Influences of harvest date and location on the levels of beta-carotene, ascorbic acid, total phenols, the in vitro antioxidant capacity, and phenolic profiles of five commercial varieties of mango (Mangifera indica L.)

Mango (Mangifera indica L.) is a tropical fruit grown worldwide with excellent nutritional value and widely attributed health-promoting properties. Extensive studies have been made of the high concentrations of phenolic antioxidants in mango peels, seeds, and leaves, yet less is known about the phenolic antioxidants of mango fruit pulp. Five varieties of mangoes from four countries were evaluated with multiple harvests over 1 year to compare the beta-carotene, ascorbic acid, and total phenolic contents and antioxidant capacities of the fruit pulp and to compare the phenolic profiles of the individual varieties. To minimize ripeness variability, only soft fruit (0.5-1 N compression) with a minimum of 10% soluble solids were used for these measurements. Ascorbic acid ranged from 11 to 134 mg/100 g of pulp puree, and beta-carotene varied from 5 to 30 mg/kg among the five varieties. Total phenolic content ranged from 19.5 to 166.7 mg of gallic acid equivalents (GAE)/100 g of puree. The varieties Tommy Atkins, Kent, Keitt, and Haden had similar total phenolic contents, averaging 31.2+/-7.8 mg GAE/100 g of puree, whereas the variety Ataulfo contained substantially higher values. Similar trends were observed in the DPPH radical scavenging activities among the five varieties. In contrast, the country of origin and harvest dates had far less influence on these parameters. Ataulfo mangoes contained significantly higher amounts of mangiferin and ellagic acid than the other four varieties. Large fruit-to-fruit variations in the concentrations of these compounds occurred within sets of mangoes of the same cultivar with the same harvest location and date.

Fruit antioxidant activity, ascorbic acid, total phenol, quercetin, and carotene of Irwin mango fruits stored at low temperature after high electric field pretreatment

Greenhouse-grown tree ripe (TR) and mature green (MG) mangoes (cv. Irwin) were exposed to high electric field treatment before 20 and 30 days of storage at 5 degrees C. MG fruits were allowed to ripen at room temperature after low-temperature storage. Fruit physical quality attributes, ascorbic acid, carotene, quercetin, total phenols, and antioxidant capacity were estimated before and after the storage period. Antioxidant capacity of fruit juice was estimated using the ferric reducing antioxidant power (FRAP) assay. Fruit firmness decreased significantly during storage. Titratable acidity decreased 20 days after storage. Total soluble solids did not change during storage. Antioxidant capacity of fruits remained unchanged up to 20 days of storage period and decreased thereafter. Total phenol and carotenes increased during storage. Antioxidant capacity of fruits was significantly correlated only to ascorbic acids. Peel color and carotenes were higher in TR fruits, whereas titratable acidity and firmness were higher in MG fruits. There was no significant difference in other parameters between the stages of picking. Electric field pretreatment affected the respiration and antioxidant capacity of TR fruits and did not have any significant affect on other parameters. TR mangoes of cv. Irwin are more suitable for low-temperature storage and can be successfully stored for up to 20 days at 5 degrees C without any significant losses in functional properties and quality attributes.

Evaluation of processed green and ripe mango peel and pulp flours (Mangifera indica var. Chokanan) in terms of chemical composition, antioxidant compounds and functional properties

BACKGROUND

Mango is a highly perishable seasonal fruit and large quantities are wasted during the peak season as a result of poor postharvest handling procedures. Processing surplus mango fruits into flour to be used as a functional ingredient appears to be a good preservation method to ensure its extended consumption.

RESULTS

In the present study, the chemical composition, bioactive/antioxidant compounds and functional properties of green and ripe mango (Mangifera indica var. Chokanan) peel and pulp flours were evaluated. Compared to commercial wheat flour, mango flours were significantly low in moisture and protein, but were high in crude fiber, fat and ash content. Mango flour showed a balance between soluble and insoluble dietary fiber proportions, with total dietary fiber content ranging from 3.2 to 5.94 g kg⁻¹. Mango flours exhibited high values for bioactive/antioxidant compounds compared to wheat flour. The water absorption capacity and oil absorption capacity of mango flours ranged from 0.36 to 0.87 g kg⁻¹ and from 0.18 to 0.22 g kg⁻¹, respectively.

CONCLUSION

Results of this study showed mango peel flour to be a rich source of dietary fiber with good antioxidant and functional properties, which could be a useful ingredient for new functional food formulations.

