ABSTRACT
Cone enlargement is a crucial process for seed production and reproduction in gymnosperms. Most of our knowledge of cone development is derived from observing anatomical structure during gametophyte development. Therefore, the exact molecular mechanism underlying cone enlargement after fertilization is poorly understood. Here, we demonstrate that sucrose promotes cone enlargement in Torreya grandis, a gymnosperm species with relatively low rates of cone enlargement, via the TgNGA1-TgWRKY47-TgEXPA2 pathway. Cell expansion plays a significant role in cone enlargement in T. grandis. 13C labeling and sucrose feeding experiments indicated that sucrose-induced changes in cell size and number contribute to cone enlargement in this species. RNA-sequencing analysis, transient overexpression in T. grandis cones, and stable overexpression in tomato (Solanum lycopersicum) suggested that the expansin gene TgEXPA2 positively regulates cell expansion in T. grandis cones. The WRKY transcription factor TgWRKY47 directly enhances TgEXPA2 expression by binding to its promoter. Additionally, the NGATHA transcription factor TgNGA1 directly interacts with TgWRKY47. This interaction suppresses the DNA-binding ability of TgWRKY47, thereby reducing its transcriptional activation on TgEXPA2 without affecting the transactivation ability of TgWRKY47. Our findings establish a link between sucrose and cone enlargement in T. grandis and elucidate the potential underlying molecular mechanism.
Subject(s)
Plant Proteins , Sucrose , Taxaceae , Gene Expression Regulation, Plant , Plant Proteins/metabolism , Plant Proteins/genetics , Plants, Genetically Modified , Promoter Regions, Genetic/genetics , Protein Binding/drug effects , Solanum lycopersicum/genetics , Solanum lycopersicum/growth & development , Sucrose/metabolism , Sucrose/pharmacology , Transcription Factors/metabolism , Transcription Factors/genetics , Taxaceae/genetics , Taxaceae/growth & developmentABSTRACT
Terpenes are volatile compounds responsible for aroma and the postharvest quality of commercially important xiangfei (Torreya grandis) nuts, and there is interest in understanding the regulation of their biosynthesis. Here, a transcriptomics analysis of xiangfei nuts after harvest identified 156 genes associated with the terpenoid metabolic pathway. A geranyl diphosphate (GPP) synthase (TgGPPS) involved in production of the monoterpene precursor GPP was targeted for functional characterization, and its transcript levels positively correlated with terpene levels. Furthermore, transient overexpression of TgGPPS in tobacco (Nicotiana tabacum) leaves or tomato (Solanum lycopersicum) fruit led to monoterpene accumulation. Analysis of differentially expressed transcription factors identified one basic helix-loop-helix protein (TgbHLH95) and one basic leucine zipper protein (TgbZIP44) as potential TgGPPS regulators. TgbHLH95 showed significant transactivation of the TgGPPS promoter, and its transient overexpression in tobacco leaves led to monoterpene accumulation, whereas TgbZIP44 directly bound to an ACGT-containing element in the TgGPPS promoter, as determined by yeast 1-hybrid test and electrophoretic mobility shift assay. Bimolecular fluorescence complementation, firefly luciferase complementation imaging, co-immunoprecipitation, and GST pull-down assays confirmed a direct protein-protein interaction between TgbHLH95 and TgbZIP44 in vivo and in vitro, and in combination these proteins induced the TgGPPS promoter up to 4.7-fold in transactivation assays. These results indicate that a TgbHLH95/TgbZIP44 complex activates the TgGPPS promoter and upregulates terpene biosynthesis in xiangfei nuts after harvest, thereby contributing to its aroma.
