Valorization applications of pineapple and papaya byproducts in food industry.

The recent increase in the harvesting and industrial processing of tropical fruits such as pineapple and papaya is leading to unavoidable amounts of byproducts rich in valuable compounds. Given the significance of the chemical composition of these byproducts, new research avenues are opening up to exploit them in the food industry. In this sense, the revalorization of pineapple and papaya byproducts is an emerging trend that is encouraging the full harnessing of these tropical fruits, offering the opportunity for developing innovative value-added products. Therefore, the main aim of this review is to provide an overview of the state of the art of the current valorization applications of pineapple and papaya byproducts in the field of food industry. For that proposal, comprehensive research of valorization applications developed in the last years has been conducted using scientific databases, databases, digital libraries, and scientific search engines. The latest valorization applications of pineapple and papaya byproducts in the food industry have been systematically revised and gathered with the objective of synthesizing and critically analyzing existing scientific literature in order to contribute to the advancement of knowledge in the field of tropical byproduct revalorization providing a solid foundation for further research and highlighting scientific gaps and new challenges that should be addressed in the future.

Genome-wide identification and characterization of the BBX gene family in pineapple reveals that candidate genes are involved in floral induction and flowering.

B-box zinc finger proteins contain one or two B-box domains, and sometimes, a CCT domain, which are involved in many biological processes, such as photomorphogenesis, flowering, anthocyanin synthesis and abiotic stress resistance. But the BBX gene family in pineapple has not been systematically studied. Nineteen BBX genes were detected in pineapple genome and divided into five groups according to phylogenetic analysis. The results of transcriptome analysis and RT-qPCR showed that most of AcBBX members were highly expressed during the flowering process, indicating that AcBBX gene may be involved in flower bud differentiation and morphogenesis. Transcriptional activation analysis showed that AcBBX6 and AcBBX18 had transcriptional activity and were located in the nucleus. Overexpression of AcBBX18 promoted flowering in Arabidopsis thaliana. These results provided a basis for further study functions and regulatory mechanism of BBX members in pineapple floral induction and flower development.

Efficacy and safety of bromelain: A systematic review and meta-analysis.

Background: Pineapple has an important role in ethnopharmacology and its enzyme, bromelain, has been extensively investigated for its medicinal properties. Aim: This systematic review and meta-analysis aimed to assess clinical evidence concerning the efficacy and safety of bromelain. Methods: A systematic search was conducted from conception to August 2022 using CINAHL Complete, MEDLINE, ScienceDirect, Scopus, and Thai Journal Online (TJO). The risk of bias was assessed using Risk of Bias 2 or ROBIN-I. A random-effect model with inverse variance weighting and DerSimonian and Laird method was used for meta-analysis. The heterogeneity was evaluated by I2 statistics. Results: We included 54 articles for qualitative summary and 39 articles for meta-analysis. The systematic review found that bromelain presented in serum with retained proteolytic activity after oral absorption. Bromelain may be effective against sinusitis but was not effective for cardiovascular diseases. Pain reduction from oral bromelain was slightly but significantly better than controls (mean difference in pain score = -0.27; 95% CI: -0.45, -0.08; n = 9; I2 = 29%). Adverse events included flatulence, nausea, and headache. Topical bromelain significantly reduced the time to complete debridement (mean difference in time = -6.89 days; 95% CI: -7.94, -5.83; n = 4; I2 = 2%). Adverse events may be irrelevant and include burning sensation, pain, fever, and sepsis. Conclusions: Moderate-quality studies demonstrated the potential of oral bromelain in pain control and topical bromelain in wound care. Major health risks were not reported during the treatment with bromelain.

Genome-Wide Identification and Characterization of R2R3-MYB Provide Insight into Anthocyanin Biosynthesis Regulation Mechanism of Ananas comosus var. bracteatus.

