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Anthracnose, caused by several Colletotrichum species, is a major restricting factor for guava production, but no comprehensive study of the causal agent has been conducted from the plant host centre of diversity. This work characterizes isolates from guava, mainly from the fruit, but also leaves and flowers, representing most Brazilian physiographies according to the partial sequences of the rDNA‐ITS, ApMAT, TUB2, HIS3 and GAPDH gene regions. In addition, the pathogenicity and aggressiveness to fruits of two widely planted guava varieties (SLG and RM) are described. Guava‐derived Colletotrichum isolates were found in five complexes: gloeosporioides, acutatum, boninense, gigasporum and orchidearum. The gloeosporioides complex was the most prevalent (81%), followed by the acutatum complex (14%). A total of 16 Colletotrichum species were naturally associated with guava anthracnose: C. aeschynomenes, C. asianum, C. chrysophilum, C. fructicola, C. gigasporum, C. gloeosporioides, C. karsti, C. melonis, C. musae, C. nymphaeae, C. paranaense, C. siamense, C. sojae, C. syzygicola, C. theobromicola and C. tropicale. Apart from C. nymphaeae and C. gloeosporioides, all the remaining 14 taxa are reported for the first time in P. guajava. The most aggressive species belonged to the C. gloeosporioides complex. C. siamense was the most prevalent, especially in warmer regions, followed by C. chrysophilum, mostly in temperate environments. The most aggressive species were C. siamense, C. chrysophilum, C. fructicola and C. tropicale. Fruits of the variety SLG were consistently more resistant to anthracnose than the fruits of RM. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Pathology is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Castor bean (Ricinus communis) is a crop of great economic importance in Brazil. It is used for producing oil used in the manufacture of cosmetics and biodiesel. The genus Phytophthora contains pathogens with a wide range of host plants, including ornamentals, fruit and vegetable crops. Among the symptoms induced by Phytophthora species are collar and root rot. This study aimed to identify Phytophthora species causing collar and root rot in castor bean seedlings in the Federal District and test their pathogenicity. Samples of symptomatic plants were collected in four satellite cities in Distrito Federal, Brazil. Fourteen isolates were obtained, and they were initially identified through the morphology of reproductive structures. The isolates were subjected to molecular characterization using phylogeny of the sequences from the ITS region and the Cytochrome Oxidase II gene. Ten isolates of the pathogen were tested for pathogenicity on seedlings of two castor bean accessions and species known to be hosts of P. nicotianae. The isolates were identified as P. nicotianae (12 isolates) and P. palmivora (two isolates). In the pathogenicity test, all isolates were capable of causing disease in castor beans. The isolates of P. nicotianae and P. palmivora varied in pathogenicity to other plant species. This is the first report of P. nicotianae causing collar and root rot in castor bean in the Central‐West Region of Brazil. It is also the first report of P. palmivora causing diseases in castor beans in South America. [ABSTRACT FROM AUTHOR]

Pythium tracheiphilum is a narrow host range oomycete first described infecting lettuce in Italy. Subsequently, the pathogen was reported in many other countries. From 2015 to 2019, Pythium isolates were recovered from lettuce plants with symptoms of leaf rot, wilting and vascular necrosis, collected from commercial fields in different rural localities of Brasilia‐DF, Brazil. The isolates were identified as P. tracheiphilum based on morphological and molecular genetic analysis. Pathogenicity tests conducted with four P. tracheiphilum isolates confirmed that the isolates were pathogenic to detached leaves of a loose‐hearted lettuce cultivar. This is the first report of P. tracheiphilum infecting lettuces in Brazil. [ABSTRACT FROM AUTHOR]

Foliar samples were collected from the tomato (Solanum lycopersicum) cultivar ‘IPA-6’ exhibiting begomovirus-like symptoms (apical leaf curling and chlorosis) in Iranduba (Brazilian Amazon). PCR tests with degenerate primers targeting DNA–A and DNA–B components of a sample designated as AM–035 were positive for both genomic regions. Full-length cognate DNA–A and DNA–B components of AM–035 were cloned and sequenced via Sanger dideoxy termination reaction. The complete sequence of the DNA–A component (MK878452) comprised 2,630 nucleotides (organized in five open reading frames – ORFs), and the DNA–B component (MK878451) displayed 2,593 nucleotides (two ORFs). The highest identities ranged from 90 to 92% with tomato chlorotic mottle Guyane virus (ToCMoGV) isolates from French Guiana, indicating a highly divergent Brazilian strain of this virus. The present work reinforces the scenario of the high diversity of tomato-infecting begomoviruses in Brazil. Further studies are needed to determine the distribution and prevalence of ToCMoGV across tomato-producing areas in the Brazilian Amazon River Basin. [ABSTRACT FROM AUTHOR]

Aim An extensive survey was done to clarify the prevalent Stemphylium species on Solanaceae plants across Brazil, and their host ranges. Methods and Results Eighty nine (89) Stemphylium isolates were obtained from naturally infected tomatoes as well as S. paniculatum , potato, eggplant, scarlet eggplant (Solanum aethiopicum var. gilo), Physalis angulata , and Capsicum species. Phylogenetic analyses encompassing the ITS-5.8S rDNA and glyceraldehyde-3-phosphate dehydrogenase genomic regions placed the isolates into two distinct groupings with either Stemphylium lycopersici or S. solani. Isolates of S. lycopersici (n  = 81) were obtained infecting tomato, potato, eggplant, S. paniculatum , and P. angulata. Isolates of S. solani (n  = 8) were detected in natural association with scarlet eggplant and tomato. Two isolates of S. lycopersici displayed a wide experimental host range in greenhouse bioassays, infecting accessions of 12 out of 18 species. Ocimum basilicum (Lamiaceae) was the only experimental host outside the Solanaceae family. [ABSTRACT FROM AUTHOR]

Wilting and crown‐rot symptoms were observed in sweet pepper (Capsicum annuum) plants in field surveys carried out in 2021 across major vegetable‐producing areas of three municipalities of Guatemala. Phytophthora capsici (Peronosporales, Peronosporaceae) isolates were identified in association with these symptoms based upon morphological and phylogenetic analyses using nucleotide sequence information of the Cox2 mitochondrial DNA (mtDNA) region. Biological tests confirmed P. capsici mating type A1 isolates as the causal agents of the disease. Symptoms similar to those observed in the field were obtained after controlled inoculation of C. annuum 'Tico' seedlings. Solanum habrochaites 'LA 404' and C. annuum 'Criollo de Morelos' displayed strong resistance reaction against all Guatemalan isolates. Even though P. capsici is a cosmopolitan pathogen, this is the first molecular confirmation of this pathogen infecting C. annuum in Guatemala. [ABSTRACT FROM AUTHOR]

