Ecology of Diaporthe eres, the causal agent of hazelnut defects.

Diaporthe eres has been recently reported as the causal agent of hazelnut defects, with characteristic brown spots on the kernels surface and internal fruit discoloration. Knowledge regarding the ecology of this fungus is poor but, is critical to support a rationale and effective hazelnut crop protection strategy. Therefore, a study was performed to describe and model the effect of different abiotic factors such as temperature (T, 5-35°C, step 5°C) and water activity (aw 0.83-0.99, step 0.03) regimes on D. eres mycelial growth, pycnidial conidiomata development and asexual spore production during a 60-day incubation period. Alpha conidia germination was tested in the same T range and at different relative humidities (RH = 94, 97 and 100%) over 48 h incubation period. Fungal growth was observed from the first visual observation; regarding pycnidia and cirrhi, their development started after 8 and 19 days of incubation, respectively and increased over time. The optimum T for growth was 20-25°C and for pycnidia and cirrhi development was 30°C; aw ≥ 0.98 was optimal for the tested steps of the fungal cycle. The best condition for conidial germination of D. eres was at 25°C with RH = 100%. Quantitative data obtained were fitted using non- linear regression functions (Bete, logistic and polynomial), which provided a very good fit of the biological process (R2 = 0.793-0.987). These functions could be the basis for the development of a predictive model for the infection of D. eres of hazelnuts.

Advances in cultivar choice, hazelnut orchard management, and nut storage to enhance product quality and safety: an overview.

European hazelnut (Corylus avellana L.) is a major species of interest for nutritional use within the Betulaceae family and its nuts are widely used throughout the world in the chocolate, confectionery, and bakery industries. Recently its cultivation has been expanded in traditional producer countries and established in new places in the southern hemisphere, including Chile, South Africa, and Australia. Introducing hazelnut in new environments could reduce its productivity, lead the trees to experience eco-physiological disorders, and expose the crop to high pressure from common and new pests and diseases. Thus, new approaches in cultivar choice guidance, in the sustainable orchard management and even in nut storage and kernel quality evaluation are urgently required to improve the hazelnut production and processing chain. The main objective of this study was to systematize the published information regarding recent findings about the cultural operations that directly influence nut and kernel quality, support varietal choice for new plantations, and list the recent advances in nut storage and in quality and safety evaluation. © 2020 Society of Chemical Industry.

Kaolin, Ascophyllum nodosum and salicylic acid mitigate effects of summer stress improving hazelnut quality.

BACKGROUND: Various strategies are needed to mitigate the negative impact on or to increase fruit quality. The effect of spraying kaolin (K), Ascophyllum nodosum (An) and salicylic acid (SA), in trees with and without irrigation, on quality and sensorial attributes of hazelnut (Grada de Viseu cultivar) was investigated during two consecutive years (2016 and 2017) in a commercial orchard located in Moimenta da Beira, Portugal. RESULTS: The treatments affected positively the biometric parameters nut and kernel weight, length, width, thickness and volume as well as the vitamin E level, antioxidant activity and content of some individual phenolics, such as protocatechuic acid, gallocatechin, catechin and epicatechin. The levels of amino acids in hazelnut kernels decreased in all the assayed treatments, while the kernel colour and sensorial attributes were not affected by the treatments. Hazelnut physical properties (nut and kernels), chemical and phytochemical composition and antioxidant activities were positively related. CONCLUSIONS: The application of K, An and SA improved the hazelnut tree response to climate change, without compromising the hazelnut chemical and sensorial quality. Furthermore, due to the similar observations for the same treatments with and without irrigation, it can be stated that K, An and SA can be efficient and cost-effective tools to mitigate summer stress in rain-fed orchards. © 2020 Society of Chemical Industry.

Projected impacts of climate change on the range and phenology of three culturally-important shrub species.