Modeling effects of weather and source-sink relationships on mango fruit growth

We modeled the effects of weather and source-sink factors on mango fruit growth. The peach fruit-growth model "Cashoo" was adapted for mango fruit. The model accounts for the main processes of fruit growth, i.e., leaf photosynthesis, fruit demand, fruit respiration, and storage and mobilization of leaf and stem reserves. Simulations for three successive years and for various leaf-to-fruit ratio treatments showed good agreement with observed fruit growth data. Simulations of fruit growth under different climatic conditions, especially with contrasting temperature and radiation, and for different values of initial fruit dry mass and leaf-to-fruit ratio, showed that variations in fruit growth among years can be partly explained by climatic variations through their effects on leaf photosynthesis, fruit demand and fruit growth rate. However, climatic changes contribute substantially less to observed variability in fruit growth than to initial fruit dry mass and leaf-to-fruit ratio.

Processing 'Ataulfo' Mango into Juice Preserves the Bioavailability and Antioxidant Capacity of Its Phenolic Compounds

The health-promoting effects of phenolic compounds depend on their bioaccessibility from the food matrix and their consequent bioavailability. We carried out a randomized crossover pilot clinical trial to evaluate the matrix effect (raw flesh and juice) of 'Ataulfo' mango on the bioavailability of its phenolic compounds. Twelve healthy male subjects consumed a dose of mango flesh or juice. Blood was collected for six hours after consumption, and urine for 24 h. Plasma and urine phenolics were analyzed by electrochemical detection coupled to high performance liquid chromatography (HPLC-ECD). Five compounds were identified and quantified in plasma. Six phenolic compounds, plus a microbial metabolite (pyrogallol) were quantified in urine, suggesting colonic metabolism. The maximum plasma concentration (Cmax) occurred 2-4 h after consumption; excretion rates were maximum at 8-24 h. Mango flesh contributed to greater protocatechuic acid absorption (49%), mango juice contributed to higher chlorogenic acid absorption (62%). Our data suggests that the bioavailability and antioxidant capacity of mango phenolics is preserved, and may be increased when the flesh is processed into juice.

Antioxidant and enzymatic responses to oxidative stress induced by cold temperature storage and ripening in mango (Mangifera indica L. cv. 'Cogshall') in relation to carotenoid content

The effects of 15 days of storage at 12 °C and 7 °C followed by fruit ripening at 20 °C on oxidative status, antioxidant defense systems and carotenoid accumulation were studied for two successive years in mango fruits (Mangifera indica L.) cv. Cogshall. Changes in the non-enzymatic (ascorbate) and enzymatic (SOD, CAT, APX, MDHAR, DHAR and GR) antioxidant systems, as well as oxidative parameters (H₂O₂ and MDA) and the contents of the major carotenoids were measured for three maturity stages, at harvest and after ripening following cold temperature storage. In control conditions (20 °C), ripening induced an increase in oxidation resulting in ROS production and a decrease in ascorbate content. Fruit tissue protection was activated by means of antioxidant and ascorbate regeneration enzyme systems. Carotenoid accumulated exponentially during ripening. Storage at low temperatures increased respiration crisis intensity and therefore increased oxidation in the fruit pulp. Fruit response to this increase varied according to the maturity stage, i.e., enzymatic responses in younger fruits were very low in comparison to the control, whereas second harvest fruits had a significantly higher degree of enzymatic activity to cope with the oxidative stress. Carotenoid contents decreased with low temperatures and first harvest fruits showed significantly lower values than the control, in opposition to second harvest fruits that appeared not to be affected. We also suggest that, based on a review of the literature, a link can be made between antioxidant system defense and carotenoid metabolism since ROS seems to play a central role as a stress signal in plants.

Response of the physiological parameters of mango fruit (transpiration, water relations and antioxidant system) to its light and temperature environment

Depending on the position of the fruit in the tree, mango fruit may be exposed to high temperature and intense light conditions that may lead to metabolic and physiological disorders and affect yield and quality. The present study aimed to determine how mango fruit adapted its functioning in terms of fruit water relations, epicarp characteristics and the antioxidant defence system in peel, to environmental conditions. The effect of contrasted temperature and light conditions was evaluated under natural solar radiation and temperature by comparing well-exposed and shaded fruit at three stages of fruit development. The sun-exposed and shaded peels of the two sides of the well-exposed fruit were also compared. Depending on fruit position within the canopy and on the side of a well-exposed fruit, the temperature gradient over a day affected fruit characteristics such as transpiration, as revealed by the water potential gradient as a function of the treatments, and led to a significant decrease in water conductance for well-exposed fruits compared to fruits within the canopy. Changes in cuticle thickness according to fruit position were consistent with those of fruit water conductance. Osmotic potential was also affected by climatic environment and harvest stage. Environmental conditions that induced water stress and greater light exposure, like on the sunny side of well-exposed fruit, increased the hydrogen peroxide, malondialdehyde and total and reduced ascorbate contents, as well as SOD, APX and MDHAR activities, regardless of the maturity stage. The lowest values were measured in the peel of the shaded fruit, that of the shaded side of well-exposed fruit being intermediate. Mango fruits exposed to water-stress-induced conditions during growth adapt their functioning by reducing their transpiration. Moreover, oxidative stress was limited as a consequence of the increase in antioxidant content and enzyme activities. This adaptive response of mango fruit to its climatic environment during growth could affect postharvest behaviour and quality.

