Expression profile of EXP, Succ-CoA and ALDH genes in soursop (Annona muricata L.) fruits during ripening in response to refrigeration conditions

254-262Soursop (Annona muricata L.) is a climacteric fruit characterized by its rapid softening. Although many studies have improved the understanding of postharvest shelf life in soursop, the expression of genes involved in the loss of flesh firmness, organic acids and acetaldehyde metabolism are less well understood. We evaluated the expression profile of genes related to fruit softening, tricarboxylic acid cycle and acetaldehyde metabolism during ripening of soursop fruit stored at 28 ± 2oC and 15 ± 2oC. The fruit stored at 15 ± 2ºC prolonged the postharvest shelf life up to 9 days and showed higher firmness at 3 days compared to those stored at 28 ± 2ºC. Moreover, the postharvest storage at 15 ± 2ºC induced the expression of expansin (EXP),  succinyl CoA ligase (Succ-CoA) and aldehyde dehydrogenases  (ALDH) genes at 3 days. On the other hand, we recorded an increase in the gene expression of EXP and Succ-CoA at 6 days in fruit stored at 28 ± 2ºC. Based on the different gene expression patterns, we concluded that the postharvest storage at 15 ± 2ºC triggers the expression of EXP, Succ-CoA and ALDH genes at the early stages of soursop ripening. This suggests their role in cell disorganization, organic acids, acetaldehyde metabolism as well as in response to refrigeration during ripening

Efecto del quitosano en la inducción de resistencia contra Colletotrichum sp. en mango (Mangifera indica L.) cv. Tommy Atkins

Mango is susceptible to a postharvest disease called anthracnose, caused by pathogen Colletotrichum sp. Chemical fungicides have been used against postharvest fungal diseases, but they cause damage to the environment. Chitosan shows antimicrobial properties, and induces resistance in plants highlighting the activity of some enzymes like peroxidase. The objective of this research was to evaluate the chitosan effect in the induction of resistance mechanism against Colletotrichum sp., in mango fruits. Chitosan inhibited spore germination, germ tube elongation, and mycelial growth of Colletotrichum sp. in vitro. For postharvest fruits the chitosan at 1.0% and 1.5% Colletotrichum sp. was completely inhibited in fruits inoculated with the fungi. Compared with the control, chitosan at 1.0% induced a significant increase in the enzymatic activity and gene expression of POD during the incubation period, suggesting that an enhanced gene expression of POD plays an important role as one of the main action mechanisms of chitosan.El mango es susceptible a una enfermedad postcosecha denominada antracnosis, causada por el patógeno Colletotrichum sp. Los fungicidas han sido utilizados para controlar las enfermedades ocasionadas por hongos; sin embargo, ocasionan daño al medio ambiente. El quitosano posee propiedades antimicrobianas e induce resistencia en las plantas, en esta resaltan algunas enzimas, como la peroxidasa (POD). El objetivo de esta investigación fue evaluar el efecto del quitosano en la inducción de resistencia contra Colletotrichum sp. en frutos de mango. A nivel in vitro el quitosano inhibió la germinación de esporas, la elongación del tubo germinativo y el crecimiento micelial de Colletotrichum sp. Para los tratamientos aplicados a los frutos en postcosecha, el quitosano a concentraciones de 1.0 y 1.5% inhibió por completo a Colletotrichum sp. Comparado con el control, el quitosano al 1.0% aumentó la actividad enzimática y la expresión del gen que codifica para la peroxidasa, esta respuesta pudiera considerarse como un posible mecanismo de acción del quitosano en frutos de mango

Growth Promoting Activity of Annona muricata L. Leaf Extracts on Lactobacillus casei

Soursop leaves are a source of phytochemical compounds, such as phenolic acids, flavonoids, hydrolyzable tannins, and acetogenins. These compounds can have several types of biological activities. Lactic acid bacteria can uptake phenolic compounds present in plants or fruits. The aim of the present work was to investigate the in vitro effect of hexane, acetone, methanolic, and aqueous extracts of soursop leaves (Annona muricata L.) on the growth, motility, and biofilm formation of Lactobacillus casei, and to determine compounds related to growth. The minimum concentration promoting growth, motility (swimming, swarming, and twitching), and biofilm-forming capacity (crystal violet) were evaluated. The results showed the growth-promoting capacity of acetone and aqueous extracts at low doses 25–50 mg/L, and an inhibition in the four extracts at higher doses of 100 mg/L. The L. casei growth is related to ellagic acid, quercetin rhamnoside, kaempferol dihexoside, quercetin hexoside, secoisolariciresinol, and kaempferol hexoside-rhamnoside. Hexane extract increased the three types of motility, while aqueous maintained swimming and twitching motility similar to control. The four extracts inhibited the biofilm formation capacity

