Banana Fruit Ripening Research Articles

Genome-wide analysis of the trihelix gene family reveals that MaGT21 modulates fruit ripening by regulating the expression of MaACO1 in Musa acuminata

The trihelix transcription factor (GT) gene family members play vital roles in plant growth and development, responses to abiotic or biotic stress, and fruit ripening. However, its role in banana fruit ripening remains unclear. Here, 59 MaGT gene members were identified in banana and clustered into five subfamilies, namely GT1, GT2, GTγ, SIP1, and SH4. This classification is completely supported by their gene structures and conserved motif analysis. Transcriptome data analysis indicated that MaGT14, MaGT21, and MaGT27 demonstrated significant differential expression during fruit ripening. Quantitative real-time PCR analysis revealed that these three genes were highly induced by ethylene treatment, responded to cold and heat stress, and had a high expression abundance in ripe fruit. Subcellular localization demonstrated that MaGT21 and MaGT27 functioned as nuclear proteins, while MaGT14 functioned as a nuclear and cell membrane protein. Further investigation indicated MaGT21 could positively stimulate the transcription of the key ethylene biosynthesis gene MaACO1 by directly targeting the GT motif in the promoter. MaGT21 transient overexpression in banana fruit upregulated MaACO1 and accelerated fruit ripening. Our findings provide comprehensive and valuable information for further functional studies of MaGT genes in banana, help to understand the roles of MaGTs during banana fruit ripening.

Changes in hemicellulose metabolism in banana peel during fruit development and ripening

Hemicellulose is key in determining the fate of plant cell wall in almost all growth and developmental stages. Nevertheless, there is limited knowledge regarding its involvement in the development and ripening of banana fruit. This study investigated changes in the temporal-spatial distribution of various hemicellulose components, hemicellulose content, activities of the main hydrolysis enzymes, and transcription level of the main hemicellulose-related gene families in banana peels. Both hemicellulose and xylan contents were positively correlated to the fruit firmness observed in our previous study. On the contrary, the xylanase activity was negatively correlated to xylan content and the fruit firmness. The vascular bundle cells, phloem, and cortex of bananas are abundant in xyloglucan, xylan, and mannan contents. Interestingly, the changes in the signal intensity of the CCRC-M104 antibody recognizing non-XXXG type xyloglucan are positively correlated to hemicellulose content. According to RNA-Seq analysis, xyloglucan and xylan-related genes were highly active in the early stages of growth, and the expression of MaMANs and MaXYNs increased as the fruit ripened. The abundance of plant hormonal and growth-responsive cis-acting elements was detected in the 2 kb upstream region of hemicellulose-related gene families. Interaction between hemicellulose and cell wall-specific proteins and MaKCBP1/2, MaCKG1, and MaHKL1 was found. The findings shed light on cell wall hemicellulose's role in banana fruit development and ripening, which could improve nutrition, flavor, and reduce postharvest fruit losses.

Study on a Mechanism of Improving MaAPX1 Protein Activity by Mutating Methionine to Lysine.

Ascorbate peroxidases (APXs) are key components of the ascorbate-glytathione cycle, which plays an important role in removing excess reactive oxygen species (ROS) in plants. Herein, MaAPX1 was verified as being involved in the ripening and senescence of banana fruit, exhibiting responsiveness to the accumulation of ROS and the oxidation of proteins. Site-directed mutation was applied to explore the mechanism of MaAPX1 activity changes. We found that the 32-site cysteine (Cys, C) served as a potential S-nitrosylation site. The mutant MaAPX1C32S activity was decreased significantly when Cys32 was mutated to serine (Ser, S). Intriguingly, the neighboring conserved 36-site methionine (Met, M), which is adjacent to Cys32, displayed an enzyme activity that was approximately five times higher than that of the wild-type MaAPX1 when mutated to lysine (Lys, K). Utilizing LC-MS/MS spectroscopy coupled with stopped-flow analysis showed that the enhanced MaAPX1M36K activity might be due to the increased S-nitrosylation level of Cys32 and the promotion of intermediate (compound I, the first intermediate product of the reaction of APX with H2O2) production. Molecular docking simulations showed that the S-N bond between Cys32 and Lys36 in MaAPX1M36K might have a function in protecting the thiol of Cys32 from oxidation. MaAPX1M36K, a promising mutant, possesses immense potential for improving the antioxidant capabilities of APX in the realm of bioengineering technology research.

