Molecular Characteristics and Functional Identification of a Key Alpha-Amylase-Encoding Gene AMY11 in Musa acuminata.

Alpha-amylase (AMY) plays a significant role in regulating the growth, development, and postharvest quality formation in plants. Nevertheless, little is known about the genome-wide features, expression patterns, subcellular localization, and functional regulation of AMY genes (MaAMYs) in the common starchy banana (Musa acuminata). Twelve MaAMY proteins from the banana genome database were clustered into two groups and contained a conserved catalytic domain. These MaAMYs formed collinear pairs with the AMYs of maize and rice. Three tandem gene pairs were found within the MaAMYs and are indicative of putative gene duplication events. Cis-acting elements of the MaAMY promoters were found to be involved in phytohormone, development, and stress responses. Furthermore, MaAMY02, 08, 09, and 11 were actively expressed during fruit development and ripening. Specifically, MaAMY11 showed the highest expression level at the middle and later stages of banana ripening. Subcellular localization showed that MaAMY02 and 11 were predominately found in the chloroplast, whereas MaAMY08 and 09 were primarily localized in the cytoplasm. Notably, transient attenuation of MaAMY11 expression resulted in an obvious increase in the starch content of banana fruit, while a significant decrease in starch content was confirmed through the transient overexpression of MaAMY11. Together, these results reveal new insights into the structure, evolution, and expression patterns of the MaAMY family, affirming the functional role of MaAMY11 in the starch degradation of banana fruit.

Cannabidiol-Loaded Poly Lactic-Co-Glycolic Acid Nanoparticles with Improved Bioavailability as a Potential for Osteoarthritis Therapeutic.

Cannabidiol (CBD) is a non-intoxicating cannabinoid from cannabis sativa that has demonstrated efficacious against inflammation, which can be considered as a potential drug for arthritis treatment. However, the poor solubility and low bioavailability limit its clinical application. Here, we report an effective strategy to fabricate Cannabidiol-loaded poly(lactic-co-glycolic acid) copolymer (CBD-PLGA) nanoparticles (NPs), with a spherical morphology and an average diameter of 238 nm. CBD was sustained release from CBD-PLGA-NPs, which improved the bioavailability of CBD. The CBD-PLGA-NPs effectively protect the damage of LPS to cell viability. We observed that CBD-PLGA-NPs significantly suppressed LPS-induced primary rat chondrocyte expression of inflammatory cytokines, including interleukin 1ß (IL-1ß), interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and matrix metalloproteinase 13 (MMP-13). Remarkably, CBD-PLGA-NPs also showed better therapeutic effects of inhibiting the degradation of the extracellular matrix of chondrocytes than equivalent CBD solution. In general, the fabrication CBD-PLGA-NPs showed good protection of primary chondrocytes in vitro and is a promising system for osteoarthritis treatment.

Wetting effect of branched anionic Gemini surfactant aqueous solution on PMMA surface.

In this paper, the adsorption behaviour and wetting modification ability of the sodium salts of bis-octadecenoyl succinate (GeminiC3, GeminiC6) and monomers on polymethyl methacrylate (PMMA) surfaces were investigated. The difference in spacer length led to slightly different behaviour of surfactant molecules in solution. The large molecular structure and short flexible spacer of GeminiC3 led to a complex self-aggregation behaviour in solution, forming micelles at low concentrations, leading to a rapid decrease in surface tension and subsequent transition to monolayer or multilayer vesicles. In GeminiC6, the longer flexible spacer groups act as spatial structure modifiers that hinder the formation of vesicles. The adsorption behaviour of the gas-liquid interface was analysed in three stages for the peculiar inflection points where surface tension appears. Combining contact angle measurements, adhesion tension and interfacial tension data showed that GeminiC3 and C6 formed a saturated monolayer on the adsorbed PMMA surface at low concentrations and a bilayer structure at high concentrations. Due to the low resistance of molecular space sites, the monomers adsorbed heavily on the PMMA surface, forming semi-colloidal aggregates with the lowest contact angle of monomeric surfactant solutions reaching 38° on the PMMA surface. Also, the monomer and GeminiC3 and C6 surfactants in this paper have a very high hydrophilic modification ability on the PMMA surface compared to other literature.

