NAC domain gene VvNAC26 interacts with VvMADS9 and influences seed and fruit development

MdWRKY31-MdNAC7 regulatory network: orchestrating fruit softening by modulating cell wall-modifying enzyme MdXTH2 in response to ethylene signalling

Softening in fruit adversely impacts their edible quality and commercial value, leading to substantial economic losses during fruit ripening, long-term storage, long-distance transportation, and marketing. As the apple fruit demonstrates climacteric respiration, its firmness decreases with increasing ethylene release rate during fruit ripening and postharvest storage. However, the molecular mechanisms underlying ethylene-mediated regulation of fruit softening in apple remain poorly understood. In this study, we identified a WRKY transcription factor (TF) MdWRKY31, which is repressed by ethylene treatment. Using transgenic approaches, we found that overexpression of MdWRKY31 delays softening by negatively regulating xyloglucan endotransglucosylase/hydrolases 2 (MdXTH2) expression. Yeast one-hybrid (Y1H), electrophoretic mobility shift (EMSA), and dual-luciferase assays further suggested that MdWRKY31 directly binds to the MdXTH2 promoter via a W-box element and represses its transcription. Transient overexpression of ethylene-induced MdNAC7, a NAC TF, in apple fruit promoted softening by decreasing cellulose content and increasing water-soluble pectin content in fruit. MdNAC7 interacted with MdWRKY31 to form a protein complex, and their interaction decreased the transcriptional repression of MdWRKY31 on MdXTH2. Furthermore, MdNAC7 does not directly regulate MdXTH2 expression, but the protein complex formed with MdWRKY31 hinders MdWRKY31 from binding to the promoter of MdXTH2. Our findings underscore the significance of the regulatory complex NAC7-WRKY31 in ethylene-responsive signalling, connecting the ethylene signal to XTH2 expression to promote fruit softening. This sheds light on the intricate mechanisms governing apple fruit firmness and opens avenues for enhancing fruit quality and reducing economic losses associated with softening.

Integrative genomics reveals the polygenic basis of seedlessness in grapevine

Seedlessness is a crucial quality trait in table grape (Vitis vinifera L.) breeding. However, the development of seeds involved intricate regulations, and the polygenic basis of seed abortion remains unclear. Here, we combine comparative genomics, population genetics, quantitative genetics, and integrative genomics to unravel the evolution and polygenic basis of seedlessness in grapes. We generated the haplotype-resolved genomes for two seedless grape cultivars, "Thompson Seedless" (TS, syn. "Sultania") and "Black Monukka" (BM). Comparative genomics identified a ∼4.25 Mb hemizygous inversion on Chr10 specific in seedless cultivars, with seedless-associated genes VvTT16 and VvSUS2 located at breakpoints. Population genomic analyses of 548 grapevine accessions revealed two distinct clusters of seedless cultivars, and the identity-by-descent (IBD) results indicated that the origin of the seedlessness trait could be traced back to "Sultania." Introgression, rather than convergent selection, shaped the evolutionary history of seedlessness in grape improvement. Genome-wide association study (GWAS) analysis identified 110 quantitative trait loci (QTLs) associated with 634 candidate genes, including previously unidentified candidate genes, such as three 11S GLOBULIN SEED STORAGE PROTEIN and two CYTOCHROME P450 genes, and well-known genes like VviAGL11. Integrative genomic analyses resulted in 339 core candidate genes categorized into 13 functional categories related to seed development. Machine learning-based genomic selection achieved a remarkable prediction accuracy of 97% for seedlessness in grapevines. Our findings highlight the polygenic nature of seedlessness and provide candidate genes for molecular genetics and an effective prediction for seedlessness in grape genomic breeding.

MicroRNA164e suppresses NAC100 transcription factor-mediated synthesis of seed storage proteins in chickpea

