RESUMO
Nut kernel color is a crucial quality indicator affecting the consumers first impression of the product. While growing evidence suggests that plant phenolics and their derivatives are linked to nut kernel color, the compounds (biomarkers) responsible for kernel color stability during storage remain elusive. Here, pathway-based metabolomics with machine learning algorithms were employed to identify key metabolites of postharvest pecan color stability. Metabolites in phenylpropanoid, flavonoid, and anthocyanin biosynthetic pathways were analyzed in the testa of nine pecan cultivars using liquid chromatography-mass spectrometry. With color measurements, different machine learning models were compared to find relevant biomarkers of pecan color phenotypes. Results revealed potential marker compounds that included flavonoid precursors and anthocyanidins as well as anthocyanins (e.g., peonidin, delphinidin-3-O-glucoside). Our findings provide a foundation for future research in the area, and will help select genes/proteins for the breeding of pecans with stable and desirable kernel color.
Assuntos
Cor , Aprendizado de Máquina , Metabolômica , Carya/química , Carya/metabolismo , Antocianinas/química , Antocianinas/metabolismo , Algoritmos , Flavonoides/química , Flavonoides/metabolismoRESUMO
The health benefits of nut consumption have been extensively demonstrated in observational studies and intervention trials. Besides the high nutritional value, countless evidences show that incorporating nuts into the diet may contribute to health promotion and prevention of certain diseases. Such benefits have been mostly and certainly attributed not only to their richness in healthy lipids (plentiful in unsaturated fatty acids), but also to the presence of a vast array of phytochemicals, such as polar lipids, squalene, phytosterols, tocochromanols, and polyphenolic compounds. Thus, many nut chemical compounds apply well to the designation "nutraceuticals," a broad umbrella term used to describe any food component that, in addition to the basic nutritional value, can contribute extra health benefits. This contribution analyses the general chemical profile of groundnut and common tree nuts (almond, walnut, cashew, hazelnut, pistachio, macadamia, pecan), focusing on lipid components and phytochemicals, with a view on their bioactive properties. Relevant scientific literature linking consumption of nuts, and/or some of their components, with ameliorative and/or preventive effects on selected diseases - such as cancer, cardiovascular, metabolic, and neurodegenerative pathologies - was also reviewed. In addition, the bioactive properties were analyzed in the light of known mechanistic frameworks.
Assuntos
Suplementos Nutricionais , Juglans , Nozes , Compostos Fitoquímicos , Pistacia , Nozes/química , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/farmacologia , Humanos , Suplementos Nutricionais/análise , Juglans/química , Pistacia/química , Lipídeos/análise , Valor Nutritivo , Anacardium/química , Macadamia/química , Corylus/química , Fitosteróis/análise , Carya/química , Prunus dulcis/química , Doenças Cardiovasculares/prevenção & controleRESUMO
Pecan (Carya illinoinensis) is an economically important nut crop known for its genetic diversity and adaptability to various climates. Understanding the growth variability, phenological traits, and population structure of pecan populations is crucial for breeding programs and conservation. In this study, plant growth and phenological traits were evaluated over three consecutive seasons (2015-2017) for 550 genotypes from 26 provenances. Significant variations in plant height, stem diameter, and budbreak were observed among provenances, with Southern provenances exhibiting faster growth and earlier budbreak compared to Northern provenances. Population structure analysis using SNP markers revealed eight distinct subpopulations, reflecting genetic differentiation among provenances. Notably, Southern Mexico collections formed two separate clusters, while Western collections, such as 'Allen 3', 'Allen 4', and 'Riverside', were distinguished from others. 'Burkett' and 'Apache' were grouped together due to their shared maternal parentage. Principal component analysis and phylogenetic tree analysis further supported subpopulation differentiation. Genetic differentiation among the 26 populations was evident, with six clusters highly in agreement with the subpopulations identified by STRUCTURE and fastSTRUCTURE. Principal components analysis (PCA) revealed distinct groups, corresponding to subpopulations identified by genetic analysis. Discriminant analysis of PCA (DAPC) based on provenance origin further supported the genetic structure, with clear separation of provenances into distinct clusters. These findings provide valuable insights into the genetic diversity and growth patterns of pecan populations. Understanding the genetic basis of phenological traits and population structure is essential for selecting superior cultivars adapted to diverse environments. The identified subpopulations can guide breeding efforts to develop resilient rootstocks and contribute to the sustainable management of pecan genetic resources. Overall, this study enhances our understanding of pecan genetic diversity and informs conservation and breeding strategies for the long-term viability of pecan cultivation.