The R2R3-MYB proteins comprise the largest class of MYB transcription factors, which play an essential role in regulating anthocyanin synthesis in various plant species. Ananas comosus var. bracteatus is an important colorful anthocyanins-rich garden plant. The spatio-temporal accumulation of anthocyanins in chimeric leaves, bracts, flowers, and peels makes it an important plant with a long ornamental period and highly improves its commercial value. We conducted a comprehensive bioinformatic analysis of the R2R3-MYB gene family based on genome data from A. comosus var. bracteatus. Phylogenetic analysis, gene structure and motif analysis, gene duplication, collinearity, and promoter analysis were used to analyze the characteristics of this gene family. In this work, a total of 99 R2R3-MYB genes were identified and classified into 33 subfamilies according to phylogenetic analysis, and most of them were localized in the nucleus. We found these genes were mapped to 25 chromosomes. Gene structure and protein motifs were conserved among AbR2R3-MYB genes, especially within the same subfamily. Collinearity analysis revealed four pairs of tandem duplicated genes and 32 segmental duplicates in AbR2R3-MYB genes, indicating that segmental duplication contributed to the amplification of the AbR2R3-MYB gene family. A total of 273 ABRE responsiveness, 66 TCA elements, 97 CGTCA motifs, and TGACG motifs were the main cis elements in the promoter region under response to ABA, SA, and MEJA. These results revealed the potential function of AbR2R3-MYB genes in response to hormone stress. Ten R2R3-MYBs were found to have high homology to MYB proteins reported to be involved in anthocyanin biosynthesis from other plants. RT-qPCR results revealed the 10 AbR2R3-MYB genes showed tissue-specific expression patterns, six of them expressed the highest in the flower, two genes in the bract, and two genes in the leaf. These results suggested that these genes may be the candidates that regulate anthocyanin biosynthesis of A. comosus var. bracteatus in the flower, leaf, and bract, respectively. In addition, the expressions of these 10 AbR2R3-MYB genes were differentially induced by ABA, MEJA, and SA, implying that these genes may play crucial roles in hormone-induced anthocyanin biosynthesis. Our study provided a comprehensive and systematic analysis of AbR2R3-MYB genes and identified the AbR2R3-MYB genes regulating the spatial-temporal anthocyanin biosynthesis in A. comosus var. bracteatus, which would be valuable for further study on the anthocyanin regulation mechanism of A. comosus var. bracteatus.

The Synergistic Mechanism of Photosynthesis and Antioxidant Metabolism between the Green and White Tissues of Ananas comosus var. bracteatus Chimeric Leaves.

Ananas comosus var. bracteatus (Ac. bracteatus) is a typical leaf-chimeric ornamental plant. The chimeric leaves are composed of central green photosynthetic tissue (GT) and marginal albino tissue (AT). The mosaic existence of GT and AT makes the chimeric leaves an ideal material for the study of the synergistic mechanism of photosynthesis and antioxidant metabolism. The daily changes in net photosynthetic rate (NPR) and stomatal conductance (SCT) of the leaves indicated the typical crassulacean acid metabolism (CAM) characteristic of Ac. bracteatus. Both the GT and AT of chimeric leaves fixed CO2 during the night and released CO2 from malic acid for photosynthesis during the daytime. The malic acid content and NADPH-ME activity of the AT during the night was significantly higher than that of GT, which suggests that the AT may work as a CO2 pool to store CO2 during the night and supply CO2 for photosynthesis in the GT during the daytime. Furthermore, the soluble sugar content (SSC) in the AT was significantly lower than that of GT, while the starch content (SC) of the AT was apparently higher than that of GT, indicating that AT was inefficient in photosynthesis but may function as a photosynthate sink to help the GT maintain high photosynthesis activity. Additionally, the AT maintained peroxide balance by enhancing the non-enzymatic antioxidant system and antioxidant enzyme system to avoid antioxidant damage. The enzyme activities of reductive ascorbic acid (AsA) and the glutathione (GSH) cycle (except DHAR) and superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were enhanced, apparently to make the AT grow normally. This study indicates that, although the AT of the chimeric leaves was inefficient at photosynthesis because of the lack of chlorophyll, it can cooperate with the GT by working as a CO2 supplier and photosynthate store to enhance the photosynthetic ability of GT to help chimeric plants grow well. Additionally, the AT can avoid peroxide damage caused by the lack of chlorophyll by enhancing the activity of the antioxidant system. The AT plays an active role in the normal growth of the chimeric leaves.

Molecular Docking and In Vitro Studies of Ochratoxin A (OTA) Biodetoxification Testing Three Endopeptidases.