Development of protein-enriched chickpea varieties necessitates an understanding of specific genes and key regulatory circuits that govern the synthesis of seed storage proteins (SSPs). Here, we demonstrated the novel involvement of Ca-miR164e-CaNAC100 in regulating SSP synthesis in chickpea. Ca-miRNA164e was significantly decreased during seed maturation, especially in high-protein accessions. The miRNA was found to directly target the transactivation conferring C-terminal region of a nuclear-localized transcription factor, CaNAC100 as revealed using RNA ligase-mediated-rapid amplification of cDNA ends and target mimic assays. The functional role of CaNAC100 was demonstrated through seed-specific overexpression (NACOE) resulting in significantly augmented seed protein content (SPC) consequential to increased SSP transcription. Further, NACOE lines displayed conspicuously enhanced seed weight but reduced numbers and yield. Conversely, a downregulation of CaNAC100 and SSP transcripts was evident in seed-specific overexpression lines of Ca-miR164e that culminated in significantly lowered SPC. CaNAC100 was additionally demonstrated to transactivate the SSP-encoding genes by directly binding to their promoters as demonstrated using electrophoretic mobility shift and dual-luciferase reporter assays. Taken together, our study for the first time established a distinct role of CaNAC100 in positively influencing SSP synthesis and its critical regulation by CamiR164e, thereby serving as an understanding that can be utilized for developing SPC-rich chickpea varieties.

A tomato NAC transcription factor, SlNAP1, directly regulates gibberellin-dependent fruit ripening

In tomato (Solanum lycopersicum), the ripening of fruit is regulated by the selective expression of ripening-related genes, and this procedure is controlled by transcription factors (TFs). In the various plant-specific TF families, the no apical meristem (NAM), Arabidopsis thaliana activating factor 1/2 (ATAF1/2), and cup-shaped cotyledon 2 (CUC2; NAC) TF family stands out and plays a significant function in plant physiological activities, such as fruit ripening (FR). Despite the numerous genes of NAC found in the tomato genome, limited information is available on the effects of NAC members on FR, and there is also a lack of studies on their target genes. In this research, we focus on SlNAP1, which is a NAC TF that positively influences the FR of tomato. By employing CRISPR/Cas9 technology, compared with the wild type (WT), we generated slnap1 mutants and observed a delay in the ethylene production and color change of fruits. We employed the yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays to confirm that SlNAP1 directly binds to the promoters of two crucial genes involved in gibberellin (GA) degradation, namely SlGA2ox1 and SlGA2ox5, thus activating their expression. Furthermore, through a yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BIFC) and luciferase (LUC) assays, we established an interaction between SlNAP1 and SlGID1. Hence, our findings suggest that SlNAP1 regulates FR positively by activating the GA degradation genes directly. Additionally, the interaction between SlNAP1 and SlGID1 may play a role in SlNAP1-induced FR. Overall, our study provides important insights into the molecular mechanisms through which NAC TFs regulate tomato FR via the GA pathway.

NAC61 regulates late- and post-ripening osmotic, oxidative, and biotic stress responses in grapevine

During late- and post-ripening stages, grape berry undergoes profound biochemical and physiological changes whose molecular control is poorly understood. Here, we report the role of NAC61, a grapevine NAC transcription factor, in regulating different processes involved in berry ripening progression. NAC61 is highly expressed during post-harvest berry dehydration and its expression pattern is closely related to sugar concentration. The ectopic expression of NAC61 in Nicotiana benthamiana leaves resulted in low stomatal conductance, high leaf temperature, tissue collapse and a higher relative water content. Transcriptome analysis of grapevine leaves transiently overexpressing NAC61 and DNA affinity purification and sequencing analyses allowed us to narrow down a list of NAC61-regulated genes. Direct regulation of the stilbene synthase regulator MYB14, the osmotic stress-related gene DHN1b, the Botrytis cinerea susceptibility gene WRKY52, and NAC61 itself was validated. We also demonstrate that NAC61 interacts with NAC60, a proposed master regulator of grapevine organ maturation, in the activation of MYB14 and NAC61 expression. Overall, our findings establish NAC61 as a key player in a regulatory network that governs stilbenoid metabolism and osmotic, oxidative, and biotic stress responses that are the hallmark of late- and post-ripening grape stages.

Molecular regulation of apple and grape ripening: exploring common and distinct transcriptional aspects of representative climacteric and non-climacteric fruits

Fleshy fruits of angiosperms are organs specialized for promoting seed dispersal by attracting herbivores and enticing them to consume the organ and the seeds it contains. Ripening can be broadly defined as the processes serving as a plant strategy to make the fleshy fruit appealing to animals, consisting of a coordinated series of changes in color, texture, aroma, and flavor that result from an intricate interplay of genetically and epigenetically programmed events. The ripening of fruits can be categorized into two types: climacteric, which is characterized by a rapid increase in respiration rate typically accompanied by a burst of ethylene production, and non-climacteric, in which this pronounced peak in respiration is absent. Here we review current knowledge of transcriptomic changes taking place in apple (Malus × domestica, climacteric) and grapevine (Vitis vinifera, non-climacteric) fruit during ripening, with the aim of highlighting specific and common hormonal and molecular events governing the process in the two species. With this perspective, we found that specific NAC transcription factor members participate in ripening initiation in grape and are involved in restoring normal physiological ripening progression in impaired fruit ripening in apple. These elements suggest the existence of a common regulatory mechanism operated by NAC transcription factors and auxin in the two species.

