Alternate bearing in 'Hass' avocado: fruit load-induced changes in bud auxin homeostasis are associated with flowering repression.

In 'Hass' avocado (Persea americana), fruit presence reduces next season flowering. Recent fruit tree studies proposed that heavy fruit load (HFL) generates an auxin (indole-3-acetic acid, IAA) signal in the buds that represses flowering. However, the nature of this signal remains unknown. Here, we investigated the effect of avocado HFL on bud IAA accumulation and flowering transition. We found that IAA-aspartate and IAA-glutamate conjugate levels were significantly higher in buds from fully loaded ('on') than low-loaded ('off') trees, hinting that free IAA levels were higher in the former. Expression analysis showed that coinciding with flowering reduction, HFL induced the floral repressor PaTFL1, and suggested that accumulation of IAA in buds as imposed by HFL was associated with its conjugation to aspartate and glutamate and resulted both from de novo IAA synthesis and from reduced IAA export. Accordingly, experiments involving radiolabelled [14C]IAA demonstrated that HFL reduced shoot basipetal IAA transport. Finally, we confirmed the negative effects of IAA on flowering, showing that IAA and polar auxin transport blocker (2,3,5-triiodobenzoic acid) treatments delayed 'off' trees' inflorescence development, reducing their inflorescence axis and inducing PaTFL1 expression. Together, our data indicate that avocado HFL generates IAA signalling in buds that induces PaTFL1, leading to repression of inflorescence development.

Combined Analysis of Transcriptome and Metabolome Provides Insights in Response Mechanism under Heat Stress in Avocado (Persea americana Mill.).

Plants generate a range of physiological and molecular responses to sustain their growth and development when suffering heat stress. Avocado is a type of tropical fruit tree with high economic value. Most avocado cultivars delete, wither, or even die when exposed to heat stress for a long time, which seriously restricts the introduction and cultivation of avocados. In this study, samples of a heat-intolerant variety ('Hass') were treated under heat stress, and the transcriptomics and metabolomics were analyzed, with the expectation of providing information on the variety improvement and domestication of avocados. The differentially expressed genes identified using transcriptome analysis mainly involved metabolic pathways such as plant hormone signal transduction, plant-pathogen interaction, and protein processing in the endoplasmic reticulum. Combined transcriptome and metabolome analysis indicated that the down-regulation of Hass.g03.10206 and Hass.g03.10205 in heat shock-like proteins may result in the reduced Trehalose and Sinapoyl aldehyde content. Metabolomics analysis results indicated that the decrease in Trehalose and Sinapoyl aldehyde content may be an important factor for heat intolerance. These results provide important clues for understanding the physiological mechanisms of adaptation to heat stress in avocados.

Changes in the expression of genes encoding xanthophyl acyltransferases during the postharvest ripening of avocado (Persea americana) fruit.

BACKGROUND: Avocado fruit is rich in xanthophylls, which have been related to positive effects on human health. Xanthophyl acetyltransferases (XATs) are enzymes catalyzing the esterification of carboxylic acids to the hydroxyl group of the xanthophyll molecule. This esterification is thought to increase the lipophilic nature of the xanthophyll and its stability in a lipophilic environment. Studies on XATs in fruits are very scarce, and no studies had been carried out in avocado fruit during postharvest. The objective of this work was to investigate the changes in the expression of genes encoding XAT, during avocado fruit ripening. RESULTS: Avocado fruits were obtained from a local market and stored at 15 °C for 8 days. The fruit respiration rate, ethylene production, and fruit peel's color space parameters (L*, a*, b*) were measured during storage. Fruit mesocarp samples were taken after 1, 3, 5, and 7 days of storage and frozen with liquid nitrogen. Total RNA was extracted from fruit mesocarp, and the quantification of the two genes designated as COGE_ID: 936743791 and COGE_ID: 936800185 encoding XATs was performed with real-time quantitative reverse transcription polymerase chain reaction using actin as a reference gene. The presence of a climacteric peak and large changes in color were recorded during postharvest. The two genes studied showed a large expression after 3 days of fruit storage. CONCLUSIONS: We conclude that during the last stages of ripening in avocado fruit there was an active esterification of xanthophylls with carboxylic acids, which suggests the presence of esterified xanthophylls in the fruit mesocarp. © 2024 Society of Chemical Industry.