Assuntos
Carya , Variação Genética , Fenótipo , Carya/genética , Carya/crescimento & desenvolvimento , Filogenia , Genótipo , México , Polimorfismo de Nucleotídeo Único , Análise de Componente Principal , Genética PopulacionalRESUMO
Longer-term pecan consumption has shown appetite-regulating effects as a part of a free-living diet, yet the physiologic appetite responses to a single pecan-containing meal are unclear. The purpose of this study was to compare the acute physiologic, subjective, and direct appetite responses of a pecan-containing meal to an energy- and macronutrient-matched control meal. This was an acute meal challenge study utilizing a double-blinded randomized crossover design with two periods. Participants were young, healthy adults (BMI: 22.9 ± 3.3 kg/m2, age: 22 ± 3 y) who consumed a meal containing either 68 g of pecans (PEC; 795 kcal) or an energy- and macronutrient-matched control meal (CON; 794 kcal) on separate testing days. At both testing visits, five postprandial blood draws, and visual analog scale (VAS) questionnaires (in-lab) were used to determine differences in peptide YY (PYY), ghrelin, and subjective appetite over a 4-h postprandial period. Participants also completed VAS questionnaires (at-home) and food records for the rest of the day after leaving the testing visits. Thirty-one out of thirty-two randomized participants completed the study. There was a greater overall postprandial PYY response (p < 0.001), and a greater suppression of postprandial ghrelin after time point 120 min (p < 0.001), with the PEC vs. CON meal. Further, there was a greater increase in subjective fullness (p = 0.001), and suppression of at-home overall appetite (p = 0.02), from time 240-780 min post-meal with PEC vs. CON meals. There were no differences in self-reported EI between meals or any other VAS measure. In conclusion, a pecan-containing breakfast shake produced more favorable physiologic and subjective improvements in appetite compared to an energy- and macronutrient-matched control meal. This trial is registered at clinicaltrials.gov (NCT05230212).
Assuntos
Apetite , Carya , Estudos Cross-Over , Grelina , Refeições , Peptídeo YY , Período Pós-Prandial , Humanos , Masculino , Feminino , Adulto Jovem , Peptídeo YY/sangue , Adulto , Método Duplo-Cego , Grelina/sangue , Ingestão de Energia , Inquéritos e QuestionáriosRESUMO
In-shell pecans are typically harvested after falling from trees to the ground, presenting a potential route of contamination of foodborne pathogens from soil contact. In-shell pecans are often subjected to various processing or washing steps prior to being shelled. This study determined Shiga toxin-producing Escherichia coli (STEC) reductions after treatment with antimicrobial washes on direct and soil-inoculated in-shell pecans and evaluated the cross-contamination potential of the spent pecan washes after treatment. Pecans were directly and soil-inoculated with an STEC cocktail (O157:H7, O157:NM, O121, O26). Direct inoculation was achieved by spraying the STEC cocktail on the pecans. For soil-inoculation pecans, autoclaved soil was sprayed with the STEC cocktail, homogenized for 2 min, and used to coat in-shell pecans. Inoculated pecans were washed in treatments of 2% lactic acid (LA), 1,000 ppm free chlorine (sodium hypochlorite; NaClO), hot water (HW; 85 ± 2 °C), or ambient water (C [control]; 18 ± 2 °C) for 2, 5, and 10 min and diluted to enumerate STEC populations. After treatments, 100 mL of the spent wash was vacuum filtered through a 0.45-µm membrane and plated on selective agar. HW significantly reduced STEC populations from pecans with and without soil regardless of treatment time (p < 0.05), NaClO reduced STEC populations more than the ambient control wash on directly inoculated pecans, but there were no significant differences between STEC reductions from ambient water (C), LA, and NaClO treatments on soil-inoculated pecans (p > 0.05). Larger STEC populations were enumerated from ambient water wash compared to the antimicrobial washes (p < 0.05). The HW, LA, and NaClO treatments were effective at maintaining the quality of the wash water, with STEC levels being generally at or below the detection limit (<1 CFU/100 mL), while HW was the most effective at reducing STEC from in-shell pecans with and without a soil coating (>5-log CFU/mL reductions).