Climate change is shifting both the habitat suitability and the timing of critical biological events, such as flowering and fruiting, for plant species across the globe. Here, we ask how both the distribution and phenology of three food-producing shrubs native to northwestern North America might shift as the climate changes. To address this question, we compared gridded climate data with species location data to identify climate variables that best predicted the current bioclimatic niches of beaked hazelnut (Corylus cornuta), Oregon grape (Mahonia aquifolium), and salal (Gaultheria shallon). We also developed thermal-sum models for the timing of flowering and fruit ripening for these species. We then used multi-model ensemble future climate projections to estimate how species range and phenology may change under future conditions. Modelling efforts showed extreme minimum temperature, climate moisture deficit, and mean summer precipitation were predictive of climatic suitability across all three species. Future bioclimatic niche models project substantial reductions in habitat suitability across the lower elevation and southern portions of the species' current ranges by the end of the 21st century. Thermal-sum phenology models for these species indicate that flowering and the ripening of fruits and nuts will advance an average of 25 days by the mid-21st century, and 36 days by the late-21st century under a high emissions scenario (RCP 8.5). Future changes in the climatic niche and phenology of these important food-producing species may alter trophic relationships, with cascading impacts on regional ecosystems.

Identification of a caleosin associated with hazelnut (Corylus avellana L.) oil bodies.

Caleosins are involved in several cellular and biological processes that are closely associated with the synthesis, degradation and stability of oil bodies (OB). Because of the importance and the multiple roles of these OB-associated proteins, in silico identification of sequences corresponding to putative caleosins in the hazelnut genome has been performed, and the association with seed OB was verified using a proteomic approach. Five full-length sequences (CavCLO-H1, CavCLO-H2, CavCLO-H3, CavCLO-L1, CavCLO-L2), belonging to the two groups of caleosins (H and L), have been identified in the hazelnut genome. The number of identified caleosins is in agreement with that previously observed in other plant species, confirming that caleosins comprise small gene families in plants. A proteomic approach allowed us to verify only the presence of CavCLO-H1 in hazelnut OB, suggesting that several members inside this family could have different roles during plant growth and development. In silico analysis also suggests that CavCLO-H1 may act as a peroxygenase.

Changes in Antioxidant Activity, Profile, and Content of Polyphenols and Tocopherols in Common Hazel Seed (Corylus avellana L.) Depending on Variety and Harvest Date.

The aim of the study was to evaluate the influence of variety and the date of harvest of hazelnut seeds on their antioxidant potential and the profile and content of polyphenols and tocopherols. The research material included the hazelnut seeds of six varieties, harvested from July to September at equal 30-day intervals. Hazelnuts were analyzed for total fat content and antioxidant properties, whereby UPLC-PDA-ESI-MS analysis was used to determine the profile and content of polyphenols, and the HPLC method to determine the content of tocopherols. It was found that the content of fat and tocopherols in nuts increased with the ripening of the nuts. The highest fat content was found in walnut seeds of the Katalonski variety (September) and tocopherols in walnut seeds of the Olbrzym z Halle variety (177.67 mg/kg d.m.). In turn, antioxidant properties and total polyphenols content decreased with the later harvest date. The strongest antioxidant potential was found in the case of Cosford nuts harvested in July (66.93 mmol TE/100 g d.m.). These nuts were also characterized by the highest total polyphenol content (1704.9 mg/100 g d.m.). UPLC-MS analysis allowed the identification of 15 polyphenolic compounds such as phenolic acids, catechins and ellagic acid hexoside in nut seeds.

Repeated long-distance dispersal and convergent evolution in hazel.

Closely related species with a worldwide distribution provide an opportunity to understand evolutionary and biogeographic processes at a global scale. Hazel (Corylus) is an economically important genus of tree and shrub species found in temperate regions of Asia, North America and Europe. Here we use multiple nuclear and chloroplast loci to estimate a time-calibrated phylogenetic tree of the genus Corylus. We model the biogeographic history of this group and the evolutionary history of tree and shrub form. We estimate that multiple Corylus lineages dispersed long distances between Europe and Asia and colonised North America from Asia in multiple independent events. The geographic distribution of tree versus shrub form of species appears to be the result of 4-5 instances of convergent evolution in the past 25 million years. We find extensive discordance between our nuclear and chloroplast trees and potential evidence for chloroplast capture in species with overlapping ranges, suggestive of past introgression. The important crop species C. avellana is estimated to be closely related to C. maxima, C. heterophylla var. thunbergii and the Colurnae subsection. Our study provides a new phylogenetic hypothesis or Corylus and reveals how long-distance dispersal can shape the distribution of biodiversity in temperate plants.

Analysis of European hazelnut (Corylus avellana) reveals loci for cultivar improvement and the effects of domestication and selection on nut and kernel traits.

