR-based detection systems exhibit higher levels of sensitivity than conventional techniques, but when applied to seed tests they require the extraction of PCR-quality DNA from target organisms in backgrounds of saprophytic organisms and inhibitory seed-derived compounds. To overcome these limitations, a new detection protocol for C. lupini based on a biological enrichment step followed by a PCR assay was developed. Several enrichment protocols were compared with Yeast Malt Broth amended with ampicillin, streptomycin, and lactic acid were the most efficient. A species-specific C. lupini primer pair was developed based on rDNA IGS sequences. The specificity was evaluated against 17 strains of C. lupini, 23 different Colletotrichum species, and 21 different organisms isolated from seeds of Lupinus albus cv. Multitalia, L. luteus cv. Mister, and L. angustifolius cv. Tango. The protocol described here enabled the detection of C. lupini in samples artificially infected with less than 1/10,000 infected seed.

Structure of micromycete complex of feed crops in the forest steppe of Western Siberia

The article highlights the experimental results on the structure of micromycete complex of feed crops seeds in the forest-steppe of Western Siberia. The researchers investigated more than 50 sets of seeds of different soya varieties (Glycine hispida), chick-pea (Cicer arietinum), spring rape (Brassica napus), red clover (Trifolium pratense) and lupine (Lupínus polyphyllus). The authors observed that micromycete complex contains a lot of seed infections in the mafic hyphomycetes of the genus Alternaria (average of 15.8–52.3 %) and Cladosporium (5,7–38,0 %), less common were Fusarium fungi and fungi. The distinguished fungi contained smaller number of Pythium, Botrytis, Verticillium, Rhizoctonia, Curvularia, Peronospora, Stemphylium, Ascochyta, Trichotecium and Corynespora. The article reveals the features of the structure of micromycetes complex on the lupine seeds. The seed material was strongly infected by Colletotrichum lupini (Bondar) Nirenberg, Feiler & Hagedorn (from 37.5 to 62.5%, depends on the variety), which strongly damaged the crops during the growing season (the disease development index varied from 30 to 100 %). The concentration of Fusarium fungi on the seeds of all crops varied from 2.6 to 15.4%; the authors observed the dominating species as F. oxysporum, F. oxysporum var. orthoceras, F. solani, F. solani var. argillaceum, F. sambucinum, F. sambucinum. var. minus, F. gibbosum, F. avenaceum, F. sporotrichiella var. poae. The authors found out that fungi (species of Penicillium, Aspergillus, etc.) is more extracted from the seeds in humid years like 2015, compared with more droughty years like 2016 and 2017. They were mostly observed in the rape seeds (20,2%) and chick-pea (15.8 %). The results of the phytoexpertise show that the problem of contamination of fodder crops by pathogens and the saprophytic mycoflora leads to bed quality of forage crops and seed germination. This problem is very urgent and relevant in, the conditions of forest-steppe of Western Siberia. The high level of seed infection indicates the necessity to strong following the procedure of storage and pre-treatment of seeds with chemical or biological agents.

КОЛЛЕКЦИЯ ИЗОЛЯТОВ ВОЗБУДИТЕЛЯ АНТРАКНОЗА ЛЮПИНА COLLETOTRICHUM LUPINI COMB. NOV. И ХАРАКТЕРИСТИКА ИХ РОСТА IN VITRO

КОЛЛЕКЦИЯ ИЗОЛЯТОВ ВОЗБУДИТЕЛЯ АНТРАКНОЗА ЛЮПИНА COLLETOTRICHUM LUPINI COMB. NOV. И ХАРАКТЕРИСТИКА ИХ РОСТА IN VITRO

Exploration of essential oils as alternatives to conventional fungicides in lupin cultivation