Assuntos
Contagem de Colônia Microbiana , Escherichia coli Shiga Toxigênica , Escherichia coli Shiga Toxigênica/efeitos dos fármacos , Carya , Humanos , Microbiologia de Alimentos , Contaminação de Alimentos/análise , Anti-Infecciosos/farmacologia , Microbiologia do Solo , Hipoclorito de Sódio/farmacologia , Escherichia coli O157/efeitos dos fármacosRESUMO
Advances in molecular ecology can overcome many challenges in understanding host-parasitoid interactions. Genetic characterization of the key-players in systems helps to confirm species and identify trophic linkages essential for ecological service delivery by biological control agents; however, relatively few agroecosystems have been explored using this approach. Pecan production consists of a large tree perennial system containing an assortment of seasonal pests and natural enemies. As a first step to characterizing host-parasitoid associations in pecan food webs, we focus on aphid species and their parasitoids. Based on DNA barcoding of field-collected and reared specimens, we confirmed the presence of 3 species of aphid, one family of primary parasitoids, and 5 species of hyperparasitoids. By applying metabarcoding to field-collected aphid mummies, we were able to identify multiple species within each aphid mummy to unravel a complex food web of 3 aphids, 2 primary parasitoids, and upward of 8 hyperparasitoid species. The results of this study demonstrate that multiple hyperparasitoid species attack a single primary parasitoid of pecan aphids, which may have negative consequences for successful aphid biological control. Although further research is needed on a broader spatial scale, our results suggest multiple species exist in this system and may suggest a complex set of interactions between parasitoids, hyperparasitoids, and the 3 aphid species. This was the first time that many of these species have been characterized and demonstrates the application of novel approaches to analyze the aphid-parasitoid food webs in pecans and other tree crop systems.
Assuntos
Afídeos , Cadeia Alimentar , Interações Hospedeiro-Parasita , Animais , Afídeos/parasitologia , Afídeos/genética , Carya/parasitologia , Código de Barras de DNA Taxonômico , Vespas/fisiologia , Vespas/genéticaRESUMO
The pecan nutshell [Carya illinoinensis (Wangenh) C. Koch] (PNS) is a source of bioactives with important beneficial properties for the human health. PNS represents between 40-50 % of total mass of the nut, resulting as waste without any added value for the food industry. Even though a variety of methods were already developed for bioactive extraction from this waste, unconventional methodologies, or those which apart from green chemistry principles, were discarded considering the cost of production, the sustainable development goals of United Nations and the feasibility of real inclusion of the technology in the food chain. Then, to add-value to this waste, a low-cost, green and easy-scalable extraction methodology was developed based on the determination of seven relevant factors by means of a factorial design and a Response Surface Methodology, allowing the extraction of bioactives with antioxidant capacity. The pecan nutshell extract had a high concentration of phenolic compounds (166 mg gallic acid equivalents-GAE/g dry weight-dw), flavonoids (90 mg catechin equivalent-CE/g dw) and condensed tannins (189 mg CE/g dw) -related also to the polymeric color (74.6 %)-, with high antioxidant capacities of ABTS+. radical inhibition (3665 µmol Trolox Equivalent-TE/g dw) and of iron reduction (1305 µmol TE/g dw). Several compounds associated with these determinations were identified by HPLC-ESI-MS/MS, such as [Epi]catechin-[Epi]catechin-[Epi]gallocatechin, myricetin, dihydroquercetins, dimers A and B of protoanthocyanidins, ellagitannins and ellagic acid derivatives. Hence, through the methodology developed here, we obtained a phenolic rich extract with possible benefits for human health, and of high industrial scalability for this co-product transformation.