Ochratoxin A (OTA) is considered one of the main mycotoxins responsible for health problems and considerable economic losses in the feed industry. The aim was to study OTA's detoxifying potential of commercial protease enzymes: (i) Ananas comosus bromelain cysteine-protease, (ii) bovine trypsin serine-protease and (iii) Bacillus subtilis neutral metalloendopeptidase. In silico studies were performed with reference ligands and T-2 toxin as control, and in vitro experiments. In silico study results showed that tested toxins interacted near the catalytic triad, similar to how the reference ligands behave in all tested proteases. Likewise, based on the proximity of the amino acids in the most stable poses, the chemical reaction mechanisms for the transformation of OTA were proposed. In vitro experiments showed that while bromelain reduced OTA's concentration in 7.64% at pH 4.6; trypsin at 10.69% and the neutral metalloendopeptidase in 8.2%, 14.44%, 45.26% at pH 4.6, 5 and 7, respectively (p < 0.05). The less harmful α-ochratoxin was confirmed with trypsin and the metalloendopeptidase. This study is the first attempt to demonstrate that: (i) bromelain and trypsin can hydrolyse OTA in acidic pH conditions with low efficiency and (ii) the metalloendopeptidase was an effective OTA bio-detoxifier. This study confirmed α-ochratoxin as a final product of the enzymatic reactions in real-time practical information on OTA degradation rate, since in vitro experiments simulated the time that food spends in poultry intestines, as well as their natural pH and temperature conditions.

First Report of Bacterial Pineapple Heart Rot Caused by Dickeya zeae in Puerto Rico.

In Puerto Rico, the agricultural production of pineapple (Ananas comosus (L.) Merr.) comprises nearly 5,000 tons harvested annually from over 250 ha (USDA 2018). With an annual income of approximately $3 million USD, pineapple ranks fourth in importance among Puerto Rican crops (USDA 2018). Recently, the pineapple industry on the island underwent a change from growing a local cultivar known as "Cabezona" to cultivar MD2, introduced from Hawaii around 1996 (SEA 2015), because this cultivar produces fruit more than once during a single growing season. In August 2018 (when the rainy season normally starts in Puerto Rico), soft rot symptoms appeared at commercial fields in Manatí (WGS 84 Lat 18.42694, Lng -66.44779) and persisted through 2019. Symptoms observed in the field included foliar water-soaked lesions with gas-filled blisters, especially at the base of the leaf. Leaves exhibited brown discoloration and a fetid odor (rot) at the basal portion of the plant. Finally, leaves collapsed at the center of the pineapple crown, effectively killing the apex and preventing the fruit from developing. Disease incidence ranged from 25% to 40% depending on the weather and season; when there was more rain, there was higher disease incidence. Symptomatic leaves were collected in February 2019, disinfected with 70% ethanol, and rinsed with sterile distilled water. Tissue sections (5mm2) were placed in nutrient agar. Bacterial colony-forming units (CFU) were a translucent cream color, circular, with a flat convex surface and wavy edge. Biochemical analysis showed that bacteria were Gram-negative, oxidase positive, catalase positive, and facultatively anaerobic. Pathogenicity was tested on leaves of one-and-a-half-year-old pineapple seedlings in humid chambers. Bacteria were grown on sterile nutrient agar for 3 days at 25 ± 2°C. Inoculation assays (three replications) were performed using 1X108 CFU/ml of bacteria suspended in sterile water and applied with a cotton swab to leaves wounded with a needle. The inoculated tissue was incubated at 28°C and kept in a dark environment. Negative controls were inoculated with sterile water. Five days after inoculation, foliar water-soaked lesions were observed, followed by the formation of brown leaf tissue and gas-filled blisters, the same symptoms observed in the field. A partial DNA sequence of the 16S rRNA gene of the bacterial isolate and the re-isolated bacteria were amplified using primers 27F and 1492R (Lane et al. 1985) and sequenced. The isolate was determined to the genus Dickeya through a BLAST® search against sequences available in the database of the National Center for Biotechnology Information (NCBI). This partial 16S rRNA sequence of the bacterial isolate was deposited in GenBank® at NCBI (Accession no. MT672704). To determine the identity of the Dickeya species, we sequenced the genes dnaA, gyrB, dnaX, and recN (Marrero et al. 2013) for the bacterial isolate (GenBank accession nos. OM276852, OM276853, OM276854, and OM276855) and conducted a Multilocus Sequence Analysis including reference Dickeya sequences of Marrero et al., 2013. The Phylogenetic analysis (using WinClada) resolved the Puerto Rican isolate as belonging to a clade broadly ascribable to D. zeae, most closely related to strains isolated from earlier Hawaiian pineapple bacterial heart rot outbreaks. Dickeya zeae was responsible for bacterial heart rot of pineapple in Malaysia and was later reported as the causal agent for outbreaks in Costa Rica and Hawaii (Kaneshiro et al. 2008; Sueno et al. 2014; Ramachandran et al. 2015). D. zeae had not previously been reported as causing bacterial heart rot in pineapples in Puerto Rico and this study points to a close relationship with strains first detected in Hawaii and which should further be explored to determine the precise nature of this relationship. This information should facilitate the adoption of effective control measures for this disease on the island, promote more effective methods of preventing future introductions of pathogens, and encourage further investigations into the occurrence of D. zeae on the island.