The Study of Interfacial Adsorption Behavior for Hydroxyl-Substituted Alkylbenzene Sulfonates by Interfacial Tension Relaxation Method.

In order to explore the interface adsorption mechanism of hydroxyl-substituted alkylbenzene sulfonates, the interfacial tension relaxation method was used to investigate the dilational rheology properties of sodium 2-hydroxy-3-octyl-5-octylbenzene sulfonate (C8C8OHphSO3Na) and sodium 2-hydroxy-3-octyl-5-decylbenzene sulfonate (C8C10OHphSO3Na) at the gas-liquid interface and oil-water interface. The effect of the length of the hydroxyl para-alkyl chain on the interfacial behavior of the surfactant molecules was investigated, and the main controlling factors of the interfacial film properties under different conditions were obtained. The experimental results show that for the gas-liquid interface, the long-chain alkyl groups adjacent to the hydroxyl group in the hydroxyl-substituted alkylbenzene sulfonate molecules tend to extend along the interface, showing strong intermolecular interaction, which is the main reason why the dilational viscoelasticity of the surface film is higher than that of ordinary alkylbenzene sulfonates. The length of the para-alkyl chain has little effect on the viscoelastic modulus. With the increase in surfactant concentration, the adjacent alkyl chain also began to extend into the air, and the factors controlling the properties of the interfacial film changed from interfacial rearrangement to diffusion exchange. For the oil-water interface, the presence of oil molecules will hinder the interface tiling of the hydroxyl-protic alkyl, and the dilational viscoelasticity of C8C8 and C8C10 will be greatly reduced relative to the surface. The main factor controlling the properties of the interfacial film is the diffusion exchange of surfactant molecules between the bulk phase and the interface from the beginning.

Construction of Fe-doped NiS-NiS2 Heterostructured Microspheres Via Etching Prussian Blue Analogues for Efficient Water-Urea Splitting.

Developing efficient and robust non-precious-metal-based catalysts to accelerate electrocatalytic reaction kinetics is crucial for electrochemical water-urea splitting. Herein, Fe-doped NiS-NiS2 heterostructured microspheres, an electrocatalyst, are synthesized via etching Prussian blue analogues following a controlled annealing treatment. The resulting microspheres are constructed by mesoporous nanoplates, granting the virtues of large surface areas, high structural void porosity, and accessible inner surface. These advantages not only provide more redox reaction centers but also strengthen structural robustness and effectively facilitate the mass diffusion and charge transport. Density functional theory simulations validate that the Fe-doping improves the conductivity of nickel sulfides, whereas the NiS-NiS2 heterojunctions induce interface charge rearrangement for optimizing the adsorption free energy of intermediates, resulting in a low overpotential and high electrocatalytic activity. Specifically, an ultralow overpotential of 270 mV at 50 mA cm-2 for the oxygen evolution reaction (OER) is achieved. After adding 0.33 M urea into 1 M KOH, Fe-doped NiS-NiS2 obtains a strikingly reduced urea oxidation reaction potential of 1.36 V to reach 50 mA cm-2 , around 140 mV less than OER. This work provides insights into the synergistic modulation of electrocatalytic activity of non-noble catalysts for applications in energy conversion systems.

Genome-Wide Identification and Transcript Analysis of TCP Gene Family in Banana (Musa acuminata L.).

Plant-specific TEOSINTE-BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1 (TCP) gene family has versatile functions in diverse aspects of plants. However, less research on banana TCPs was done comprehensively. Accordingly, 48 banana TCP genes were characterized on aspects of gene structure, conserved motifs, phylogenetic relationship, and expression patterns. Members of the MaTCP gene family were unevenly distributed among 11 chromosomes and purification selection was the driving force of the MaTCP gene family. Gene duplication analysis indicated that segmental duplication is the major contributor to family expansion. Promoter analysis showed that MaTCPs might be involved in banana growth, development, and abiotic stress responses. Further, the expression of 12 MaTCPs was analyzed by real-time quantitative RT-PCR, and the protein interaction analysis showed that MaPCF10 and MaPCF13 may have an important function in banana fruit development and ripening. These results lay the foundation for further study of the functions of TCP genes in banana.