Purification and characterization of avocado (Persea americana) polyphenol oxidase by affinity chromatography.

Polyphenol oxidase (PPO) enzyme was purified from avocado (Persea americana) by ammonium sulfate precipitation 0-80%, dialysis and affinity chromatography. Characterization studies were performed with catechol (0.10 M, pH: 7.2, 37 °C), 4-methyl catechol (0.10 M, pH: 6.0, 37 °C), pyrogallol (0.02 M, pH: 8.5, 5 °C), chlorogenic acid (0.20 M, pH: 6.8, 10 °C) and caffeic acid (0.20 M, pH: 8.5, 10 °C), respectively. Vmax and KM values were determined for catechol (15789.96 U*mL-1*min-1, 10 mM), 4-methyl catechol (6768.40 U*mL-1*min-1, 2 mM), pyrogallol (6802.72 U*mL-1*min-1, 4 mM), chlorogenic acid (1377.97 U*mL-1*min-1, 14.29 mM) and caffeic acid (2567.24 U*mL-1*min-1, 5 mM). PPO was purified as 147.73-fold and 154.00-fold by Sepharose 4B-L-Tyrosine-p-aminobenzoic acid and Sepharose-6B-L-Tyrosine-p-aminobenzoic acid, respectively. 4B isolated PPO gave two bands at 35 and 50 kDa in SDS-PAGE while visible and slightly visible bands at 50-70 kDa and 100 kDa in Native-PAGE. 6B isolated PPO gave bands as distinctively at 50 kDa and unclearly at around 35 kDa in SDS-PAGE while visible and slightly visible bands at 50-70 and 100 kDa in Native-PAGE. The synthesis of original 6B-affinity gel and no any study found in literature on affinity purification of avocado PPO show importance of our study.

Understanding the Anti-Obesity Potential of an Avocado Oil-Rich Cheese through an In Vitro Co-Culture Intestine Cell Model.

Nowadays, with consumers' requirements shifting towards more natural solutions and the advent of nutraceutical-based approaches, new alternatives for obesity management are being developed. This work aimed to show, for the first time, the potential of avocado oil-fortified cheese as a viable foodstuff for obesity management through complex in vitro cellular models. The results showed that oleic and palmitic acids' permeability through the Caco-2/HT29-MTX membrane peaked at the 2h mark, with the highest apparent permeability being registered for oleic acid (0.14 cm/s). Additionally, the permeated compounds were capable of modulating the metabolism of adipocytes present in the basal compartment, significantly reducing adipokine (leptin) and cytokine (MPC-1, IL-10, and TNF-α) production. The permeates (containing 3.30 µg/mL of palmitic acid and 2.16 µg/mL of oleic acid) also presented an overall anti-inflammatory activity upon Raw 264.7 macrophages, reducing IL-6 and TNF-α secretion. Despite in vivo assays being required, the data showed the potential of a functional dairy product as a valid food matrix to aid in obesity management.

Avocado Consumption for 12 Weeks and Cardiometabolic Risk Factors: A Randomized Controlled Trial in Adults with Overweight or Obesity and Insulin Resistance.