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Downy mildew of cucurbits is a disease caused by the Oomycete Pseudoperonospora cubensis. It can cause considerable losses in cucurbit crops. Phylogenetic studies point to the existence of cryptic species of Pseudoperonospora. The objective of this study was to determine, the phylogeny of Pseudoperonospora species affecting cucurbits in different regions of Brazil. For this, leaves with symptoms of downy mildew were collected in areas of cucurbits production in the states of Pernambuco, Minas Gerais, Ceará, and the Distrito Federal. For phylogenetic analyses, DNA extraction was performed, and PCR reactions were carried out using primers DC-6 and LR-0, Cox2-F and Cox2-RC4, OomCox1-levup and OomCox1-levlo, FM79-C1 and FMPHY-10b, for amplification of the internal transcribed spacer (ITS) region, the mitochondrial cytochrome c oxidase subunit II (cox2), the mitochondrial cytochrome c oxidase subunit I (cox1) and cox2-cox1 intergenic spacer respectively. The nucleotide sequences were analyzed, edited, and aligned to perform Bayesian Inference analysis. The results of the phylogenetic analyses presented in the cox2-cox1-cox2_1-ITS concatenated tree indicate that in Brazil, the downy mildew of cucurbits is caused by phylogenetically distinct lineages of P. cubensis. [ABSTRACT FROM AUTHOR]

Septoria leaf spot, caused by Septoria lactucae, is one of the major open-field diseases of lettuce (Lactuca sativa) in tropical and subtropical regions. However, there are few available studies dealing with the identification of useful sources of resistance to this disease. Here, a genetically diverse collection of 42 lettuce accessions was evaluated for Septoria leaf spot reaction under open-field conditions (natural inoculum) during the rainy season. The experimental design was randomized blocks with three replications (16 plants each). Although no immunity-like source was detected, 21 accessions displayed superior levels of rate-reducing resistance with significant lower Area Under Disease Progress Curve (AUDPC) values, encompassing seven accessions of the 'Crispy green loose-leaf', eight of the 'Crispy purple loose-leaf', two of the 'Cos/Romaine', two of the 'Loose-leaf super crispy', one accession of the 'Butterhead', and one accession of the 'Iceberg' morphotype. A subgroup of nine accessions with the highest levels of field resistance was also inoculated under greenhouse conditions with four S. lactucae isolates (collected in distinct geographic areas) in two assays at two distinct phenological stages. The cultivars 'BRS Mediterrânea' and 'Vanda' displayed lowest AUDPC values at the late vegetative/reproductive phenological phase. The remaining accessions displayed intermediate values of AUDPC, with the exception of the cultivar 'Rubi' (control), which exhibited moderate levels of susceptibility. The availability for lettuce breeding programs of genetic sources with higher and stable levels of resistance to S. lactucae will enable the development of more adapted commercial cultivars, increasing the sustainability of this crop across Neotropical regions. [ABSTRACT FROM AUTHOR]

The causal agent of chayote (Sechium edule) powdery mildew (PM) was identified in Brazil. Microscopic examinations revealed hyaline and ovoid conidia, borne in chains and displaying distinctive extra‐vacuolar fibrosin bodies. Morphology agreed to the standard description of the anamorph of Podosphaera xanthii. To confirm this identification, genomic DNA was extracted from field isolates and used in PCR assays with ITS primers. Amplicons were Sanger‐sequenced and the nucleotide alignments of all isolates displayed identity levels above 97% with P. xanthii isolates in GenBank database. Phylogenetic analyses indicated only P. xanthii isolates as the PM‐inducing pathogens in chayote. Inoculation assays were performed using chayote, zucchini and a set of muskmelon differential cultigens for determination of the physiological races of P. xanthii. All chayote isolates were pathogenic to chayote and zucchini seedlings. Five isolates were also pathogenic to the muskmelon cultigens 'Hale's Best Jumbo', 'Védrantais', 'PMR‐45' and 'Edisto 47', whereas 'PMR‐5' was asymptomatic during the experimental period. The virulence profile of chayote‐infecting isolates allowed their classification as P. xanthii race 2. To the best of our knowledge, this is the first worldwide report of P. xanthii race 2 in chayote. This report has relevant epidemiological and disease management implications, allowing more sustainable chayote cultivation under tropical and subtropical conditions. [ABSTRACT FROM AUTHOR]

A fungal complex belonging to the order Helotiales (including Erysiphaceae) has been reported inducing powdery mildew (PM) on members of the Brassicaceae family worldwide. However, no formal report is available employing comprehensive taxonomic analyses of the PM-inducing fungi on these hosts in Brazil. Herein, PM isolates from six Brassicaceae vegetables (viz. broccoli, cauliflower, kale, Chinese cabbage, Indian mustard, and wild mustard) were collected in five geographic areas in the Brazilian Cerrado biome. Morphological aspects of hyphae, conidiophores, and conidia of these isolates were employed in combination with phylogenetic analyses of the sequences of the internal transcribed spacer (ITS) region of rDNA obtained with the pair of Erysiphaceae-specific primers (PMITS1 and PMITS2). Erysiphe cruciferarum was identified as the sole causal PM agent in all six Brassicaceae vegetables. Pathogenicity of the isolates was evaluated by spraying conidial suspension on Brassicaceae seedlings under greenhouse conditions. All isolates were pathogenic to their original hosts. PM has become an emergent foliar disease of Brassicaceae in Brazil especially in dry areas under dripping irrigation systems. This disease has been a limiting factor in the Cerrado region where a long and well-defined dry season favours disease onset and progression. [ABSTRACT FROM AUTHOR]