Subject(s)
Taxaceae , Transcription Factors , Transcription Factors/genetics , Transcription Factors/metabolism , Nuts/metabolism , Terpenes/metabolism , Monoterpenes/metabolism , Taxaceae/metabolism , Gene Expression Regulation, Plant , Plant Proteins/genetics , Plant Proteins/metabolismABSTRACT
Terpene aroma compounds are key quality attributes of postharvest Torreya grandis nuts, contributing to their commercial value. However, terpene biosynthesis and regulatory networks in different T. grandis cvs. are still poorly understood. Here, chief cvs. 'Xi Fei' and 'Xiangya Fei' were investigated for their differences in terpene biosynthesis and gene expression levels during postharvest ripening using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and transcriptomic datasets. A total of 28 and 22 aroma compounds were identified in 'Xi Fei' and 'Xiangya Fei', respectively. Interestingly, differences in aroma composition between the two cvs. were mostly attributed to D-limonene and α-pinene levels as key determinants in Torreya nuts' flavor. Further, transcriptome profiling, correlation analysis, and RT-qPCR annotated two novel genes, TgTPS1 in 'Xi Fei' and TgTPS2 in 'Xiangya Fei', involved in terpene biosynthesis. In addition, six transcription factors (TFs) with comparable expression patterns to TgTPS1 and four TFs to TgTPS2 were identified via correlation analysis of a volatile and transcriptome dataset to be involved in terpene biosynthesis. Our study provides novel insight into terpene biosynthesis and its regulation at the molecular level in T. grandis nut and presents a valuable reference for metabolic engineering and aroma improvement in this less explored nut.
Subject(s)
Gas Chromatography-Mass Spectrometry , Gene Expression Profiling , Gene Expression Regulation, Plant , Terpenes , Terpenes/metabolism , Gas Chromatography-Mass Spectrometry/methods , Gene Expression Profiling/methods , Transcriptome , Plant Proteins/genetics , Plant Proteins/metabolism , Odorants/analysisABSTRACT
BACKGROUND: Understanding the epidemiology of Coronavirus Disease of 2019 (COVID-19) in a local context is valuable for both future pandemic preparedness and potential increases in COVID-19 case volume, particularly due to variant strains. METHODS: Our work allowed us to complete a population-based study on patients who tested positive for COVID-19 in Alberta from March 1, 2020 to December 15, 2021. We completed a multi-centre, retrospective population-based descriptive study using secondary data sources in Alberta, Canada. We identified all adult patients (≥ 18 years of age) tested and subsequently positive for COVID-19 (including only the first incident case of COVID-19) on a laboratory test. We determined positive COVID-19 tests, gender, age, comorbidities, residency in a long-term care (LTC) facility, time to hospitalization, length of stay (LOS) in hospital, and mortality. Patients were followed for 60 days from a COVID-19 positive test. RESULTS: Between March 1, 2020 and December 15, 2021, 255,037 adults were identified with COVID-19 in Alberta. Most confirmed cases occurred among those less than 60 years of age (84.3%); however, most deaths (89.3%) occurred among those older than 60 years. Overall hospitalization rate among those who tested positive was 5.9%. Being a resident of LTC was associated with substantial mortality of 24.6% within 60 days of a positive COVID-19 test. The most common comorbidity among those with COVID-19 was depression. Across all patients 17.3% of males and 18.6% of females had an unplanned ambulatory visit subsequent to their positive COVID-19 test. CONCLUSIONS: COVID-19 is associated with extensive healthcare utilization. Residents of LTC were substantially impacted during the COVID-19 pandemic with high associated mortality. Further work should be done to better understand the economic burden associated with related healthcare utilization following a COVID-19 infection to inform healthcare system resource allocation, planning, and forecasting.