Differential Responses of Antioxidative System during the Interaction of Soursop Fruits (Annona muricata L.) and Nectria haematococca at Postharvest Storage

Soursop fruit (Annona muricata L.) production is diminished by the attack of pathogens such as Nectria haematococca. However, the fruit–pathogen interaction at the biochemical and molecular levels is still unknown. The objective of this study was to analyze the response of the soursop fruit to the presence of N. haematococca during postharvest storage. Soursop fruits were inoculated with the pathogen and total phenolic compounds, antioxidant capacity by Ferric reducing/antioxidant power (FRAP), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS•+), and 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH•), as well as enzymatic activity and transcript levels of polyphenol oxidase (PPO) and superoxide dismutase (SOD), were evaluated at 1, 3, and 5 days of storage. The noninoculated fruits were the controls of the experiment. The highest total phenol content was recorded on day one in the inoculated fruits. FRAP, ABTS, and DPPH activity presented the highest values on day three in the control fruits. Inoculated fruits recorded the highest PPO activity on day five and a five-fold induction in the PPO transcript on day three. SOD activity showed a decrease during the days of storage and 10-fold induction of SOD transcript on day three in the inoculated fruits. Principal component analysis showed that total phenols were the variable that contributed the most to the observed variations. Furthermore, a positive correlation between total phenols and SOD activity, PPO expression, and SOD expression, as well as between DPPH and FRAP, was recorded. The results showed a differential response in antioxidant capacity, enzymatic activity, and gene expression during the interaction of soursop fruits–N. haematococca at postharvest storage

Novel Edible Coating of Starch-Based Stenospermocarpic Mango Prolongs the Shelf Life of Mango “Ataulfo” Fruit

Edible coatings based on 2% starch (w/v) extracted from tropical fruits were applied on stenospermocarpic mango fruits with the objective to prolong its shelf life during storage and give them an added value since they have no commercial value. In this regard, stenospermocarpic mangoes were coated with starch from banana “Pear” (T1 and T2), starch from soursop (T3 and T4), and starch from stenospermocarpic mango (T5 and T6), and two uncoated control treatments (T7 and T8). The fruit of T1, T3, T5, and T7 treatments were stored for 15 days (10 days at 10 ± 2°C and then at 22 ± 2°C for 5 days). The fruit of T2, T4, T6, and T8 treatments were stored for 10 days at 22 ± 2°C. Data were analyzed with a 4×2 factorial experimental design. Weight loss (g), firmness (N), total soluble solids content (%), titratable acidity (%), and color (L∗h∗C∗) were evaluated. The fruit coated with mango starch (T5) showed less weight loss (2.57%), greater firmness (18.6 N), as well as a high content of TSS (28.76%) compared with the control. The T5 extended the shelf life of the fruit up to 15 days (10 days at 10 ± 2°C and 5 days at 22 ± 2°C)

Pathogenic Fungi Associated with Soursop Fruits (Annona muricata L.) during Postharvest in Nayarit, Mexico

Nayarit ranks first in national soursop production (Annona muricata L.). However, the soursop fruits are perishable and susceptible to microorganisms attack, reaching up to 60% of the postharvest losses. Due to the previously mentioned points, the objective of the present study was to isolate, identify, and determine the pathogenicity of fungi related to postharvest diseases in soursop fruits in the main producing areas of Nayarit, Mexico. Several fungi belonging to the genera Fusarium sp., Rhizopus, Lasiodiplodia, Gliocladium, and Colletotrichum were isolated and morphologically identified. Further, bioinformatics sequence analysis of the ITS1-5.8S-ITS2 region of the rDNA identified that most pathogen species were Lasiodiplodia theobromae, Lasiodiplodia pseudotheobromae, and Nectria haematococca, which cause postharvest diseases in soursop fruit, affecting their quality. Lasiodiplodia causes the highest postharvest damage in soursop among the pathogenic species identified

Edible Coating Based on Roselle (Hibiscus sabdariffa L.) Mucilage Applied to Soursop Fruits in Postharvest Storage