Encapsulating Fe2 O3 Nanotubes into Carbon-Coated Co9 S8 Nanocages Derived from a MOFs-Directed Strategy for Efficient Oxygen Evolution Reactions and Li-Ions Storage.

The development of high-efficiency, robust, and available electrode materials for oxygen evolution reaction (OER) and lithium-ion batteries (LIBs) is critical for clean and sustainable energy system but remains challenging. Herein, a unique yolk-shell structure of Fe2 O3 nanotube@hollow Co9 S8 nanocage@C is rationally prepared. In a prearranged sequence, the fabrication of Fe2 O3 nanotubes is followed by coating of zeolitic imidazolate framework (ZIF-67) layer, chemical etching of ZIF-67 by thioacetamide, and eventual annealing treatment. Benefiting from the hollow structures of Fe2 O3 nanotubes and Co9 S8 nanocages, the conductivity of carbon coating and the synergy effects between different components, the titled sample possesses abundant accessible active sites, favorable electron transfer rate, and exceptional reaction kinetics in the electrocatalysis. As a result, excellent electrocatalytic activity for alkaline OER is achieved, which delivers a low overpotential of 205 mV at the current density of 10 mA cm-2 along with the Tafel slope of 55 mV dec-1 . Moreover, this material exhibits excellent high-rate capability and excellent cycle life when employed as anode material of LIBs. This work provides a novel approach for the design and the construction of multifunctional electrode materials for energy conversion and storage.

Transcription factor MaMADS36 plays a central role in regulating banana fruit ripening.

Bananas are model fruits for studying starch conversion and climactericity. Starch degradation and ripening are two important biological processes that occur concomitantly in banana fruit. Ethylene biosynthesis and postharvest fruit ripening processes, i.e. starch degradation, fruit softening, and sugar accumulation, are highly correlated and thus could be controlled by a common regulatory switch. However, this switch has not been identified. In this study, we transformed red banana (Musa acuminata L.) with sense and anti-sense constructs of the MaMADS36 transcription factor gene (also MuMADS1, Ma05_g18560.1). Analysis of these lines showed that MaMADS36 interacts with 74 other proteins to form a co-expression network and could act as an important switch to regulate ethylene biosynthesis, starch degradation, softening, and sugar accumulation. Among these target genes, musa acuminata beta-amylase 9b (MaBAM9b, Ma05_t07800.1), which encodes a starch degradation enzyme, was selected to further investigate the regulatory mechanism of MaMADS36. Our findings revealed that MaMADS36 directly binds to the CA/T(r)G box of the MaBAM9b promoter to increase MaBAM9b transcription and, in turn, enzyme activity and starch degradation during ripening. These results will further our understanding of the fine regulatory mechanisms of MADS-box transcription factors in regulating fruit ripening, which can be applied to breeding programs to improve fruit shelf-life.

Hierarchical CoFe LDH/MOF nanorods array with strong coupling effect grown on carbon cloth enables efficient oxidation of water and urea.

Oxygen evolution reaction (OER) and urea oxidation reaction (UOR) play important roles in the fields of hydrogen energy production and pollution treatment. Herein, a facile one-step chemical etching strategy is provided for fabricating one-dimensional hierarchical nanorods array composed of CoFe layered double hydroxide (LDH)/metal-organic frameworks (MOFs) supported on carbon cloth as efficient and stable OER and UOR catalysts. By precisely controlling the etching rate, the ligands from Co-MOFs are partially removed, the corresponding metal centers then coordinate with hydroxyl ions to generate ultrathin amorphous CoFe LDH nanosheets. The resultant CoFe LDH/MOFs catalyst possesses large active surface area, enhanced conductivity and extended electron/mass transfer channels, which are beneficial for catalytic reactions. Additionally, the intimate contact between CoFe LDH and MOFs modulates the local electronic structure of the catalytic active site, leading to enhanced adsorption of oxygen-containing intermediates to facilitate fast electrocatalytic reaction. As a result, the optimized CoFe LDH/MOF-0.06 exhibits superior OER activity with a low overpotential of 276 at a current density of 10 mA cm-2with long-term durability. Additionally, it merely requires a voltage of 1.45 V to obtain 10 mA cm-2in 1 M KOH solution with 0.33 urea and is 56 mV lower than the one in pure KOH. The work presented here may hew out a brand-new route to construct multi-functional electrocatalysts for water splitting, CO2reduction, nitrogen reduction reactions and so on.