An analysis of elastic and plastic fruit growth of mango in response to various assimilate supplies

Changes in elastic and plastic components of mango (Mangifera indica L. cv 'Cogshall') fruit growth were analyzed with a model of fruit growth over time and in response to various assimilate supplies. The model is based on water relations (water potential and osmotic and turgor pressures) at the fruit level. Variation in elastic fruit growth was modeled as a function of the elastic modulus and variation in turgor pressure. Variation in plastic fruit growth was modeled using the Lockhart (1965) equation. In this model, plastic growth parameters (yield threshold pressure and cell wall extensibility) varied during fruit growth. Outputs of the model were diurnal and seasonal fruit growth, and fruit turgor pressure. These variables were simulated with good accuracy by the model, particularly the observed increase in fruit size with increasing availability of assimilate supply. Shrinkage was sensitive to the surface conductance of fruit peel, the elasticity modulus and the hydraulic conductivity of fruit, whereas fruit growth rate was highly sensitive to parameters linked to changes in wall extensibility and yield threshold pressure, regardless of the assimilate supply. According to the model, plastic growth was generally zero during the day and shrinkage and swelling were linked to the elastic behavior of the fruit. During the night, plastic and elastic growths were positive, resulting in fruit expansion.

Expression profiling of various genes during the fruit development and ripening of mango

Mango (Mangifera indica L. cv. Alphonso) development and ripening are the programmed processes; conventional indices and volatile markers help to determine agronomically important stages of fruit life (fruit-setting, harvesting maturity and ripening climacteric). However, more and precise markers are required to understand this programming; apparently, fruit's transcriptome can be a good source of such markers. Therefore, we isolated 18 genes related to the physiology and biochemistry of the fruit and profiled their expression in developing and ripening fruits, flowers and leaves of mango using relative quantitation PCR. In most of the tissues, genes related to primary metabolism, abiotic stress, ethylene response and protein turnover showed high expression as compared to that of the genes related to flavor production. Metallothionin and/or ethylene-response transcription factor showed highest level of transcript abundance in all the tissues. Expressions of mono- and sesquiterpene synthases and 14-3-3 lowered during ripening; whereas, that of lipoxygenase, ethylene-response factor and ubiquitin-protein ligase increased during ripening. Based on these expression profiles, flower showed better positive correlation with developing and ripening fruits than leaf. Most of the genes showed their least expression on the second day of harvest, suggesting that harvesting signals significantly affect the fruit metabolism. Important stages in the fruit life were clearly indicated by the significant changes in the expression levels of various genes. These indications complemented those from the previous analyses of fruit development, ripening and volatile emission, revealing the harmony between physiological, biochemical and molecular activities of the fruit.

Mango Fruit Load Estimation Using a Video Based MangoYOLO-Kalman Filter-Hungarian Algorithm Method

: Pre-harvest fruit yield estimation is useful to guide harvesting and marketing resourcing, but machine vision estimates based on a single view from each side of the tree ("dual-view") underestimates the fruit yield as fruit can be hidden from view. A method is proposed involving deep learning, Kalman filter, and Hungarian algorithm for on-tree mango fruit detection, tracking, and counting from 10 frame-per-second videos captured of trees from a platform moving along the inter row at 5 km/h. The deep learning based mango fruit detection algorithm, MangoYOLO, was used to detect fruit in each frame. The Hungarian algorithm was used to correlate fruit between neighbouring frames, with the improvement of enabling multiple-to-one assignment. The Kalman filter was used to predict the position of fruit in following frames, to avoid multiple counts of a single fruit that is obscured or otherwise not detected with a frame series. A "borrow" concept was added to the Kalman filter to predict fruit position when its precise prediction model was absent, by borrowing the horizontal and vertical speed from neighbouring fruit. By comparison with human count for a video with 110 frames and 192 (human count) fruit, the method produced 9.9% double counts and 7.3% missing count errors, resulting in around 2.6% over count. In another test, a video (of 1162 frames, with 42 images centred on the tree trunk) was acquired of both sides of a row of 21 trees, for which the harvest fruit count was 3286 (i.e., average of 156 fruit/tree). The trees had thick canopies, such that the proportion of fruit hidden from view from any given perspective was high. The proposed method recorded 2050 fruit (62% of harvest) with a bias corrected Root Mean Square Error (RMSE) = 18.0 fruit/tree while the dual-view image method (also using MangoYOLO) recorded 1322 fruit (40%) with a bias corrected RMSE = 21.7 fruit/tree. The video tracking system is recommended over the dual-view imaging system for mango orchard fruit count.