Assuntos
Antioxidantes , Carya , Resíduos Industriais , Nozes , Extratos Vegetais , Carya/química , Nozes/química , Resíduos Industriais/análise , Resíduos Industriais/economia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Antioxidantes/isolamento & purificação , Antioxidantes/química , Antioxidantes/economia , Flavonoides/isolamento & purificação , Flavonoides/química , Fenóis/isolamento & purificação , Fenóis/química , Química VerdeRESUMO
Grafting is a widely used technique for pecan propagation; however, the background molecular events underlying grafting are still poorly understood. In our study, the graft partners during pecan [Carya illinoinensis (Wangenh.) K. Koch] graft union formation were separately sampled for RNA-seq, and the transcriptional dynamics were described via weighted gene co-expression network analysis. To reveal the main events underlying grafting, the correlations between modules and grafting traits were analyzed. Functional annotation showed that during the entire graft process, signal transduction was activated in the scion, while messenger RNA splicing was induced in the rootstock. At 2 days after grafting, the main processes occurring in the scion were associated with protein synthesis and processing, while the primary processes occurring in the rootstock were energy release-related. During the period of 7-14 days after grafting, defense response was a critical process taking place in the scion; however, the main process functioning in the rootstock was photosynthesis. From 22 to 32 days after grafting, the principal processes taking place in the scion were jasmonic acid biosynthesis and defense response, whereas the highly activated processes associated with the rootstock were auxin biosynthesis and plant-type secondary cell wall biogenesis. To further prove that the graft partners responded asymmetrically to stress, hydrogen peroxide contents as well as peroxidase and ß-1,3-glucanase activities were detected, and the results showed that their levels were increased in the scion not the rootstock at certain time points after grafting. Our study reveals that the scion and rootstock might respond asymmetrically to grafting in pecan, and the scion was likely associated with stress response, while the rootstock was probably involved in energy supply and xylem bridge differentiation during graft union formation.
Assuntos
Carya , Carya/genética , Regulação da Expressão Gênica de PlantasRESUMO
Pecan nuts are rich in lipids that tend to deteriorate during storage. Tandem mass-tag-based quantitative proteomics and transcriptomics were used to investigate the changes in the protein and gene profiles of stored pecan kernels for the first time. Our previous lipidomic data were jointly analyzed to elucidate the coordinated changes in lipid molecules and related proteins/genes. The mechanism underlying lipid deterioration in pecan kernels during storage was revealed by multiomics analyses. Lipid metabolism-related pathways were activated during pecan storage. Phospholipases, triacylglycerol lipases, lipoxygenases, and oil body-related proteins/genes were highly expressed during storage, revealing their involvement in lipid deterioration. These data provide rich information and will be valuable for future genetic or chemical research to alleviate lipid deterioration in pecans.
Assuntos
Carya , Armazenamento de Alimentos , Metabolismo dos Lipídeos , Proteínas de Plantas , Proteômica , Carya/química , Carya/genética , Carya/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Lipídeos/química , Perfilação da Expressão Gênica , TranscriptomaRESUMO
Pecans [Carya illinoinensis (Wangenh.) K. Koch] are highly valued for their abundance of quality healthy lipids, positively impacting human health and making themselves a preferred choice for nutritionally rich foods. However, a comprehensive understanding of the high-resolution characteristics of pecan fruit lipid composition and its dynamic changes, as well as the transfer between embryo and pericarp during development, remains incomplete. In this study, through integrated multi-omics analysis, we observed significant spatiotemporal heterogeneity in lipid changes between the pericarp and embryo. It showed smaller fluctuations and more stable lipid levels in the pericarp while exhibiting a dynamic pattern of initially increasing and then decreasing lipid content in the embryo. In this study, a total of 52 differentially expressed genes were identified, related to fatty acid synthesis and metabolism pathways in the two tissues, with changes in oleic acid and linoleic acid composition being the primary features of the embryo. This research lays the foundation for further understanding the differential regulation mechanisms of lipid metabolism between embryo and pericarp. Overall, this study filled the knowledge gap regarding dynamic changes in pericarp lipid metabolites, provided crucial insights into the lipid metabolism network during pecan fruit development, and established a scientific basis for the genetic improvement of pecan crops.