Utilization of Eco-Friendly and Microfiber Wrapping Fabrics in Prolonging the Shelf Life of Ripe Banana Fruit

Utilization of Eco-Friendly and Microfiber Wrapping Fabrics in Prolonging the Shelf Life of Ripe Banana Fruit

MaC2H2-IDD regulates fruit softening and involved in softening disorder induced by cold stress in banana.

Chilling stress causes banana fruit softening disorder and severely impairs fruit quality. Various factors, such as transcription factors, regulate fruit softening. Herein, we identified a novel regulator, MaC2H2-IDD, whose expression is closely associated with fruit ripening and softening disorder. MaC2H2-IDD is a transcriptional activator located in the nucleus. The transient and ectopic overexpression of MaC2H2-IDD promoted "Fenjiao" banana and tomato fruit ripening. However, transient silencing of MaC2H2-IDD repressed "Fenjiao" banana fruit ripening. MaC2H2-IDD modulates fruit softening by activating the promoter activity of starch (MaBAM3, MaBAM6, MaBAM8, MaAMY3, and MaISA2) and cell wall (MaEXP-A2, MaEXP-A8, MaSUR14-like, and MaGLU22-like) degradation genes. DLR, Y1H, EMSA, and ChIP-qPCR assays validated the expression regulation. MaC2H2-IDD interacts with MaEBF1, enhancing the regulation of MaC2H2-IDD to MaAMY3, MaEXP-A2, and MaGLU22-like. Overexpressing/silencing MaC2H2-IDD in banana and tomato fruit altered the transcript levels of the cell wall and starch (CWS) degradation genes. Several differentially expressed genes (DEGs) were authenticated between the overexpression and control fruit. The DEGs mainly enriched biosynthesis of secondary metabolism, amino sugar and nucleotide sugar metabolism, fructose and mannose metabolism, starch and sucrose metabolism, and plant hormones signal transduction. Overexpressing MaC2H2-IDD also upregulated protein levels of MaEBF1. MaEBF1 does not ubiquitinate or degrade MaC2H2-IDD. These data indicate that MaC2H2-IDD is a new regulator of CWS degradation in "Fenjiao" banana and cooperates with MaEBF1 to modulate fruit softening, which also involves the cold softening disorder.

Evaluation of Post-Harvest Microbial Deterioration of Ripe Banana Fruits in Different Markets

Evaluation of Post-Harvest Microbial Deterioration of Ripe Banana Fruits in Different Markets

Banana MabHLH28 positively regulates the expression of softening-related genes to mediate fruit ripening independently or via cooperating with MaWRKY49/111.

Texture softening is a physiological indicator of fruit ripening, which eventually contributes to fruit quality and the consumer's acceptance. Despite great progress having been made in identification of the genes related to fruit softening, the upstream transcriptional regulatory pathways of these softening-related genes are not fully elucidated. Here, a novel bHLH gene, designated as MabHLH28, was identified because of its significant upregulation in banana fruit ripening. DAP-Seq analysis revealed that MabHLH28 bound to the core sequence of 'CAYGTG' presented in promoter regions of fruit softening-associated genes, such as the genes related to cell wall modification (MaPG3, MaPE1, MaPL5, MaPL8, MaEXP1, MaEXP2, MaEXPA2, and MaEXPA15) and starch degradation (MaGWD1 and MaLSF2), and these bindings were validated by EMSA and DLR assays. Transient overexpression and knockdown of MabHLH28 in banana fruit resulted in up- and down-regulation of softening-related genes, thereby hastening and postponing fruit ripening. Furthermore, overexpression of MabHLH28 in tomato accelerated the ripening process by elevating the accumulation of softening-associated genes. In addition, MabHLH28 showed interaction withMaWRKY49/111 and itself to form protein complexes, which could combinatorically strengthen the transcription of softening-associated genes. Taken together, our findings suggest that MabHLH28 mediates fruit softening by upregulating the expression of softening-related genes either alone or in combination with MaWRKY49/111.

MANAGING THE PRODUCTION PROCESSES - OPTIMIZATION OF THE TECHNOLOGICAL PROCESS OF BANANA RIPENING BY APPLYING THE SIMPLE ADDITIVE WEIGHTING METHOD

The realization of company goals is greatly influenced by the manager’s decisions in the activities of managing production processes. To make decisions, managers use different decision-making methods, taking into account different criteria on the basis of which they choose the best alternative. The paper presents the optimization of the technological process of banana ripening using the simple additive weighting (SAW) method. The research monitored temperature correction, ripening gas dosage concentration, duration of treatment, commodity loss, including correction of accompanying factors of green banana fruit ripening. By applying the SAW method on 400 performed ripenings in the period from 2017 to 2020, the best results were achieved at a temperature of 18.5 °C, with an ethylene concentration of 840 ppm, process time of 112 h and achieved kalo of 233 kg. The total cost of ripening based on the examined parameters is 250.12 € which can save 81.42 € and meet the finishing standards.