Identification and expression of the BAHD family during development, ripening, and stress response in banana.

The BAHD family is involved in different biological roles in plants, including secondary metabolite synthesis, improving abiotic/biotic stress resistance, and influencing fruit quality. However, the knowledge about BAHD in banana, an important fruit crop, is limited. In this study, 46 banana BAHD genes (MaBAHDs) were identified and divided into four groups according to phylogenetic analysis. Most of the MaBAHD genes in the same group presented similar conserved motifs and genetic structures. MaBAHD genes have similar expression patterns in two banana varieties, and more genes showed high expressions in the roots. The comprehensive MaBAHD gene expression patterns obtained from two varieties of banana showed valuable information regarding their participation in fruit development, ripening, and response to abiotic/biotic stresses, suggesting that they play key roles in these processes. The systematic analysis of MaBAHD genes offered basic insight for further gene functional assays and potential applications in genetically improving banana cultivars.

Identification of transcription factors interacting with a 1274 bp promoter of MaPIP1;1 which confers high-level gene expression and drought stress Inducibility in transgenic Arabidopsis thaliana.

BACKGROUND: Drought stress can severely affect plant growth and crop yield. The cloning and identification of drought-inducible promoters would be of value for genetically-based strategies to improve resistance of crops to drought. RESULTS: Previous studies showed that the MaPIP1;1 gene encoding an aquaporin is involved in the plant drought stress response. In this study, the promoter pMaPIP1;1, which lies 1362 bp upstream of the MaPIP1;1 transcriptional initiation site, was isolated from the banana genome..And the transcription start site(A) is 47 bp before the ATG. To functionally validate the promoter, various lengths of pMaPIP1;1 were deleted and fused to GUS to generate pMaPIP1;1::GUS fusion constructs that were then transformed into Arabidopsis to generate four transformants termed M-P1, M-P2, M-P3 and M-P4.Mannitol treatment was used to simulate drought conditions. All four transformants reacted well to mannitol treatment. M-P2 (- 1274 bp to - 1) showed the highest transcriptional activity among all transgenic Arabidopsis tissues, indicating that M-P2 was the core region of pMaPIP1;1. This region of the promoter also confers high levels of gene expression in response to mannitol treatment. Using M-P2 as a yeast one-hybrid bait, 23 different transcription factors or genes that interacted with MaPIP1;1 were screened. In an dual luciferase assay for complementarity verification, the transcription factor MADS3 positively regulated MaPIP1;1 transcription when combined with the banana promoter. qRT-PCR showed that MADS3 expression was similar in banana leaves and roots under drought stress. In banana plants grown in 45% soil moisture to mimic drought stress, MaPIP1;1 expression was maximized, which further demonstrated that the MADS3 transcription factor can synergize with MaPIP1;1. CONCLUSIONS: Together our results revealed that MaPIP1;1 mediates molecular mechanisms associated with drought responses in banana, and will expand our understanding of how AQP gene expression is regulated. The findings lay a foundation for genetic improvement of banana drought resistance.

Identification, Expression, and Interaction Network Analyses of the CDPK Gene Family Reveal Their Involvement in the Development, Ripening, and Abiotic Stress Response in Banana.

Calcium-dependent protein kinases (CDPKs) play vital roles in the regulation of plant growth, development, and tolerance to various abiotic stresses. However, little information is available for this gene family in banana. In this study, 44 CDPKs were identified in banana and were classified into four groups based on phylogenetic, gene structure, and conserved motif analyses. The majority of MaCDPKs generally exhibited similar expression patterns in the different tissues. Transcriptome analyses revealed that many CDPKs showed strong transcript accumulation at the early stages of fruit development and postharvest ripening in both varieties. Interaction network and co-expression analysis further identified some CDPKs-mediated network that was potentially active at the early stages of fruit development. Comparative expression analysis suggested that the high levels of CDPK expression in FJ might be related to its fast ripening characteristic. CDPK expression following the abiotic stress treatments indicated a significant transcriptional response to osmotic, cold, and salt treatment, as well as differential expression profiles, between BX and FJ. The findings of this study elucidate the transcriptional control of CDPKs in development, ripening, and the abiotic stress response in banana. Some tissue-specific, development/ripening-dependent, and abiotic stress-responsive candidate MaCDPK genes were identified for further genetic improvement of banana.

