Chestnut Cultivars Research Articles

Chemical characterization and comparison of two chestnut rose cultivars from different regions

Chestnut rose (Rosa roxburghii Tratt.) is a native fruit in China, rich in bioactive compounds. Chemical properties and bioactive compounds in the largest two cultivars (Gui Nong No. 5 and Golden Cili) of chestnut rose from different regions were analyzed and compared. Meanwhile, catechin, quercetin, myricetin, kaempferol, ellagic acid and ellagic acid glucuronide were identified. By comparison, Guinong No. 5 showed higher SOD actitviy (5,687.67–5,797.48 U/g), ascorbic acid (1.38–1.47 g/100 g), catechin (971.67–1405.75 mg/100 g) and myricetin (851.32–876.32 mg/100 g), antioxidant capacity, while Golden Cili was characterized with higher total flavnoids (263.30–278.63 mg/100 g), β-carotene (747.31–859.21 μg/100 g) and zeaxanthin (186.03–268.78 μg/100 g), glucose (10.32–12.03 g/100 g) and arabinose (3.22–3.43 g/100 g), tartaric acid (0.20–0.52 g/100 g), quercetin (1,034.63–1,411.08 mg/100 g). The principal components analysis method can be used to separate two cultivars well and partial least squares discrimination analysis method can be used to distinguish different planting regions well.

Reservoir of the European chestnut diversity in Switzerland

In Switzerland, chestnut forests cover about 27,100 ha, plus some 6800 ha of mixed stands. Due to environmental and historical reasons, most of these still existing forests are located in the Swiss Southern Alps, whereas in the northern parts of the country the chestnut cultivation and the related knowledge strongly regressed since the Little Ice Age period. Nevertheless, Switzerland still hosts valuable genetic resources of the sweet chestnut tree. The present genetic study bases on a nationwide inventory, identification and precise localisation of old and/or grafted chestnut trees for conservation purposes. The main objectives were: (1) to evaluate the genetic diversity and the genetic structure of Castanea sativa in Switzerland, and (2) to define a program of conservation including the proposal of a defined core collection. We genetically analysed a pre-selection of 962 accessions (out of 14,165 inventoried trees throughout Switzerland), profiling them with 24 microsatellites. We identified 675 different genotypes out of 962 accessions with a 29.8% of repetitiveness due to clonality. A structural analysis based on a Bayesian method allowed to identify two main clusters, one mostly related to the genetic group from southern Europe (Reconstructed Panmictic Population RPP1) and a second one (RPP2) which revealed to be independent and genetically different from other European groups of chestnut cultivars. The Swiss RPP2 represents a new genetic group, and consequently a complement to genetic resources of chestnut tree in Europe. Genetic analysis allowed defining a core collection of 46 genotypes, which should be used in priority for the Swiss conservation program.

Pollen morphology of chestnut cultivars in southern China by using scanning electron microscope

The morphological characteristics of pollen grains of 16 cultivars belonging to two species of the genus Castanea (Castanea mollissima and C. henryi) collected from southern China were observed by using scanning electron microscope (SEM). The length of polar axis (PL), the equatorial diameter (ED), the length of colpus (CL) of grain, P/E ratio (polar axis to equatorial diameter), P/C ratio (polar axis to colpus length), and C/E ratio (colpus length to equatorial diameter) were measured and their variations were compared among studied taxa. The result of this study indicated that chestnut pollen grain was a tricolporate in aperture type, and aperprolate type in equatorial view. The morphological characteristics were mainly represented by PL, ED and CL as revealed by principal components analysis, which accounted for 99.56% of the total variations. The cluster analysis by the UPGMA tree divided the taxa into three groups and showed a great morphological affinity among the 16 cultivars.