Assuntos
Carya , Frutas , Metabolismo dos Lipídeos , Lipidômica , Transcriptoma , Carya/metabolismo , Carya/genética , Carya/crescimento & desenvolvimento , Frutas/genética , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Lipídeos/análise , Regulação da Expressão Gênica de Plantas , Perfilação da Expressão GênicaRESUMO
Pecan (Carya illinoinensis) is a valuable crop in the southern United States. Scab (caused by Venturia effusa) is a major biotic constraint to pecan production in the southeastern region and requires 10 to 15 or more fungicide applications for control. Spray application relies on large standard radial airflow air blast sprayers (SSs). Some SSs have been adapted to include a volute on one side to project spray higher into the canopy because of a decline in coverage with height. A grower-designed and engineered double volute-generated focused airflow air blast sprayer (DVS) was assessed for scab control and spray coverage compared with an SS. Over three seasons, on foliage and fruit, scab control was either equal to or superior using the DVS sprayer. On mature fruit, in 2017, scab severity on the control was 9.07%, on the DVS it was 0.19%, and on the SS it was 0.24%; in 2018 severity was 84.4, 18.4, and 29.1%, respectively; and in 2019 it was 32.7, 7.0, and 11.6%, respectively. There were no discernable gradients in scab severity with tree height with either sprayer in 2017, but in 2018 the difference was significant, with the DVS having a shallower gradient, and in 2019 the DVS slope was numerically less steep compared with the SS. Mature fruit weight was significantly greater on trees treated using the DVS compared with the SS in 2017 and 2018 but was not different in 2019. Spray coverage studies showed that the DVS sprayer had significantly more coverage at heights >13.8 m (up to 19.0 m), ranging from 18.4 to 14.1%, compared with coverage using the SS, which ranged from 7.9 to 2.9%. The slope in decline of spray coverage with height was significantly shallower with the DVS sprayer, and spray profiles reflected these differences. Disease control was improved overall when using the DVS, and the DVS provided greater spray coverage at heights >13.8 m when compared with the SS sprayer. The DVS design may offer economical, superior scab control in pecan orchards where trees are >13.8 m tall.
Assuntos
Carya , Fungicidas Industriais , Doenças das Plantas , Doenças das Plantas/prevenção & controle , Doenças das Plantas/microbiologia , Carya/microbiologia , Fungicidas Industriais/farmacologia , Ascomicetos/fisiologia , Árvores/microbiologia , Frutas/microbiologiaRESUMO
Lasiodiplodia theobromae, as one of the causative agents associated with Chinese hickory trunk cankers, has caused huge economic losses to the Chinese hickory industry. Although the biological characteristics of this pathogen and the occurrence pattern of this disease have been well studied, few studies have addressed the related mechanisms due to the poor molecular and genetic study basis of this fungus. In this study, we sequenced and assembled L. theobromae strain LTTK16-3, isolated from a Chinese hickory tree (cultivar of Linan) in Linan, Zhejiang province, China. Phylogenetic analysis and comparative genomics analysis presented crucial cues in the prediction of LTTK16-3, which shared similar regulatory mechanisms of transcription, DNA replication, and DNA damage response with the other four Chinese hickory trunk canker-associated Botryosphaeria strains including, Botryosphaeria dothidea, Botryosphaeria fabicerciana, Botryosphaeria qingyuanensis, and Botryosphaeria corticis. Moreover, it contained 18 strain-specific protein clusters (not conserved in the other L. theobromae strains, AM2As and CITRA15), with potential roles in specific host-pathogen interactions during the Chinese hickory infection. Additionally, an efficient system for L. theobromae protoplast preparation and polyethylene glycol (PEG) -mediated genetic transformation was firstly established as the foundation for its future mechanisms study. Collectively, the high-quality genome data and the efficient transformation system of L. theobromae here set up the possibility of targeted molecular improvements for Chinese hickory canker control.IMPORTANCEFungi with disparate genomic features are physiologically diverse, possessing species-specific survival strategies and environmental adaptation mechanisms. The high-quality genome data and related molecular genetic studies are the basis for revealing the mechanisms behind the physiological traits that are responsible for their environmental fitness. In this study, we sequenced and assembled the LTTK16-3 strain, the genome of Lasiodiplodia theobromae first obtained from a diseased Chinese hickory tree (cultivar of Linan) in Linan, Zhejiang province, China. Further phylogenetic analysis and comparative genomics analysis provide crucial cues in the prediction of the proteins with potential roles in specific host-pathogen interactions during the Chinese hickory infection. An efficient PEG-mediated genetic transformation system of L. theobromae was established as the foundation for the future mechanisms exploration. The above genetic information and tools set up valuable clues to study L. theobromae pathogenesis and assist in Chinese hickory canker control.
