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Completion of the Chloroplast Genomes of Five Chinese Juglans and Their Contribution to Chloroplast Phylogeny
L. (walnuts and butternuts) is an economically and ecologically important genus in the family Juglandaceae. All
are important nut and timber trees.
(Common walnut),
(Iron walnut),
(Chinese walnut),
(Ma walnut), and
(Manchurian walnut) are native to or naturalized in China. A strongly supported phylogeny of these five species is not available due to a lack of informative molecular markers. We compared complete chloroplast genomes and determined the phylogenetic relationships among the five Chinese
using IIumina sequencing. The plastid genomes ranged from 159,714 to 160,367 bp encoding 128 functional genes, including 88 protein-coding genes and 40 tRNA genes each. A complete map of the variability across the genomes of the five
species was produced that included single nucleotide variants, indels (insertions and deletions), and large structural variants, as well as differences in simple sequence repeats (SSR) and repeat sequences. Molecular phylogeny strongly supported division of the five walnut species into two previously recognized sections (
and
) with a 100% bootstrap (BS) value using the complete cp genomes, protein coding sequences (CDS), and the introns and spacers (IGS) data. The availability of these genomes will provide genetic information for identifying species and hybrids, taxonomy, phylogeny, and evolution in
, and also provide insight into utilization of
plants.
Journal Article
Walnut Fruit Processing Equipment: Academic Insights and Perspectives
The walnut varieties in China are rich, the planting area in the country is wide, and the yield ranks at the forefront of the world. Walnut kernel is the most important application part of the walnut fruit. An in-depth study found that the by-products of walnut, such as green husk and walnut shell, also have great application potential and are cheap raw materials for the extraction of important medical ingredients and the production of industrial products. However, the by-products are often burned or discarded as waste during processing, which not only wastes resources but also causes environmental pollution. To realize the high value-added application of the walnut fruit, a deep processing of each part of the walnut should be considered. Preliminary processing is the key link before walnuts enter the field of intensive processing and consumption. The advanced level of the required technological equipment can help to determine the quality of the walnut products. The preliminary processing of walnuts in China is mainly divided into six steps: green husk removal, walnut drying, walnut size classification, walnut shell-breaking, walnut shell–kernel separation, and walnut kernel skin removal. This paper starts with a presentation of the importance of each link and the existing bottleneck. Then, the paper systematically discusses the analysis of the current situation and the development of devices required for each link. The working mechanism of each link type and its influence on the design of a corresponding device are summarized. On the basis of the corresponding working mechanism, this study classifies and summarizes the characteristics of the core mechanism of the devices for each preliminary process link; then, it evaluates and analyzes the existing typical mechanical devices according to their types. Finally, the influence rule of the various devices for each link in the preliminary processing is analyzed as a means of ensuring high-quality walnuts.
Journal Article
Laura Ingalls is ruining my life
Charlotte struggles to adjust when her mother moves the family to Walnut Grove, Minnesota, the small, boring town where pioneer author Laura Ingalls Wilder grew up, in hopes of finding inspiration for her writing career.
BOOK
Unravelling the genetic diversity and population structure of common walnut in the Iranian Plateau
Background
Common walnut (
Juglans regia
L.) has a long cultivation history, given its highly valuable wood and rich nutritious nuts. The Iranian Plateau has been considered as one of the last glaciation refugia and a centre of origin and domestication for the common walnut. However, a prerequisite to conserve or utilize the genetic resources of
J. regia
in the plateau is a comprehensive evaluation of the genetic diversity that is conspicuously lacking. In this regard, we used 31 polymorphic simple sequence repeat (SSR) markers to delineate the genetic variation and population structure of 508
J. regia
individuals among 27 populations from the Iranian Plateau.
Results
The SSR markers expressed a high level of genetic diversity (
H
O
= 0.438, and
H
E
= 0.437). Genetic differentiation among the populations was moderate (
F
ST
= 0.124), and genetic variation within the populations (79%) significantly surpassed among populations (21%). The gene flow (
N
m
= 1.840) may have remarkably influenced the population genetic structure of
J. regia
, which can be attributed to anthropological activities and wind dispersal of pollen. The STRUCTURE analysis divided the 27 populations into two main clusters. Comparing the neighbor-joining and principal coordinate analysis dendrograms and the Bayesian STRUCTURE analysis revealed the general agreement between the population subdivisions and the genetic relationships among the populations. However, a few geographically close populations dispersed into different clusters. Further, the low genetic diversity of the Sulaymaniyah (SMR) population of Iraq necessitates urgent conservation by propagation and seedling management or tissue culture methods; additionally, we recommend the indispensable preservation of the Gonabad (RGR) and Arak (AKR) populations in Iran.
Conclusions
These results reflected consistent high geographical affinity of the accession across the plateau. Our findings suggest that gene flow is a driving factor influencing the genetic structure of
J. regia
populations, whereas ecological and geological variables did not act as strong barriers. Moreover, the data reported herein provide new insights into the population structure of
J. regia
germplasm, which will help conserve genetic resources for the future, hence improving walnut breeding programs’ efficiency.