Lupin (Lupinus L.) has the potential to become a true alternative for soybean as protein source, especially in the more temperate regions in the world. However, diseases such as anthracnose (Colletotrichum lupini), gray mold (Botrytis cinerea), and root rot or brown spot (Pleiochaeta setosa) are important threats for lupin production, leading to yield and quality losses. Although conventional fungicides offer a solution to these problems, there is a growing interest in the use of alternative (biological) treatments. In this research, the applicability of four pure plant essential oils (clove oil, juniper oil, tea tree oil, and thyme essential oil) and timbor® (a Thymus vulgaris-derived plant extract) as alternatives for synthetic fungicides towards the lupin pathogens—C. lupini, B. cinerea, and P. setosa—was investigated. The anti-fungal effect of juniper oil was limited, whereas the other oils and timbor® clearly suppressed the growth and spore germination of all fungi. The in vitro experiments revealed that thyme essential oil and timbor® were most effective to inhibit conidial germination and mycelium growth. Furthermore, the results of the pot experiments demonstrated that these Thymus-derived compounds were able to suppress P. setosa brown spot and root rot symptoms. Additional trials are necessary to evaluate the effect of these compounds under field conditions. However, based on these in vitro and pot experiments, it can be concluded that pure essential oils and Thymus-derived plant extracts are promising anti-fungal agents, having the potential to become true alternatives for conventional fungicides in lupin cultivation. To the best of our knowledge, this is the first study demonstrating the potential of plant-derived compounds to treat the main diseases affecting lupin production.

Metabolic response of narrow leaf lupine (Lupinus angustifolius) plants to elicitation and infection with Colletotrichum lupini under field conditions

Lupine (Lupinus spp.) is one of the crop plants from the Fabaceae family cultivated on a moderate scale in Europe, Australia and South America; however, its cultivation suffers from a severe fungal disease anthracnose caused by Colletotrichum lupini fungus. The search for resistant plant genotypes as well as methods of plant immunization against such infections is of importance. Plant interaction with pathogenic microorganisms results in complex regulation of many biochemical and physiological processes. Activation of expression of defence genes that leads to the induction of bioactive secondary metabolites biosynthesis is among them. The aim of the presented work was to investigate changes in the isoflavonoids quantities as the reaction of narrow leaf lupine (Lupinus angustifolius) plants growing in the field conditions to infection with the pathogenic fungus (C. lupini) or treatment with its phytotoxic metabolites followed after 48 h with infection with the fungus. The metabolic profiling after field experiments revealed variety-specific changes of these compounds. Elicitation of plants with fungal phytotoxin prior to infection resulted in higher levels of prenylated isoflavones, especially phytoalexins luteone and wighteone and their various glycoconjugates in comparison to those observed in plants infected only with the fungal spores. The metabolomic analyses were supported by the transcriptomic view of genes involved in isoflavonoids biosynthesis. Infection of Lupinus angustifolius by Colletotrichum lupini combined with former elicitation of plants results in accumulation of prenylated isoflavonoids and change in the isoflavone prenyltransferase gene expression pattern.

Characterization and mapping of LanrBo: a locus conferring anthracnose resistance in narrow-leafed lupin (Lupinus angustifolius L.).

A novel and highly effective source of anthracnose resistance in narrow-leafed lupin was identified. Resistance was shown to be governed by a single dominant locus. Molecular markers have been developed, which can be used for selecting resistant genotypes in lupin breeding. A screening for anthracnose resistance of a set of plant genetic resources of narrow-leafed lupin (Lupinus angustifolius L.) identified the breeding line Bo7212 as being highly resistant to anthracnose (Colletotrichum lupini). Segregation analysis indicated that the resistance of Bo7212 is inherited by a single dominant locus. The corresponding resistance gene was given the designation LanrBo. Previously published molecular anchor markers allowed us to locate LanrBo on linkage group NLL-11 of narrow-leafed lupin. Using information from RNAseq data obtained with inoculated resistant vs. susceptible lupin entries as well as EST-sequence information from the model genome Lotus japonicus, additional SNP and EST markers linked to LanrBo were derived. A bracket of two LanrBo-flanking markers allows for precise marker-assisted selection of the novel resistance gene in narrow-leafed lupin breeding programs.