Exploring the function of MaPHO1 in starch degradation and its protein interactions in postharvest banana fruits

Banana is a quintessential fruit known for its starch conversion process. During development, substantial starch accumulates in banana fruit and subsequently undergoes rapid degradation, contributing to flavor development during postharvest ripening. However, the genes orchestrating this crucial starch degradation process have not been comprehensively studied thus far. Through temporal transcriptomic analysis, we screened 63 active genes that were actively expressed in association with starch degradation during the ripening of banana fruits. The results found that phosphorolytic enzymes primarily regulate starch degradation at the early to middle stages of fruit ripening and that hydrolytic enzymes significantly contribute to starch degradation at the later stage. The expression of Musa acuminata starch phosphorylase 1 (MaPHO1) was the highest at the early to middle stages of banana ripening, characterized by the insertion of an L80 domain. While MaPHO1 was predominately found in the chloroplast, MaPHO2 was localized to the cell membrane. Starch accumulation was significantly increased by transient attenuation of MaPHO1 expression, whereas a drastic reduction in starch content was triggered by transient overexpression of MaPHO1, affirming its functional role in banana fruit ripening. By constructing a co-expression network, 29 categories, including 74 proteins interacting with MaPHO1 were identified. Tripartite interactions between MaPHO1 and both glucan, water dikinase 1 (GWD1) and enolase 1 (ENO1) were revealed by further validation through yeast two-hybrid and glutathione-S-transferase pull-down analyses.

MaNAC19–MaXB3 regulatory module mediates sucrose synthesis in banana fruit during ripening

Sucrose, a predominant sweetener in banana (Musa acuminata) fruit, determines sweetness and consumer preferences. Although sucrose phosphate synthase (SPS) is known to catalyze starch conversion into sucrose in banana fruit during the ripening process, the SPS regulatory mechanism during ripening still demands investigation. Hence, this study discovered that the MaSPS1 expression was promoted during ethylene-mediated ripening in banana fruit. MaNAC19, recognized as the MaSPS1 putative binding protein using yeast one-hybrid screening, directly binds to the MaSPS1 promoter, thereby transcriptionally activating its expression, which was verified by transient overexpression experiments, where the sucrose synthesis was accelerated through MaNAC19-induced transcription of MaSPS1. Interestingly, MaXB3, an ethylene-inhibited E3 ligase, was found to ubiquitinate MaNAC19, making it prone to proteasomal degradation, inhibiting transactivation of MaNAC19 to MaSPS1, thereby attenuating MaNAC19-promoted sucrose accumulation. This study's findings collectively illustrated the mechanistic basis of a MaXB3-MaNAC19-MaSPS1 regulatory module controlling sucrose synthesis during banana fruit ripening. These outcomes have broadened our understanding of the regulation mechanisms that contributed to sucrose metabolism occurring in transcriptional and post-transcriptional stages, which might help develop molecular approaches for controlling ripening and improving fruit quality.

The Zinc Finger Protein MaCCCH33-Like2 Positively Regulates Banana Fruit Ripening by Modulating Genes inStarch andCell Wall Degradation.

As zinc finger protein transcription factors (TFs), the molecular mechanism of Cys-Cys-Cys-His (CCCH) TFs in regulating plant development, growth and stress response has been well studied. However, the roles of CCCH TFs in fruit ripening are still obscure. Herein, we report that MaCCCH33-like2 TF and its associated proteins modulate the fruit softening of 'Fenjiao' bananas. MaCCCH33-like2 interacts directly with the promoters of three genes: isoamylase2 (MaISA2), sugar transporter14-like (MaSUR14-like) and β-d-xylosidase23 (MaXYL23), all of which are responsible for encoding proteins involved in the degradation of starch and cell wall components. Additionally, MaCCCH33-like2 forms interactions with abscisic acid-insensitive 5 (ABI5)-like and ethylene F-box protein 1 (MaEBF1), resulting in enhanced binding and activation of promoters of genes related to starch and cell wall degradation. When MaCCCH33-like2 is transiently and ectopically overexpressed in 'Fenjiao' banana and tomato fruit, it facilitates softening and ripening processes by promoting the degradation of cell wall components and starch and the production of ethylene. Conversely, the temporary silencing of MaCCCH33-like2 using virus-induced gene silencing (VIGS) inhibits softening and ripening in the 'Fenjiao' banana by suppressing ethylene synthesis, as well as starch and cell wall degradation. Furthermore, the promoter activity of MaCCCH33-like2 is regulated by MaABI5-like. Taken together, we have uncovered a novel MaCCCH33-like2/MaEBF1/MaABI5-like module that participates in fruit softening regulation in bananas.