Genome-wide analysis of AP2/ERF transcription factors in pineapple reveals functional divergence during flowering induction mediated by ethylene and floral organ development.

The APETALA2/ethylene-responsive factor (AP2/ERF) has important roles in regulating developmental processes and hormone signaling transduction in plants. Pineapple demonstrates a special sensitivity to ethylene, and AP2/ERFs may contribute to this distinct sensitivity of pineapples to ethylene. However, little information is available on the AP2/ERF of pineapple. In this study, 97 AP2/ERF family members were identified from the pineapple genome. The AcAP2/ERF superfamily could be further divided into five subfamilies, and different subfamily existed functional divergence in multifarious biological processes. ERF and RAV subfamily genes might play important roles in the process of ethylene response of pineapple; ERF and DREB subfamily genes had particular functions in the floral organ development. This study is the first to provide detailed information on the features of AP2/ERFs in pineapple, provide new insights into the potential functional roles of the AP2/ERF superfamily members, and will facilitate a better understanding of the molecular mechanism of flower in pineapple.

Fruit Extract Derived from a Mixture of Noni, Pineapple and Mango Capable of Coagulating Milk and Producing Curd with Antidiabetic Activities.

Research background: Morinda citrifolia L. (noni), Ananas comosus L. cv. Sarawak (pineapple) and Mangifera indica L. cv. Apple (mango) represent fruits capable of coagulating milk and forming a curd. Plant-derived milk coagulants have antidiabetic phytochemicals that enrich the curd. Hence this work evaluates the dual benefits of the fruits in coagulating milk and the antidiabetic activities found in the obtained curd. Experimental approach: The three fruits were mixed to form a supercoagulant (a milk coagulant mixture of the extracts at a ratio of 1:1:1), and the milk coagulation time was measured. The milk was coagulated by the supercoagulant, and thus fortified curd was tested for its ability to inhibit α-glucosidase and α-amylase activities. Then, the fortified curd was fed daily to streptozotocin-induced diabetic rats and their biochemical markers such as blood glucose level, aspartate aminotransferase, alanine transaminase, etc. as well as histopathology of their liver and kidney tissues were compared with the untreated diabetic rats and normal rats. Results and conclusion: The supercoagulant had a milk coagulation time of (28±3) s at a 50 mg/mL concentration. Its fortified curd inhibited α-glucosidase and α-amylase activities, with IC50 values of (4.04±0.03) and (3.42±0.02) mg/mL, respectively. The average mass of the streptozotocin-induced diabetic rats fed daily with curd formed by the supercoagulant was (201±10) g on day 20 compared to diabetic control rats with (149±16) g. The blood glucose concentration for rats treated with the supercoagulant after fasting was (15±1) mmol/L compared to the diabetic control rats ((26±2) mmol/L). Blood tests on the treated rats showed aspartate aminotransferase, alanine transaminase, γ-glutamyl transferase and alkaline phosphatase (liver function tests) amounts of (214±78), (91±13), 3 and (510±138) U/L, respectively, while the total protein and renal function tests showed the concentrations of albumin, globulin, urea and creatinine of (37±2) g/L, (30±2) g/L, (11±1) mmol/L and (42±3) µmol/L, respectively. These concentrations were found to be similar to those of the normal rats on day 20. Furthermore, a histopathological study performed on the liver and kidney of the rats found no apparent damage. Novelty and scientific contribution: This supercoagulant derived from a mixture of fruits is able to coagulate milk rapidly, and its curd is fortified with safe antidiabetic agents. The supercoagulant is potentially useful in producing functional dairy food to prevent diabetes or as a supplement for diabetics to control their blood sugar. Such products are capable of replacing dairy products derived from animal enzymes and provide consumers with additional functional dairy products.