Subject(s)
COVID-19 , Internship and Residency , Male , Adult , Female , Humans , COVID-19/epidemiology , Long-Term Care , Retrospective Studies , Alberta/epidemiology , Pandemics , Patient Acceptance of Health CareABSTRACT
The RAV (related to ABI3/viviparous 1) group of transcription factors (TFs) play multifaceted roles in plant development and stress responses. Here, we show that strawberry (Fragaria × ananassa) FaRAV1 positively regulates anthocyanin accumulation during fruit ripening via a hierarchy of activation processes. Dual-luciferase assay screening of all fruit-expressed AP2/ERFs showed FaRAV1 had the highest transcriptional activation of the promoter of FaMYB10, a key activator of anthocyanin biosynthesis. Yeast one-hybrid and electrophoretic mobility shift assays indicated that FaRAV1 could directly bind to the promoter of FaMYB10. Transient overexpression of FaRAV1 in strawberry fruit increased FaMYB10 expression and anthocyanin production significantly. Correspondingly, transient RNA interference-induced silencing of FaRAV1 led to decreases in FaMYB10 expression and anthocyanin content. Transcriptome analysis of FaRAV1-overexpressing strawberry fruit revealed that transcripts of phenylpropanoid and flavonoid biosynthesis pathway genes were up-regulated. Luciferase assays showed that FaRAV1 could also activate the promoters of strawberry anthocyanin biosynthetic genes directly, revealing a second level of FaRAV1 action in promoting anthocyanin accumulation. These results show that FaRAV1 stimulates anthocyanin accumulation in strawberry both by direct activation of anthocyanin pathway gene promoters and by up-regulation of FaMYB10, which also positively regulates these genes.
Subject(s)
Fragaria , Anthocyanins , Fragaria/genetics , Fragaria/metabolism , Fruit/genetics , Fruit/metabolism , Gene Expression Regulation, Plant/genetics , Plant Proteins/genetics , Plant Proteins/metabolism , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
4-Hydroxy-2,5-dimethyl-3(2H)-furanone is a major contributor to the aroma of strawberry (Fragaria × ananassa) fruit, and the last step in its biosynthesis is catalyzed by strawberry quinone oxidoreductase (FaQR). Here, an ethylene response factor (FaERF#9) was characterized as a positive regulator of the FaQR promoter. Linear regression analysis indicated that FaERF#9 transcript levels were correlated significantly with both FaQR transcripts and furanone content in different strawberry cultivars. Transient overexpression of FaERF#9 in strawberry fruit significantly increased FaQR expression and furaneol production. Yeast one-hybrid assays, however, indicated that FaERF#9 by itself did not bind to the FaQR promoter. An MYB transcription factor (FaMYB98) identified in yeast one-hybrid screening of the strawberry cDNA library was capable of both binding to the promoter and activating the transcription of FaQR by â¼5.6-fold. Yeast two-hybrid assay and bimolecular fluorescence complementation confirmed a direct protein-protein interaction between FaERF#9 and FaMYB98, and in combination, they activated the FaQR promoter 14-fold in transactivation assays. These results indicate that an ERF-MYB complex containing FaERF#9 and FaMYB98 activates the FaQR promoter and up-regulates 4-hydroxy-2,5-dimethyl-3(2H)-furanone biosynthesis in strawberry.
Subject(s)
Fragaria/metabolism , Furans/metabolism , NAD(P)H Dehydrogenase (Quinone)/metabolism , Plant Proteins/metabolism , Transcription Factors/metabolism , Fragaria/genetics , Fruit/genetics , Fruit/metabolism , Gene Expression Profiling , Gene Expression Regulation, Plant , Multiprotein Complexes/metabolism , NAD(P)H Dehydrogenase (Quinone)/genetics , Plant Proteins/genetics , Promoter Regions, Genetic/genetics , Protein Binding , Transcription Factors/genetics , Two-Hybrid System TechniquesABSTRACT
BACKGROUND: The processing of the three major crustaceans (shrimp, lobster, and crab) is associated with inevitable by-products, high waste disposal costs, environmental and human health issues, loss of multiple biomaterials (chitin, protein hydrolysates, lipids, astaxanthin and minerals). Nowadays, these bioresources are underutilized owing to the lack of effective and standardized technologies to convert these materials into valued industrial forms. AIM OF REVIEW: This review aims to provide a holistic overview of the various bioactive ingredients and applications within major crustaceans by-products. This review aims to compare various extraction methods in crustaceans by-products, which will aid identify a more workable platform to minimize waste disposal and maximize its value for best valorization practices. KEY SCIENTIFIC CONCEPTS OF REVIEW: The fully integrated applications (agriculture, food, cosmetics, pharmaceuticals, paper industries, etc.) of multiple biomaterials from crustaceans by-products are presented. The pros and cons of the various extraction methods, including chemical (acid and alkali), bioprocesses (enzymatic or fermentation), physical (microwave, ultrasound, hot water and carbonic acid process), solvent (ionic liquids, deep eutectic solvents, EDTA) and electrochemistry are detailed. The rapid development of corresponding biotechnological attempts present a simple, fast, effective, clean, and controllable bioprocess for the comprehensive utilization of crustacean waste that has yet to be applied at an industrial level. One feasible way for best valorization practices is to combine innovative extraction techniques with industrially applicable technologies to efficiently recover these valuable components.