Assessing adaptation and mitigation potential of roadside trees under the influence of vehicular emissions: A case study of Grevillea robusta and Mangifera indica planted in an urban city of India

The ever-increasing vehicle counts have resulted in a significant increase in air pollution impacting human and natural ecosystems including trees, and physical properties. Roadside plantations often act as a first defense line against the vehicular emissions to mitigate the impacts of pollutants. However, they are themselves vulnerable to these pollutants with varying levels of tolerance capacity. This demands a scientific investigation to assess the role of roadside plantation for better management and planning for urban sprawl where selected trees could be grown to mitigate the impacts of harmful pollutants. The present study assesses the impacts of vehicular emissions on the adaptation and mitigation potential of two important roadside tree species i.e. Grevillea robusta and Mangifera indica planted along roadsides in the capital city of Uttarakhand. Uttarakhand is one of the Indian Western Himalayan State and its capital city is situated on the foothills of Himalaya. The adaptation and mitigation potential were evaluated by studying the response of pollutants on the functional traits which drive the physiology of the trees. The CO₂ assimilation rate, transpiration rate, stomatal conductance, water use efficiency (WUE), air pollution tolerance index (APTI), copper and proline accumulation, dust removal efficiency (DRE), leaf thickness and cooling created by plantation were studied to evaluate the response of trees exposed to roadside traffics. To compare the influence of pollutants, traits of trees grown in a control site with few or absence of vehicular movement were compared with the roadside trees. The control site represented part of a reserve forest where human interference is controlled and human-induced activities are prohibited. The vehicular frequency was found to modulate tree characteristics. The tree characteristics representing WUE, APTI, proline and copper accumulation, leaf thickness, cooling impact, and DRE were enhanced significantly, while the decreased CO₂ assimilation rate was observed near roadside trees compared to the control site. We found both of the species to perform well to be used as one of the potential species for roadside and urban greening. However, there is a need to assess the potential of other species in reference to the present study.

Global Potential Distribution of Bactrocera carambolae and the Risks for Fruit Production in Brazil

The carambola fruit fly, Bactrocera carambolae, is a tephritid native to Asia that has invaded South America through small-scale trade of fruits from Indonesia. The economic losses associated with biological invasions of other fruit flies around the world and the polyphagous behaviour of B. carambolae have prompted much concern among government agencies and farmers with the potential spread of this pest. Here, ecological niche models were employed to identify suitable environments available to B. carambolae in a global scale and assess the extent of the fruit acreage that may be at risk of attack in Brazil. Overall, 30 MaxEnt models built with different combinations of environmental predictors and settings were evaluated for predicting the potential distribution of the carambola fruit fly. The best model was selected based on threshold-independent and threshold-dependent metrics. Climatically suitable areas were identified in tropical and subtropical regions of Central and South America, Sub-Saharan Africa, west and east coast of India and northern Australia. The suitability map of B. carambola was intersected against maps of fruit acreage in Brazil. The acreage under potential risk of attack varied widely among fruit species, which is expected because the production areas are concentrated in different regions of the country. The production of cashew is the one that is at higher risk, with almost 90% of its acreage within the suitable range of B. carambolae, followed by papaya (78%), tangerine (51%), guava (38%), lemon (30%), orange (29%), mango (24%) and avocado (20%). This study provides an important contribution to the knowledge of the ecology of B. carambolae, and the information generated here can be used by government agencies as a decision-making tool to prevent the carambola fruit fly spread across the world.

Is axis position within tree architecture a determinant of axis morphology, branching, flowering and fruiting? An essay in mango

BACKGROUND AND AIMS

Growth and reproductive strategies of plants are often related to particular, although usually poorly characterized, spatial distributions of shoots within the plant's architecture. In this study it is therefore hypothesized that a close relationship exists between architectural position, axis morphology (length, diameter, leaf area), and functional behaviour (branching, flowering and fruiting). The study focused on the architectural position of mango growth units, defined here as being the relative position, apical or lateral, on the parent growth unit, i.e. growing from the apical or a lateral meristem, respectively.