Physicochemical stability of pineapple suspensions: the integrated effects of enzymatic processes and homogenization by shear.

The pineapple (Ananas comosus) is an important tropical fruit in the world market. Its pulp has significant nutritional value while the peel and the core, in spite of being high in dietary fibre and nutrients, are generally considered to be agro-industrial waste. The aim of this research was to evaluate the effect that the integrated enzymatic and shear homogenization processes have on the physicochemical stability of pineapple base suspensions (pulp, core, and peel extract). Initially, an enzymatic hydrolysis process was evaluated with a completely randomized factorial design. Independent variables: incubation time (tinc) (1-4 h) and [enzyme] (0-200 ppm). Dependent variables: viscosity (µ) and particle sizes (D[3;2] and D[4;3]). The results showed a reduction of (µ) (70.7%), D[3;2] (54.2%), and D[4;3] (61.8%) for the optimized treatment (tinc = 3.2 h and [enzyme] = 200 ppm) compared to the control (t = 0, without enzyme). The effect of the integrated enzymatic treatment with a serial homogenization process was subsequently evaluated. Independent variables: high-speed homogenization time (t1) (15-20 min), recirculation time in high pressure homogenizer (t2) (3-7 min), and arabic gum (AG) (0.6-1.0%). Dependent variables: total suspension solids (TSS), zeta potential (ζ), µ, spectral stability index (R), D[3;2], and D[4;3]. The application of the integrated processes of enzymatic treatment and serial homogenization was more effective to be able to obtain a stable pineapple-based suspension. The experimental optimization of multiple responses defined t1 = 16.4 min, t2 = 7 min, AG = 0.98%, and TSs = 15.7 ± 0.5%, ζ = - 23.1 ± 0.4 mV, µ = 221 ± 11 cP, D[3;2] = 56.8 ± 2 µm and D[4;3] = 120.6 ± 4 µm and R = 0.58 ± 0.02 were obtained.

Metabolome and transcriptome profiling reveals anthocyanin contents and anthocyanin-related genes of chimeric leaves in Ananas comosus var. bracteatus.

BACKGROUND: Ananas comosus var. bracteatus is a colorful plant used as a cut flower or landscape ornamental. The unique foliage color of this plant includes both green and red leaves and, as a trait of interest, deserves investigation. In order to explore the pigments behind the red section of the chimeric leaves, the green and red parts of chimeric leaves of Ananas comosus var. bracteatus were sampled and analyzed at phenotypic, cellular and molecular levels in this study. RESULTS: The CIELAB results indicated that the a* values and L* values samples had significant differences between two parts. Freehand sections showed that anthocyanin presented limited accumulation in the green leaf tissues but obviously accumulation in the epidermal cells of red tissues. Transcriptomic and metabolomic analyses were performed by RNA-seq and LC-ESI-MS/MS. Among the 508 identified metabolites, 10 kinds of anthocyanins were detected, with 6 significantly different between the two samples. The cyanidin-3,5-O-diglucoside content that accounts for nearly 95.6% in red samples was significantly higher than green samples. RNA-Seq analyses showed that 11 out of 40 anthocyanin-related genes were differentially expressed between the green and red samples. Transcriptome and metabolome correlations were determined by nine quadrant analyses, and 9 anthocyanin-related genes, including MYB5 and MYB82, were correlated with 7 anthocyanin-related metabolites in the third quadrant in which genes and metabolites showing consistent change. Particularly, the PCCs between these two MYB genes and cyanidin-3,5-O-diglucoside were above 0.95. CONCLUSION: Phenotypic colors are closely related to the tissue structures of different leaf parts of Ananas comosus var. bracteatus, and two MYB transcription factors might contribute to differences of anthocyanin accumulation in two parts of Ananas comosus var. bracteatus chimeric leaves. This study lay a foundation for further researches on functions of MYBs in Ananas comosus var. bracteatus and provides new insights to anthocyanin accumulation in different parts of chimeric leaves.

Integrated analysis of DNA methylome and transcriptome reveals epigenetic regulation of CAM photosynthesis in pineapple.