Turkey is a rich source of European hazelnut (Corylus avellana) germplasm with nearly 400 accessions in the national collection. This genetic material encompasses cultivars, landraces and wild genotypes which were characterized for 12 nut and 13 kernel traits over 2 years in the 1990s. Analysis of these attributes revealed both the positive and negative impacts that human selection and breeding have had on hazelnut. Thus, while selection has resulted in larger nuts and kernels, cultivars have fewer nuts per cluster and kernels with larger internal cavities. Breeding has also resulted in a propensity for cultivars to have higher proportions of double kernels and empty nuts, two traits which reduce quality and yield. In addition, it is clear that while selection has successfully increased hazelnut fat content it has not impacted overall flavor, a much more complex trait. The nut and kernel phenotypic data were combined with genotypic data from 406 simple sequence repeat marker alleles for association mapping of the quantitative trait loci (QTL) for the traits. A total of 78 loci were detected in the population with the highest proportions for nut (24%) and kernel (26%) appearance parameters followed by quality (19%), shell thickness (16%) and yield-related (15%) traits. It is hoped that some of the identified QTL will be useful for future breeding of hazelnut for improved nut and kernel yield and quality.

Identification of genes regulating ovary differentiation after pollination in hazel by comparative transcriptome analysis.

BACKGROUND: Hazel (Corylus spp.) exhibits ovary differentiation and development that is initiated from the ovary primordium after pollination, conferring the plant with a unique delayed fertilization. Failure of development of the ovary and ovule after pollination can lead to ovary abortion and blank fruit formation, respectively, with consequent yield loss. However, the genes involved in ovary and ovule differentiation and development are largely unknown. RESULTS: In unpollinated pistillate inflorescences (stage F), the stigma shows an extension growth pattern. After pollination, a rudimentary ovary begins to form (stage S), followed by ovule differentiation (stage T) and growth (stage FO). Total RNA was obtained from pistillate inflorescences or young ovaries at stage F, S, T and FO, and sequencing was carried out on a HiSeq 4000 system. De novo assembly of sequencing data yielded 62.58 Gb of nucleotides and 90,726 unigenes; 5524, 3468, and 8714 differentially expressed transcripts were identified in F-vs-S, S-vs-T, and T-vs-FO paired comparisons, respectively. An analysis of F-vs-S, S-vs-T, and T-vs-FO paired comparisons based on annotations in the Kyoto Encyclopedia of Genes and Genomes revealed six pathways that were significantly enriched during ovary differentiation, including ko04075 (Plant hormone signal transduction). Auxin level increased after pollination, and an immunohistochemical analysis indicated that auxin was enriched at the growth center of pistillate inflorescences and young ovaries. These results indicate that genes related to auxin biosynthesis, transport, signaling, the floral quartet model, and flower development may regulate ovary and ovule differentiation and development in hazel. CONCLUSIONS: Our findings provide insight into the molecular mechanisms of ovary differentiation and development after pollination in this economically valuable plant.

High density SNP mapping and QTL analysis for time of leaf budburst in Corylus avellana L.

The growing area of European hazelnut (Corylus avellana L.) is increasing, as well as the number of producing countries, and there is a pressing need for new improved cultivars. Hazelnut conventional breeding process is slow, due to the length of juvenile phase and the high heterozygosity level. The development of genetic linkage maps and the identification of molecular markers tightly linked to QTL (quantitative trait loci) of agronomic interest are essential tools for speeding up the selection of seedlings carrying desired traits through marker-assisted selection. The objectives of this study were to enrich a previous linkage map and confirm QTL related to time of leaf budburst, using an F1 population obtained by crossing Tonda Gentile delle Langhe with Merveille de Bollwiller. Genotyping-by-Sequencing was used to identify a total of 9,999 single nucleotide polymorphism markers. Well saturated linkage maps were constructed for each parent using the double pseudo-testcross mapping strategy. A reciprocal translocation was detected in Tonda Gentile delle Langhe between two non-homologous chromosomes. Applying a bioinformatic approach, we were able to disentangle 'pseudo-linkage' between markers, removing markers around the translocation breakpoints and obtain a linear order of the markers for the two chromosomes arms, for each linkage group involved in the translocation. Twenty-nine QTL for time of leaf budburst were identified, including a stably expressed region on LG_02 of the Tonda Gentile delle Langhe map. The stability of these QTL and their coding sequence content indicates promise for the identification of specific chromosomal regions carrying key genes involved in leaf budburst.

Changes in phenolic profiles of red-colored pellicle walnut and hazelnut kernel during ripening.