Subject(s)
Brachyura , Decapoda , Humans , Animals , Nephropidae , Seafood , Biocompatible MaterialsABSTRACT
The microbiology of cardiac implantable electronic device (CIED) infections in Calgary, Alberta was described, identifying 50 infections from 2013 to 2019. The majority were Staphylococcus aureus (40.0%). There is significant economic burden, mostly related to inpatient costs, associated with CIED infections. However, there were no significant differences in costs stratified by organism.
ABSTRACT
Secondary metabolites are a group of small molecules with critical roles in plants fitness in addition to their potential bioactivities in humans. Most of these compounds are associated with the flavor and quality formation of fruits or nuts during the development or the postharvest stages. Change in metabolic profiles and shifts underpinning the post-ripening process in T. grandis nuts are not yet reported. In this study, a large scale untargeted metabolomics approach was employed in T. grandis nuts, revealing for a total of 140 differential accumulated metabolites. Among them, nearly 60% of metabolites belonging to terpenoids, coumarins and phenolic acids, and phytohormones were showed a gradual accumulation pattern, while most of compounds in flavonoids were decreased during post-ripening. An in-depth analysis of changes in these metabolite classes suggest a framework for post-ripening process effect associated with the postharvest quality of T. grandis nuts for the first time.
Subject(s)
Nuts , Taxaceae , Humans , Nuts/metabolism , Metabolomics , Fruit/metabolism , MetabolomeABSTRACT
BACKGROUND: Cardiac implantable electronic devices (CIED) are being inserted with increasing frequency. Severe surgical site infections (SSI) that occur after device implantation substantially impact patient morbidity and mortality and can result in multiple hospital admissions and repeat surgeries. It is important to understand the costs associated with these infections as well as healthcare utilization. Therefore, we conducted a population-based study in the province of Alberta, Canada to understand the economic burden of these infections. METHODS: A cohort of adult patients in Alberta who had CIEDs inserted or generators replaced between January 1, 2011 and December 31, 2019 was used. A validated algorithm of International Classification of Diseases (ICD) codes to identify complex (deep/organ space) SSIs that occurred within the subsequent year was applied to the cohort. The overall mean 12-month inpatient and outpatient costs for the infection and non-infection groups were assessed. In order to control for variables that may influence costs, propensity score matching was completed and incremental costs between those with and without infection were calculated. As secondary outcomes, number of outpatient visits, hospitalizations and length of stay were assessed. RESULTS: There were 26,049 procedures performed during our study period, of which 320 (1.23%) resulted in SSIs. In both unadjusted costs and propensity score matched costs the infection group was associated with increased costs. Overall mean cost was $145,312 in the infection group versus $34,264 in the non-infection group. The incremental difference in those with infection versus those without in the propensity score match was $90,620 (Standard deviation $190,185). Approximately 70% of costs were driven by inpatient hospitalizations. Inpatients hospitalizations, length of stay and outpatient visits were all increased in the infection group. CONCLUSIONS: CIED infections are associated with increased costs and are a burden to the healthcare system. This highlights a need to recognize increasing SSI rates and implement measures to minimize infection risk. Further studies should endeavor to apply this work to full economic evaluations to better understand and identify cost-effective infection mitigation strategies.