Genomic and Transcriptional Analysis of Banana Ovate Family Proteins Reveals Their Relationship with Fruit Development and Ripening.

Ovate Family Proteins (OFPs) belong to a plant-specific transcription factor family. They have been found to have significant roles in growth and development in Arabidopsis and tomato; however, little is known regarding their role in banana. Thus, a genome-wide study of OFP genes in banana was conducted for the first time in the present study. The results demonstrated that 49 OFP family members are unequally distributed across 11 chromosomes. Phylogenetic analysis grouped these genes into two subfamilies and eight subgroups, which was confirmed by the conserved motif and gene structure analysis. Furthermore, MaOFPs genes duplicates were found to have originated from whole-genome duplication (WGD). The expression patterns of the genes in the various tissues and at different fruit development and ripening stages in the BaXi Jiao (BX) and Feng Jiao (FJ), banana cultivars were elucidated using transcriptome analysis. Using co-expression network analysis, MaOFP1 was found to interact not only with MaMADS36 but also with hormone response proteins. These findings improve our understanding of the functions of MaOFPs genes in the control of plant hormone signal transduction pathways during banana growth and ripening, which should inform the genetic improvement of important agricultural characters.

Effect of cultivating Pleurotus ostreatus on substrates supplemented with herb residues on yield characteristics, substrates degradation, and fruiting bodies' properties.

BACKGROUND: Inappropriate disposal of herb residues in China has caused major problems for the immediate environment and to human safety. Here, three herb residues, compound Kushen injection (CKI), Qizhi Tongluo capsule (QTC), and Shenbai Shuxin capsule (SSC), were applied as substrates to corncob at various ratios (30:60, 45:45, and 60:30) for the propagation of the mushroom Pleurotus ostreatus. The effects of supplementation using herb residues on yield, biodegradation ability, bioactive compounds, antioxidant properties, and safety of P. ostreatus were assessed. RESULTS: Different spawn running times were observed using growth medium, whereas 45CKI, 60QTC, and 30SSC media were determined as optimal-performing substrate combinations, resulting in yields of 843 g kg-1 , 828 g kg-1 , and 715 g kg-1 respectively. Biodegradation analysis of consumed substrates revealed a significant decrease in cellulose and hemicellulose levels compared with lignin. Furthermore, chemical analysis of fruiting bodies revealed that the 45CKI and 60QTC substrates resulted in higher total phenol, flavonoid, terpenoid, and vitamin C levels, but significantly reduced water-soluble polysaccharides compared with the corncob medium. The methanol extract of fruiting bodies grown on substrates containing herb residues exhibited higher antioxidant properties than the control, as it was more effective in scavenging 2,2-diphenyl-1-picrylhydrazyl radicals, had greater reducing power, and more strongly inhibiting lipid peroxidation. Furthermore, high-performance liquid chromatography studies indicated that fruiting bodies did not generate matrine (a specific toxin produced in Kushen) when cultivated using the CKI substrate. CONCLUSIONS: P. ostreatus cultivation on substrates mixed with herb residues facilitates herb residue management as well as bioactivity-rich and non-toxic fruit body formation. © 2020 Society of Chemical Industry.

Volumetric enhancement of Raman scattering for fast detection based on a silver-lined hollow-core fiber.