BACKGROUND: Diets emphasizing unsaturated fat and high fiber are associated with reducing cardiometabolic risk factors. Avocados are rich in MUFA and PUFA fats and fiber. OBJECTIVES: Assess replacement of carbohydrate energy with avocado energy for 12 wk on glucose homeostasis and cardiometabolic risk factors in self-selecting free-living adults who are overweight or with obesity and have insulin resistance. METHODS: In a single-center, randomized, 2-arm, controlled, 12-wk parallel trial, adults [n = 93; male/female: 39/54; mean ± SD age: 42 ± 12 y; BMI: 32.6 ± 3.9 (in kg/m2);  HOMA-IR: 2.7 ± 1.7] were counseled to exchange avocado (AV) or control food (C; low fat, low fiber, energy matched) for carbohydrate food in their usual diet for 12 wk. The primary outcome was the change in Matsuda Insulin Sensitivity Index (MISI) after 12-wk interventions. Secondary outcomes were changes in fasting and post-oral glucose tolerance test glycemic variables, fasting lipids, endothelial activation and inflammation markers. Automated Self-Administered 24-h Dietary Assessment Tool captured weekly dietary intake. Intervention effects were mainly determined by ANCOVA using PC-SAS version 9.4. RESULTS: Dietary total, MUFA, and PUFA fat; fiber; and vegetable intake were higher in the AV group compared with the C group (P < 0.05), and no change in body weight or composition was observed (P > 0.05). Differences between the changes in MISI after AV compared with C were not different (Δ0-12 wk, P = 0.1092). Differences in fasting insulin (Δ0-12 wk, P = 0.0855) and improved glycated hemoglobin (Δ0-12 wk, P = 0.0632) after AV compared with C were suggested. C-reactive protein was significantly lower after AV compared with C at 12 wk (P = 0.0418). Select biomarkers of endothelial activation and lipoproteins by NMR were also influenced by AV compared with C food intake. CONCLUSIONS: Avocado intake was associated with a healthier dietary pattern and trends favoring improved glucose control and reduced biomarkers of cardiometabolic risk when replacing avocado energy for carbohydrate energy in free-living adults who are overweight or with obesity and have insulin resistance. This trial was registered at clinicaltrials.gov as NCT02695433.

Ameliorative effect of avocado oil against lufenuron induced testicular damage and infertility in male rats.

Lufenuron is a benzoylurea pesticide that causes significant histological and histochemical damage in mammals. Avocado is a common food in the human diet that contains antioxidant and antitumor properties. In male rats, avocado oil's protection against lufenuron-induced reproductive deterioration, oxidative stress, and DNA damages was investigated. Twenty-eight mature male rats were selected and distributed into four groups: Group 1, control group were administered distilled water orally; Group 2 received 4 ml/kg avocado; Group 3 was given lufenuron (1.6 mg/kg), and Group 4 was given avocado oil/lufenuron. The findings show that lufenuron treatment reduces reproductive hormone levels, sperm count, motility, viability and causes negative histopathological changes in testicular tissue, such as decreased epithelial height and increased luminal diameter degenerated spermatogenesis. Furthermore, lufenuron reduced the content of antioxidant enzymes while increasing the level of malondialdehyde, nitric oxide and corresponding DNA damage. Results showed that lufenuron is associated with testicular function impairment, which leads to infertility. Treatment with avocado oil improved reproductive hormone secretions, enzymatic activity, histological and DNA damage parameters in testis tissues, reducing the negative effects of lufenuron, proving that it may have a therapeutic role against lufenuron-mediated testicular toxicity.

Avocado Seeds-Mediated Alleviation of Cyclosporine A-Induced Hepatotoxicity Involves the Inhibition of Oxidative Stress and Proapoptotic Endoplasmic Reticulum Stress.

Previous studies reported disrupted hepatic function and structure following the administration of cyclosporine A (CsA) in humans and animals. Recently, we found that avocado seeds (AvS) ameliorated CsA-induced nephrotoxicity in rats. As a continuation, herein we checked whether AvS could also attenuate CsA-induced hepatotoxicity in rats. Subcutaneous injection of CsA (5 mg/kg) for 7 days triggered hepatotoxicity in rats, as indicated by liver dysfunction, redox imbalance, and histopathological changes. Oral administration of 5% AvS powder for 4 weeks ameliorated CsA-induced hepatotoxicity, as evidenced by (1) decreased levels of liver damage parameters (alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin), (2) resumed redox balance in the liver (reduced malondialdehyde (MDA) and increased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)), (3) downregulated hepatic expression of endoplasmic reticulum (ER) stress-related genes (X-box binding protein 1 (XBP1), binding immunoglobulin protein (BIP), C/EBP homologous protein (CHOP)), and apoptosis-related genes (Bax and Casp3), (4) upregulated expression of the anti-apoptotic gene Bcl2, (5) reduced DNA damage, and (6) improved liver histology. These results highlight the ability of AvS to ameliorate CsA-induced hepatotoxicity via the inhibition of oxidative stress and proapoptotic ER stress.