Floral characterization and pollen germination protocol for Castanea crenata Siebold & Zucc

Chestnuts have staminate (male) and androgynous (hermaphrodite) flowers in the same individual. The male flowers are grouped into unisexual catkins, while the female flowers are located at the base of male inflorescences. There is divergence in the functionality of pollen grains among chestnut species. As this species requires cross-pollination, germination tests are essential in breeding programs. The objective of this study was to comparatively evaluate pollen viability as a function of the type of flower using colorimetric assays, to develop a culture medium protocol for in vitro pollen germination and characterize the floral morphology of the Japanese chestnut (C. crenata). Eleven Japanese chestnut cultivars were evaluated for characterization and description of the floral morphology, pollen viability by staining, and in vitro germination with determination of the percentage of viability regarding the type of inflorescence (staminate x androgynous). In addition, a culture medium was established to induce germination of chestnut pollen and determination of the percentage of in vitro pollen germination, as well as quantification of the number of anthers per flower and pollen grains per anther and per flower for all cultivars. There was no difference in pollen viability between androgynous and staminate catkins. The culture medium containing 6 g L−1 of agar, 46.5 g L−1 of sucrose, and 460.23 mg L−1 of boric acid in the absence of calcium nitrate, pH 5.25, promoted the best conditions for in vitro pollen germination. Cultivars with the highest percentage of viability recorded the lowest amounts of pollen per anther and per flower. This characteristic may influence the number of flowers necessary for extraction of anthers in crosses and the success of hybridization in the field.

The Asian Chestnut Gall Wasp in Italy: Surveys on its Native and Exotic Parasitoids as Well as on Chestnut Cultivar Susceptibility

In the context of biological control against the Asian chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) in Italy, the aim of this study was to survey its native parasitoids as well as the exotic Torymus sinensis Kamijo which had been introduced and released as a biological control agent. Furthermore, both parasitism and pest susceptibility of local chestnut trees were investigated. Surveys were carried out in 2014 in the Municipality of Sambuca Pistoiese (Pistoia), in a chestnut forest which included three cultivars: Nerattino, Carpinese, and Pastinese. On a total of 35 trees, selected among the three cultivars, 24 current-year shoots were randomly collected and examined in the laboratory. After the damage by the cynipid had been assessed, leaf samples were used for molecular analyses. Galls were also collected on the 35 selected trees both for dissection and to rear parasitoid specimens in the laboratory. The three cultivars were confirmed by genetic tests. The Carpinese cultivar resulted to be the most damaged, with highest percentage of attacked shoots (84.38%). Moreover it was also the cultivar with the lower parasitism rate (about 16%). From reared galls seven parasitoid species emerged, all belonging to the superfamily of Chalcidoidea. Exception made for the non-native T. sinensis, the other six were native species associated to oak gall wasps. Native parasitoids were more scarcely present, while the exotic T. sinensis amounted for the 84.27% of all emerged parasitoids. Our results confirm how chestnut susceptibility to D. kuriphilus varies depending on the cultivar. Overall, the Nerattino cultivar resulted as the best among the three examined: it was subject to a less intense attack than the other cultivars, and the resulting smaller galls were more effectively exploited by parasitoids.

Valorization of the agro-forestry wastes from Italian chestnut cultivars for the recovery of bioactive compounds

Chestnut is a very promising forest species that may be used as biomass to recover high value-added biomolecules. Four cultivars coming from the Italian Park “Roccamonfina-Foce Garigliano” were characterized at biochemical level by phenolic chromatographic profiling and by means of antioxidant activity. The phenolic compounds were extracted from leaves, burs, and shells for all cultivars and the inner shells resulted the richest by-product in all varieties. Comparison of data sets using principal component analysis led to conclusions regarding the biochemical relationships among all cultivars. Furthermore, cluster analysis with HPLC data on the phytochemical compounds produced a dendrogram showing the relationships within Italian cultivars, so confirming the same pattern showed in PCA. In conclusion, high added-value bioactive compounds, utilized as dietary and pharmaceutical supplements, can be achieved from non-edible chestnut components discarded during post-harvest and food processing, so improving the valuable capacity of recycling of chestnut wastes.

Dissecting Resistance to Phytophthora cinnamomi in Interspecific Hybrid Chestnut Crosses Using Sequence-Based Genotyping and QTL Mapping