The soursop fruit (Annona muricata L.) is a crop of significant economic value for Nayarit, which is characterized by having a bittersweet taste, making it attractive to the consumer. However, the soursop has rapid maturation which causes a short shelf life. Several postharvest management techniques have been applied to reduce its metabolic processes, such as refrigeration, use of 1-methylcyclopropene (1-MCP), and controlled and modified atmospheres. In recent years, polysaccharide-based coatings have been applied to fruits. Therefore, the objective of this investigation was to evaluate the physicochemical and biochemical changes, as well as the antioxidant activity of soursop fruits with a mucilage-based coating (2%), stored at 22°C and 15°C with a 90% RH. Weight loss, firmness, color, soluble solids, acidity, pH, phenols, flavonoids, vitamin C, and antioxidant activity were evaluated. The results obtained in the coated fruits stored at 15°C showed lower weight loss (6.4%), lower firmness (29.7 N), higher TSS concentration (10.4°Bx), and lower acidity (0.38%) compared with the uncoated fruits. The total phenolic content decreased in coated fruits stored at 22°C (54.3 mg EGA/100 g FW). The highest antioxidant activity (DPPH method) was recorded in fruits coated and stored at 15°C with an average value of 257.9 mg EAA/100 g FW. Moreover, a high concentration of vitamin C was observed in fruits coated and stored at 15°C and 22°C (20.5 and 17.5 mg EAA/100 g FW), concluding that the coating based on roselle mucilage (2%) in combination with a temperature of 15°C prevents weight loss, decreases titratable acidity, and increases the content of phenols and vitamin C. Furthermore, an increase in the shelf life up to eight days and in the antioxidant activity at the maturity of consumption was observed in the fruits coated with 2% roselle mucilage stored at 15°C

Identification of Fungal Pathogens of Mango and Soursop Fruits Using Morphological and Molecular Tools and Their Control Using Papaya and Soursop Leaf and Seed Extracts

Fruit and vegetable products are susceptible to the attack of fungi during postharvest handling. Chemical fungicides are the most commonly used technique to control fungal diseases. However, an alternative product is the use of plant extracts, which have been reported in in vitro and in vivo conditions. The objective of this investigation was to identify one of the main pathogens of mango and soursop fruits using morphological and molecular tools as well as to evaluate the in vitro inhibitory effect of papaya and soursop leaf and seed extracts. Two pathogens were isolated and identified by their morphological and molecular characteristics from mango and soursop fruits. We obtained extracts from leaves and seeds of soursop and papaya using five solvents of increasing polarity (hexane, acetone, ethanol, methanol, and water) through the ultrasound-assisted extraction technique at a frequency of 35 kHz and 160 W for 14 min. In vitro evaluations of the extracts were performed using the Kirby–Bauer technique. The extracts with the highest percentage of inhibition were analyzed qualitatively and quantitatively using standardized techniques of colorimetry and spectrophotometry. Furthermore, we determined the content of total phenols, flavonoids, alkaloids, terpenoids, anthraquinones, coumarins, and saponins. As a result, we identified the pathogens as Colletotrichum fructicola and Nectria haematococca. Aqueous extracts (water as a solvent) showed a higher percentage of inhibition of both pathogens compared with the other extracts. Furthermore, the aqueous extract of papaya leaf was the most effective among all extracts. The aqueous papaya leaf extract exhibited a percentage of inhibition of 49.86% for C. fructicola and 47.89% for N. haematococca. The aqueous extracts of papaya leaf and seed (AqEPL and AqEPS) presented the greatest amount of metabolites (except anthraquinones and coumarins). The aqueous soursop leaf extract (AqESL) presented the greatest amount of phenols, tannins, and flavonoids (219.14 ± 8.52 mg GAE/L, 159.84 ± 10 mg GAE/g dm and 0.13 ± 1.12 × 10−4, respectively). The aqueous soursop seed extract (AqESS) had the highest saponin content with 1.2 ± 0.1 mg QSES/g dm and the papaya leaf accusative extract (AqEPL) had the highest alkaloid content (6.413 ± 1 × 10−3 mg AE/g dm) compared with the other extracts. The AqESS had a lower content of secondary metabolites (sterols, alkaloids, and saponins), while AqESL showed no presence of alkaloids and coumarins

Transcriptome Analysis of Soursop (<i>Annona muricata</i> L.) Fruit under Postharvest Storage Identifies Genes Families Involved in Ripening

Soursop (Annona muricata L.) is climacteric fruit with a short ripening period and postharvest shelf life, leading to a rapid softening. In this study, transcriptome analysis of soursop fruits was performed to identify key gene families involved in ripening under postharvest storage conditions (Day 0, Day 3 stored at 28 ± 2 °C, Day 6 at 28 ± 2 °C, Day 3 at 15 ± 2 °C, Day 6 at 15 ± 2 °C, Day 9 at 15 ± 2 °C). The transcriptome analysis showed 224,074 transcripts assembled clustering into 95, 832 unigenes, of which 21, 494 had ORF. RNA-seq analysis showed the highest number of differentially expressed genes on Day 9 at 15 ± 2 °C with 9291 genes (4772 up-regulated and 4519 down-regulated), recording the highest logarithmic fold change in pectin-related genes. Enrichment analysis presented significantly represented GO terms and KEGG pathways associated with molecular function, metabolic process, catalytic activity, biological process terms, as well as biosynthesis of secondary metabolites, plant hormone signal, starch, and sucrose metabolism, plant–pathogen interaction, plant–hormone signal transduction, and MAPK-signaling pathways, among others. Network analysis revealed that pectinesterase genes directly regulate the loss of firmness in fruits stored at 15 ± 2 °C