A novel powdery mildew disease was observed on chickpea (Cicer arietinum) in Brazil. The morphological features of fungal colonies and conidia were in agreement with those typical for the genus Leveillula. The total DNA of three field‐collected samples were used as template in PCR assays with the pair of primer PMITS1 and PMITS2, targeting the internal transcribed space (ITS) region of Erysiphales isolates. Amplicons were Sanger sequenced and their BLAST analysis revealed 100% identity with a large number of L. taurica (lato sensu, Clade 1) isolates from GenBank. Phylogenetic analysis confirmed the pathogen identification. Equivalent symptoms were observed on chickpea seedlings after controlled inoculation, fulfilling the Koch's postulates. Leveillula taurica (lato sensu, Clade 1) isolates have been reported infecting Fabaceae hosts worldwide, including chickpeas in North America, Africa and Asia. However, this is the first record of L. taurica infecting this crop in Brazil and South America. [ABSTRACT FROM AUTHOR]

Jackfruit (Artocarpus heterophyllus) is an important fruit crop in Brazil, and it is commonly found in commercial plantations or spontaneous plants across the whole country. Anthracnose caused by Colletotrichum spp. is among the most important diseases of jackfruit. However, it is unclear which Colletotrichum species is responsible for this disease in Brazil. In 2018, in Goiás, Paraná and São Paulo states, and Distrito Federal (Brazil), jackfruit leaves presented necrotic foliar lesions with dark edges, light center, and chlorotic halo. Incidence of diseased leaves per plant was low (1 to 5%) and lesions were concentrated on the older leaves. Eight Colletotrichum isolates obtained from symptomatic leaves were assigned to the species C. siamense based on phenotypical and molecular features. Their pathogenicity was confirmed by inoculation on jackfruit seedlings and reisolation of the pathogen from induced lesions. Also, the isolates were pathogenic to leaves of soursop, cashew, and mango, which indicates non-host specificity to the original host. [ABSTRACT FROM AUTHOR]

Verticillium dahliae is a soil-borne fungal pathogen responsible for vascular wilt diseases in more than 300 dicotyledonous species, including solanaceous vegetable crops. In this study, a collection of 89 Brazilian V. dahliae isolates was characterized by combing molecular information for mating type and physiological race determination, as well as via virulence bioassays employing a set of differentials. Based on the virulence assays, three isolates were classified as race 1, 76 were classified as race 2, whereas ten isolates did not cause any symptom on the tested cultivars." In race-specific detection, a total of six isolates were identified as race 1, 70 as race 2, and 13 isolates displayed no amplicon with any primer set employed. Therefore, V. dahliae race 2 isolates are currently ubiquitous across major Solanaceae-producing areas in Brazil. Both MAT idiomorphs were detected, but a larger number of the V. dahliae isolates displayed the MAT1–1 (82%) pattern in our molecular analyses. The simultaneous presence of both MAT idiomorphs opens the possibility of sporadic events of sexual reproduction among V. dahliae populations from Brazil, enabling the potential emergence of either new recombinant isolates with broader host ranges or novel physiological races. Our results clearly indicated the need to intensify the search for effective sources of resistance to V. dahliae race 2 in tomato breeding programs under Brazilian conditions. [ABSTRACT FROM AUTHOR]

Fourteen Rhizoctonia isolates obtained from coriander plants with symptoms of damping-off and web blight were collected in vegetable production areas between the years 2015 and 2017 in five geographical regions of Brazil. Identification was performed using phylogenetic analysis of the internal transcribed spacer region of ribosomal DNA, evaluation of morphological characteristics and pathogenicity test. Phylogenetic analysis revealed seven isolates belonging to the AG4-HGI group and two isolates to the AG2-2LP group; two isolates of the genus Rhizoctonia did not group with any anastomosis group, representing a new lineage, and two Waitea sp. isolates and one binucleate isolate grouped with Ceratobasidium ramicola. Based on nuclear staining, thirteen isolates were multinucleated, while one isolate was binucleated. The isolates of Rhizoctonia produced irregularly shaped and brown sclerotia, while the Waitea isolate produced orange sclerotia. In plants the formation of hymenia with the presence of unicellular basidiospores was observed. The basidiospore-producing fungus is represented by the new phylogenetic lineage of Rhizoctonia. All isolates were pathogenic in coriander seedlings, causing damping-off. This is the first report of Rhizoctonia solani (AG4-HGI and AG2-2LP), Waitea sp and C. ramicola in coriander in Brazil. [ABSTRACT FROM AUTHOR]

Recent outbreaks of Verticillium wilt diseases in various vegetable crops have been reported in Brazil. This fact was our initial stimulus to carry out a nationwide survey aiming to determine their causal agent(s). Thus far, Verticillium dahliae has been reported as the predominant species based solely on morphological traits. As other Verticillium species can be associated with wilt diseases, we characterized a collection of 80 isolates, collected across 10 agricultural Brazilian regions, by combining morphological, biological, and molecular traits. A multilocus approach was employed for identification of Verticillium species with information from three genomic regions (ribosomal internal transcribed spacer region, glyceraldehyde‐3‐phosphate dehydrogenase, and actin genes). Only 21 out of the 80 isolates were unable to produce microsclerotia in culture. The analyses of all genomic regions indicated V. dahliae as the sole species associated with vascular wilt of distinct hosts, including major solanaceous vegetables and other hosts such as strawberry, okra, and cacao. Pathogenicity tests confirmed the infection by the V. dahliae isolates and the development of typical disease symptoms on their original hosts. This is the first nationwide characterization of Verticillium isolates associated with major vegetable crops in Neotropical areas. This provides valuable information to design sound management strategies for these diseases, mainly for establishing efficient rotation systems and for the development of resistant cultivars. [ABSTRACT FROM AUTHOR]

Grafting has been increasingly used to overcome soilborne pathogens. The commercial rootstock hybrids AF-8253 (Sakata) and Fortaleza (Takii), as well as Embrapa's new hybrid, BRS Acará, were evaluated as rootstocks for the bell pepper hybrids Margarita (Syngenta) and Pampa (Clause) as scions, under natural infestation of Ralstonia pseudosolanacearum, as well as upon artificial inoculation with a) ten Ralstonia isolates, b) one Phytophthora capsici isolate, c) Meloidogyne incognita race 1, and d) Meloidogyne enterolobii (only rootstocks for c and d). Grafted bell peppers consistently showcased a higher productivity than did non-grafted ones under natural R. pseudosolanacearum infestation, and the rootstock genotype affected fruit size distribution. Rootstocks presented higher resistance than did commercial bell pepper hybrids (scions) for 6 out of 10 Ralstonia isolates. AF-8253 and BRS Acará displayed an immunelike response to P. capsici, while Fortaleza was moderately resistant (25% symptomatic plants) and the bell pepper hybrids (scions) were susceptible (100% symptomatic plants). Rootstocks were immune to M. incognita race 1, but slightly (AF-8253 and BRS Acará) or moderately (Fortaleza) resistant to M. enterolobii. Grafting with BRS Acará, as well as with AF-8253 or Fortaleza, is recommended for managing bacterial wilt, Phytophthora blight, and root-knot nematodes. [ABSTRACT FROM AUTHOR]