Subject(s)
Communicable Diseases , Financial Stress , Adult , Humans , Alberta/epidemiology , Hospitalization , Surgical Wound Infection/epidemiologyABSTRACT
Astringency removal is important for the quality of Torreya grandis nut and occurs after harvest. Here, we evaluated the effect of NaHCO3 treatment on astringency removal and compared the differential metabolites of the seed coat and kernel using a UHPLC QQQ-MS-based metabolomics approach. The result revealed the nut astringency was primarily enriched in the seed coat with more soluble tannins. The NaHCO3 treatment greatly shortened the de-astringency process, as indicated by a faster conversion of soluble tannins to insoluble tannins and more acetaldehyde production. Besides, a total of 293 metabolites, including 92 phenolic acids and 37 flavonoids, were tentatively characterized in the seed coat. A further comparative analysis of the metabolomics indicated epigallocatechin, gallocatechin, catechin, procyanidin B1, B2, B3 and C1 to be the major metabolites influenced by the NaHCO3 treatment. This study provides new insights regarding the metabolite differences of Torreya grandis nuts processed with different de-astringent treatments.
Subject(s)
Astringents , Taxaceae , Metabolomics , Nuts/metabolism , Tannins/metabolismABSTRACT
Amino acids play critical roles in physiological processes and also contribute significantly to fruit quality. In this study, the effect of exogenous ethylene on amino acids metabolism and related genes expression in Torreya grandis were investigated. The results revealed that ethylene treatment (3000 µL L-1 for 24 h) significantly increased amino acids level. Umami amino acids were distinctly upregulated in ethylene-treated versus control nuts, with glutamic and aspartic acids to demonstrate 1.9-fold and 2.1-fold increase. Transcriptome analysis revealed that deferentially expressed genes were mainly enriched in alanine aspartate and glutamate metabolism. RT-qPCR confirmed that ethylene treatment up-regulated expression of their biosynthesis genes (TgGOGAT1, TgAATC1, TgAATC4) concurrent with suppression of their degradation enzymes (TgGS2, TgGAD1, TgGAD3, TgASNS1). Ethylene treatment appears to promote umami taste-active amino acids and improve T. grandis nut quality post-harvest.
Subject(s)
Amino Acids , Taxaceae , Amino Acids/analysis , Taste , Nuts/chemistry , Ethylenes/pharmacology , Aspartic AcidABSTRACT
OBJECTIVE: To establish the epidemiology of cardiac implantable electronic device (CIED) infections in Alberta, Canada, using validated administrative data. DESIGN: Retrospective, population-based cohort study. SETTING: Alberta Health Services is a province-wide health system that services all of Alberta, Canada. PARTICIPANTS: Adult patients who underwent first-time CIED implantation or generator replacement in Alberta, Canada, between January 1, 2011, and December 31, 2019. METHODS: CIED implant patients were identified from the Paceart database. Patients who developed an infection within 1 year of the index procedure were identified through validated administrative data (International Classification of Diseases, Tenth Revision in Canada). Demographic characteristics of patients were summarized. Logistic regression models were used to analyze device type, comorbidities, and demographics associated with infection rates and mortality. RESULTS: Among 27,830 CIED implants, there were 205 infections (0.74%). Having 2 or more comorbidities was associated with higher infection risk. Generator replacement procedures (odds ratio [OR], 0.55; 95% confidence interval [CI], 0.34-0.84; P = .008), age increase of every 10 years (OR, 0.73; 95% CI, 0.66-0.82; P ≤ .001), and index procedure after 2014 were associated with decreased risk. Comparing the infected to uninfected groups, the hospitalization rates were 2.63 compared to 0.69, and the mortality rates were 10.73% compared to 3.49%, respectively (P < .001). CONCLUSIONS: There is a slightly lower overall rate of CIED infections Alberta, Canada compared to previously described epidemiology. Implants after 2014, and generator replacements showed a decreased burden of infection. Patients with younger age, and 2 or more comorbidities are at greatest risk of CIED infection. The burden of hospitalization and mortality is substantially higher in infected patients.