Genome-Wide Identification, Evolution and Expression Profile Analysis of NAC Transcription Factor in Simmondsia chinensis

NAC transcription factors (TFs) are one of the largest plant-specific gene families and play important roles in plant growth, development, and the biotic and abiotic stress response. Although the sequencing of Jojoba (Simmondsia chinensis) has been completed, the genome-wide identification and analysis of its NAC TFs has not been reported. In this study, a total of 57 genes were identified in Jojoba, which were divided into eight groups based on phylogenetic analysis. The genes clustered in the same groups have a similar gene structure and motif distribution. Based on the analysis of cis-elements in NAC TFs, nine cis-acting elements were identified in the promoter region that involved in light response, hormonal response, and stress response. Synteny analysis showed a greater collinearity between Jojoba and V. vinifera than Arabidopsis thaliana. The 24 genes in the Jojoba NAC TFs are derived from fragment replication, which may be the main source of NAC amplification. Gene expression analysis identified seven genes that were highly expressed in seeds. The differential expression analysis of NAC TFs in cotyledon and embryonic axis tissues showed that the expression of 10 genes was up-regulated and 1 gene was down-regulated. This study provides more information on the classification, gene structure, conserved motif, and evolution of NAC TFs in Jojoba, facilitating further exploration of their specific functional analysis in Jojoba seed development.

Comparative Anatomical and Transcriptomics Reveal the Larger Cell Size as a Major Contributor to Larger Fruit Size in Apricot

Fruit size is one of the essential quality traits and influences the economic value of apricots. To explore the underlying mechanisms of the formation of differences in fruit size in apricots, we performed a comparative analysis of anatomical and transcriptomics dynamics during fruit growth and development in two apricot cultivars with contrasting fruit sizes (large-fruit Prunus armeniaca 'Sungold' and small-fruit P. sibirica 'F43'). Our analysis identified that the difference in fruit size was mainly caused by the difference in cell size between the two apricot cultivars. Compared with 'F43', the transcriptional programs exhibited significant differences in 'Sungold', mainly in the cell expansion period. After analysis, key differentially expressed genes (DEGs) most likely to influence cell size were screened out, including genes involved in auxin signal transduction and cell wall loosening mechanisms. Furthermore, weighted gene co-expression network analysis (WGCNA) revealed that PRE6/bHLH was identified as a hub gene, which interacted with 1 TIR1, 3 AUX/IAAs, 4 SAURs, 3 EXPs, and 1 CEL. Hence, a total of 13 key candidate genes were identified as positive regulators of fruit size in apricots. The results provide new insights into the molecular basis of fruit size control and lay a foundation for future breeding and cultivation of larger fruits in apricot.

Identification of the NAC Transcription Factor Family during Early Seed Development in Akebia trifoliata (Thunb.) Koidz

This study aimed to gain an understanding of the possible function of NACs by examining their physicochemical properties, structure, chromosomal location, and expression. Being a family of plant-specific transcription factors, NAC (petunia no apical meristem and Arabidopsis thaliana ATAF1, ATAF2, and CUC2) is involved in plant growth and development. None of the NAC genes has been reported in Akebia trifoliata (Thunb.) Koidz (A. trifoliata). In this study, we identified 101 NAC proteins (AktNACs) in the A. trifoliata genome by bioinformatic analysis. One hundred one AktNACs were classified into the following twelve categories based on the phylogenetic analysis of NAC protein: NAC-a, NAC-b, NAC-c, NAC-d, NAC-e, NAC-f, NAC-g, NAC-h, NAC-i, NAC-j, NAC-k, and NAC-l. The accuracy of the clustering results was demonstrated based on the gene structure and conserved motif analysis of AktNACs. In addition, we identified 44 pairs of duplication genes, confirming the importance of purifying selection in the evolution of AktNACs. The morphology and microstructure of early A. trifoliata seed development showed that it mainly underwent rapid cell division, seed enlargement, embryo formation and endosperm development. We constructed AktNACs co-expression network and metabolite correlation network based on transcriptomic and metabolomic data of A. trifoliata seeds. The results of the co-expression network showed that 25 AtNAC genes were co-expressed with 233 transcription factors. Metabolite correlation analysis showed that 23 AktNACs were highly correlated with 28 upregulated metabolites. Additionally, 25 AktNACs and 235 transcription factors formed co-expression networks with 141 metabolites, based on correlation analysis involving AktNACs, transcription factors, and metabolites. Notably, AktNAC095 participates in the synthesis of 35 distinct metabolites. Eight of these metabolites, strongly correlated with AktNAC095, were upregulated during early seed development. These studies may provide insight into the evolution, possible function, and expression of AktNACs genes.