Fast detection and identification of chemicals are of utmost importance for field testing and real-time monitoring in many fields. Raman spectroscopy is the predominant technique in principle, but its wide application is limited on account of weak scattering efficiency. Surface Enhanced Raman Spectroscopy (SERS) technique provides a solution for signal enhancement, but may not good at fast detection due to cross contamination and bulky instruments. Hollow-core fiber-based Raman cell with long interaction length can achieve high detection sensitivity, but it also suffers from low flow rate, bulky high-pressure equipment and light coupling structure, which also restricts its application for fast detection. In order to solve those problems, we proposed a portable Raman cell, by using metal-lined hollow-core fibers (MLHCF) with large bandwidth, good field confinement, extremely large numerical aperture and arbitrary length. With our proposed fiber inserted light coupling and light reflecting method, a Raman cell of 3.1 cm in length provides nearly 50 times of signal enhancement compared with direct detection using bare fiber tip. Furthermore, the sample exchange rate could be as fast as 1 second even under normal pressure without any cross contamination. At last, we also demonstrated the underlying general mechanism of signal enhancement and summarized it as volumetric enhancement of Raman scattering (VERS). Both the experiment results and the theoretical analysis demonstrated that our device has the potential for fast online Raman detection, which also possesses high-sensitivity and high-accuracy.

MuMADS1 and MaOFP1 regulate fruit quality in a tomato ovate mutant.

Fruit ripening and quality are common botanical phenomena that are closely linked and strictly regulated by transcription factors. It was previously discovered that a banana MADS-box protein named MuMADS1 interacted with an ovate family protein named MaOFP1 to regulate banana fruit ripening. To further investigate the role of MuMADS1 and MaOFP1 in the regulation of fruit quality, a combination of genetic transformation and transcriptional characterization was used. The results indicated that the co-expression of MuMADS1 and MaOFP1 in the ovate mutant could compensate for fruit shape and inferior qualities relating to fruit firmness, soluble solids and sugar content. The number of differentially expressed genes (DEGs) was 1395 in WT vs. ovate, with 883 up-regulated and 512 down-regulated genes, while the numbers of DEGs gradually decreased with the transformation of MuMADS1 and MaOFP1 into ovate. 'Starch and sucrose metabolism' constituted the primary metabolic pathway, and the gene numbers in this pathway were obviously different when MuMADS1 and MaOFP1 were integrated into ovate. A series of metabolic genes involved in cell wall biosynthesis were up-regulated in the WT vs. ovate, which probably resulted in the firmer texture and lower sugar contents in the ovate fruit. These results demonstrate that MuMADS1 and MaOFP1 are coregulators of fruit quality, facilitating the dissection of the molecular mechanisms underlying fruit quality formation.

Overexpression of a Novel ROP Gene from the Banana (MaROP5g) Confers Increased Salt Stress Tolerance.

Rho-like GTPases from plants (ROPs) are plant-specific molecular switches that are crucial for plant survival when subjected to abiotic stress. We identified and characterized 17 novel ROP proteins from Musa acuminata (MaROPs) using genomic techniques. The identified MaROPs fell into three of the four previously described ROP groups (Groups II⁻IV), with MaROPs in each group having similar genetic structures and conserved motifs. Our transcriptomic analysis showed that the two banana genotypes tested, Fen Jiao and BaXi Jiao, had similar responses to abiotic stress: Six genes (MaROP-3b, -5a, -5c, -5f, -5g, and -6) were highly expressed in response to cold, salt, and drought stress conditions in both genotypes. Of these, MaROP5g was most highly expressed in response to salt stress. Co-localization experiments showed that the MaROP5g protein was localized at the plasma membrane. When subjected to salt stress, transgenic Arabidopsis thaliana overexpressing MaROP5g had longer primary roots and increased survival rates compared to wild-type A. thaliana. The increased salt tolerance conferred by MaROP5g might be related to reduced membrane injury and the increased cytosolic K⁺/Na⁺ ratio and Ca2+ concentration in the transgenic plants as compared to wild-type. The increased expression of salt overly sensitive (SOS)-pathway genes and calcium-signaling pathway genes in MaROP5g-overexpressing A. thaliana reflected the enhanced tolerance to salt stress by the transgenic lines in comparison to wild-type. Collectively, our results suggested that abiotic stress tolerance in banana plants might be regulated by multiple MaROPs, and that MaROP5g might enhance salt tolerance by increasing root length, improving membrane injury and ion distribution.

The core regulatory network of the abscisic acid pathway in banana: genome-wide identification and expression analyses during development, ripening, and abiotic stress.