Septoria leaf spot, caused by Septoria lycopersici, is considered one of the most important diseases of tomato in Brazil. Despite its importance, the disease agent is still poorly studied. Septoria isolates collected from different production regions of Brazil were characterized by molecular, morphological, and pathogenic methods. A set of 104 isolates was sequenced for the DNA Tub, Cal, and EF1‐α loci. Ten isolates were selected, according to geographical region of origin and type of leaf lesion (typical or atypical), for morphological characterization and for evaluation of aggressiveness on tomato cultivar Santa Clara. To evaluate the pathogen host range, cultivated and wild Solanaceae plants were inoculated with four selected isolates. The results showed that all isolates grouped with the type isolate of S. lycopersici in maximum likelihood and Bayesian inference trees. The isolates were morphologically similar. All isolates selected for pathogenicity testing on tomato were able to induce typical symptoms of the disease, but differed in their aggressiveness. A total of eight species of Solanaceae were also identified as potential alternative hosts for S. lycopersici. This information will provide a more accurate assessment of the risks involved with the introduction of new crops, especially of the genus Solanum, in areas where the species is already present. In addition, it will provide the basis for the establishment of more efficient methods in the management of Septoria leaf spot of tomatoes in natural conditions and in the different production systems. [ABSTRACT FROM AUTHOR]

In Brazil, sour rot is an important postharvest disease on fruits and vegetables. Geotrichum candidum (synonym Galactomyces candidus) has been reported as the main species causing this disease. However, the identity of the causal agent is still uncertain. This research aimed to determine the identity of 165 fungal isolates associated with sour rot obtained from fruits and vegetables in Brazil, and to evaluate the effect of different temperatures on the incidence of sour rot on artificially inoculated tomato fruits. Based on the phylogenetic analyses of DNA sequences from the D1/D2 domain of the large subunit (LSU) rRNA gene and morphological analyses, 129 samples belonged to Galactomyces candidus, 15 to G. candidum var. citri‐aurantii, 6 to G. phurueaense, 2 to Gal. pseudocandidus, 1 to Hyphopichia burtonii, 1 to H. khmerensis, 3 to Saccharomycopsis crataegensis, 1 to S. vini, 1 to Magnusiomyces tetrasperma, 1 to Trichosporon coremiiforme, and 1 to Zygoascus meyerae. Two new species were found, namely, Geotrichum solani (on potato) and Geotrichum spondiadis (on red mombin). All isolates were pathogenic when inoculated on healthy tomato fruits, including the new species of Geotrichum, which were also inoculated into their respective hosts, that is, potatoes and red mombins. To the best of our knowledge, this study is the first to report the presence of five other genera besides Geotrichum associated with sour rot on fruits and vegetables in Brazil, which demonstrates the diversity of fungi and yeasts associated with this disease. [ABSTRACT FROM AUTHOR]

Black pod disease, caused by Phytophthora species, is among the main limiting factors of cacao (Theobroma cacao L.) production. High incidence levels of black pod disease have been reported in Brazil, being induced by Phytophthora capsici , Phytophthora citrophthora , Phytophthora heveae , and Phytophthora palmivora. To assess the diversity of Phytophthora species affecting cacao in Brazil, 40 new isolates were obtained from cacao pods exhibiting symptoms of black pod disease collected in different smallholder farms in 2017. Further, ten cacao-infecting isolates morphologically identified as P. citrophthora and P. palmivora were molecularly characterized. The genomic regions beta-tubulin, elongation factor 1 alpha, heat shock protein 90, and internal transcribed spacer, and the mitochondrially encoded cytochrome c oxidase I and II genes were PCR-amplified and Sanger-sequenced from the cacao-infecting Phytophthora isolates. The morphological characterization and evaluation of the mycelial growth rates for the Phytophthora isolates were performed in vitro. Based on the molecular analysis and morphological comparisons, 19 isolates were identified as P. palmivora (clade 4). Interestingly, 31 isolates grouped together in the phylogenetic tree and were placed apart from previously known species in Phytophthora clade 2. Therefore, these isolates are considered as a new species herein referred to as Phytophthora theobromicola sp. nov., which produced papillate, semipapillate, and persistent sporangia on simple sporangiophores. The P. palmivora isolates were identified as A1 mating type by pairing each isolate with known A1 and A2 tester strains of P. capsici , but no oogonia/antheridia were observed when P. theobromicola was paired with the different tester strains. The P. theobromicola and P. citrophthora isolates showed higher mycelial growth rates, when compared to P. palmivora , on different media at 10, 15, and 20°C, but similar values were observed when grown on clarified CA media at 25 and 30°C. The pathogenicity tests carried out on pods of four cacao clones (CCN51, PS1319, Cepec2004, and CP49) showed significant variability among the isolates of both Phytophthora species, with P. theobromicola inducing higher rates of necrotic lesion expansion, when compared to P. palmivora. Here, two Phytophthora species were found associated with black pod disease in the state of Bahia, Brazil, and the previously undescribed P. theobromicola seems to be prevalent in field conditions. This is the first report of P. theobromicola on T. cacao. Also, these findings are crucial to improve the disease control strategies, and for the development of cacao materials genetically resistant to Phytophthora. [ABSTRACT FROM AUTHOR]