Xylem Embolism Resistance Determines Leaf Mortality during Drought in Persea americana.

The driver of leaf mortality during drought stress is a critical unknown. We used the commercially important tree Persea americana, in which there is a large variation in the degree of drought-induced leaf death across the canopy, to test whether embolism formation in the xylem during drought drives this leaf mortality. A large range in the number of embolized vessels in the petioles of leaves was observed across the canopy of plants that had experienced drought. Despite considerable variation between leaves, the amount of embolized vessels in the xylem of the petiole strongly correlated with area of drought-induced tissue death in individual leaves. Consistent with this finding was a large interleaf variability in xylem resistance to embolism, with a 1.45 MPa variation in the water potential at which 50% of the xylem in the leaf midrib embolized across leaves. Our results implicate xylem embolism as a driver of leaf mortality during drought. Moreover, we propose that heterogeneity in drought-induced leaf mortality across a canopy is caused by high interleaf variability in xylem resistance to embolism, which may act as a buffer against complete canopy death during prolonged drought in P. americana.

Nephroprotective and anti-inflammatory potential of aqueous extract from Persea americana seeds against cadmium-induced nephrotoxicity in Wistar rats.

Cadmium is a toxic metal and poses a high environmental risk to animals and humans, alike. It is thus pertinent to search for medicinal plants in protecting against cadmium toxicity. This study aims at investigating the ability of aqueous extract of Persea americana seeds (AEPA) in ameliorating the toxic effects of cadmium in the kidneys of cadmium-exposed Wistar rats. Male Wistar rats were grouped into five, of six animals each. Different groups of animals received normal saline (control group), 200 mg/kg body weight AEPA, 400 mg/kg AEPA, and standard drug, Livolin Forte, respectively. A last group of animals was left untreated. To induce toxicity, all animals, except the control group, were exposed to cadmium (200 mg/L, as CdCl2) in their main drinking water for 21 days. Biochemical analysis of serum kidney markers, oxidative stress and antioxidant status, as well as anti-inflammatory activities, was done using standard methods and kits. In silico analysis was performed on phytochemicals reported to be abundant in AEPA. Treatment with 400 mg/kg AEPA significantly reversed (P ≤ 0.05) the adverse effect of cadmium on serum creatinine, urea, uric acid and blood urea nitrogen, and restored (P ≤ 0.05) antioxidant status, evidenced by its significant effect on superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, reduced glutathione, and lipid peroxidation activities. AEPA, at 400 mg/kg also exhibited significant anti-inflammatory effects, which was shown by reduced interleukin-2 and tumour necrosis factor α activities. Molecular docking of phytochemicals with the selected protein target also confirmed the therapeutic potential of AEPA. The study concluded that aqueous extract of AEPA protects against cadmium-induced kidney toxicity and inflammation.

Cytotoxicity of a Lipid-Rich Extract from Native Mexican Avocado Seed (Persea americana var. drymifolia) on Canine Osteosarcoma D-17 Cells and Synergistic Activity with Cytostatic Drugs.

Osteosarcoma is the most common malignant bone tumor in both children and dogs. It is an aggressive and metastatic cancer with a poor prognosis for long-term survival. The search for new anti-cancer drugs with fewer side effects has become an essential goal for cancer chemotherapy; in this sense, the bioactive compounds from avocado have proved their efficacy as cytotoxic molecules. The objective of this study was to determine the cytotoxic and antiproliferative effect of a lipid-rich extract (LEAS) from Mexican native avocado seed (Persea americana var. drymifolia) on canine osteosarcoma D-17 cell line. Also, the combined activity with cytostatic drugs was evaluated. LEAS was cytotoxic to D-17 cells in a concentration-dependent manner with an IC50 = 15.5 µg/mL. Besides, LEAS induced caspase-dependent cell apoptosis by the extrinsic and intrinsic pathways. Moreover, LEAS induced a significant loss of mitochondrial membrane potential and increased superoxide anion production and mitochondrial ROS. Also, LEAS induced the arrest of the cell cycle in the G0/G1 phase. Finally, LEAS improved the cytotoxic activity of cisplatin, carboplatin, and in less extension, doxorubicin against the canine osteosarcoma cell line through a synergistic effect. In conclusion, avocado could be a potential source of bioactive molecules in the searching treatments for osteosarcoma.