MaMADS1-MaNAC083 transcriptional regulatory cascade regulates ethylene biosynthesis during banana fruit ripening.

The hormone ethylene is crucial in the regulation of ripening in climacteric fruit, such as bananas. The transcriptional regulation of ethylene biosynthesis throughout banana fruit ripening has received much study, but the cascaded transcriptional machinery of upstream transcriptional regulators implicated in the ethylene biosynthesis pathway is still poorly understood. Here we report that ethylene biosynthesis genes, including MaACS1, MaACO1, MaACO4, MaACO5, and MaACO8, were upregulated in ripening bananas. NAC (NAM, ATAF, CUC) transcription factor, MaNAC083, a ripening and ethylene-inhibited gene, was discovered as a potential binding protein to the MaACS1 promoter by yeast one-hybrid screening. Further in vitro and in vivo experiments indicated that MaNAC083 bound directly to promoters of the five ethylene biosynthesis genes, thereby transcriptionally repressing their expression, which was further verified by transient overexpression experiments, where ethylene production was inhibited through MaNAC083-modulated transcriptional repression of ethylene biosynthesis genes in banana fruits. Strikingly, MaMADS1, a ripening-induced MADS (MCM1, AGAMOUS, DEFICIENS, SRF4) transcription factor, was found to directly repress the expression of MaNAC083, inhibiting trans-repression of MaNAC083 to ethylene biosynthesis genes, thereby attenuating MaNAC083-repressed ethylene production in bananas. These findings collectively illustrated the mechanistic basis of a MaMADS1-MaNAC083-MaACS1/MaACOs regulatory cascade controlling ethylene biosynthesis during banana fruit ripening. These findings increase our knowledge of the transcriptional regulatory mechanisms of ethylene biosynthesis at the transcriptional level and are expected to help develop molecular approaches to control ripening and improve fruit storability.

Application of exogenous cytokinin regulates cytokinin oxidase and antioxidant activity to maintain chlorophyll pigment during ripening of banana fruit

Banana fruit ripening is accompanied by changes in activity of chlorophyll degradation. Herein, the application of exogenous cytokinin of forchlorfenuron (CPPU) to delay the ripening process by retarding degradation of chlorophyll was investigated. The changes in peel color, hue angle, chlorophyll fluorescence, and chlorophyll content were significantly inhibited by exogenous application of cytokinin. Content of endogenous cytokinin of t-zeatin was maintained and the increase of cytokinin oxidase (CKX) activity was retarded. Similar change trends were verified in the isolated peel tissues treated with CPPU. Relative expression level of the genes involved in cytokinin synthesis (MaIPT1/12) were upregulated, and CKX-related (MaCKX1/12) and chlorophyll degradation-related catabolism (MaPAO1, MaCLH1, MaSGR1, MaRCCR1, and MaRCCR12) were downregulated during storage. In addition, the scavenging activity of free radicals and membrane integrity were stabilized. Application of exogenous cytokinin of CPPU was proposed to competitively inhibit CKX activity to maintain endogenous cytokinin level, which further delayed chlorophyll degradation during banana fruit ripening.

Banana MKK1 modulates fruit ripening via the MKK1-MPK6-3/11-4-bZIP21 module

The mitogen-activated protein kinase (MAPK) cascade consisting of MKKK, MKK, and MPK plays an indispensable role in various plant physiological processes. Previously, we showed that phosphorylation of MabZIP21 by MaMPK6-3 is involved in banana fruit ripening, but the regulatory mechanism by which MKK controls banana fruit ripening remains unclear. Here, ripening-induced MaMKK1 from banana fruit is characterized, and transiently overexpressing and silencing of MaMKK1 in banana fruit accelerates and inhibits fruit ripening, respectively, possibly by influencing phosphorylation and activity of MPK. MaMKK1 interacts with and phosphorylates MaMPK6-3 and MaMPK11-4 mainly at the pTEpY residues, resulting in MPK activation. MaMPK11-4 phosphorylates MabZIP21 to elevate its transcriptional activation ability. Transgenic tomato fruit expressing MabZIP21 ripen quickly with a concomitant increase in MabZIP21 phosphorylation. Additionally, MabZIP21 activates MaMPK11-4 and MaMKK1 transcription to form a regulatory feedback loop. Collectively, here we report a regulatory pathway of the MaMPK6-3/11-4-MabZIP21 module in controlling banana fruit ripening.