Foliar anthracnose is one of the main diseases of onion (Allium cepa L.) under tropical and subtropical conditions. Thus far, only Colletotrichum gloeosporioides has been reported as the causal agent of this disease in Brazil. However, there are no extensive studies characterizing Colletotrichum isolates associated with onion anthracnose in the country. Here, 38 Colletotrichum isolates obtained from onion plants displaying foliar anthracnose across major Brazilian onion-producing regions were characterized using morphometric and molecular information. The Bayesian and Maximum Liklihood methods were used for an initial analysis of the β-tubulin gene (tub2) sequences of all isolates, resulting in the discrimination of nine haplotypes. Three haplotypes grouped with the reference species of the C. acutatum complex and six with the C. gloeosporioides complex. Sequences of either the glyceraldehyde-3-phosphate dehydrogenase (gapdh), actin (act), and calmodulin genes or the intergenic spacer (IGS) region between DNA lyase (apn2) gene and the mating-type mat1–2-1 locus were used to characterize a subset of isolates representing these nine distinct tub2 gene haplotypes. These analyses revealed five anthracnose-inducing Colletotrichum species, including three members of the C. acutatum species complex (C. nymphaeae, C. scovillei, and C. tamarilloi) and two of the C. gloeosporioides species complex (C. fructicola and C. theobromicola). Bioassays confirmed that all these Colletotrichum species are pathogenic to onion, inducing typical anthracnose symptoms on bulbs and leaves. Twenty-six out of 38 isolates were identified as C. theobromicola, indicating this fungus as the prevalent anthracnose pathogen under Brazilian conditions. This Colletotrichum species diversity will affect anthracnose management strategies, including chemical and cultural control as well as the identification and deployment of onion cultivars with species-specific and/or wide-spectrum tolerance/resistance. [ABSTRACT FROM AUTHOR]

Yield losses induced by a complex of begomoviruses are observed across all major tomato-producing areas in Brazil. Tomato severe rugose virus (ToSRV) is the most widespread begomovirus in the country. Conversely, tomato common mosaic virus (ToCmMV) displays a more restricted geographical distribution to areas associated with the Atlantic Rain Forest (ARF) biome, encompassing the States of Espírito Santo–ES, Minas Gerais–MG, and Rio de Janeiro–RJ. Here, we characterized 277 tomato-infecting isolates collected in fields located within the ARF biome from 2006 to 2018. ToSRV displayed the highest prevalence (n = 157), followed by ToCmMV (n = 95) and tomato interveinal chlorosis virus (n = 14). Four other begomoviruses were also detected, but with very low incidences. ToCmMV was the predominant begomovirus in the ARF biome up to 2014–2015 with very low ToSRV incidence. Subsequently, ToSRV became the most prevalent species in ES and RJ, but ToCmMV was still predominating in the "Zona da Mata" meso-region in MG. Due to the remarkable endemic distribution of ToCmMV, we carried out phylogeographical studies of this virus using information from all 28 available isolates with complete DNA–A sequences. The closest common ancestor of ToCmMV was more likely originated around Coimbra–MG area ≈ 25 years before the formal report of this viral species. So far, all surveys indicated tomatoes as the only natural hosts of ToCmMV with outbreaks occurring mainly (but not exclusively) in highland areas. ToSRV shows a more widespread incidence across both highland and lowland areas of the ARF biome. [ABSTRACT FROM AUTHOR]

Mulberry (Morus spp.), represents a set of plants grown in Brazil for production of fruits, leaves for feeding silkworms and ruminant animals, and for landscape. In 2017 mulberry leaves with symptoms of spots were collected in Santa Catarina (SC) state and in the Distrito Federal (DF). Three fungal isolates obtained from M. nigra in DF and one isolate obtained from M. alba in SC state were characterized by both molecular and morphological tools. Phylogenetic analysis showed that all isolates were grouped with isolates belonging to the species Neophloeospora maculans. All isolates were pathogenic on leaves of M. nigra seedlings under greenhouse conditions and were re-isolated in pure culture, completing the Koch's postulates. One isolate was morphologically characterized, and it showed colonies with slow growth, grayish-white color and conidia hyaline, septated, filiform, straight or curved, measuring 56 (25–70) × 4.5 (2.5–5) that confirms the molecular identification. This work reposts M. nigra as a new host of N. maculans in Brazil, as well as expands the geographic distribution of this fungus in the country. This information is potentially relevant for establishing effective disease management strategies. [ABSTRACT FROM AUTHOR]

Anthracnose is the main fungal disease on cashew orchards in Brazil, occurring on both vegetative and reproductive organs of cultivated and noncultivated host plants. Understanding the effect of physical and chemical exogenous factors on the biological traits of Colletotrichum spp. and determining their host range are key to developing appropriate anthracnose control measures. The present study aimed to estimate the optimum temperatures for mycelial growth, sporulation, and conidial germination of seven Colletotrichum species (C. chrysophilum, C. fragariae, C. fructicola, C. gloeosporioides, C. queenslandicum, C. siamense, and C. tropicale) associated with cashew anthracnose in Brazil. Their aggressiveness on cashew leaves and six alternative host fruits, and their sensitivity to three fungicides were also investigated. The optimum temperatures for mycelial growth, sporulation, and conidial germination ranged from about 25 to about 33°C. All Colletotrichum species induced anthracnose symptoms on wounded cashew leaves, but none of them caused lesions on intact leaf surfaces. The Colletotrichum species, except for C. fragariae and C. fructicola, were pathogenic to wounded fruits of avocado, banana, guava, mango, and papaya, and some isolates also produced lesions on nonwounded fruit tissues. No symptoms were observed on passion fruits, regardless of the inoculation method. Mycelial growth, sporulation, conidial germination, and/or appressorial formation of the seven Colletotrichum species were inhibited by azoxystrobin, difenoconazole, and thiophanate‐methyl to varying degrees. The present study will contribute to the development of forecasting models based on prevailing weather of cashew cropping zones and improve cashew anthracnose management in Brazil. [ABSTRACT FROM AUTHOR]