First Report of Anthracnose Caused by Colletotrichum lupini on Yellow Lupin in Korea

Yellow lupin (Lupinus luteus L.) is native to the Mediterranean region of southern Europe. In Korea, yellow lupins are cultivated for ornamental purposes. In May 2013, hundreds of yellow lupins that were grown in pots for 7 weeks in polyethylene-film-covered greenhouses were observed severely damaged by a previously unknown disease with about 30% disease incidence in a flower farm in Yongin City, Korea. Voucher specimens were deposited in the Korea University Herbarium (KUS). Early symptoms on petioles and stems appeared as small, slightly sunken, water-soaked, and circular spots. Lesions increased in size (4 to 12 μm in diameter), became more depressed, with a darkened central portion. As the disease progressed, affected areas sometimes girdled the stem and killed the shoot. Leaves were partly blighted, but less damaged. The darkened areas contained blackish acervuli from which masses of pale salmon-colored conidia were released in moist weather. Acervuli were circular to ellipsoid, 80 to 400 μm in diameter. Acervular setae were not observed. Conidia (n = 30) were long obclavate to oblong-elliptical, aguttulate, hyaline, and 10 to 18 × 3.6 to 5.2 μm with a length/width ratio of 2.6 to 3.6. Appressoria were single or occasionally in small dense clusters, medium brown, elliptical to round in outline with a smooth to lobate margin, and 8 to 14 × 6 to 9 μm. These characters were consistent with the description of Colletotrichum lupini (Bondar) Damm, P.F. Cannon & Crous (1,3). An isolate was deposited in the Korean Agricultural Culture Collection (Accession No. KACC47254). Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting 545-bp sequence was deposited in GenBank (Accession No. KJ447119). The sequence showed 100% identity with sequences of C. lupini (e.g., GenBank AJ301968, JN943480, JQ948162, and KF207599). To confirm pathogenicity, inoculum was prepared by harvesting conidia with sterile distilled water from 3-week-old cultures on potato dextrose agar. A conidial suspension (2 × 105 conidia/ml) was sprayed until runoff onto the aerial parts of five healthy plants. Control plants were sprayed with sterile water. The plants were covered with plastic bags to maintain a relative humidity of 100% for 48 h and then transferred to a greenhouse. Typical symptoms of necrotic spots appeared on the inoculated leaves 6 days after inoculation, and were identical to the ones observed in the field. C. lupini was re-isolated from symptomatic leaf tissues. No symptoms were observed on control plants. The pathogenicity test was repeated twice. Anthracnose associated with C. lupini on lupins has been known from Europe (Germany, Ukraine, Austria, and Netherlands), North America (Canada and the United States), South America (Bolivia and Brazil), and Oceania (Australia and New Zealand) (2,4). To our knowledge, this is the first report of C. lupini on yellow lupins in Asia as well as in Korea. The presence of C. lupini on lupins in Asia can be considered as a potentially new and serious threat to this ornamental plant.

A single amino-acid substitution allows endo-polygalacturonase of Fusarium verticillioides to acquire recognition by PGIP2 from Phaseolus vulgaris.

Polygalacturonases (PGs) are secreted by phytopathogenic fungi to degrade the plant cell wall homogalacturonan during plant infection. To counteract Pgs, plants have evolved polygalacturonase-inhibiting proteins (PGIPs) that slow down fungal infection and defend cell wall integrity. PGIPs favour the accumulation of oligogalacturonides, which are homogalacturonan fragments that act as endogenous elicitors of plant defence responses. We have previously shown that PGIP2 from Phaseolus vulgaris (PvPGIP2) forms a complex with PG from Fusarium phyllophilum (FpPG), hindering the enzyme active site cleft from substrate. Here we analyse by small angle X-ray scattering (SAXS) the interaction between PvPGIP2 and a PG from Colletotrichum lupini (CluPG1). We show a different shape of the PG-PGIP complex, which allows substrate entry and provides a structural explanation for the different inhibition kinetics exhibited by PvPGIP2 towards the two isoenzymes. The analysis of SAXS structures allowed us to investigate the basis of the inability of PG from Fusarium verticilloides (FvPG) to be inhibited by PvPGIP2 or by any other known PGIP. FvPG is 92.5% identical to FpPG, and we show here, by both loss- and gain-of-function mutations, that a single amino acid site acts as a switch for FvPG recognition by PvPGIP2.