Opuntia ficus indica mucilage coatings regulate cell wall softening enzymes and delay the ripening of banana fruit stored at retail conditions

Rapid ripening and softening due to cell wall polysaccharide degradation and disassembly pose major challenges in extending fruit storability. This study aimed to examine the efficacy of Opuntia ficus indica mucilage (OFIM) edible coating in minimizing softening in bananas under retail conditions. Mucilage was extracted from freshly harvested prickly pear cladodes and dried into a powder. Phenolic compounds in OFIM powder were quantified using liquid chromatography-mass spectrometry (LC-MS). OFIM concentrations (1, 2 and 3 % (w/v)) were prepared, and their physicochemical properties were examined. The prepared coatings were applied to harvested banana fruit by dipping and stored at room temperature for 12 days. During the experiment, several parameters were measured, including fruit weight loss, total soluble solids (TSS), titratable acidity (TA), peel color, pulp firmness, ethylene production, respiration rate, ion leakage, malondialdehyde (MDA) content, total chlorophyll and carotenoids, chlorophyll-degrading enzymes, protopectin content and water-soluble pectin (WSP) and softening-related enzymes in the peel. Results showed that mucilage treatments effectively delayed cell wall and chlorophyll degradation, as well as carotenoid accumulation, thus inhibiting ripening-associated processes compared to control fruit. OFIM-treated fruit exhibited significantly higher firmness, chlorophyll content, and TA, lower TSS content, ethylene production, respiration rate, MDA concentration, ion leakage and protopectin content than uncoated fruit. This suggests that OFIM edible coating has the potential to maintain quality and extend the shelf life of bananas by suppressing softening enzymes during storage.

Determination of Heavy Metals Recovered from Artificially Ripe Banana with Calcium Carbide

Calcium carbide is frequently used by vendors to hasten the ripening of banana fruits, and this practice has a long history. Calcium carbide is connected to the negative consequences of heavy metals. Measurements of heavy metal concentrations on artificially ripe bananas using calcium carbide in Katsina state and throughout Nigeria are essential to assist the competent authorities in regulating the use of chemical ripening agents for food safety and consumption. This study aims to assess the levels of heavy metals in banana fruits that have been artificially made to ripen. A sample was collected from Mairuwa Fadama of Katsina state's Funtua local government Area. The Banana pulp and peel were analyzed for heavy metals (arsenic, calcium, lead and cadmium) content using standard methods. Results showed that heavy metal concentrations in the banana peel are higher than in the banana pulp. The findings detail the heavy metals content of the banana peel and pulp eaten in Katsina State. The findings also showed that banana peels contain more heavy metals than pulp.

Cold pretreatment promotes chlorophyll degradation of green ripening banana peel by activating MaCBF1 to MaCBR and MaSGR1

Inhibition of peel de-greening in postharvest bananas under high temperature storage, resulting in green ripening, causes significant deterioration in fruit quality. Herein, we reported that cold treatment accelerated chlorophyll degradation of postharvest banana fruit at 30 °C, which was associated with the upregulated expression of MaCBR (Chlorophyll b reductase) and MaSGR1 (Stay-green 1). Moreover, cold treatment increased the expression of C-repeat binding factor MaCBF1. MaCBF1 bound directly to the promoters of MaCBR and MaSGR1 and activated their expressions. More importantly, transient expression of MaCBF1 in bananas enhanced chlorophyll degradation and weakened the repression of de-greening caused by high temperature. In summary, the cold treatment promotes chlorophyll catabolism by activating MaCBF1-induced transcriptional activation of MaCBR and MaSGR1, and attenuates high temperature-caused green ripening in bananas. These results study expand the understanding of the molecular events of high temperature-inhibited chlorophyll degradation and provide a feasible strategy to alleviate green ripening of banana fruit.