METHODS

Stem length and leaf characteristics (area, dry weight) were measured on apical and lateral growth units of four mango cultivars over two years. Branching, flowering and fruiting were assessed for both growth unit types using an exhaustive description of tree vegetative and reproductive growth over two years. The relationships between growth unit diameter and flowering and fruiting were assessed for one of the four cultivars.

KEY RESULTS

A pronounced morphological dimorphism was observed for the four cultivars. Across cultivars, stem length was significantly 1.31-1.34 times longer and total leaf area was 2.54-3.47 times larger in apical compared to lateral growth units. Apical growth units tended to branch, flower and fruit more than lateral growth units. The relationship between growth unit diameter and flowering rate was quadratic and dependent on growth unit position. The relationship between growth unit diameter and fruiting rate was linear and independent of growth unit position.

CONCLUSIONS

Morphological traits of mango growth units were clearly involved in the determinism of flowering and fruiting, although in different ways. The results, however, showed that current hypotheses of flowering, such as carbohydrate availability and florigenic promoters, are not sufficient in themselves if they neglect the hierarchical relationships between axes, i.e. their relative position, apical or lateral.

Differential expression of the mango alcohol dehydrogenase gene family during ripening

Alcohol dehydrogenases play an important role during fruit ripening and aroma production. Three full-length cDNAs (MiAdh1, 2 and 3) encoding alcohol dehydrogenases were obtained from mango fruit pulp using RT-PCR approaches. All three members displayed strong homology in the coding region when compared at the protein and nucleotide levels, however showed variations in untranslated regions. Expression patterns of these ADHs were different during fruit development and ripening. MiADH1 and MiADH2 transcripts accumulated at the onset of ripening in mango fruit whereas MiADH3 accumulated during early development of fruit. Expression analysis also indicated that mango ADHs were responsive to ethylene but regulated differently by ABA. MiADH1 was induced by ABA treatment whereas MiADH2 transcript was negatively regulated by ABA. MiADH3 did not respond to ABA in ripening fruit. Differences in substrate specificity for NADH and NADPH were also observed between the three enzymes. Total ADH enzyme activity correlated positively with increased transcript levels at the initiation of ripening.

The 'Tommy Atkins' mango genome reveals candidate genes for fruit quality

BACKGROUND

Mango, Mangifera indica L., an important tropical fruit crop, is grown for its sweet and aromatic fruits. Past improvement of this species has predominantly relied on chance seedlings derived from over 1000 cultivars in the Indian sub-continent with a large variation for fruit size, yield, biotic and abiotic stress resistance, and fruit quality among other traits. Historically, mango has been an orphan crop with very limited molecular information. Only recently have molecular and genomics-based analyses enabled the creation of linkage maps, transcriptomes, and diversity analysis of large collections. Additionally, the combined analysis of genomic and phenotypic information is poised to improve mango breeding efficiency.

RESULTS

This study sequenced, de novo assembled, analyzed, and annotated the genome of the monoembryonic mango cultivar 'Tommy Atkins'. The draft genome sequence was generated using NRGene de-novo Magic on high molecular weight DNA of 'Tommy Atkins', supplemented by 10X Genomics long read sequencing to improve the initial assembly. A hybrid population between 'Tommy Atkins' x 'Kensington Pride' was used to generate phased haplotype chromosomes and a highly resolved phased SNP map. The final 'Tommy Atkins' genome assembly was a consensus sequence that included 20 pseudomolecules representing the 20 chromosomes of mango and included ~ 86% of the ~ 439 Mb haploid mango genome. Skim sequencing identified ~ 3.3 M SNPs using the 'Tommy Atkins' x 'Kensington Pride' mapping population. Repeat masking identified 26,616 genes with a median length of 3348 bp. A whole genome duplication analysis revealed an ancestral 65 MYA polyploidization event shared with Anacardium occidentale. Two regions, one on LG4 and one on LG7 containing 28 candidate genes, were associated with the commercially important fruit size characteristic in the mapping population.

CONCLUSIONS

The availability of the complete 'Tommy Atkins' mango genome will aid global initiatives to study mango genetics.