Journal Article
Quantification and Comparison of Nutritional Components in Oni Walnut (Juglans ailanthifolia Carr.), Hime Walnut (Juglans subcordiformis Dode.), and Cultivars
Walnuts are rich sources of lipids and polyunsaturated fatty acids and are expected to promote health. There are two Japanese native walnut species: Oni walnut (Juglans ailanthifolia Carr.) and Hime walnut (Juglans subcordiformis Dode.). However, despite the fact that these Japanese native walnuts have long been consumed in local cuisine, their nutritional composition is largely unknown. This study aimed to assess the concentrations of total lipids, and fatty acid composition including polyunsaturated fatty acids, in the kernels of Oni walnut and Hime walnut. In addition, we assessed various aspects related to their nutritional and functional values, by measuring the total protein, amino acids, minerals, and total polyphenols. The concentrations of the measured compounds in the two native species were compared with those in the English walnut (Juglans regia L.), a globally recognized cultivar, and its counterpart cultivated in Japan, Shinano walnut (Juglans regia L.). The results showed that Oni walnut and Hime walnut contained significantly higher protein and minerals and lower lipid content than conventional cultivars. However, both Oni and Hime walnuts contained higher ratios of unsaturated fatty acids in total fatty acids. This study offers novel insights into the nutritional components of Oni and Hime walnuts, contributing to a deeper understanding of their nutritional value and potential applications as unique native walnut species. The findings of this study highlight the relationship between the different types of walnut species and their nutritional composition, and the value of native walnuts used in local cuisine, and will lead to new developments in functional foods from walnut species consumed around the world. It will contribute to the development of functional and processed foods by increasing the production of native walnut species, which are rich in protein, unsaturated fatty acids and minerals and by using them in local cuisines and health-promoting foods.
Journal Article
Plant growth-promoting rhizobacteria for protecting walnut plants from root-lesion nematode (Pratylenchus vulnus)
Chile is one of the world’s leading walnut producers, but the endoparasitic migratory nematode Pratylenchus vulnus considerably affects walnut plants and decreases crop yield. This study assessed the biological control effects of three selected native rhizobacteria species (Bacillus weihenstephanensis FB25M, Brevibacterium frigoritolerans FB37BR, and Oerskovia turbata FB55) against P. vulnus and its damage to walnut plants. The direct effect of the bacterial filtrates of the three species on population of P. vulnus was evaluated in vitro for 72 h at 20 °C and nematode mortality registered every 24 h. The antagonistic effect of a bacterial suspension was measured under greenhouse conditions using 3-month-old potted walnut plants. The growing substrate of the plants was inoculated with a suspension of 1 × 106 colony-forming units (CFU/ml) of each rhizobacteria strain or their mixture, followed by P. vulnus inoculation. As control treatments, two commercial products (chemical: cadusafos; and biological: rhizobacterial mix) and unbacterized plants with and without nematodes were used. Results under in vitro conditions showed that after 72 h exposure of P. vulnus to rhizobacterial filtrates, all bacterial treatments were effective in controlling the nematode (P < 0.01), reaching values between 98 and 100% and exhibiting nematicidal and nemastatic effects. The greenhouse experiments had consistent results; rhizobacteria-treated walnut plants exhibited the maximum biocontrol (mortality) values (67–77%) (P < 0.05). Similarly, rhizobacterial treatments demonstrated the highest root weight compared with the untreated and chemical control treatments (P < 0.05). The evaluated rhizobacterial species showed nematicidal and root growth-promoting effects, which can offer a potential alternative for controlling and protecting walnut plants from P. vulnus.
Journal Article
Genome-wide identification, transcriptome dynamics, and expression regulation of the key lignin biosynthesis gene families PAL and CAD in black walnut shell
Background
Walnut (
Juglans
), cultivated globally for their nuts and timber, holds significant economic and ecological value. The eastern black walnut (EBW,
J. nigra
). a diploid species, an important woody species. Key enzymes in the plant lignin biosynthesis pathway include Phenylalanine ammonia-lyase (
PAL
) and Cinnamyl alcohol dehydrogenase (
CAD
). Although the gene families of
PAL
and
CAD
have been extensively characterized in various plants, comprehensive genomic resources and expression profiles specific to the EBW remain limited.
Results
Based on RNA sequencing of shells and kernels from black walnut (
Juglans nigra
) among three development stages, S1 (80 days after flowering, DAF), S2 (111 DAF), and S3(140 DAF) in black walnut shells and kernels, we found the genes related to lignin biosynthesis. genes such as
JnPAL
,
JnC4H
,
Jn4CL1
,
Jn4CL2
,
JnHCT
,
JnCOMT
,
Jn
CAD2, and
Jn
CAD-like exhibited significant differential expression across all three developmental stages. Both
PAL
and
CAD
genes were expressed significantly in walnut shells compared to kernels across three developmental stages. We conducted a genome-wide identification and discovered 7 PAL and 3 CAD proteins in
J. nigra
and 5 PAL and 3 CAD proteins in
J. microcarpa
genome, respectively. Transcriptome DEGs (differential expressed genes) analysis and identified three candidates
PAL
(
JnPAL1
,
JnPAL2
, and
JnPAL6
) and 2
CAD
genes (
JnCAD2
and
JnCAD3
) were upregulated during the development of walnut kernels and shells. In addition, it was higher expressed of these
PAL
and
CAD
genes in the shell than kernel.
Conclusions
We conducted a comprehensive involving genome-wide identification, transcriptome dynamics, and expression regulation of the key lignin biosynthesis gene families PAL and CAD across three development stages of shells. This study not only constitutes a valuable resource for elucidating the role of
PAL
and
CAD
genes in determining shell thickness in black walnut but also holds significant potential for informing gene-assisted breeding strategies in walnut cultivation.
Journal Article