The genus Gliocephalotrichum (Nectriaceae), originally described as a soil-borne fungus, has been associated with postharvest diseases, especially of tropical fruits. Taxonomic studies using both morphological and molecular phylogenetic analyses have contributed to recognition of novel species in several countries. However, in Brazil, only three isolates of Gliocephalotrichum have been collected from soil samples and roots since the late 1970s. Our study expands the sample range using many Gliocephalotrichum isolates obtained from rotting fruits of tropical plant species in different states of Brazil. Polyphasic taxonomy was assessed with phylogenetic analyses of DNA sequences from four nuclear loci, morphological comparisons, and pathogenicity tests. As a result, three known species (G. bulbilium, G. longibrachium, and G. simplex) were identified from new hosts and locations in Brazil. In addition, three new species are described—G. abrachium, G. brasiliense, and G. caryocaris. A key to all Gliocephalotrichum species worldwide is provided. Although species of Gliocephalotrichum have not been considered to be important plant pathogens, this study shows they may cause postharvest fruit rot in tropical fruits and therefore have an impact in communities that depend economically on the harvest and sale of these fruits. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f. sp. lycopersici (FOL) races 1 and 2 were, up to recent years, the only pathogenic Fusaria associated with tomatoes (Solanum lycopersicum L.) in Brazil. However, recent outbreaks of F. oxysporum isolates with the ability to breakdown the I–2-mediated resistance prompted us to conduct nationwide surveys of the pathogens associated with vascular wilt of tomatoes. During these surveys, eight atypical F. oxysporum isolates (collected across five tomato–producing Brazilian states) displayed a peculiar ability of infecting accessions carrying the I–3 and I–7 genes (controlling resistance to FOL race 3 isolates). These observations suggested the involvement of either a new FOL race or of F. oxysporum f. sp. radicis-lycopersici (FORL) isolates. Koch's postulates were fulfilled for these eight atypical isolates via root dipping inoculation (106 conidia mL− 1) of seedlings from two tomato cultivars 'Ponderosa' and 'Dominador'. All eight isolates induced crown-rot symptoms only in 'Ponderosa', but not in 'Dominador' (which is resistant to FORL). To confirm the FORL identity, PCR assays were done using a set of race-specific and forma specialis-specific primers. A single amplicon of ≈ 947 bp was observed with the primer pair Sprl only with DNA template obtained from standard FORL isolates and from the eight atypical isolates, confirming the first detection of this forma specialis in Brazil. The geographical distribution of FORL isolates across major tomato–producing areas may require the incorporation of resistant factors into adapted cultivars. [ABSTRACT FROM AUTHOR]

Late blight is caused by the oomycete Phytophthora infestans, and it is the most devastating disease of potato in Southern Brazil. The objective of this work was to evaluate the variability of P. infestans isolates collected from potatoes in Rio Grande do Sul (RS), Paraná (PR) and Santa Catarina (SC) states for their mating type (MT) and virulence. One hundred and twenty-eight isolates of P. infestans were collected between 2010 and 2012. They were characterized for mating type and subsequently evaluated for virulence/avirulence using a differential series of 11 potato clones. The virulence study was conducted in vitro by the leaf disc method, where the potato clones were inoculated with each isolate. Seventy-six isolates were identified as MTA2, 24 as MTA1, 17 as MTA1A2 and 11 as self-fertile. In addition, 79 pathotypes of P. infestans were detected in the survey and the largest number of races was identified in RS. The most frequent pathotypes identified were '14' and '21' and the vast majority of isolates overcame the R7 resistance gene, followed by the R3, R1 and R11 genes. Smaller numbers of virulent isolates were detected to the clones carrying the R5, R2 and R9 genes. Higher percentages of virulent and complex isolates were identified in the MTA2. High indices of diversity were observed in populations grouped by mating type and by state of collection. The highest value of the Gleason index HGR = (0.95) was obtained for the isolates from PR. Higher complex P. infestans populations were found in RS, and the least complex population was in PR. [ABSTRACT FROM AUTHOR]

Sixty-seven isolates of Rhizoctonia obtained from potato stems and tubers in the main potato growing regions of Brazil between 2013 and 2014 were analyzed for their molecular and pathogenicity characteristics. Using phylogenetic analysis of the internal transcribed spacer region of ribosomal DNA, 49 isolates were identified as R. solani and 18 isolates as binucleate Rhizoctonia (BNR). Twenty-five isolates (37.3%) belonged to anastomosis group (AG)-3 PT, 20 (29.9%) to AG-4 HGI, 15 (22.4%) to AG-R, three (4.5%) to AG-2-1, three (4.5%) to AG-A, and one (1.5%) to AG-1 IB. Most of the AG-3 PT, AG-4 HGI, AG-A and AG-R isolates, and all isolates of AG-2-1 and AG-1 IB were obtained from tubers with black scurf symptoms. AG-4 HGI isolates were widely distributed and recovered from six out of seven Brazilian states, including 11 potato-growing fields. All isolates were pathogenic to potato, causing necrotic lesions on subterraneous stems, but there were differences in aggressiveness among different AGs. AG-4 HGI was significantly more aggressive to potato plants than other AGs. To our knowledge, this is the first detailed report of the AG composition of Rhizoctonia populations causing potato diseases in different Brazilian regions. [ABSTRACT FROM AUTHOR]

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Fusarium udum is the causal agent of a wilt disease on pigeon pea (Cajanus cajan) in tropical regions. This species shares morphological characteristics with F. oxysporum, leading to misidentification when the diagnosis is solely based on morphological markers. The sexual stage of this fungus was observed on stems of Cajanus in India and was formally described as Gibberella indica. In Brazil, a wilt disease is reported on Crotalaria, but the etiological agent has not been identified correctly so far. In this study, we tested the hypothesis that the causal agent of a wilt on Crotalaria belongs to the same species pathogenic to C. cajan. Strains obtained from diseased Crotalaria spp. were characterized through molecular phylogeny of TEF, TUB and RPB2, laboratory crosses, morphological markers, and pathogenicity tests. Strains from Crotalaria from Brazil formed a well-supported clade with F. udum strains from Crotalaria and Cajanus from other countries. Strains from Brazil intercrossed among themselves and also with others from all geographic regions, and formed fertile perithecia, defining a distinct mating population inside the Fusarium fujikuroi species complex. One strain obtained from Cajanus cajan in India is indicated as epitype, and female-fertile tester strains of both mating types were selected for the identification of field isolates through sexual crosses. These results confirm that the species associated with wilt disease on Crotalaria and Cajanus is F. udum. Wilt symptoms caused by F. udum in Cr. ochroleuca are described and illustrated. [ABSTRACT FROM AUTHOR]