In studies of secondary metabolites in nuts, many constituents in the kernel remain unidentified due to a high content of phenolic compounds in the pellicle. In the present study, we focused on the investigation of the phenolic and dicarboxylic acid profiles of walnut and hazelnut pellicle-less kernels. High-performance liquid chromatography with diode array and mass spectrometric detection (HPLC-DAD-MSn) was used to carry out the determination of individual phenolics and dicarboxylic acids in brown and red-pellicle walnut and hazelnut. Results show that hexahydroxydiphenic acid (HHDP) di-galloyl hexose isomer, vanillic acid hexoside, quinic acid derivative and catechin are the main constituents of the phenolic profile of walnut, while galloylquinic derivative, caffeoyl hexoside and catechin are the main constituents of the hazelnut kernel. Even though both walnut and hazelnut kernels have a considerably lower content of phenolic compounds and dicarboxylic acids in comparison to the pellicles, when calculated as a percentage of the total mass, the kernel makes a significant contribution to the total phenolic content of the whole nut.

A Novel Medium for Enhancing Callus Growth of Hazel (Corylus avellana L.).

Paclitaxel is a powerful antimitotic agent with excellent activity against a range of cancers. Hazel has been described as a paclitaxel-producing species among angiosperms. Fast-growing callus is a prerequisite for the success of callus production and then paclitaxel production. Therefore, optimizing the medium culture for enhancing callus growth is a crucial step for paclitaxel production. In this research, Murashige and Skoog (1962) (MS) medium was optimized for improving callus growth of hazel (Corylus avellana L.). The M10 medium (MS medium with pH 6.0 and supplemented with 1000 mg l-1 spirulina powder, 1000 mg l-1 casein hydrolysate and 3 g l-1 gelrite) significantly improved hazel callus growth. This modified MS medium increased callus fresh weight (55.8%) as compared to the control. M10 medium increased fatty acids yield of callus (66.7%) as compared to the control. Liquid M10 medium maintained growth over a longer period of time and also increased slightly, the paclitaxel production as compared to the control. This novel medium is promising for facilitating the mass production of hazel callus as a source of valuable metabolites including paclitaxel, linoleic and oleic acids.

Hazelnut and neuroprotection: Improved memory and hindered anxiety in response to intra-hippocampal Aß injection.

OBJECTIVES: Corylus avellana L. (hazelnut) is known to be a delicious and nutritious food. This study was carried out to evaluate the use of hazelnut as a therapy for memory impairment because in Iranian traditional medicine, it is recommended for those suffering from a particular type of dementia, with symptoms of Alzheimer's disease. METHODS: In this study, rats were fed with hazelnut kernel [(without skin) 800 mg/kg/day] during 1 week before stereotaxic surgery to 24 hours before behavioral testing (in general, for 16 consecutive days) and the effect of hazelnut eating on memory, anxiety, neuroinflammation and apoptosis was assessed in the amyloid beta-injected rat. RESULTS: The results of this study showed that feeding with hazelnut improved memory, (which was examined by using Y-maze test and shuttle box apparatus), and reduced anxiety-related behavior, that was evaluated using elevated plus maze. Also, western blotting analysis of cyclooxygenase-2, interleukin-1ß, tumor necrosis factor-α, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein, and caspase-3 showed that hazelnut has an ameliorating effect on the neuroinflammation and apoptosis caused by Aß. DISCUSSION: These findings suggest that hazelnut, as a dietary supplement, improves healthy aging and could be a beneficial diet for the treatment of AD.

Extensive Field Survey, Laboratory and Greenhouse Studies Reveal Complex Nature of Pseudomonas syringae-Associated Hazelnut Decline in Central Italy.

Pseudomonas avellanae (Pav) has been reported as the causal agent of bacterial decline and bacterial canker of hazelnut in Italy and Greece, respectively. Both hazelnut diseases were reported to be similar in terms of symptoms, severity and persistence. In this study, we found that both symptomatic and asymptomatic trees in the field were colonized by Pav. Multilocus Sequence Typing (MLST) analysis showed that Pav strains isolated during this study in Italy belong to the P. syringae phylogroup 1 and they are closely related to Pav strains previously isolated in Greece from hazelnut bacterial canker. On the other hand, strains isolated in earlier studies from hazelnut decline in Italy belong to both phylogroup 1 and 2 of P. syringae. Both phylogroup 1 strains of P. syringae from Greece and Italy are different than strains isolated in this study in terms of their capacity to excrete fluorescent pigments on different media. Despite the same plant genotype and cropping practices adopted, the incidence of hazelnut decline ranged from nearly 0 to 91% across our study sites. No disease developed on plants inoculated with Pav through wounding while leaf scar inoculations produced only mild disease symptoms. Based on our results and the previously reported correlation between pedo-climatic conditions and hazelnut decline, we conclude that hazelnut decline in central Italy could be incited by a combination of predisposing (adverse pedo-climatic conditions) and contributing factors (Pav). Because this is a true decline different from "bacterial canker" described in Greece, we refer to it as hazelnut decline (HD).