Assuntos
Ascomicetos , Carya , Filogenia , Genômica , Transformação GenéticaRESUMO
Many machine learning techniques are used as drug discovery tools with the intent to speed characterization by determining relationships between compound structure and biological function. However, particularly in anticancer drug discovery, these models often make only binary decisions about the biological activity for a narrow scope of drug targets. We present a feed-forward neural network, PECAN (Prediction Engine for the Cytostatic Activity of Natural product-like compounds), that simultaneously classifies the potential antiproliferative activity of compounds against 59 cancer cell lines. It predicts the activity to be one of six categories, indicating not only if activity is present but the degree of activity. Using an independent subset of NCI data as a test set, we show that PECAN can reach 60.1% accuracy in a six-way classification and present further evidence that it classifies based on useful structural features of compounds using a "within-one" measure that reaches 93.0% accuracy.
Assuntos
Produtos Biológicos , Carya , Citostáticos , Aprendizado Profundo , Neoplasias , Humanos , Citostáticos/farmacologia , Produtos Biológicos/farmacologiaRESUMO
Across much of the eastern United States, oak forests are undergoing mesophication as shade-tolerant competitors become more abundant and suppress oak regeneration. Given the historical role of anthropogenic surface fires in promoting oak dominance, prescribed fire has become important in efforts to reverse mesophication and sustain oaks. In 2000 we established the Ohio Hills Fire and Fire Surrogate (FFS) study to examine whether repeated prescribed fire (Fire), mechanical partial harvest (Mech), and their combined application (Mech + Fire) reduced the dominance of subcanopy mesophytic competitors, increased the abundance of large oak-hickory advance regeneration, created a more diverse and productive ground-layer flora, and produced fuel beds more conducive to prescribed fire, reducing the risk of high-severity wildfire. Here we report on the ~20-year effects of treatments on vegetation and fuels and examine the support for interactive effects across a topographic-moisture and energy gradient. In general, we found that Fire and Mech + Fire treatments tended to reverse mesophication while the Mech-only treatment did not. The moderate and occasionally high-intensity fires resulted in effects that were ultimately very similar between the two fire treatments but were modulated by topography with increasing fire severity on drier sites. In particular, we found support for an interaction effect between treatment and topography on forest structure and tree regeneration responses. Fire generally reduced mesophytic tree density in the midstory and sapling strata across all site conditions, while leading to substantial gains in the abundance of large oak-hickory advance regeneration on dry and intermediate landscape positions. Fire also promoted ground-layer diversity and created compositionally distinct communities across all site conditions, primarily through the increased richness of native perennial herbs. However, the fire had limited effects on fine surface fuel loading and increased the loading of large woody fuels, potentially increasing the risk of high-severity wildfire during drought conditions. We conclude that two decades of repeated fires, with and without mechanical density reduction, significantly shifted the trajectory of mesophication across most of the landscape, particularly on dry and intermediate sites, highlighting the capacity of a periodic fire regime to sustain eastern oak forests and promote plant diversity but modulated by topography.
Assuntos
Carya , Incêndios , Quercus , Incêndios Florestais , Florestas , Árvores , EcossistemaRESUMO
Consistent efficacy is required for entomopathogenic nematodes to gain wider adoption as biocontrol agents. Recently, we demonstrated that when exposed to nematode pheromone blends, entomopathogenic nematodes showed increased dispersal, infectivity, and efficacy under laboratory and greenhouse conditions. Prior to this study, the impact of entomopathogenic nematode-pheromone combinations on field efficacy had yet to be studied. Steinernema feltiae is a commercially available entomopathogenic nematode that has been shown to increase mortality in insect pests such as the pecan weevil Curculio caryae. In this study, the pecan weevil was used as a model system to evaluate changes in S. feltiae efficacy when treated with a partially purified ascaroside pheromone blend. Following exposure to the pheromone blend, the efficacy of S. feltiae significantly increased as measured with decreased C. caryae survival despite unfavorable environmental conditions. The results of this study highlight a potential new avenue for using entomopathogenic nematodes in field conditions. With increased efficacy, using entomopathogenic nematodes will reduce reliance on conventional management methods in pecan production, translating into more environmentally acceptable practices.