BACKGROUND: Crassulacean acid metabolism (CAM) photosynthesis is an important carbon fixation pathway especially in arid environments because it leads to higher water-use efficiency compared to C3 and C4 plants. However, the role of DNA methylation in regulation CAM photosynthesis is not fully understood. RESULTS: Here, we performed temporal DNA methylome and transcriptome analysis of non-photosynthetic (white base) and photosynthetic (green tip) tissues of pineapple leaf. The DNA methylation patterns and levels in these two tissues were generally similar for the CG and CHG cytosine sequence contexts. However, CHH methylation was reduced in white base leaf tissue compared with green tip tissue across diel time course in both gene and transposon regions. We identified thousands of local differentially methylated regions (DMRs) between green tip and white base at different diel periods. We also showed that thousands of genes that overlapped with DMRs were differentially expressed between white base and green tip leaf tissue across diel time course, including several important CAM pathway-related genes, such as beta-CA, PEPC, PPCK, and MDH. CONCLUSIONS: Together, these detailed DNA methylome and transcriptome maps provide insight into DNA methylation changes and enhance our understanding of the relationships between DNA methylation and CAM photosynthesis.

Pineapple stem-derived bromelain based priming improves pepper seed protein reserve mobilization, germination, emergence and plant growth.

Pepper seeds are slow to germinate and emergence is often non-uniform and incomplete, reducing gains from this cash crop. This study investigated the effects of pineapple stem- derived protease (stem bromelain) based priming on pepper seed germination in relation to reserve mobilization (specifically, proteins and amino acids), germination, emergence and plant growth. These parameters were compared across two controls, (1) unsoaked seeds and (2) seeds soaked in deionized water, and seeds soaked in pineapple stem bromelain crude extract (treatment). Seeds were soaked in bromelain crude extract possessing a proteolytic activity of 6.25 tU or deionized water (first control) for 3 h at 35 °C. Light microscopy revealed an abundance of protein bodies in the endosperm of the seeds prior to imbibition. When observed for a period of 96 h, these bodies were progressively degraded, with the rate of this degradation being fastest in bromelain-treated seeds. Quantitative analysis of protein levels confirmed this observation: 17.2 mg proteins/g FW at 120 h after priming in bromelain-treated seeds compared with 22.1 mg/g FW in controls (average). The bromelain treatment also increased levels of free amino acids from 3.9 mg/g FW in the controls to 4.6 mg/g FW after 120 h of imbibition. Germination and emergence percentages were initially higher in bromelain-treated seeds: 92.0% germination in bromelain-treated seeds vs. ~ 52.2% in the controls at 18 d; 100% emergence in protease-treated seeds vs. ~ 72.2% in the controls at 18 d. However, these parameters were comparable across the treatment and the controls at 28 d. Importantly, plant fresh and dry weights were significantly higher when seeds were primed with bromelain. The results suggest the use of bromelain extracts for priming pepper seeds based on their proteolytic activity, since germination is dependent on the availability of crude protein and essential amino acids. The benefits of bromelain seed priming appear to translate into improved seedling growth as well.

Systematic identification and comparative analysis of lysine succinylation between the green and white parts of chimeric leaves of Ananas comosus var. bracteatus.

BACKGROUND: Lysine succinylation, an important protein posttranslational modification (PTM), is widespread and conservative. The regulatory functions of succinylation in leaf color has been reported. The chimeric leaves of Ananas comosus var. bracteatus are composed of normal green parts and albino white parts. However, the extent and function of lysine succinylation in chimeric leaves of Ananas comosus var. bracteatus has yet to be investigated. RESULTS: Compared to the green (Gr) parts, the global succinylation level was increased in the white (Wh) parts of chimeric leaves according to the Western blot and immunohistochemistry analysis. Furthermore, we quantitated the change in the succinylation profiles between the Wh and Gr parts of chimeric leaves using label-free LFQ intensity. In total, 855 succinylated sites in 335 proteins were identified, and 593 succinylated sites in 237 proteins were quantified. Compared to the Gr parts, 232 (61.1%) sites in 128 proteins were quantified as upregulated targets, and 148 (38.9%) sites in 70 proteins were quantified as downregulated targets in the Wh parts of chimeric leaves using a 1.5-fold threshold (P < 0.05). These proteins with altered succinylation level were mainly involved in crassulacean acid metabolism (CAM) photosynthesis, photorespiration, glycolysis, the citric acid cycle (CAC) and pyruvate metabolism. CONCLUSIONS: Our results suggested that the changed succinylation level in proteins might function in the main energy metabolism pathways-photosynthesis and respiration. Succinylation might provide a significant effect in the growth of chimeric leaves and the relationship between the Wh and Gr parts of chimeric leaves. This study not only provided a basis for further characterization on the function of succinylated proteins in chimeric leaves of Ananas comosus var. bracteatus but also provided a new insight into molecular breeding for leaf color chimera.