The effects of short- and long-term air pollutants on plant phenology and leaf characteristics.

Pollution adversely affects vegetation; however, its impact on phenology and leaf morphology is not satisfactorily understood yet. We analyzed associations between pollutants and phenological data of birch, hazel and horse chestnut in Munich (2010) along with the suitability of leaf morphological parameters of birch for monitoring air pollution using two datasets: cumulated atmospheric concentrations of nitrogen dioxide and ozone derived from passive sampling (short-term exposure) and pollutant information derived from Land Use Regression models (long-term exposure). Partial correlations and stepwise regressions revealed that increased ozone (birch, horse chestnut), NO2, NOx and PM levels (hazel) were significantly related to delays in phenology. Correlations were especially high when rural sites were excluded suggesting a better estimation of long-term within-city pollution. In situ measurements of foliar characteristics of birch were not suitable for bio-monitoring pollution. Inconsistencies between long- and short-term exposure effects suggest some caution when interpreting short-term data collected within field studies.

Sulfadiazine uptake and effects in common hazel (Corylus avellana L.).

Soil contamination by antibiotics is a possible consequence of animal husbandry waste, sewage sludge, and reclaimed water spreading in agriculture. In this study, 1-year-old hazel plants (Corylus avellana L.) were grown in pots for 64 days in soil spiked with sulfadiazine (SDZ) in the range 0.01-100 mg kg(-1) soil. Leaf gas exchanges, fluorescence parameters and plant growth were measured regularly during the experiment, whereas plant biomass, sulfonamide concentrations in soil and plant tissues, and the quantitative variation of culturable bacterial endophytes in leaf petiole were analyzed at the end of the trial. During the experiment, photosynthesis and leaf transpiration as well as fluorescence parameters were progressively reduced by the antibiotic. Effects were more evident for leaf transpiration and for the highest SDZ spiking concentrations, whereas growth analyses did not reveal negative effects of the antibiotic. At the end of the trial, a high number of culturable endophytic bacteria in the leaf petiole of plants treated with 0.1 and 0.01 mg kg(-1) were observed, and SDZ was extractable from soil and plant roots for spiking concentrations ≥1 mg kg(-1). Inside plants, the antibiotic was mainly stored at the root level with bioconcentration factors increasing with the spiking dose, and the hydroxylated derivate 4-OH-SDZ was the only metabolite detected. Overall results show that 1-year-old hazel plants can contribute to the reduction of sulfonamide concentrations in the environment, however, sensitive reactions to SDZ can be expected at the highest contamination levels.

Transcriptome analysis and gene expression profiling of abortive and developing ovules during fruit development in hazelnut.

BACKGROUND: A high ratio of blank fruit in hazelnut (Corylus heterophylla Fisch) is a very common phenomenon that causes serious yield losses in northeast China. The development of blank fruit in the Corylus genus is known to be associated with embryo abortion. However, little is known about the molecular mechanisms responsible for embryo abortion during the nut development stage. Genomic information for C. heterophylla Fisch is not available; therefore, data related to transcriptome and gene expression profiling of developing and abortive ovules are needed. METHODOLOGY/PRINCIPAL FINDINGS: In this study, de novo transcriptome sequencing and RNA-seq analysis were conducted using short-read sequencing technology (Illumina HiSeq 2000). The results of the transcriptome assembly analysis revealed genetic information that was associated with the fruit development stage. Two digital gene expression libraries were constructed, one for a full (normally developing) ovule and one for an empty (abortive) ovule. Transcriptome sequencing and assembly results revealed 55,353 unigenes, including 18,751 clusters and 36,602 singletons. These results were annotated using the public databases NR, NT, Swiss-Prot, KEGG, COG, and GO. Using digital gene expression profiling, gene expression differences in developing and abortive ovules were identified. A total of 1,637 and 715 unigenes were significantly upregulated and downregulated, respectively, in abortive ovules, compared with developing ovules. Quantitative real-time polymerase chain reaction analysis was used in order to verify the differential expression of some genes. CONCLUSIONS/SIGNIFICANCE: The transcriptome and digital gene expression profiling data of normally developing and abortive ovules in hazelnut provide exhaustive information that will improve our understanding of the molecular mechanisms of abortive ovule formation in hazelnut.