Subject(s)
Defibrillators, Implantable , Pacemaker, Artificial , Prosthesis-Related Infections , Adult , Humans , Child, Preschool , Child , Cohort Studies , Retrospective Studies , Defibrillators, Implantable/adverse effects , Alberta/epidemiology , Prosthesis-Related Infections/epidemiology , Pacemaker, Artificial/adverse effects , Risk FactorsABSTRACT
The postharvest ripening stage is necessary for Torreya grandis (T. grandis) nuts to complete aromatic synthesis, which requires appropriate temperature and relative humidity (RH). Currently, scarce information is available regarding the changes in aroma profiles in T. grandis nuts and the relationship with their response to different environmental conditions. Therefore, the interaction of temperature (20 °C or 30 °C) and relative humidity (70% RH or 90% RH) was investigated on aromatic substances after harvest. The results showed that 56 aromatic components were detected by a gas chromatography-mass spectrometer (GC-MS) and mainly divided into five categories, among which terpenes were the most abundant (56.2-86.7%). Principal component analysis (PCA) showed that both temperature and humidity can affect the aroma composition, and terpenes were mainly influenced by humidity. Specifically, d-limonene occupied the largest proportion of terpenes (63.0-90.8%) and was significantly upregulated by high humidity.
Subject(s)
Nuts , Taxaceae , Humidity , Odorants , TemperatureABSTRACT
The seeds of Torreya grandis are necessary to go through a ripening process, which eventually leads to nutrition conversion and the production of edible nuts. However, the molecular basis of nutrition conversion remains unclear. Here, transcriptome sequencing was performed on seeds treated with different temperature and humidity. A total of 881 unigenes related to nutrition conversion were identified. The correlations between nutrient content and gene expression suggested that sucrose phosphate synthase (SPS), dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex (DLST), glycerol-3-phosphate acyltransferase (GPAT) and Pyruvate kinase (PK) may play key roles in nutrition conversion. Transient over-expression of TgDLST, TgPK and TgGPAT in tobacco leaves promoted nutritional conversion. Moreover, enzyme activity analysis indicated that diacylglycerol acyltransferase (DGAT) and pyruvate dehydrogenase (PDH) activities may also accelerate the nutritional conversion. This study uncovers the molecular basis of nutrition conversion in T. grandis seeds, which critical for shortening the time of nutrition conversion.
Subject(s)
Nuts , Taxaceae , Humidity , Nuts/chemistry , Plant Leaves , Seeds/genetics , Taxaceae/chemistryABSTRACT
Torreya grandis 'Merrillii' is a famous nut with great nutritional value and high medicinal value. Aril cracking is an important process for seed dispersal, which is also an indicator of seed maturation. However, the cracking mechanism of T. grandis aril during the maturation stage remains largely unknown. Here, we provided a comprehensive view of the physiological and molecular levels of aril cracking in T. grandis by systematically analyzing its anatomical structure, physiological parameters, and transcriptomic response during the cracking process. These results showed that the length of both epidermal and parenchymatous cell layers significantly increased from 133 to 144 days after seed protrusion (DASP), followed by a clear separation between parenchymatous cell layers and kernel, which was accompanied by a breakage between epidermal and parenchymatous cell layers. Moreover, analyses of cell wall composition showed that a significant degradation of cellular wall polysaccharides occurred during aril cracking. To examine the global gene expression changes in arils during the cracking process, the transcriptomes (96 and 141 DASP) were analyzed. KEGG pathway analysis of DEGs revealed that 4 of the top 10 enriched pathways were involved in cell wall modification and 2 pathways were related to ethylene biosynthesis and ethylene signal transduction. Furthermore, combining the analysis results of co-expression networks between different transcription factors, cell wall modification genes, and exogenous ethylene treatments suggested that the ethylene signal transcription factors (ERF11 and ERF1A) were involved in aril cracking of T. grandis by regulation of EXP and PME. Our findings provided new insights into the aril cracking trait in T. grandis.