BACKGROUND: Abscisic acid (ABA) signaling plays a crucial role in developmental and environmental adaptation processes of plants. However, the PYL-PP2C-SnRK2 families that function as the core components of ABA signaling are not well understood in banana. RESULTS: In the present study, 24 PYL, 87 PP2C, and 11 SnRK2 genes were identified from banana, which was further supported by evolutionary relationships, conserved motif and gene structure analyses. The comprehensive transcriptomic analyses showed that banana PYL-PP2C-SnRK2 genes are involved in tissue development, fruit development and ripening, and response to abiotic stress in two cultivated varieties. Moreover, comparative expression analyses of PYL-PP2C-SnRK2 genes between BaXi Jiao (BX) and Fen Jiao (FJ) revealed that PYL-PP2C-SnRK2-mediated ABA signaling might positively regulate banana fruit ripening and tolerance to cold, salt, and osmotic stresses. Finally, interaction networks and co-expression assays demonstrated that the core components of ABA signaling were more active in FJ than in BX in response to abiotic stress, further supporting the crucial role of the genes in tolerance to abiotic stress in banana. CONCLUSIONS: This study provides new insights into the complicated transcriptional control of PYL-PP2C-SnRK2 genes, improves the understanding of PYL-PP2C-SnRK2-mediated ABA signaling in the regulation of fruit development, ripening, and response to abiotic stress, and identifies some candidate genes for genetic improvement of banana.

The AGPase Family Proteins in Banana: Genome-Wide Identification, Phylogeny, and Expression Analyses Reveal Their Involvement in the Development, Ripening, and Abiotic/Biotic Stress Responses.

ADP-glucose pyrophosphorylase (AGPase) is the first rate-limiting enzyme in starch biosynthesis and plays crucial roles in multiple biological processes. Despite its importance, AGPase is poorly studied in starchy fruit crop banana (Musa acuminata L.). In this study, eight MaAGPase genes have been identified genome-wide in M. acuminata, which could be clustered into the large (APL) and small (APS) subunits. Comprehensive transcriptomic analysis revealed temporal and spatial expression variations of MaAPLs and MaAPSs and their differential responses to abiotic/biotic stresses in two banana genotypes, Fen Jiao (FJ) and BaXi Jiao (BX). MaAPS1 showed generally high expression at various developmental and ripening stages and in response to abiotic/biotic stresses in both genotypes. MaAPL-3 and -2a were specifically induced by abiotic stresses including cold, salt, and drought, as well as by fungal infection in FJ, but not in BX. The presence of hormone-related and stress-relevant cis-acting elements in the promoters of MaAGPase genes suggests that MaAGPases may play an important role in multiple biological processes. Taken together, this study provides new insights into the complex transcriptional regulation of AGPases, underlying their key roles in promoting starch biosynthesis and enhancing stress tolerance in banana.

Activation of salicylic acid metabolism and signal transduction can enhance resistance to Fusarium wilt in banana (Musa acuminata L. AAA group, cv. Cavendish).

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cubens (Foc) is the most serious disease that attacks banana plants. Salicylic acid (SA) can play a key role in plant-microbe interactions. Our study is the first to examine the role of SA in conferring resistance to Foc TR4 in banana (Musa acuminata L. AAA group, cv. Cavendish), which is the greatest commercial importance cultivar in Musa. We used quantitative real-time reverse polymerase chain reaction (qRT-PCR) to analyze the expression profiles of 45 genes related to SA biosynthesis and downstream signaling pathways in a susceptible banana cultivar (cv. Cavendish) and a resistant banana cultivar (cv. Nongke No. 1) inoculated with Foc TR4. The expression of genes involved in SA biosynthesis and downstream signaling pathways was suppressed in a susceptible cultivar and activated in a resistant cultivar. The SA levels in each treatment arm were measured using high-performance liquid chromatography. SA levels were decreased in the susceptible cultivar and increased in the resistant cultivar. Finally, we examined the contribution of exogenous SA to Foc TR4 resistance in susceptible banana plants. The expression of genes involved in SA biosynthesis and signal transduction pathways as well as SA levels were significantly increased. The results suggest that one reason for banana susceptibility to Foc TR4 is that expression of genes involved in SA biosynthesis and SA levels are suppressed and that the induced resistance observed in banana against Foc TR4 might be a case of salicylic acid-dependent systemic acquired resistance.