Biochemical characterization of sap (latex) of a few Indian mango varieties

Mango sap (latex) from four Indian varieties was studied for its composition. Sap was separated into non-aqueous and aqueous phases. Earlier, we reported that the non-aqueous phase contained mainly mono-terpenes having raw mango aroma (Phytochemistry 52 (1999) 891). In the present study biochemical composition of the aqueous phase was studied. Aqueous phase contained little amount of protein (2.0-3.5 mg/ml) but showed high polyphenol oxidase (147-214 U/mg protein) and peroxidase (401-561 U/mg protein) activities. It contained low amounts of polyphenols and protease activities. On native PAGE, all the major protein bands exhibited both polyphenol oxidase and peroxidase activities. Both polyphenol oxidase and peroxidase activities were found to be stable in the aqueous phase of sap at 4 degrees C. Sap contained large amount of non-dialyzable and non-starchy carbohydrate (260-343 mg/ml sap) which may be responsible for maintaining a considerable pressure of fluid in the ducts. Thus, the mango sap could be a valuable by-product in the mango industry as it contains some of the valuable enzymes and aroma components.

Effect of postharvest ethylene treatment on sugar content, glycosidase activity and its gene expression in mango fruit

BACKGROUND

Ripening-associated softening is one of the important attributes that largely determines the shelf-life of mango (Mangifera indica Linn.) fruits. To reveal the effect of pre-climacteric ethylene treatment on ripening-related softening of Alphonso mango, ethylene treatment was given to mature, raw Alphonso fruits. Changes in the pool of reducing and non-reducing sugars, enzymatic activity of three glycosidases: β-d-galactosidase, α-d-mannosidase and β-d-glucosidase and their relative transcript abundance were analysed for control and ethylene treated fruits during ripening.

RESULTS

Early activity of all the three glycosidases and accelerated accumulation of reducing and non-reducing sugars on ethylene treatment was evident. β-d-Galactosidase showed the highest activity among three glycosidases in control fruits and marked increase in activity upon ethylene treatment. This was confirmed by the histochemical assay of its activity in control and ethylene treated ripe fruits. Relative transcript abundance revealed high transcript levels of β-d-galactosidase in control fruits. Ethylene-treated fruits showed early and remarkable increase in the β-d-galactosidase transcripts while α-d-mannosidase transcript variants displayed early accumulation.

CONCLUSION

The findings suggest reduction in the shelf-life of Alphonso mango upon pre-climacteric ethylene treatment, a significant role of β-d-galactosidase and α-d-mannosidase in the ripening related softening of Alphonso fruits and transcriptional regulation of their expression by ethylene. © 2016 Society of Chemical Industry.

Occurrence of alk(en)ylresorcinols in the fruits of two mango (Mangifera indica L.) cultivars during on-tree maturation and postharvest storage

Regarding their relevance for the fungal resistance of mangoes in long supply chains, the alk(en)ylresorcinols (AR) were quantitated in peel and mesocarp throughout storage (27 days, 14 °C, ethylene absorption). The 12 'Chok Anan' and 11 'Nam Dokmai #4' lots picked between 83 and 115 days after full bloom (DAFB) had different harvest maturity indices. The development of dry matter and fruit growth indicated physiological maturity ∼100 DAFB. During storage, all fruits ripened slowly, mostly until over-ripeness and visible decay. The total AR contents always ranged at 73 ± 4.5 and 6.4 ± 0.7 mg hg(-1) of 'Chok Anan' and 'Nam Dokmai #4' peel dry weight, respectively, but only at 6.7 ± 0.7 and 0.9 ± 0.1 mg hg(-1) for the corresponding mesocarp (P ≤ 0.05). These narrow concentration ranges were contradictory to the decreasing fungal resistance. Accordingly, the alk(en)ylresorcinols have not been a deciding factor for the fungal resistance.

Cloning and molecular characterization of an ethylene receptor gene, MiERS1, expressed during mango fruitlet abscission and fruit ripening

We isolated and characterized a mango (Mangifera indica L.) cDNA homolog of the ethylene receptor gene ERS1, designated MiERS1. Genomic Southern blot analysis suggested the existence of a second gene with homology to MiERS1. Spatial and temporal expression patterns of MiERS1 were first studied during fruitlet drop and compared with those of a previously identified MiETR1 gene that encodes an ETR1-type ethylene receptor. Experiments were conducted on developing fruitlet explants in which fruitlet abscission was induced by ethephon treatment. Northern analysis revealed a notable increase in MiERS1 mRNA levels in the fruitlet's activated abscission zone within 24 h of ethephon application, followed by a decreasing pattern 48 h post-treatment. A transient, albeit lesser, increase in MiERS1 mRNA levels was also observed in treated fruitlet seed and mesocarp tissues. In contrast, in the abscission zone, accumulation of MiETR1 transcript remained unchanged; a temporal increase in MiETR1 transcript level was observed in the fruitlet mesocarp, whereas in the seed, MiETR1 expression had already dropped by 24 h. Expression profiles of MiERS1 and MiETR1 were then studied during fruit ripening. In agreement with a previous study and coinciding with the climacteric rise in ethylene production, RNA blot analysis revealed that during fruit ripening, MiETR1 mRNA level increases in both mesocarp and seed tissues. Unexpectedly, however, in those same tissues, MiERS1 transcript accumulation was barely detected. Collectively, our data highlight MiERS1's possible specific function in regulating fruitlet abscission rather than fruit ripening.