SSR markers developed using next-generation sequencing technology in pineapple, Ananas comosus (L.) Merr.

Simple sequence repeat (SSR) markers provide a reliable tool for the identification of accessions and the construction of genetic linkage maps because of their co-dominant inheritance. In the present study, we developed new SSR markers with next-generation sequencing using the Roche 454 GS FLX+ platform. Five hundred SSR primer sets were tested for the genetic identification of pineapple, including 100 each for the di-, tri-, tetra-, penta-, and hexa-nucleotide motif SSRs. In total, 160 SSR markers successfully amplified fragments and exhibited polymorphism among accessions. The SSR markers revealed the number of alleles per locus (ranging from 2 to 13), the expected heterozygosity (ranging from 0.041 to 0.823), and the observed heterozygosity (ranging from 0 to 0.875). A total of 117 SSR markers with tri- or greater nucleotide motifs were shown to be effective at facilitating accurate genotyping. Using the SSR markers, 25 accessions were distinguished genetically, with the exception of accessions 'MD-2' and 'Yonekura'. The developed SSR markers could facilitate the establishment of efficient and accurate genetic identification systems and the construction of genetic linkage maps in the future.

AcoMYB4, an Ananas comosus L. MYB Transcription Factor, Functions in Osmotic Stress through Negative Regulation of ABA Signaling.

Drought and salt stress are the main environmental cues affecting the survival, development, distribution, and yield of crops worldwide. MYB transcription factors play a crucial role in plants' biological processes, but the function of pineapple MYB genes is still obscure. In this study, one of the pineapple MYB transcription factors, AcoMYB4, was isolated and characterized. The results showed that AcoMYB4 is localized in the cell nucleus, and its expression is induced by low temperature, drought, salt stress, and hormonal stimulation, especially by abscisic acid (ABA). Overexpression of AcoMYB4 in rice and Arabidopsis enhanced plant sensitivity to osmotic stress; it led to an increase in the number stomata on leaf surfaces and lower germination rate under salt and drought stress. Furthermore, in AcoMYB4 OE lines, the membrane oxidation index, free proline, and soluble sugar contents were decreased. In contrast, electrolyte leakage and malondialdehyde (MDA) content increased significantly due to membrane injury, indicating higher sensitivity to drought and salinity stresses. Besides the above, both the expression level and activities of several antioxidant enzymes were decreased, indicating lower antioxidant activity in AcoMYB4 transgenic plants. Moreover, under osmotic stress, overexpression of AcoMYB4 inhibited ABA biosynthesis through a decrease in the transcription of genes responsible for ABA synthesis (ABA1 and ABA2) and ABA signal transduction factor ABI5. These results suggest that AcoMYB4 negatively regulates osmotic stress by attenuating cellular ABA biosynthesis and signal transduction pathways.

Modulatory Activities of Plant Extracts on Jellyfish Cytotoxicity.

INTRODUCTION: The potential efficacy of selected plant extracts to counteract the dermal toxicity of jellyfish envenomation was investigated using an in vitro cell culture model. METHODS: We studied plant extracts from Carica papaya, Ananas comosus, and Bouvardia ternifolia, known for their antivenom properties, in pairwise combinations with tissue homogenates of the jellyfish Pelagia noctiluca, Phyllorhiza punctata, and Cassiopea andromeda, to evaluate modulations of jellyfish cytotoxic effects. L929 mouse fibroblasts were incubated with pairwise jellyfish/plant extract combinations and examined by MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide). RESULTS: C papaya and A comosus significantly lowered the cytotoxicity of P noctiluca and P punctata but induced a slight worsening of C andromeda cytotoxicity. Conversely, B ternifolia was protective against P punctata, ineffective against P noctiluca, and worsened C andromeda cytotoxicity. CONCLUSIONS: Data showed species-specific and contrasting effects of plant extracts, suggesting that those containing protease activities, namely A comosus and C papaya, are more effective in lowering the cytotoxicity of jellyfish venom containing toxic peptidic factors such as phospholipase A. However, all examined plants require further investigation in vivo to evaluate their ability to counteract jellyfish injury to the skin.

