Improving Avocado Fruit Quality and Market Potential by Identifying Pre- and Postharvest Factors and Mechanisms Affecting Decay Development by Colletotrichum gloeosporioides

2011 ◽  
Author(s):  
Dov Prusky ◽  
Peter Hofman ◽  
Elizabeth Dann ◽  
Lindy Coates ◽  
Robert Fluhr
Keyword(s):  
Fruit Quality ◽  
Colletotrichum Gloeosporioides ◽  
Market Potential ◽  
Avocado Fruit ◽  
Decay Development

scholarly journals Metabolism of the Flavonoid Epicatechin by Laccase of Colletotrichum gloeosporioides and Its Effect on Pathogenicity on Avocado Fruits

2005 ◽  
Vol 95 (11) ◽  
pp. 1341-1348 ◽  
Author(s):  
R. Guetsky ◽  
I. Kobiler ◽  
X. Wang ◽  
N. Perlman ◽  
N. Gollop ◽  
...  
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Laccase Activity ◽  
Thioglycolic Acid ◽  
Culture Media ◽  
Antifungal Compounds ◽  
Symptom Development ◽  
Fungal Attack ◽  
Avocado Fruit ◽  
Laccase Enzyme ◽  
Unripe Fruits

During avocado fruit ripening, decreasing levels of the flavonoid epicatechin have been reported to modulate the metabolism of preformed antifungal compounds and the activation of quiescent Colletotrichum gloeosporioides infections. Epicatechin levels decreased as well when C. gloeosporioides was grown in the presence of epicatechin in culture. Extracts of laccase enzyme obtained from decayed tissue and culture media fully metabolized the epicatechin substrate within 4 and 20 h, respectively. Purified laccase protein from C. gloeosporioides showed an apparent MW of 60,000, an isoelectric point at pH 3.9, and maximal epicatechin degradation at pH 5.6. Inhibitors of fungal laccase such as EDTA and thioglycolic acid reduced C. gloeosporioides symptom development when applied to ripening susceptible fruits. Isolates of C. gloeosporioides with reduced laccase activity and no capability to metabolize epicatechin showed reduced pathogenicity on ripening fruits. On the contrary, Mexican isolates with increasing capabilities to metabolize epicatechin showed early symptoms of disease in unripe fruits. Transcript levels of cglac1, encoding C. gloeosporioides laccase, were enhanced during fungal development in the presence of epicatechin at pH 6.0, where avocado fruits are susceptible to fungal attack. But transcript increase was not detected at pH 5.0, where the fruit is resistant to fungal attack. The present results suggest that biotransformation of epicatechin by C. gloeosporioides in ripening fruits is followed by the decline of the preformed antifungal diene compound, resulting in the activation of quiescent infections.

Susceptibility of Fuerte avocado fruit at various stages of growth, to infection by anthracnose and stem end rot fungi

1978 ◽  
Vol 18 (90) ◽  
pp. 158 ◽  
Author(s):  
RA Peterson
Keyword(s):  
Field Experiments ◽  
Colletotrichum Gloeosporioides ◽  
Natural Infection ◽  
Persea Americana ◽  
Glomerella Cingulata ◽  
Stages Of Growth ◽  
Small Fruit ◽  
Avocado Fruit ◽  
Time Of Infection

In a series of field experiments, Fuerte avocado fruit (Persea americana) were susceptible to infection by Glomerella cingulata var. minor (Colletotrichum gloeosporioides var, minor) and Dothiorella aromatics, from set until harvest. Natural infection was detected from December to May and field inoculations demonstrated that small fruit in October were also susceptible. The time of infection varied with the season and was related to rainfall incidence. The significance of this finding is discussed.

scholarly journals Differential Activation of Ammonium Transporters During the Accumulation of Ammonia by Colletotrichum gloeosporioides and Its Effect on Appressoria Formation and Pathogenicity

2013 ◽  
Vol 26 (3) ◽  
pp. 345-355 ◽  
Author(s):  
Chen Shnaiderman ◽  
Itay Miyara ◽  
Ilana Kobiler ◽  
Amir Sherman ◽  
Dov Prusky
Keyword(s):  
Gene Disruption ◽  
Colletotrichum Gloeosporioides ◽  
Ammonium Transporter ◽  
Ammonium Transport ◽  
Wild Type ◽  
Ammonia Accumulation ◽  
Ammonium Transporters ◽  
Avocado Fruit ◽  
Appressoria Formation ◽  
Encoding Genes