Characterization of the NAC Transcription Factor in Passion Fruit (Passiflora edulis) and Functional Identification of PeNAC-19 in Cold Stress

The NAC (NAM, ATAF and CUC) gene family plays an important role in plant development and abiotic stress response. However, up to now, the identification and research of the NAC (PeNAC) family members of passion fruit are still lacking. In this study, 25 PeNACs were identified from the passion fruit genome, and their functions under abiotic stress and at different fruit-ripening stages were analyzed. Furthermore, we analyzed the transcriptome sequencing results of PeNACs under four various abiotic stresses (drought, salt, cold and high temperature) and three different fruit-ripening stages, and verified the expression results of some genes by qRT-PCR. Additionally, tissue-specific analysis showed that most PeNACs were mainly expressed in flowers. In particular, PeNAC-19 was induced by four various abiotic stresses. At present, low temperatures have seriously endangered the development of passion fruit cultivation. Therefore, PeNAC-19 was transformed into tobacco, yeast and Arabidopsis to study their function of resisting low temperature. The results show that PeNAC-19 responded to cold stress significantly in tobacco and Arabidopsis, and could improve the low temperature tolerance of yeast. This study not only improved the understanding of the PeNAC gene family characteristics and evolution, but also provided new insights into the regulation of the PeNAC gene at different stages of fruit maturation and abiotic stresses.

Genetic changes in the genus Vitis and the domestication of vine

The genus Vitis belongs to the Vitaceae family and is divided into two subgenera: Muscadinia and Vitis, the main difference between these subgenera being the number of chromosomes. There are many hypotheses about the origin of the genus, which have been formed with archaeological studies and lately with molecular analyses. Even though there is no consensus on the place of origin, these studies have shown that grapes have been used by man since ancient times, starting later on its domestication. Most studies point to the Near East and Greece as the beginning of domestication, current research suggests it took place in parallel in different sites, but in all cases Vitis vinifera (L.) subsp. sylvestris [Vitis vinifera (L.) subsp. sylvestris (Gmelin) Hagi] seems to be the species chosen by our ancestors to give rise to the now known Vitis vinifera (L.) subsp. vinifera [=sativa (Hegi)= caucasica (Vavilov)]. Its evolution and expansion into other territories followed the formation of new empires and their expansion, and this is where the historical importance of this crop lies. In this process, plants with hermaphrodite flowers were preferentially selected, with firmer, sweeter, larger fruits of different colors, thus favoring the selection of genes associated with these traits, also resulting in a change in seed morphology. Currently, genetic improvement programs have made use of wild species for the introgression of disease resistance genes and tolerance to diverse soil and climate environments. In addition, the mapping of genes of interest, both linked to agronomic and fruit quality traits, has allowed the use of molecular markers for assisted selection. Information on the domestication process and genetic resources help to understand the gene pool available for the development of cultivars that respond to producer and consumer requirements.

The NAC transcription factors play core roles in flowering and ripening fundamental to fruit yield and quality

Fruits are derived from flowers and play an important role in human food, nutrition, and health. In general, flowers determine the crop yield, and ripening affects the fruit quality. Although transcription factors (TFs) only account for a small part of plant transcriptomes, they control the global gene expression and regulation. The plant-specific NAC (NAM, ATAF, and CUC) TFs constitute a large family evolving concurrently with the transition of both aquatic-to-terrestrial plants and vegetative-to-reproductive growth. Thus, NACs play an important role in fruit yield and quality by determining shoot apical meristem (SAM) inflorescence and controlling ripening. The present review focuses on the various properties of NACs together with their function and regulation in flower formation and fruit ripening. Hitherto, we have a better understanding of the molecular mechanisms of NACs in ripening through abscisic acid (ABA) and ethylene (ETH), but how NACs regulate the expression of the inflorescence formation-related genes is largely unknown. In the future, we should focus on the analysis of NAC redundancy and identify the pivotal regulators of flowering and ripening. NACs are potentially vital manipulation targets for improving fruit quantity and quality.