Regulation of the levels of health promoting compounds: lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit: a review

There is a demand for feasible methodologies that can increase/maintain the levels of health-promoting phytochemicals in horticultural produce, due to strong evidence that these compounds can reduce risk of chronic diseases. Mango (Mangifera indica L.), ranks fifth among the most cultivated fruit crops in the world, is naturally rich in phytochemicals such as lupeol, mangiferin and phenolic acids (e.g. gallic acid, chlorogenic acid and vanillic acid). Yet, there is still much scope for up-regulating the levels of these compounds in mango fruit through manipulation of different preharvest and postharvest practices that affect their biosynthesis and degradation. The process of ripening, harvest maturity, physical and chemical elicitor treatments such as low temperature stress, methyl jasmonate (MeJA), salicylic acid (SA) and nitric oxide (NO) and the availability of enzyme cofactors (Mg²⁺ , Mn²⁺ and Fe²⁺ ) required in terpenoid biosynthesis were identified as potential determinants of the concentration of health-promoting compounds in mango fruit. The effectiveness of these preharvest and postharvest approaches in regulating the levels of lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit will be discussed. In general spray application of 0.2% iron(II) sulphate (FeSO₄ ) 30 days before harvest, harvest at sprung stage, storage of mature green fruit at 5 °C for 12 days prior to ripening, fumigation of mature green fruit with 10^-5  mol L^-1 and/or 10^-4  mol L^-1 MeJA for 24 h or 20 and/or 40 µL L^-1 NO for 2 h upregulate the levels of lupeol, mangiferin and phenolic acids in pulp and peel of ripe mango fruit. © 2019 Society of Chemical Industry.

Spatial and temporal variations in mango colour, acidity, and sweetness in relation to temperature and ethylene gradients within the fruit

Managing fruit quality is complex because many different attributes have to be taken into account, which are themselves subjected to spatial and temporal variations. Heterogeneous fruit quality has been assumed to be partly related to temperature and maturity gradients within the fruit. To test this assumption, we measured the spatial variability of certain mango fruit quality traits: colour of the peel and of the flesh, and sourness and sweetness, at different stages of fruit maturity using destructive methods as well as vis-NIR reflectance. The spatial variability of mango quality traits was compared to internal variations in thermal time, simulated by a physical model, and to internal variations in maturity, using ethylene content as an indicator. All the fruit quality indicators analysed showed significant spatial and temporal variations, regardless of the measurement method used. The heterogeneity of internal fruit quality traits was not correlated with the marked internal temperature gradient we modelled. However, variations in ethylene content revealed a strong internal maturity gradient which was correlated with the spatial variations in measured mango quality traits. Nonetheless, alone, the internal maturity gradient did not explain the variability of fruit quality traits, suggesting that other factors, such as gas, abscisic acid and water gradients, are also involved.

Infection dynamics of Fusarium mangiferae, causal agent of mango malformation disease

Conditions affecting germination and growth of Fusarium mangiferae, causal agent of mango malformation disease, were studied in vitro. Both conidial germination and colony growth required temperatures >5 degrees C and reached a peak at 28 and 25 degrees C, respectively. A minimum 2-h wetness period was required for conidial germination, reaching a peak after 8 h of wetness. High incidence of fungal colonization in buds, predominantly the apical buds, was detected compared with inoculated leaves. The pathogen was detected in the roots of inoculated soil 19 weeks postinoculation but not in aboveground parts of the plants, and symptoms of the disease were not observed, either. Dry, malformed inflorescence debris serving as a source of inoculum caused significantly higher colonization (52 and 20%) of inoculated buds, compared with that (0%) of the untreated controls. Incidence of sampled leaf disks bearing propagules of F. mangiferae from an infected orchard peaked in June and July and decreased during the following months, whereas airborne infections on 1-month-old branches was the highest in May and June, corresponding with inoculum availability released from infected inflorescences. Colonization pattern, determined in naturally infected vegetative and woody branches, was significantly higher in node sections than in the internode sections. This study sheds light on infection dynamics, colonization patters, and the disease cycle of F. mangiferae in mango.