The tree was rooted with the species Pseudoperonospora humuli Original article has been updated. 1 Symptoms of downy mildew of cucurbits on different hosts in Brazil. a-b, Cucumis sativus. c-d, Cucumis melo. e-f, Cucurbita moschata. g-h, Cucumis anguria Figure 2: Phylogenetic tree obtained by Bayesian Inference of the concatenated cox2, cox2-1, cox1 and ITS regions. [Extracted from the article]

In June 2021, anthracnose symptoms were observed on yam ( I Dioscorea cayennensis i ) plants from Pernambuco and Paraiba States (Brazil). Keywords: Pathogenicity; Phylogeny; Yam EN Pathogenicity Phylogeny Yam 381 382 2 03/16/23 20230201 NES 230201 Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s42161-022-01298-6. [Extracted from the article]

Fusarium wilt, caused by Fusarium oxysporum f. sp. lactucae (FOLac), is amongst the main diseases affecting lettuce in subtropical regions. Although nationwide surveys indicated the exclusive presence of FOLac race 1 in Brazil, no detailed studies are available providing molecular evidences if these isolates were introduced into the country via contaminated seeds or if they are endemic populations. The translation elongation factor 1α (EF-1α) gene and rDNA intergenic spacer (IGS-rDNA) region represent the most comprehensive databases for comparative analyses of Fusarium isolates. Our aim was to assess the genetic relationships of 23 Brazilian FOLac race 1 isolates with a collection of FOLac isolates of worldwide origin, using the information from these genomic regions. A consistent single-cluster pattern was observed for FOLac race 1 isolates from Brazil, California-USA, Arizona-USA, Japan, Italy, as well as the novel FOLac race 4 isolates from the Netherlands based upon the EF-1α (604 nucleotides) and the IGS-rDNA (1859 nucleotides) sequences. Our analysis (based upon six single nucleotide polymorphisms identified only in the IGS-rDNA sequence) allowed the identification of intra-race 1 variation with the discrimination of four haplotypes. Isolates from Brazil, Italy, and a subset from the USA were classified into a single haplotype. The low diversity levels and the presence of only a single haplotype across the entire country are strong indications that Brazilian FOLac race 1 isolates are result of recent introduction event(s). This fast and widespread distribution of FOLac race 1 in Brazil has occurred more likely via importation and planting of contaminated seeds. [ABSTRACT FROM AUTHOR]

The knowledge about the array of host and non-host plant species of the cosmopolitan soil-borne pathogen Phytophthora capsici is potentially useful in establishing efficient crop rotation systems. In the present work, pathogenicity bioassays were carried out aiming to re-examine the host range of P. capsici using 4 isolates obtained from taxonomically distinct species: snap bean, strawberry, bell-pepper and squash. Ninety-six plant accessions (72 species within 40 genera and 17 botanical families) were inoculated at seedling stage with zoospore suspensions. Reaction of fruits, pods, tubers, roots, or bulbs of 25 plant species was also determined. Twenty-two species were found to be susceptible to P. capsici at the seedling stage, and 20 species displayed varying levels of fruit/pod/tuber/bulb susceptibility. We report one Cucurbitaceae (Sicana odorifera) and eight Solanaceae species: Physalis angulata, Solanum aethiopicum var. gilo, S. betaceum (former Cyphomandra betaceae), S. chilense, S. paniculatum, S. torvum, Capsicum praetermissum and Nicotiana benthamiana as novel experimental hosts of P. capsici at seedling stage. We also present the first formal report of Solenostemon autranii (Lamiaceae) as a new experimental host at seedling stage. Infection by at least one P. capsici isolate was also reported for the first time in pods of cowpea (Vigna unguiculata) and in potato (S. tuberosum) tubers. Sechium edule (chayote) and Cucumis anguria (gherkin) were identified as novel cucurbitaceous hosts at the fruit stage, but these species were not infected by all isolates at seedling stage. An updated list of all currently reported hosts is provided. [ABSTRACT FROM AUTHOR]

Commercial plantations of teak (Tectona grandis L.f.) are affected by many economically important fungal diseases under Brazilian conditions. Teak plants exhibiting distinctive vascular wilt symptoms were observed in Mirassol do Oeste (MT), Brazil. Trunk samples of the affected trees were collected, disinfected, and plated onto potato dextrose agar. Fungal cultures obtained displayed morphological characteristics typical of the Fusarium oxysporum species complex. A representative F. oxysporum isolate was used in pathogenicity assays. Teak plants displayed symptoms similar to those observed under field conditions approx. 60 d after root-dipping inoculation. Amplicons corresponding to segments of the translation elongation factor 1-α (TEF-1α) and RNA polymerase II second largest subunit (RPB2) genes were obtained using as template the genomic DNA extracted from two Fusarium isolates obtained from teak. Phylogenetic analyses of the amplicon sequences placed the isolates into the same cluster of isolates belonging to the F. oxysporum species complex. To our knowledge, this is the first report of vascular wilt of teak caused by F. oxysporum in the Neotropical region. [ABSTRACT FROM AUTHOR]

Although I S. vesicarium i has already been reported infecting garlic plants in Brazil (Boiteux et al. [1]), this is the first report of this fungus on onion in the Country. A garlic (Allium sativum) leaf blight caused by Stemphylium vesicarium in Brazil. Onion plants of cultivar Mercedes were inoculated with the isolates by spraying conidial suspension of 1 × 10 SP 5 sp spores/mL on the unwounded or wounded leaves. [Extracted from the article]

The use of resistant cultivars is one of the most efficient strategies for reducing the amount of pesticides in agricultural crops. Several species of the Solanaceae and Cucurbitaceae families are susceptible to diseases caused by Phytophthora capsici isolates. Even though sources of resistance have been identified in other host plants, reports of resistance to P. capsici in cultivated and wild tomato species [genus Solanum (section Lycopersicon)] germplasm are yet scarce. The main objective of the present work was to characterize the reaction of 244 Solanum ( Lycopersicon) accessions to P. capsici under controlled greenhouse experiments. In the first set of experiments, tomato seedlings were inoculated at the collar area with a 3 mL of a spore suspension (2 × 10 zoospores mL). Disease incidence (dead plants/total plants) was assessed 14 days after inoculation. The accessions were separated in five well-defined reaction groups: highly resistant (HR), resistant (R), moderately susceptible (MR), susceptible (S), and highly susceptible (HS). The reaction of a group of the ten accessions with the highest levels of resistance was then evaluated against a collection of five P. capsici isolates. Differential reaction was observed among accessions and isolates. The resistant response was host species-dependent with susceptibility being more often found in S. peruvianum accessions, whereas sources of resistance were identified more frequently among accessions of the cultivated tomato ( S. lycopersicum). [ABSTRACT FROM AUTHOR]