The soilborne oomycete Phytophthora cinnamomi-which causes root rot, trunk cankers, and stem lesions on an estimated 5,000 plant species worldwide-is a lethal pathogen of American chestnut (Castanea dentata) as well as many other woody plant species. P. cinnamomi is particularly damaging to chestnut and chinquapin trees (Castanea spp.) in the southern portion of its native range in the United States due to relatively mild climatic conditions that are conductive to disease development. Introduction of resistant genotypes is the most practical solution for disease management in forests because treatment with fungicides and eradication of the pathogen are neither practical nor economically feasible in natural ecosystems. Using backcross families derived from crosses of American chestnuts with two resistant Chinese chestnut cultivars Mahogany and Nanking, we constructed linkage maps and identified quantitative trait loci (QTLs) for resistance to P. cinnamomi that had been introgressed from these Chinese chestnut cultivars. In total, 957 plants representing five cohorts of three hybrid crosses were genotyped by sequencing and phenotyped by standardized inoculation and visual examination over a 6-year period from 2011 to 2016. Eight parental linkage maps comprising 7,715 markers were constructed, and 17 QTLs were identified on four linkage groups (LGs): LG_A, LG_C, LG_E, and LG_K. The most consistent QTLs were detected on LG_E in seedlings from crosses with both 'Mahogany' and 'Nanking' and LG_K in seedlings from 'Mahogany' crosses. Two consistent large and medium effect QTLs located ∼10 cM apart were present in the middle and at the lower end of LG_E; other QTLs were considered to have small effects. These results imply that the genetic architecture of resistance to P. cinnamomi in Chinese chestnut × American chestnut hybrid progeny may resemble the P. sojae-soybean pathosystem, with a few dominant QTLs along with quantitatively inherited partial resistance conferred by multiple small-effect QTLs.

Biochemical characterization of leaves, burs and shells of ‘Bouche de Bétizac’ chestnut cultivar

Biochemical characterization of leaves, burs and shells of ‘Bouche de Bétizac’ chestnut cultivar

Productive Performance of Chestnut Trees for Cultivation in Tropical Regions

Chestnut trees are economically exploited in temperate regions of Asian countries, Oceania and the European Iberian Peninsula. Chestnuts are sources of protein and carbohydrates and are eaten in many ways, mainly roasted during cold temperatures. Chestnuts may be suitable for cultivation in tropical regions, but to do this, the potential cultivars’ productive performances should be quantified. Thus, this study determined the performances of chestnut cultivars in a tropical region using the Taishowase, Isumo, Tamatsukuri and Okuni cultivars. The cultivars’ phenological development, including the beginning and end of flowering and harvesting, as well as each cultivar’s nut production were evaluated over four production cycles. The Taishowase and Okuni cultivars were shown to be the most promising for tropical regions because they showed greater adaptability and production stability.

The complete chloroplast genome of a variety of Castanea mollissima 'Hongli' (Fagaceae)

Chinese Chestnut (Castanea mollissima) is an economically valuable tree in China. More than 300 wild and cultivated varieties were reported. In this study, we reported and characterized the complete chloroplast genome sequence of Chinese Chestnut cultivar ‘Hongli’, variant dominant strain with high yield, good quality of nuts, especially with red coloration in their leaves, twigs, and involucres of fruits. The chloroplast genome was determined to be 160,871 bp in length. It contained large single-copy (LSC) and small single-copy (SSC) regions of 90,498 and 18,971 bp, respectively, which were separated by a pair of 25,701 bp inverted repeat (IR) regions. The genome is predicted to contain 130 genes, including 83 protein-coding genes, 37 tRNA genes, 8 rRNA genes, and 2 pseudo genes. The overall GC content of the genome is 36.7%. A phylogenetic tree reconstructed by 25 chloroplast genomes reveals that C. mollissima 'Hongli' is most closely related to wild C. mollissima that was collected from China.

Instant domestication process of European chestnut cultivars

This study presents the results of the first genetic analysis of ancient chestnut trees (Castanea sativa Mill.) in Italy and in the Iberian Peninsula to better understand the effect of grafting on the domestication process of chestnut and to investigate the impacts of early selection and improvement on the genetic diversity retained. We evaluated 105 giant ancient trees from Italy, Spain and Portugal and compared them with the European Union (EU) database of chestnut cultivars by using a set of 24 simple sequence repeats (SSRs; microsatellite markers). We measured the perimeter (girth) at the diameter at breast height (DBH). Samples from both the canopy and the roots of each tree were analysed to distinguish which trees were self‐rooted and which were grafted. Diversity was compared using standard metrics and model‐based approaches based on the expected heterozygosity (He) at equilibrium. We could differentiate 91 new genotypes; 9.6% matched known chestnut cultivars. We found the first evidences of cultivation, that is, grafting to produce “instant domestication” in Galicia and in the Douro Valley in trees of 14‐m perimeter (15th century) and in the Basque Country (first report in that area) in a tree of 11.5‐m perimeter (16th century). In Italy, the cultivar “Marrone Fiorentino” was found in some giant trees with perimeters of 8 and 9 m (17th‐18th centuries) in the Toscana and Umbria. Those findings matched with written references in Portugal from the 16th century and from the 18th century in Spain. “Instant domestication” could be dated back to the 15th century and was related to the wild populations existing in the same areas where cultivars are being propagated, without a different genetic structure for wild chestnut trees and with a high diversity maintained through the initiation of domestication.