Novel effect of Arthrocen (avocado/soy unsaponifiables) on pentylenetetrazole-induced seizure threshold in mice: Role of GABAergic pathway.

Arthrocen, an avocado/soy unsaponifiable (ASU)-containing agent, is now used in the clinic and has potentially to decrease joint inflammation and pain associated with mild to severe osteoarthritis. Phytosterols are the major component of Arthrocen with documented anti-inflammatory properties, antioxidant, and analgesic effects. Here, we evaluated ASU anticonvulsant effect by its oral administration in pentylenetetrazole (PTZ)-induced seizure threshold and Maximal Electroshock Seizure (MES) Models. Also, the involvement of N-methyl-d-aspartate (NMDA) receptor, benzodiazepine receptor, and nitric oxide (NO) pathway were studied in anticonvulsant effect of ASU in male NMRI mice. Acute administration of Arthrocen (150, 75, 30, 10 mg/kg) by oral gavage significantly (p < 0.001) increased the clonic seizure threshold induced by intravenous administration of PTZ. Nonspecific inducible NO synthase (NOS) inhibitor L-NAME (10 mg/kg) and a specific NMDA receptor antagonist MK-801 (0.05 mg/kg) did not affect the anticonvulsant effect of Arthrocen, while pretreatment with flumazenil (0.25 mg/kg), a selective benzodiazepine receptor antagonist, reversed this effect (p < 0.01). Also, Arthrocen treated mice did not affect tonic hindlimb extension in the MES model. The data showed that Arthrocen might produce its anticonvulsant effect by enhancing GABAergic neurotransmission and/or action in the brain.

De novo assembly of Persea americana cv. 'Hass' transcriptome during fruit development.

BACKGROUND: Avocado (Persea americana Mill.) is a basal angiosperm from the Lauraceae family. This species has a diploid genome with an approximated size of ~ 920 Mbp and produces a climacteric, fleshy and oily fruit. The flowering and fruit set are particularly prolonged processes, lasting between one to three months, generating important differences in physiological ages of the fruit within the same tree. So far there is no detailed genomic information regarding this species, being the cultivar 'Hass' especially important for avocado growers worldwide. With the aim to explore the fruit avocado transcriptome and to identify candidate biomarkers to monitore fruit development, we carried out an RNA-Seq approach during 4 stages of 'Hass' fruit development: 150 days after fruit set (DAFS), 240 DAFS, 300 DAFS (harvest) and 390 DAFS (late-harvest). RESULTS: The 'Hass' de novo transcriptome contains 62,203 contigs (x̅=988 bp, N50 = 1050 bp). We found approximately an 85 and 99% of complete ultra-conserved genes in eukaryote and plantae database using BUSCO (Benchmarking Universal Single-Copy Orthologs) and CEGMA (Core Eukaryotic Gene Mapping Approach), respectively. Annotation was performed with BLASTx, resulting in a 58% of annotated contigs (90% of differentially expressed genes were annotated). Differentially expressed genes analysis (DEG; with False Discovery Rate ≤ 0.01) found 8672 genes considering all developmental stages. From this analysis, genes were clustered according to their expression pattern and 1209 genes show correlation with the four developmental stages. CONCLUSIONS: Candidate genes are proposed as possible biomarkers for monitoring the development of the 'Hass' avocado fruit associated with lipid metabolism, ethylene signaling pathway, auxin signaling pathway, and components of the cell wall.

Transcriptome Profiling Provides Insight into the Genes in Carotenoid Biosynthesis during the Mesocarp and Seed Developmental Stages of Avocado (Persea americana).