MaHDA6-MaNAC154 module regulates the transcription of cell wall modification genes during banana fruit ripening

Fruit ripening and softening is a complex physiological process that is governed by the expression of a wide range of genes, and histone modification is a critical mechanism for precise gene expression. Although previous studies have indicated that NAC transcription factor (TF) and histone deacetylase individually play important roles in fruit ripening, the molecular connection between these two proteins within the regulatory system underlying banana fruit ripening is poorly understood. Here, we characterized a banana NAC MaNAC154 that was a negative regulator of banana fruit ripening. MaNAC154 was shown to localize in the nucleus, and it could target the promoters of MaEXP1/2, MaPL2, MaPG1/X3 and MaXTH5/23/28 to repress their transcription. Importantly, MaNAC154 was found to interact with a histone deacetylase MaHDA6, and their interaction significantly enhanced MaNAC154-mediated transcriptional repression capacity. Moreover, the acetylation levels of histones H3 and H4 of MaEXP1/2, MaPL2, MaPG1/X3 and MaXTH5/23/28 were elevated in the ripening stage. Overall, our data establish a coordinated mechanism underpinning histone deacetylation and TF-mediated gene repression for banana fruit ripening, providing a novel molecular basis for controlling mechanism of fruit ripening and softening.

Protocorm Like Bodies (PLBs) dendrobium orchid “Gatton Sunray”

The Dendrobium Orchid Gatton Sunray is a hybrid orchid of Dendrobium pulchellum × Dendrobium illustre. A study was aimed to find the best type of medium and type of banana for the multiplication of Protocorm-Like Bodies (PLBs) of this orchid. This research was conducted from February to September 2020 at the Plant Tissue Culture Laboratory, Faculty of Agriculture, The University of Bengkulu. Treatments included type of media and cultivar of ripe banana fruit, added as source of organic complex, consisted of 4 cultivars, namely Ambon Curup, Kepok, Tanduk and Mas. Ripe bananas were mashed and added to the in vitro medium as much as 50 g.L-1. Types of media consist of Murashige and Skoog (MS), ½ Doses of Murashige and Skoog (MS) media, and Complex of fertilizer media. The results showed that the ½ MS medium added with 50 g.L-1 cv. Kepok fruit produced the greatest multiplication (11.8 PLBs per jar), the best growth of PLBs, including the greatest PLBs number (28.5 PLBs per jar), the heaviest fresh weight (1.30 g per jar) and the longest PLBs (2.56 cm).

MaNAC029 modulates ethylene biosynthesis and fruit quality and undergoes MaXB3-mediated proteasomal degradation during banana ripening

IntroductionsEthylene regulates ripening by activating various metabolic pathways that controlcolor, aroma, flavor, texture, and consequently, the quality of fruits. However, the modulation of ethylene biosynthesis and quality formation during banana fruit ripening remains unclear. ObjectivesThe present study aimed to identify the regulatory module that regulates ethylene and fruit quality-related metabolisms during banana fruit ripening. MethodsWe used RNA-seq to compare unripe and ripe banana fruits and identified a ripening-induced NAC transcription factor, MaNAC029. We further performed DNA affinity purification sequencing to identify the MaNAC029′s target genes involved in ethylene biosynthesis and fruit quality formation, and electrophoretic mobility shift assay, chromatin immunoprecipitation with real-time polymerase chain reaction and dual luciferase assays to explore the underlying regulatory mechanisms. Immunoprecipitation combined with mass spectrometry, yeast two-hybrid assay, and bimolecular fluorescence complementation assay were used to screen and verify the proteins interacting with MaNAC029. Finally, the function of MaNAC029 and its interacting protein associated with ethylene biosynthesis and quality formation was verified through transient overexpression experiments in banana fruits. ResultsThe study identified a nucleus-localized, ripening-induced NAC transcription factor MaNAC029. It transcriptionally activated genes associated with ethylene biosynthesis and a variety of cellular metabolisms related to fruit quality formation (cell wall degradation, starch degradation, aroma compound synthesis, and chlorophyll catabolism) by directly modulating their promoter activity during ripening. Overexpression of MaNAC029 in banana fruits activated ethylene biosynthesis and accelerated fruit ripening and quality formation. Notably, the E3 ligase MaXB3 interacted with and ubiquitinated MaNAC029 protein, facilitating MaNAC029 proteasomal degradation. Consistent with this finding, MaXB3 overexpression attenuated MaNAC029-enhanced ethylene biosynthesis and quality formation. ConclusionOur findings demonstrate that a MaXB3-MaNAC029 module regulates ethylene biosynthesis and a series of cellular metabolisms related to fruit quality formation during banana ripening. These results expand the understanding of the transcriptional and post-translational mechanisms of fruit ripening and quality formation.