MADS-Box Subfamily Gene GmAP3 from Glycine max Regulates Early Flowering and Flower Development

AP3 has been studied and is reported to affect structural changes in floral organs in various plants. However, the function of the soybean AP3 genes in flower development is unknown. Here, the full-length cDNA sequence of GmAP3 was obtained by RACE and it was verified that it belongs to the MADS-box subfamily by a bioinformatics analysis. The expression of GmAP3 is closely related to the expression of essential enzyme genes related to flower development. Yeast two-hybrid assays demonstrated that GmAP3 interacts with AP1 to determine the identity of flower organ development. A follow-up analysis showed that overexpression of the GmAP3 gene advanced flowering time and resulted in changes in floral organ morphology. The average flowering time of overexpressed soybean and tobacco plants was 6-8 days earlier than that of wild-type plants, and the average flowering time of gene-edited soybean and tobacco plants was 6-11 days later than that of wild-type plants. In conclusion, GmAP3 may directly or indirectly affect the flower development of soybean. The results of this study lay the foundation for further research on the biological functions of MADS transcriptional factors in soybeans.

Review: Status and prospects of association mapping in grapevine

Thanks to current advances in sequencing technologies, novel bioinformatics tools, and efficient modeling solutions, association mapping has become a widely accepted approach to unravel the link between genotype and phenotype diversity in numerous crops. In grapevine, this strategy has been used in the last decades to understand the genetic basis of traits of agronomic interest (fruit quality, crop yield, biotic and abiotic resistance), of special relevance nowadays to improve crop resilience to cope with future climate scenarios. Genome-wide association studies have identified many putative causative loci for different traits, some of them overlapping well-known causal genes identified by conventional quantitative trait loci studies in biparental progenies, and/or validated by functional approaches. In addition, candidate-gene association studies have been useful to pinpoint the causal mutation underlying phenotypic variation for several traits of high interest in breeding programs (like berry color, seedlessness, and muscat flavor), information that has been used to develop highly informative and useful markers already in use in marker-assisted selection processes. Thus, association mapping has proved to represent a valuable step towards high quality and sustainable grape production. This review summarizes current applications of association mapping in grapevine research and discusses future prospects in view of current viticulture challenges.

The transcription factor VviNAC60 regulates senescence- and ripening-related processes in grapevine

Grapevine (Vitis vinifera L.) is one of the most widely cultivated fruit crops because the winemaking industry has huge economic relevance worldwide. Uncovering the molecular mechanisms controlling the developmental progression of plant organs will prove essential for maintaining high-quality grapes, expressly in the context of climate change, which impairs the ripening process. Through a deep inspection of transcriptomic data, we identified VviNAC60, a member of the NAC transcription factor family, as a putative regulator of grapevine organ maturation. We explored VviNAC60 binding landscapes through DNA affinity purification followed by sequencing and compared bound genes with transcriptomics datasets from grapevine plants stably and transiently overexpressing VviNAC60 to define a set of high-confidence targets. Among these, we identified key molecular markers associated with organ senescence and fruit ripening. Physiological, metabolic, and promoter activation analyses showed that VviNAC60 induces chlorophyll degradation and anthocyanin accumulation through the up-regulation of STAY-GREEN PROTEIN 1 (VviSGR1) and VviMYBA1, respectively, with the latter being up-regulated through a VviNAC60-VviNAC03 regulatory complex. Despite sharing a closer phylogenetic relationship with senescence-related homologues to the NAC transcription factor AtNAP, VviNAC60 complemented the non-ripening(nor) mutant phenotype in tomato (Solanum lycopersicum), suggesting a dual role as an orchestrator of both ripening- and senescence-related processes. Our data support VviNAC60 as a regulator of processes initiated in the grapevine vegetative- to mature-phase organ transition and therefore as a potential target for enhancing the environmental resilience of grapevine by fine-tuning the duration of the vegetative phase.