Avocado (Persea americana Mill.) is an economically important crop because of its high nutritional value. However, the absence of a sequenced avocado reference genome has hindered investigations of secondary metabolism. For next-generation high-throughput transcriptome sequencing, we obtained 365,615,152 and 348,623,402 clean reads as well as 109.13 and 104.10 Gb of sequencing data for avocado mesocarp and seed, respectively, during five developmental stages. High-quality reads were assembled into 100,837 unigenes with an average length of 847.40 bp (N50 = 1725 bp). Additionally, 16,903 differentially expressed genes (DEGs) were detected, 17 of which were related to carotenoid biosynthesis. The expression levels of most of these 17 DEGs were higher in the mesocarp than in the seed during five developmental stages. In this study, the avocado mesocarp and seed transcriptome were also sequenced using single-molecule long-read sequencing to acquired 25.79 and 17.67 Gb clean data, respectively. We identified 233,014 and 238,219 consensus isoforms in avocado mesocarp and seed, respectively. Furthermore, 104 and 59 isoforms were found to correspond to the putative 11 carotenoid biosynthetic-related genes in the avocado mesocarp and seed, respectively. The isoform numbers of 10 out of the putative 11 genes involved in the carotenoid biosynthetic pathway were higher in the mesocarp than those in the seed. Besides, alpha- and beta-carotene contents in the avocado mesocarp and seed during five developmental stages were also measured, and they were higher in the mesocarp than in the seed, which validated the results of transcriptome profiling. Gene expression changes and the associated variations in gene dosage could influence carotenoid biosynthesis. These results will help to further elucidate carotenoid biosynthesis in avocado.

Inhibitory Effects of Semiochemicals on the Attraction of an Ambrosia Beetle Euwallacea nr. fornicatus to Quercivorol.

The Euwallacea fornicatus (Eichhoff) species complex includes the polyphagous shot hole borer (PSHB), an ambrosia beetle infesting avocado limbs, Persea americana Mill. Synthetic quercivorol, a monoterpene alcohol, is known to attract females (males are flightless) over a range of release rates spanning three orders of magnitude. The upper release dose was extended 10-fold using sticky traps baited with quercivorol released at 1× (0.126 mg/day), 10×, and 108× relative rates to obtain a dose-response curve fitting a kinetic formation function. Naturally infested limbs of living avocado trees were wrapped with netting to exclude the possibility of catching emerging beetles on the encircling sticky traps. The results indicate PSHB are significantly attracted to infested limbs. Ethanol released over a 64-fold range (lowest rate of 7.5 mg/day) was moderately inhibitory of PSHB attraction to 1× quercivorol. ß-caryophyllene and eucalyptol did not appear to affect attraction at the rates tested. A field test of potential inhibitors of 1× quercivorol was done using ~1 mg/day releases of monoterpene ketones: (-)-(S)-verbenone, (+)-(R)-verbenone, 3-methyl-2-cyclo-hexen-1-one (MCH or seudenone), piperitone, (+)-(S)-carvone, and racemic cryptone. Only piperitone and the two enantiomers of verbenone were strongly inhibitory. A blend of piperitone and verbenone tested together at different distances (0, 0.5, 1, 2, and 4 m) from a 1× quercivorol baited sticky trap became increasingly ineffective in inhibiting the attractant as separation distance increased. Due to the relatively short-range repellency (<1 m), the inhibitors would need to be released from several places on each tree to effectively repel PSHB from avocado trees. Effective attraction radii, EAR, and circular EARc are estimated for the quercivorol baits released at 1×, 10× and 108× rates. Push-pull simulations of moving beetles were performed in 1 ha plots with 2, 4, or 16 traps of 10× EARc and 400 trees (0, 1, or 3 inhibitors per tree) of which ten had an infested limb (EARc = 0.5 m). The simulations indicate that push-pull methods would be more effective in reducing PSHB mating than simply using mass-trapping alone.

The predominant circular form of avocado sunblotch viroid accumulates in planta as a free RNA adopting a rod-shaped secondary structure unprotected by tightly bound host proteins.