The populations of Phytophthora infestans (Pi) in southern Brazil in 2004 and 2005 are characterized herein. The isolates were collected from potato and tomato plants in the states of Paraná (PR), Santa Catarina (SC), and Rio Grande do Sul (RS). The mating type of 131 potato and 32 tomato isolates was determined. Forty-nine isolates from potatoes and 11 from tomatoes were analyzed for their Gpi phenotype. A subset of 35 isolates was evaluated for mitochondrial (mtDNA) polymorphisms. A sample of 146 isolates was tested for sensitivity to the fungicide metalaxyl, and most isolates (64%) were moderately sensitive. Fifty-nine isolates were classified as A1 mating type and 103 as A2. One isolate behaved as both A1 and A2 mating type. All tomato isolates were A1 mating type and presented the 86/100 pattern for the enzyme GPI and mtDNA Ib, indicating that these isolates belong to the US-1 clonal lineage. Of the 131 potato isolates, 103 were A2, 27 were A1 and one was A1/A2 mating type. Among the potato isolates 27 exhibited the Gpi phenotype 100/100, the same as BR-1, and 20 were 86/100, the same as US-1. Potato isolates presented the mitochondrial haplotypes Ia (74%) and IIa (26%). The data suggest the presence of only the BR-1 clonal lineage on potatoes in the states of PR and SC. However, in the state of RS, more than one clonal lineage was observed infecting potatoes, and there may be sexual reproduction between the lineages. [ABSTRACT FROM AUTHOR]

Understanding the genetic structure of the population of Alternaria solani (AS) is an important component of epidemiological studies of early blight, a severe disease that affects potato (Po) and tomato (To) worldwide. Up to 150 isolates obtained from both hosts were analysed with RAPD and AFLP markers to estimate the amount and distribution of genetic variability of AS in Brazil. Using RAPD, gene diversity ( h = 0.20) and scaled indices of diversity of Shannon ( H′ = 0.66) and Stoddart and Taylor's ( G = 0.31) for the Po population were higher than those of the To ( h = 0.07, H′ = 0.34, G = 0.17). For AFLP, the statistics for the Po ( h = 0.17, H′ = 0.86, G = 0.49) and To ( h = 0.17, H′ = 0.85, G = 0.36) populations were similar. For each RAPD and AFLP locus, the allele frequency for the overall population ranged from 0.006 to 0.988, and 0.007 to 0.993, respectively. Genetic differentiation was high ( G = 0.41 and θ = 0.59) and moderately high ( G = 0.23 and θ = 0.37) when estimated with RAPD and AFLP, respectively. Based on cluster analyses, there was strong evidence of association of pathogen haplotypes with host species. The null hypothesis of random association of alleles was rejected in the analysis of both RAPD ( I = 13.1, P < 0.001) and AFLP ( I = 2.2, P < 0.001) markers. The average number of migrants was estimated to be around one and two individuals per generation, using RAPD and AFLP, respectively. There was no correlation between genetic distance and geographical origin of AS haplotypes for RAPD ( r = −0.07, P = 0.84) and AFLP ( r = −0.03, P = 0.70). The AS population is clonal with high genetic variability, and there is genetic differentiation between the populations that affect To and Po. [ABSTRACT FROM AUTHOR]

Ten Trichoderma isolates were studied under greenhouse conditions as potential agents for biocontrol of yam leaf spot, caused by Curvularia eragrostidis. The Trichoderma isolates demonstrated high efficiency of disease control. Application of the antagonists on the same day as C. eragrostidis inoculation showed the best results. One isolate achieved 75 percent disease severity reduction. The survival of the Trichoderma isolates decreased after its application on the phylloplane with values of 57 and 41 percent at the 49th day, in the absence and presence of the phytopathogen respectively. The antagonism persisted well against C. eragrostidis, the TN1 isolate praises 89 percent. [ABSTRACT FROM AUTHOR]

This is the first report of I V. dahliae i race 2 causing verticillium wilt on scarlet eggplant in Brazil. Keywords: Solanum aethiopicum var. gilo; Verticillium wilt; Pathogen variability EN Solanum aethiopicum var. gilo Verticillium wilt Pathogen variability 667 667 1 05/06/21 20210501 NES 210501 Verticillium wilt is an important disease of I Solanum i spp. vegetables in Brazil, including the scarlet eggplant, I Solanum aethiopicum i var. I gilo i . Solanum aethiopicum var. gilo, Verticillium wilt, Pathogen variability. [Extracted from the article]

Fusarium oxysporum f. sp. lactucae (FOLac) is responsible for significant economic losses across major lettuce-producing regions around the world. Thus far, only FOLac race 1 isolates have been reported associated with Fusarium wilt outbreaks in Brazil. The most sustainable strategy for disease control is the pyramidization of race-specific resistance factors in lettuce cultivars. The loose-leafy cultivar 'Vanda' was found as one of the most promising sources of resistance to FOLac race 1. The genetic basis of this resistance was determined by analyzing the reaction to this pathogen of segregating populations derived from the cross 'Gisele' (susceptible) × 'Vanda' (pollen donor). A single molecular marker-genotyped F1 hybrid plant was selfed and individual plants of a segregating F2 population as well as 63 families F2:F3 were inoculated with a FOLac race 1 isolate by using the root-dipping method (3 × 106 conidia/ml). Our results confirmed the high levels of resistance of 'Vanda' even under very harsh experimental conditions. Overall, the reaction of the F1 plants and the segregating patterns of the F2 population (n = 82) and of the F2:F3 families (n = 838 plants) fit a single dominant gene/locus model. However, the phenotypic expression of resistance might suffer effects of additional genetic factor(s) (e.g., locus dosage, minor modifying genes, and incomplete penetrance). Notwithstanding, the high levels of FOLac race 1 resistance and its relatively simple genetic control makes 'Vanda' a major germplasm source for lettuce-breeding programs aiming to incorporate this trait in a wide array of elite lines from distinct varietal groups. [ABSTRACT FROM AUTHOR]