ABSTRACT
Two types of bamboo shoots, high bamboo (Phyllostachys prominens) shoots (HBSes) and moso bamboo (Phyllostachys edulis) shoots (MBSes), underwent a fast post-harvest lignification process under room temperature storage. To explore the mechanism of lignification in two types of bamboo shoots after post-harvest during room temperature storage, the measurement of cell wall polymers (lignin and cellulose) and enzyme activities of phenylalanine ammonialyase (PAL) and peroxidase (POD), and relative expression of related transcription networks factors (TFs) were performed. The results suggested that the lignification process in HBSes is faster than that in MBSes because of incremental increase in lignin and cellulose contents within 6 days and the shorter shelf-life. Additionally, compared with the expression pattern of lignification-related TFs and correlation analysis of lignin and cellulose contents, MYB20, MYB43, MYB85 could function positively in the lignification process of two types of bamboo shoots. A negative regulator, KNAT7, could negatively regulate the lignin biosynthesis in two types of bamboo shoots. In addition, MYB63 could function positively in HBSes, and NST1 could function negatively in MBSes. Notably, MYB42 may function differently in the two types of bamboo shoots, that is, a positive regulator in HBSes, but a negative regulator in MBSes. Transcription networks provide a comprehensive analysis to explore the mechanism of lignification in two types of bamboo shoots after post-harvest during room temperature storage. These results suggest that the lignification of bamboo shoots was mainly due to the increased activity of POD, higher expression levels of MYB20, MYB43, MYB63, and MYB85 genes, and lower expression levels of KNAT7 and NST1 genes, and the lignification process of HBSes and MBSes had significant differences.
ABSTRACT
Temperature and relative humidity (RH) influence post-harvest ripening, a crucial stage for quality promotion in some oil plants or fruits. Torreya grandis cv. Merrillii nuts, which are rich in unsaturated fatty acids (UFA), are easily affected by temperature and humidity, and they oxidize quickly during the post-harvest ripening stage, leading to the deterioration of nut quality. In this study, the main nutraceutical components, fatty acid composition, and related metabolic parameters of lipid rancidity under four treatments (20°C and 70% RH, T20-LH; 30°C and 70% RH, T30-LH; 20°C and 90% RH, T20-HH; 30°C and 90% RH, T30-HH) were measured. The post-harvest ripening process was advanced under HH treatments (T20-HH and T30-HH) compared to LH treatments (T20-LH and T30-LH) and was associated with a shorter time for the seed coat to turn dark black and a faster reduction in starch content. The amount of unsaturated fatty acids significantly increased under the T20-HH treatment, but significantly decreased under the T30-HH treatment from 12 to 16 d of ripening time. The acid value (AV) and lipase activity under the T30-HH treatment remained virtually constant from 12 to 16 d of ripening time, and this was accompanied by a dramatic increase in peroxide value (POV), lipoxygenase (LOX) activity, and relative expression of the LOX2 gene. Meanwhile, a significant positive correlation between LOX activity and POV, malondialdehyde (MDA) content, and O2â - content was observed. The results imply that the lower amount of oxidative rancidity induced by the T20-HH treatment is related to the LOX activity induced by down-regulation of the LOX2 gene during the late after-ripening stage. Therefore, the T20-HH treatment not only promoted the post-harvest process of T. grandis 'Merrillii' nuts but also delayed lipid oxidation, which was ultimately associated with better oil quality at the late after-ripening stage.