Nut traits and nutritional composition of hazelnut (Corylus avellana L.) as influenced by zinc fertilization.

BACKGROUND: Zinc is an essential element for plants and its deficiency is a widespread problem throughout the world, causing decreased yields and nutritional quality. In this study the effect of zinc fertilization on some nut traits and the nutritional composition of 'Tombul' hazelnut (Corylus avellana L.) variety cultivated in the Black Sea region of Turkey was investigated and the contribution of this nut to human nutrition determined. Trials were carried out at 'Tombul' hazelnut orchards, and zinc fertilizers were applied at 0, 0.2, 0.4, 0.8 and 1.6 kg Zn ha(-1) in three consecutive years. RESULTS: Significant differences in some nut traits and mineral composition (protein, total oil, ash, kernel percentage, empty and wrinkled nuts, copper, boron, manganese and molybdenum) were observed with zinc fertilizer applications. In terms of daily nutritional element requirements, 100 g of hazelnut provided about 44.74% phosphorus, 13.39% potassium, 19.32% calcium, 37.49% magnesium, 0.19% sodium, 51.63% iron, 25.73% zinc and 14.05% boron of the recommended daily amounts (RDAs), while copper, manganese and molybdenum contents exceeded their RDAs. CONCLUSION: In order to improve some nut traits and the mineral composition of hazelnut, 0.8 and 1.6 kg Zn ha(-1) fertilizations could be recommended in practice.

Pistillate flower development and pollen tube growth mode during the delayed fertilization stage in Corylus heterophylla Fisch.

Unlike most angiosperms, in which fertilization occurs within several days after pollination, fertilization in hazel (Corylus Spp.) is delayed by two to three and a half months. However, the female inflorescences or young fruits are too hard or lignified to be dissected according to regular paraffin sectioning technique. So, what the nature of development during the extended progamic phases of hazel remains unknown. The female inflorescence development and pollen tube growth mode during the delayed fertilization stage in hazel were investigated by improved paraffin sectioning and aniline blue staining of pollen tubes. The results showed ovaries and ovules of hazel were invisible at the time of blooming. Early ovary and ovule primordium began to form from 15 to 20 days after blooming, respectively. Integument and mature embryo sacs differentiated from the nucellus on 40th and 55th day after blooming, respectively. Pollen tubes were retarded in the bottom of the style or the pollen tube cavity (PTC, a specifical lignified cavity structure at the bottom of style for pollen tube to rest during progamic phase) for about 26 days. Then, the pollen tubes were observed to leave the PTC and began to enter the ovary. After that, a single pollen tube passed through the vicinity of the micropyle. Finally, pollen tubes turned a corner and penetrated the embryo sac through the tissue of the chalaza instead of micropyle on 52 and 55 days after blooming, respectively. The results of more in-depth information will be beneficial to better understanding of the delayed fertilization process in hazel.

Analysis of different European hazelnut (Corylus avellana L.) cultivars: authentication, phenotypic features, and phenolic profiles.

Hazelnuts exhibit functional properties due to their content in fatty acids and phenolic compounds that could positively affect human health. The food industry requires precise traits for morphological, chemical, and physical kernel features so that some cultivars could be more suitable for specific industrial processing. In this study, agronomical and morphological features of 29 hazelnut cultivars were evaluated and a detailed structural characterization of kernel polyphenols was performed, confirming the presence of protocatechuic acid, flavan-3-ols such as catechin, procyanidin B2, six procyanidin oligomers, flavonols, and one dihydrochalcone in all the analyzed cultivars. In addition, an innovative methodology based on the MALDI-TOF mass spectrometric analysis of peptide/protein components extracted from kernels was developed for the authentication of the most valuable cultivars. The proposed method is rapid, simple, and reliable and holds the potential to be applied in quality control processes. These results could be useful in hazelnut cultivar evaluation and choice for growers, breeders, and food industry.