Assuntos
Carya , Rabditídios , Gorgulhos , Animais , Feromônios/farmacologia , Controle Biológico de Vetores/métodosRESUMO
Pecan (Carya illinoinensis) is one important exotic forest crop cultivated in South America, specifically in Brazil, Uruguay, and Argentina. However, diseases such as anthracnose, favored by high humidity conditions and high summer temperatures, make its cultivation difficult, causing important loss to pecan farmers. This study used morphological and molecular approaches to identify the Colletotrichum species causing anthracnose in pecan plantations in Southern Brazil. The isolates obtained from pecan fruits with anthracnose symptoms were grouped through quantitative morphological characteristics into three distinct morphotypes. Molecular analysis of nuclear genes allowed the identification of six species of Colletotrichum causing anthracnose in pecan: C. nymphaeae, C. fioriniae, C. gloeosporioides, C. siamense, C. kahawae, and C. karsti. Three of these species are reported for the first time as causal agents of anthracnose in pecan. Therefore, these results provide an important basis for the adoption and/or development of anthracnose management strategies in pecan orchards cultivated in southern Brazil and neighboring countries.
Assuntos
Carya , Colletotrichum , Colletotrichum/genética , Brasil , Filogenia , Doenças das PlantasRESUMO
Pecan scab is a devastating disease that causes damage to pecan (Carya illinoinensis (Wangenh.) K. Koch) fruit and leaves. The disease is caused by the fungus Venturia effusa (G. Winter) and the main management practice for controlling the disease is by application of fungicides at 2-to-3-week intervals throughout the growing season. Besides disease-related yield loss, application of fungicides can result in considerable cost and increases the likelihood of fungicide resistance developing in the pathogen. Resistant cultivars are available for pecan growers; although, in several cases resistance has been overcome as the pathogen adapts to infect resistant hosts. Despite the importance of host resistance in scab management, there is little information regarding the molecular basis of genetic resistance to pecan scab.The purpose of this study was to elucidate mechanisms of natural pecan scab resistance by analyzing transcripts that are differentially expressed in pecan leaf samples from scab resistant and susceptible trees. The leaf samples were collected from trees in a provenance collection orchard that represents the natural range of pecan in the US and Mexico. Trees in the orchard have been exposed to natural scab infections since planting in 1989, and scab ratings were collected over three seasons. Based on this data, ten susceptible trees and ten resistant trees were selected for analysis. RNA-seq data was collected and analyzed for diseased and non-diseased parts of susceptible trees as well as for resistant trees. A total of 313 genes were found to be differentially expressed when comparing resistant and susceptible trees without disease. For susceptible samples showing scab symptoms, 1,454 genes were identified as differentially expressed compared to non-diseased susceptible samples. Many genes involved in pathogen recognition, defense responses, and signal transduction were up-regulated in diseased samples of susceptible trees, whereas differentially expressed genes in pecan scab resistant samples were generally down-regulated compared to non-diseased susceptible samples.Our results provide the first account of candidate genes involved in resistance/susceptibility to pecan scab under natural conditions in a pecan orchard. This information can be used to aid pecan breeding programs and development of biotechnology-based approaches for generating pecan cultivars with more durable scab resistance.