Tropical fruit juice: effect of thermal treatment and storage time on sensory and functional properties.

Tropical fruits rich in polyphenols, ascorbic acid, and high antioxidant capacity can enhance the functional composition, flavor as well as the overall acceptance of their juices. The aim of this study was to evaluate the effects of pasteurization and storage time on the physical, chemical, and sensory quality parameters of two formulations of tropical fruit juice blends with high antioxidant capacity. Two formulations with different concentrations of acai, camu-camu, acerola, cashew apple, yellow mombin, and pineapple were pasteurized at 85 °C for 30 s, hot-filled in glass bottles, and stored in refrigerated conditions (5 °C). Analyses for color, total antioxidant activity, total polyphenols, carotenoids, ascorbic acid, and sensory quality were performed before and after pasteurization as well as at 90 and 180 day of storage. Pasteurization did not negatively affect the concentration of functional components and sensory properties. However, the storage time negatively influenced the sensory quality and reduced the ascorbic acid content of both the formulations. Further, the acceptability and the nutritional quality were still high in these products after 180-days of storage, thus, not preventing their consumption.

Temporal and spatial transcriptomic and microRNA dynamics of CAM photosynthesis in pineapple.

The altered carbon assimilation pathway of crassulacean acid metabolism (CAM) photosynthesis results in an up to 80% higher water-use efficiency than C3 photosynthesis in plants making it a potentially useful pathway for engineering crop plants with improved drought tolerance. Here we surveyed detailed temporal (diel time course) and spatial (across a leaf gradient) gene and microRNA (miRNA) expression patterns in the obligate CAM plant pineapple [Ananas comosus (L.) Merr.]. The high-resolution transcriptome atlas allowed us to distinguish between CAM-related and non-CAM gene copies. A differential gene co-expression network across green and white leaf diel datasets identified genes with circadian oscillation, CAM-related functions, and source-sink relations. Gene co-expression clusters containing CAM pathway genes are enriched with clock-associated cis-elements, suggesting circadian regulation of CAM. About 20% of pineapple microRNAs have diel expression patterns, with several that target key CAM-related genes. Expression and physiology data provide a model for CAM-specific carbohydrate flux and long-distance hexose transport. Together these resources provide a list of candidate genes for targeted engineering of CAM into C3 photosynthesis crop species.

Anti-inflammatory evaluation and characterization of leaf extract of Ananas comosus.

Ananas comosus (L.) Merr (Pineapple) is a tropical plant with an edible fruit. In the present study, the potential anti-inflammatory activity of A. comosus leaf extract (ALE) was studied. ALE prepared using soxhlet apparatus was subjected to preliminary qualitative phytochemical analysis and quantitative estimations of flavonoids and tannins. The components present in ALE were identified using liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). Inhibitory effects of ALE on protein denaturation, and proteinase activity were assessed. Its effect on secretion of pro-inflammatory cytokines and inflammatory mediators by lipopolysaccharide-stimulated macrophages was also analyzed. Further, its anti-inflammatory activity in carrageenan-induced inflammatory rat model was examined. The preliminary qualitative phytochemical analysis revealed presence of flavonoids, phenols, tannins, carbohydrates, glycosides, and proteins in the extract. Total flavonoids and total tannins were 0.17 ± 0.006 mg equivalent of quercetin/g of ALE and 4.04 ± 0.56 mg equivalent of gallic acid/g of ALE. LC-MS analysis identified the presence of 4-hydroxy pelargonic acid, 3,4,5-trimethoxycinnamic and 4-methoxycinnamic acid, whereas GC-MS analysis identified the presence of campesterol and ethyl isoallocholate that have been previously reported for anti-inflammatory activity. ALE showed significant inhibition of protein denaturation and proteinase activity and also controlled secretion of tumour necrosis factor-α, interleukin-1ß and prostaglandins, as well as the generation of reactive oxygen species by activated macrophages. ALE also significantly decreased carrageenan-induced acute paw edema. The study, therefore, identified the components present in ALE that may be responsible for its anti-inflammatory activity and thus demonstrated its potential use against acute inflammatory diseases.