Evaluation of the descriptive characteristics of chestnut

The chestnut (Castanea spp.) tree is extremely valuable for it ecological role in the environment as well as its role in the production of sweet, edible nuts, decay resistant timber, and the production of chemical compounds such as tannins. Although native to the temperate zone of the northern hemisphere, it has been planted successfully throughout the southern hemisphere including Australia, New Zealand and Chile. Currently, the genus Castanea is represented by 13 species ranging in size from shrubs to large trees. Five species of Castanea are native to East Asia, seven species are native to North America and one species is native to Europe. Many chestnut cultivars have been selected or bred for various purposes such as improving nut or timber quality, increasing yield, enhancing resistance to diseases or pests and winter hardiness. For the purpose of registering new cultivars, distinctness, uniformity and stability (DUS) of the cultivars need to be described and verified. For this aim, morphological characteristics of the cultivar candidates should be determined. There are many morphological traits used for identifying cultivar candidates. However, reliable characteristics need to be selected and scored. Generally, the International Union for the Protection of New Varieties of Plants (UPOV) criteria have been used for this purpose, but we believe the UPOV criteria need to be updated. In this review, various descriptive morphological chestnut parameters are discussed to promote the list of current and new criteria.

Progress in chestnut breeding at the Institute of Fruit Tree and Tea Science, NARO, Japan

Organized, government-funded chestnut (Castanea crenata Sieb. et Zucc.) breeding, has been conducted at the Institute of Fruit Tree and Tea Science, NARO, in Japan since 1947. The initial objective was to develop cultivars that ripen in the early or mid-season, that excel in yield, nut size, and nut quality by intra-specific cross of Japanese chestnut or interspecific cross between Japanese and Chinese chestnut. Serious damage from the chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu) (Dk) spread rapidly throughout Japan soon after the beginning of the program, and resistance to Dk was added as a goal of the program in 1952. By the early 1990s, six Japanese chestnut cultivars were released, including the currently leading cultivars, ‘Tanzawa’ (early-ripening), ‘Tsukuba’ (mid-ripening), and ‘Ishizuchi’ (late-ripening), that excel in yield, nut size, nut quality, and are resistant to Dk. With the successful establishment of Torymus sinensis, a parasitoid of Dk introduced from China, in the breeding field at NIFTS by the end of 1980s, the objective since the 1990s has been on improving nut quality by introducing genes from Chinese chestnut. ‘Shuuhou’ and ‘Mikuri’ have been released in this project. Furthermore, a simple method for evaluating the peeling pellicle ability was developed for breeding selection around the year 2000. Using this method, ‘Porotan,’ an easy peeling pellicle (EPP) cultivar of Japanese chestnut, was released in 2006. In addition, ‘Porosuke,’ which has EPP trait similar to ‘Porotan,’ and ripens one week earlier than ‘Porotan,’ was derived from the same cross as for ‘Porotan,’ and released in 2016. The current breeding objectives focus on breeding cultivars with good nut quality with EPP trait that ripen later than ‘Porotan’. To increase breeding efficiency, marker-assisted selection for easy peeling pellicle was performed in the 2010s. Furthermore, the development of DNA markers for other horticultural traits is currently in progress for future breeding.