Genome-Wide Identification and Expression Analysis of the 14-3-3 Gene Family in Mango (Mangifera indica L.)

Members of the Mi14-3-3 gene family interact with target proteins that are widely involved in plant hormone signal transduction and physiology-related metabolism and play important roles in plant growth, development and stress responses. In this study, 14-3-3s family members are identified by the bioinformatic analysis of the mango (Mangifera indica L.) genome. The gene structures, chromosomal distributions, genetic evolution, and expression patterns of these genes and the physical and chemical properties and conserved motifs of their proteins are analysed systematically. The results identified 16 members of the 14-3-3 genes family in the mango genome. The members were not evenly distributed across the chromosomes, and the gene structure analysis showed that the gene sequence length and intron number varied greatly among the different members. Protein sequence analysis showed that the Mi14-3-3 proteins had similar physical and chemical properties and secondary and tertiary structures, and protein subcellular localization showed that the Mi14-3-3 family proteins were localized to the nucleus. The sequence analysis of the Mi14-3-3s showed that all Mi14-3-3 proteins contain a typical conserved PFAM00244 domain, and promoter sequence analysis showed that the Mi14-3-3 promoters contain multiple hormone-, stress-, and light-responsive cis-regulatory elements. Expression analysis showed that the 14-3-3 genes were expressed in all tissues of mango, but that their expression patterns were different. Drought, salt and low temperature stresses affected the expression levels of 14-3-3 genes, and different 14-3-3 genes had different responses to these stresses. This study provides a reference for further studies on the function and regulation of Mi14-3-3 family members.

Low temperature stress ethylene and not Fusarium, might be responsible for mango malformation

Malformation is arguably the most crucial disease of mango (Mangifera indica L.). The etiology of the disease has not yet been successfully resolved. Here, we quantified the endogenous ethylene content in malformed and healthy vegetative and floral tissues of mango cultivars viz., Amrapali, Bombay green, Chausa, Dushehri and Mallika. Levels of ethylene were higher in malformed vegetative and floral tissues as compared with that of healthy tissues at both prior to full bloom and full bloom stages. The study also revealed that isolates of Fusarium dissected from mango exhibited most morphological similarities to the accepted standard features of Fusarium mangiferae. The growth dynamic of F. mangiferae were evaluated with varying temperatures ranging from 5 to 40 °C. Temperatures of 25 °C, 30 °C and 35 °C were better suited for growth of F. mangiferae than temperatures of 20 °C or 40 °C. Conidium germination of F. mangiferae was maximum at 30 °C and minimum at <15 °C. World-wide occurrence of mango malformation showed its most severity at 10-15 °C temperature range. Stress ethylene level is higher in diseased tissue at the same temperature range where growth of Fusaria is found to be completely restricted. The present study provides direct evidence that low temperature induced 'stress ethylene' is potentially responsible for the disease while on the other hand Fusarium role in the disease either through toxic principle or malformation inducing principle is not conclusive at <15 °C and is rather out of question.

Chlorophyll fluorescence, a nondestructive method to assess maturity of mango fruits (Cv. 'Cogshall') without growth conditions bias

The quality of ripe mango fruits depends on maturity stage at harvest, which is usually assessed by visible criteria or from estimates of the age of fruit. The present study deals with the potential of chlorophyll fluorescence as a nondestructive method to assess the degree of fruit maturity regardless of fruit growing conditions. Chlorophyll fluorescence parameters were measured along with respiration rates of fruits still attached to the tree. At the same harvest stage, based on the fruit age or the thermal time sum (degree-days) method, physical and biochemical measurements related to fruit maturity and quality were made. Shaded fruits had a significantly greener flesh color, as well as a lower fruit density and flesh dry matter content, than well-exposed fruits, showing that fruits at the top of the canopy were more mature than fruits within the canopy, which were still in a growth phase. Additionally, chlorophyll fluorescence parameters, F(o), F(m), and F(v), were significantly lower for fruits taken from the top of the canopy than for those from within the canopy. The unique relationship observed between chlorophyll fluorescence parameters and fruit maturity, estimated by internal carbon dioxide content, on fruit still attached to trees is independent of growing conditions, such as the position of the fruit in the canopy and carbohydrate supply. The chlorophyll fluorescence method evaluates maturity much more accurately than the degree-day method and, moreover, nondestructively provides values for individual fruits before harvest.