Avocado sunblotch viroid (ASBVd), the type member of the family Avsunviroidae, replicates and accumulates in chloroplasts. Whether this minimal non-protein-coding circular RNA of 246-250 nt exists in vivo as a free nucleic acid or closely associated with host proteins remains unknown. To tackle this issue, the secondary structures of the monomeric circular (mc) (+) and (-) strands of ASBVd have been examined in silico by searching those of minimal free energy, and in vitro at single-nucleotide resolution by selective 2'-hydroxyl acylation analysed by primer extension (SHAPE). Both approaches resulted in predominant rod-like secondary structures without tertiary interactions, with the mc (+) RNA being more compact than its (-) counterpart as revealed by non-denaturing polyacryamide gel electrophoresis. Moreover, in vivo SHAPE showed that the mc ASBVd (+) form accumulates in avocado leaves as a free RNA adopting a similar rod-shaped conformation unprotected by tightly bound host proteins. Hence, the mc ASBVd (+) RNA behaves in planta like the previously studied mc (+) RNA of potato spindle tuber viroid, the type member of nuclear viroids (family Pospiviroidae), indicating that two different viroids replicating and accumulating in distinct subcellular compartments, have converged into a common structural solution. Circularity and compact secondary structures confer to these RNAs, and probably to all viroids, the intrinsic stability needed to survive in their natural habitats. However, in vivo SHAPE has not revealed the (possibly transient or loose) interactions of the mc ASBVd (+) RNA with two host proteins observed previously by UV irradiation of infected avocado leaves.

Investigation into the role of endogenous abscisic acid during ripening of imported avocado cv. Hass.

BACKGROUND: The importance of ethylene in avocado ripening has been extensively studied. In contrast, little is known about the possible role of abscisic acid (ABA). The present work studied the effect of 1-methylcyclopropene (1-MCP) (0.3 µL L-1 ), e+® Ethylene Remover and the combination thereof on the quality of imported avocado cv. Hass fruit stored for 7 days at 12 °C. Ethylene production, respiration, firmness, colour, heptose (C7) sugars and ABA concentrations in mesocarp tissue were measured throughout storage. RESULTS: Treatment with e+® Ethylene Remover reduced ethylene production, respiration rate and physiological ripening compared with controls. Fruit treated with 1-MCP + e+® Ethylene Remover and, to a lesser extent 1-MCP alone, had the lowest ethylene production and respiration rate and hence the best quality. Major sugars measured in mesocarp tissue were mannoheptulose and perseitol, and their content was not correlated with ripening parameters. Mesocarp ABA concentration, as determined by mass spectrometry, increased as fruit ripened and was negatively correlated with fruit firmness. CONCLUSIONS: Results suggest a relationship between ABA and ethylene metabolism since blocking ethylene, and to a larger extent blocking and removing ethylene, resulted in lower ABA concentrations. Whether ABA influences avocado fruit ripening needs to be determined in future research. © 2017 Society of Chemical Industry.

A sarabande of tropical fruit proteomics: Avocado, banana, and mango.

The present review highlights the progress made in plant proteomics via the introduction of combinatorial peptide ligand libraries (CPLL) for detecting low-abundance species. Thanks to a novel approach to the CPLL methodology, namely, that of performing the capture both under native and denaturing conditions, identifying plant species in the order of thousands, rather than hundreds, is now possible. We report here data on a trio of tropical fruits, namely, banana, avocado, and mango. The first two are classified as "recalcitrant" tissues since minute amounts of proteins (in the order of 1%) are embedded on a very large matrix of plant-specific material (e.g., polysaccharides and other plant polymers). Yet, even under these adverse conditions we could report, in a single sweep, from 1000 to 3000 unique gene products. In the case of mango the investigation has been extended to the peel too, since this skin is popularly used to flavor dishes in Far East cuisine. Even in this tough peel 330 proteins could be identified, whereas in soft peels, such as in lemons, one thousand unique species could be detected.

Deep sequencing of the Mexican avocado transcriptome, an ancient angiosperm with a high content of fatty acids.