Особливості гетеровегетативного розмноження гіркокаштанів

Досліджено ефективність різних способів щеплення найпоширеніших у Західному регіоні України видів жовто-рожевоквіткового (Aesculus hibrida D. C.), червоноквіткових (Aesculus pavia L. і Aesculus carnea Hayne) та жовтоквіткового (Aesculus octаndra Marsh.) гіркокаштанів. Апробовано три способи гетеровегетативного розмноження – "у розщіп", "у боковий розріз" та "окуліровка" для чотирьох видів гіркокаштанів. Підщепами були 8-річні саджанці гіркокаштана кінського звичайного. Прищепами – однорічні пагони із середини крони або вертикальний верхівковий пагін, з яких нарізали здорові, зрілі, без пошкоджень живці довжиною 8–10 см. Щеплення проведено у другій декаді квітня у відкритому ґрунті шкільного відділення декоративного розсадника. За щепленими рослинами виконано агротехнічні та селекційні догляди протягом наступних років вирощування. Встановлено, що найвищою приживлюваністю відзначається спосіб "у бічний розріз" (56,0–80,0 %) під час щеплень усіх видів гіркокаштанів. Квітувати щеплені рослини почали на другий-третій рік після щеплення, а формувати плоди з повнозернистим доброякісним насінням – на четвертий-п'ятий. Виробнича собівартість одного щепленого 2-річного саджанця гіркокаштанів у відкритому ґрунті, залежно від виду прищепи, становить 80,5–115,0 грн. Проведені експериментальні щеплення саджанців різних видів гіркокаштанів засвідчили широкі технологічні можливості та значну економічну ефективність гетеровегетативного розмноження різними способами для отримання садивного матеріалу щеплених декоративних червоно- та жовтоквіткових культиварів гіркокаштанів. Застосовані способи щеплення ("у бічний розріз" та "у розщіп") рекомендовано використовувати у промислових обсягах для розмноження особливо декоративних і стійких до негативного впливу абіотичних і біотичних чинників культиварів гіркокаштанів.

Bayesian genome-wide association study of nut traits in Japanese chestnut

Japanese chestnut (Castanea crenata Sieb. et Zucc.) has a long juvenile phase, so breeders have to wait many years to evaluate nut traits. Molecular markers associated with genes of interest would accelerate selection in chestnut breeding programs. We evaluated five nut traits (nut harvest date, nut weight, pericarp splitting, insect infestation, and specific gravity) in 99 Japanese chestnut cultivars and selections. A wide range of phenotypic variation was observed for each of the traits, suggesting that the collection harbored sufficient genetic diversity for breeding. A Bayesian genome-wide association study was conducted using 162 simple sequence repeat markers and 741 single nucleotide polymorphism markers. To evaluate the potential of marker-assisted selection, we examined 12 molecular markers found to be associated with nut traits: 4 for nut harvest date, 4 for nut weight, 1 for pericarp splitting, and 3 for insect infestation. The percentages of phenotypic variance explained ranged from 4.8 to 37.1%. Although insect infestation showed only medium heritability (0.672), we obtained two quantitative trait loci (QTLs) with extremely high posterior probabilities (0.93 and 1.00). Out of the 12 molecular markers, 3 of the 4 markers for nut harvest time could be validated in a breeding population. Accuracies of genomic selection were extremely high for nut harvest date (0.841) and moderate for insect infestation (0.604), suggesting that genomic selection based on Bayesian regression would reduce the cost of phenotypic evaluation of these traits and possibly others.

Insights into the crystallinity and in vitro digestibility of chestnut starch during thermal processing

The crystallinity is of importance for in vitro digestibility of starch. Six chestnut cultivars were selected to study the relationship between the crystallinity and in vitro digestibility of chestnut starch during thermal processing. After heat treatment, the total starch and amylose content remained unchanged or decreased, but the amount of damaged starch increased significantly (P < 0.05). Thermal processing enhanced the short-range ordered structure of starch and reduced its relative crystallinity. Thermal processing also decreased the resistant starch (RS) content, but a high RS content (57.2–67.9% of total starch) still remained in cooked chestnut starch. The relative crystallinity was negatively correlated with the estimated glycemic index (eGI) (r = −0.6416), and positively correlated with RS content (r = 0.6189). Accordingly, by altering the relative crystallinity and damage degree of chestnut starch, thermal processing changed the overall starch fractions and eGI, which can affect the overall in vitro digestibility.

Construction of a SNP-Based High-Density Genetic Map Using Genotyping by Sequencing (GBS) and QTL Analysis of Nut Traits in Chinese Chestnut (Castanea mollissima Blume).