Assuntos
Ascomicetos , Carya , Fungicidas Industriais , Carya/genética , Carya/microbiologia , Transcriptoma , Árvores/genética , Ascomicetos/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Melhoramento VegetalRESUMO
Assessments of the severity of scab (Venturia effusa), an economically significant disease of pecan, are critical for determining pecan cultivar susceptibility, disease epidemiology, and integrated disease management approaches. We developed a standard area diagram (SAD) set to aid in assessments of pecan leaflet scab. Leaflets with scab lesions were harvested and scanned using a flatbed scanner at 600 dpi, and Fiji (ImageJ) was used to determine the actual percent disease severity. The SADs had 10 leaflets ranging in severity from 0.2 to 48.9%. Forty "small" (1.34 to 7.43 cm2) and 40 "large" (7.67 to 25.9 cm2) leaflet images were randomized for rater assessments. The images were assessed twice by 36 raters, first without and then with the SADs as a guide. Data were subjected to analysis using Lin's concordance correlation coefficient (LCC, pc) to determine the accuracy of ratings and by intraclass correlation coefficient (ICC) analysis to determine interrater reliability. The effects of rater experience, rater location, and leaflet size were also determined. The SADs significantly improved the agreement between raters and the actual values (LCC, pc = 0.70 and 0.84 without and with the SADs, respectively). The reliability of estimates was improved (ICC = 0.54 and 0.82 without and with the SADs, respectively). The effect of rater location on overall concordance was significant without and with the SADs based on an analysis of variance using a generalized linear model and lsmeans separation (P < 0.05). A generalized linear mixed model analysis revealed that there was a significant interaction between rater location, experience, and the use of the SADs, with some raters having greater improvement in generalized bias and concordance. Raters had a significantly better accuracy when rating "small" leaves (LCC, pc = 0.86) compared with "large" leaves (LCC, pc = 0.82) when using the SADs, highlighting the impact of psychophysics on field evaluations of plant disease severity. The proposed SADs will serve as an improved tool for performing pecan leaflet scab assessments by the pecan research community.
Assuntos
Carya , Doenças das Plantas , Folhas de Planta , Doenças das Plantas/microbiologia , Carya/microbiologia , Folhas de Planta/microbiologia , Reprodutibilidade dos Testes , Ascomicetos/fisiologia , Variações Dependentes do ObservadorRESUMO
As the core of Brassinosteroids (BR) signaling pathway, BR-resistant (BZR) transcription factor regulates thousands of targeted genes mediating photomophogenesis, pollen sterility, cell expansion and stress response. Pecan (Carya illinoinensis) is a famous trees species of Carya, and its nut has high nutritional and economic values. However, there has no report on BZR genes family in pecan yet. Herein, totals of seven CiBZR members were identified in pecan genome, which were predicted to be hydrophilic unstable proteins and located in the nucleus. CiBZR genes had close evolutionary relationships with CcBZRs and JrBZRs in both Carya cathayensis and Juglans regia. These seven CiBZR genes were located independently on 7 chromosomes without doubling or tandem duplication. Based on the analysis of conserved motifs and gene structures, CiBZR genes were divided into three categories. More than 40 cis-acting elements were found in the 2 kb promoter regions of CiBZRs, which were mainly involved in hormone, light, and stress response, and plant growth and development. Notably, some of these CiBZR proteins were mainly located in the nucleus, had the self-activation ability and interaction relationship with BIN2 kinase, and negatively regulated the expression of CiCPD and CiDWF4. Gene expressions analysis further showed that CiBZR genes could express in many tissues and shared similar expression trends during embryo development. Moreover, most CiBZR genes responded to BR, Gibberellin (GA), Strigolactone (SL), salt, acid and osmotic stress. This study provides theoretical basis for the subsequent study on the role of CiBZR family genes in plant growth, development and stress responses.
Assuntos
Carya , Carya/genética , Carya/metabolismo , Brassinosteroides/farmacologia , Brassinosteroides/metabolismo , Fatores de Transcrição/metabolismo , Estresse Fisiológico/genética , Hormônios/metabolismo , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
When plants are entirely submerged, photosynthesis and respiration are severely restricted, affecting plant growth and potentially even causing plant death. The AP2/ERF superfamily has been widely reported to play a vital role in plant growth, development and resistance to biotic and abiotic stresses. However, no relevant studies exist on flooding stress in pecan. In this investigation, we observed that CiAP2/ERF65 positively modulated the hypoxia response during submergence, whereas CiAP2/ERF106 was sensitive to submergence. The levels of physiological and biochemical indicators, such as POD, CAT and among others, in CiAP2/ERF65-OE lines were significantly higher than those in wild-type Arabidopsis thaliana, indicating that the antioxidant capacity of CiAP2/ERF65-OE lines was enhanced under submergence. The RNA-seq results revealed that the maintenance of the expression levels of the antenna protein gene, different signaling pathways for regulation, as well as the storage and consumption of ATP, might account for the opposite phenotypes of CiAP2/ERF65 and CiAP2/ERF106. Furthermore, the expression of some stress-related genes was altered during submergence and reoxygenation. Overall, these findings enhance our understanding of submergence stress in pecan, providing important candidate genes for the molecular design and breeding of hypoxia resistant in plants.