BACKGROUND: Avocado (Persea americana) is an economically important tropical fruit considered to be a good source of fatty acids. Despite its importance, the molecular and cellular characterization of biochemical and developmental processes in avocado is limited due to the lack of transcriptome and genomic information. RESULTS: The transcriptomes of seeds, roots, stems, leaves, aerial buds and flowers were determined using different sequencing platforms. Additionally, the transcriptomes of three different stages of fruit ripening (pre-climacteric, climacteric and post-climacteric) were also analyzed. The analysis of the RNAseqatlas presented here reveals strong differences in gene expression patterns between different organs, especially between root and flower, but also reveals similarities among the gene expression patterns in other organs, such as stem, leaves and aerial buds (vegetative organs) or seed and fruit (storage organs). Important regulators, functional categories, and differentially expressed genes involved in avocado fruit ripening were identified. Additionally, to demonstrate the utility of the avocado gene expression atlas, we investigated the expression patterns of genes implicated in fatty acid metabolism and fruit ripening. CONCLUSIONS: A description of transcriptomic changes occurring during fruit ripening was obtained in Mexican avocado, contributing to a dynamic view of the expression patterns of genes involved in fatty acid biosynthesis and the fruit ripening process.

Oil biosynthesis in a basal angiosperm: transcriptome analysis of Persea Americana mesocarp.

BACKGROUND: The mechanism by which plants synthesize and store high amounts of triacylglycerols (TAG) in tissues other than seeds is not well understood. The comprehension of controls for carbon partitioning and oil accumulation in nonseed tissues is essential to generate oil-rich biomass in perennial bioenergy crops. Persea americana (avocado), a basal angiosperm with unique features that are ancestral to most flowering plants, stores ~ 70 % TAG per dry weight in its mesocarp, a nonseed tissue. Transcriptome analyses of select pathways, from generation of pyruvate and leading up to TAG accumulation, in mesocarp tissues of avocado was conducted and compared with that of oil-rich monocot (oil palm) and dicot (rapeseed and castor) tissues to identify tissue- and species-specific regulation and biosynthesis of TAG in plants. RESULTS: RNA-Seq analyses of select lipid metabolic pathways of avocado mesocarp revealed patterns similar to that of other oil-rich species. However, only some predominant orthologs of the fatty acid biosynthetic pathway genes in this basal angiosperm were similar to those of monocots and dicots. The accumulation of TAG, rich in oleic acid, was associated with higher transcript levels for a putative stearoyl-ACP desaturase and endoplasmic reticulum (ER)-associated acyl-CoA synthetases, during fruit development. Gene expression levels for enzymes involved in terminal steps to TAG biosynthesis in the ER further indicated that both acyl-CoA-dependent and -independent mechanisms might play a role in TAG assembly, depending on the developmental stage of the fruit. Furthermore, in addition to the expression of an ortholog of WRINKLED1 (WRI1), a regulator of fatty acid biosynthesis, high transcript levels for WRI2-like and WRI3-like suggest a role for additional transcription factors in nonseed oil accumulation. Plastid pyruvate necessary for fatty acid synthesis is likely driven by the upregulation of genes involved in glycolysis and transport of its intermediates. Together, a comparative transcriptome analyses for storage oil biosynthesis in diverse plants and tissues suggested that several distinct and conserved features in this basal angiosperm species might contribute towards its rich TAG content. CONCLUSIONS: Our work represents a comprehensive transcriptome resource for a basal angiosperm species and provides insight into their lipid metabolism in mesocarp tissues. Furthermore, comparison of the transcriptome of oil-rich mesocarp of avocado, with oil-rich seed and nonseed tissues of monocot and dicot species, revealed lipid gene orthologs that are highly conserved during evolution. The orthologs that are distinctively expressed in oil-rich mesocarp tissues of this basal angiosperm, such as WRI2, ER-associated acyl-CoA synthetases, and lipid-droplet associated proteins were also identified. This study provides a foundation for future investigations to increase oil-content and has implications for metabolic engineering to enhance storage oil content in nonseed tissues of diverse species.