Chinese chestnut is a wildly distributed nut species with importantly economic value. The nut size and ripening period are mainly desired breeding objectives in Chinese chestnut. However, high-density linkage maps and quantitative trait loci (QTL) analyses related to nut traits are less than satisfactory, which hinders progress in the breeding of Chinese chestnut. Here, a single nucleotide polymorphism (SNP)-based high-density linkage map was constructed through genotyping-by-sequencing (GBS) of an F1 cross between the two widely grown Chinese chestnut cultivars ‘Yanshanzaofeng’ and ‘Guanting No. 10’. The genetic linkage map consists of 2,620 SNP markers with a total length of 1078.06 cM in 12 linkage groups (LGs) and an average marker distance of 0.41 cM. 17 QTLs were identified for five nut traits, specifically single-nut weight (SNW), nut width (NW), nut thickness (NT), nut height (NH), and ripening period (RP), based on phenotypic data from two successive years. Of the 17 QTLs, two major QTLs, i.e., qNT-I-1 and qRP-B-1 related to the NT and RP traits, respectively, were exploited. Moreover, the data revealed one pleiotropic QTL at 23.97 cM on LG I, which might simultaneously control SNW, NT, and NW. This study provides useful benchmark information concerning high-density genetic mapping and QTLs identification related to nut size and ripening period, and will accelerate genetic improvements for nuts in the marker-assisted selection (MAS) breeding of Chinese chestnut.

Analysis of nutritional composition and antioxidant activity of sweet potato (Ipomoea batatas L.) leaf and petiole

Two cultivars of sweet potatoes, Pumpkin and Chestnut, were planted in the didactic field of the Faculty of Horticulture, Craiova, and biochemical determinations were carried out from the blades and petioles of the leaves. This study highlights the antioxidant properties of these species, which are not well known in Romania, to encourage consumption of the vegetative parts of the plant, as well as use of the leaves in the future to develop natural antioxidants. The chlorophyll and carotene content in the blade and petiole were determined, highlighting the large amounts of petiole, depending on the cultivar. Catalase (CAT), peroxidase (POX), and vitamin C content, as well as total dry matter (TDM), reducing sugars, phenolic compounds, and antioxidant activity, were also measured. The petioles exhibited high antioxidant activity, with 62.186 μmol TE/g FW in Pumpkin and 95.168 μmol TE/g FW in Chestnut. The cultivars also exhibited differences at the blade level, with high values recorded for the Chestnut cultivar. Positive correlations between total polyphenols and reducing sugars (r = 0.89), antioxidant activity and reducing sugars (r = 0.48), and antioxidant activity and phenolic compounds (r = 0.53) were found. This study demonstrates that sweet potato leaves are a potential, inexpensive and beneficial source of natural antioxidants.

Relationship between physicochemical characteristics and in vitro digestibility of chestnut (Castanea mollissima) starch

The present study investigated the differences in starch and amylose content among six chestnut cultivars widely distributed in China, as well as the relationship between their physicochemical characteristics and in vitro digestibility. The cultivar and geographical distribution significantly influenced the characteristics of chestnut starch. The starch granule from all six cultivars was round or irregular polygonal in shape, with a particle size that varied from 1 to 20 μm. The amylose content ranged from 22.27 to 29.80% of starch, while the damaged starch was 3.44–11.94%. The volume average particle size of the chestnut starches from the six cultivars varied from 8.33 to 10.24 μm, and the median diameter ranged from 6.82 to 8.69 μm. The short-range order of the six chestnut starches exhibited no significant difference, but their X-ray patterns were different and their relative crystallinity ranged between 19.3 and 27.9%. The resistant starch accounts for 70.1–85.6% of chestnut starch, and was found to be positively correlated with the amylose content. The glycemic index was negatively correlated with the relative crystallinity, indicating that the crystalline structure of starch had a retardant effect on its digestibility.

A New Chestnut Cultivar “Huaqiao 2”

This paper introduces new chestnut cultivar “Huaqiao 2” breeding process, main characteristics, seedling and planting technique, harvesting and handling chestnuts, chestnut food, industrial development, Xiangtan Jinhu Chestnut Professional Cooperative etc., provide a theoretical basis for research and industrial development of new chestnut cultivar “Huaqiao 2”.