Integrated multi-locus genome-wide association studies and transcriptome analysis for seed yield and yield-related traits in Brassica napus

Rapeseed (Brassica napus L.), the third largest oil crop, is an important source of vegetable oil and biofuel for the world. Although the breeding and yield has been improved, rapeseed still has the lowest yield compared with other major crops. Thus, increasing rapeseed yield is essential for the high demand of vegetable oil and high-quality protein for live stocks. Silique number per plant (SN), seed per pod (SP), and 1000-seed weight (SW) are the three important factors for seed yield in rapeseed. Some yield-related traits, including plant height (PH), flowering time (FT), primary branch number (BN) and silique number per inflorescence (SI) also affect the yield per plant (YP). Using six multi-locus genome-wide association study (ML-GWAS) approaches, a total of 908 yield-related quantitative trait nucleotides (QTNs) were identified in a panel consisting of 403 rapeseed core accessions based on whole-genome sequencing. Integration of ML-GWAS with transcriptome analysis, 79 candidate genes, including BnaA09g39790D (RNA helicase), BnaA09g39950D (Lipase) and BnaC09g25980D (SWEET7), were further identified and twelve genes were validated by qRT-PCRs to affect the SW or SP in rapeseed. The distribution of superior alleles from nineteen stable QTNs in 20 elite rapeseed accessions suggested that the high-yielding accessions contained more superior alleles. These results would contribute to a further understanding of the genetic basis of yield-related traits and could be used for crop improvement in B. napus.

NAC Transcription Factor Family Regulation of Fruit Ripening and Quality: A Review

The NAC transcription factor (TF) family is one of the largest plant-specific TF families and its members are involved in the regulation of many vital biological processes during plant growth and development. Recent studies have found that NAC TFs play important roles during the ripening of fleshy fruits and the development of quality attributes. This review focuses on the advances in our understanding of the function of NAC TFs in different fruits and their involvement in the biosynthesis and signal transduction of plant hormones, fruit textural changes, color transformation, accumulation of flavor compounds, seed development and fruit senescence. We discuss the theoretical basis and potential regulatory models for NAC TFs action and provide a comprehensive view of their multiple roles in modulating different aspects of fruit ripening and quality.

Knock-Out of CmNAC-NOR Affects Melon Climacteric Fruit Ripening

Fruit ripening is an important process that affects fruit quality. A QTL in melon, ETHQV6.3, involved in climacteric ripening regulation, has been found to be encoded by CmNAC-NOR, a homologue of the tomato NOR gene. To further investigate CmNAC-NOR function, we obtained two CRISPR/Cas9-mediated mutants (nor-3 and nor-1) in the climacteric Védrantais background. nor-3, containing a 3-bp deletion altering the NAC domain A, resulted in ~8 days delay in ripening without affecting fruit quality. In contrast, the 1-bp deletion in nor-1 resulted in a fully disrupted NAC domain, which completely blocked climacteric ripening. The nor-1 fruits did not produce ethylene, no abscission layer was formed and there was no external color change. Additionally, volatile components were dramatically altered, seeds were not well developed and flesh firmness was also altered. There was a delay in fruit ripening with the nor-1 allele in heterozygosis of ~20 days. Our results provide new information regarding the function of CmNAC-NOR in melon fruit ripening, suggesting that it is a potential target for modulating shelf life in commercial climacteric melon varieties.

Genome-Wide Identification of NAC Transcription Factor Family in Juglans mandshurica and Their Expression Analysis during the Fruit Development and Ripening

The NAC (NAM, ATAF and CUC) gene family plays a crucial role in the transcriptional regulation of various biological processes and has been identified and characterized in multiple plant species. However, genome-wide identification of this gene family has not been implemented in Juglans mandshurica, and specific functions of these genes in the development of fruits remain unknown. In this study, we performed genome-wide identification and functional analysis of the NAC gene family during fruit development and identified a total of 114 JmNAC genes in the J. mandshurica genome. Chromosomal location analysis revealed that JmNAC genes were unevenly distributed in 16 chromosomes; the highest numbers were found in chromosomes 2 and 4. Furthermore, according to the homologues of JmNAC genes in Arabidopsis thaliana, a phylogenetic tree was constructed, and the results demonstrated 114 JmNAC genes, which were divided into eight subgroups. Four JmNAC gene pairs were identified as the result of tandem duplicates. Tissue-specific analysis of JmNAC genes during different developmental stages revealed that 39 and 25 JmNAC genes exhibited upregulation during the mature stage in walnut exocarp and embryos, indicating that they may serve key functions in fruit development. Furthermore, 12 upregulated JmNAC genes were common in fruit ripening stage in walnut exocarp and embryos, which demonstrated that these genes were positively correlated with fruit development in J. mandshurica. This study provides new insights into the regulatory functions of JmNAC genes during fruit development in J. mandshurica, thereby improving the understanding of characteristics and evolution of the JmNAC gene family.