Ammonium secreted by the post-harvest pathogen Colletotrichum gloeosporioides during host colonization accumulates in the host environment due to enhanced fungal nitrogen metabolism. Two types of ammonium transporter-encoding genes, AMET and MEP, are expressed during pathogenicity. Gene disruption of AMET, a gene modulating ammonia secretion, showed twofold reduced ammonia secretion and 45% less colonization on avocado fruit, suggesting a contribution to pathogenicity. MEPB, a gene modulating ammonium transport, is expressed by C. gloeosporioides during pathogenicity and starvation conditions in culture. Gene disruption of MEPB, the most highly expressed gene of the MEP family, resulted in twofold overexpression of MEPA and MEPC but reduced colonization, suggesting MEPB expression's contribution to pathogenicity. Analysis of internal and external ammonia accumulation by ΔmepB strains in mycelia and germinated spores showed rapid uptake and accumulation, and reduced secretion of ammonia in the mutant versus wild-type (WT) strains. Ammonia uptake by the WT germinating spores but not by the ΔmepB strain with compromised ammonium transport activated cAMP and transcription of PKA subunits PKAR and PKA2. ΔmepB mutants showed 75% less appressorium formation and colonization than the WT, which was partially restored by 10 mM exogenous ammonia. Thus, whereas both AMET and MEPB genes modulate ammonia secretion, only MEPB contributes to ammonia accumulation by mycelia and germinating spores that activate the cAMP pathways, inducing the morphogenetic processes contributing to C. gloeosporioides pathogenicity.

scholarly journals Evaluating the Efficacy of Edible Coatings Incorporated with Moringa Leaf Extract on Postharvest of ‘Maluma’ Avocado Fruit Quality and Its Biofungicidal Effect

HortScience ◽  
2020 ◽  
Vol 55 (4) ◽  
pp. 410-415 ◽  
Author(s):  
Sanele Fana Kubheka ◽  
Samson Zeray Tesfay ◽  
Asanda Mditshwa ◽  
Lembe Samukelo Magwaza
Keyword(s):  
Mass Loss ◽  
Fruit Quality ◽  
Mycelial Growth ◽  
Leaf Extract ◽  
Edible Coatings ◽  
In Vitro Test ◽  
Color Changes ◽  
Avocado Fruit ◽  
Quality Study ◽  
Moringa Leaf Extract

This study investigated the efficacy of edible gum arabic (GA) and carboxymethyl cellulose (CMC) containing moringa (M) leaf extract as postharvest treatments for maintaining organoleptic quality and controlling Colletotrichum gloeosporioides on ‘Maluma’ avocado fruit. For the quality study, after the fruit was dipped into the treatments: GA 10%, GA 15%, GA 10% + M, GA 15% + M, and CMC 1% + M and uncoated fruit served as control, the fruit were then stored at 5.5 °C [95% relative humidity (RH)] for 21 days, and moved to ambient conditions at 21 ± 1 °C (60% RH) for 7 days to simulate retail condition. Quality parameters that were evaluated include mass loss, firmness, and color changes (L*, a*, b*, respectively), and sensory quality attributes, such as taste, color, mouthfeel, odor, and overall acceptability. Fruit quality study results showed fruit coated with GA 15% + M and CMC 1% + M had lower mass loss (3.66%), retained firmness (62.37 N), and color changes [L* (30.85), a* (−2.33) and b* (7.14)] compared with other treatments. In this biofungicidal study on antimicrobial properties of extracts, treatments against fungi strains using an in vitro test were investigated, which showed treatments of moringa leaf extract, GA 10% + M, and GA 15% + M suppressed radial mycelial growth of C. gloeosporioides by 30%, 28%, and 33%, respectively. In conclusion, our study demonstrated that GA 15% + M and CMC 1% + M retained fruit firmness and lowered weight loss and suppressed mycelial growth of C. gloeosporioides on ‘Maluma’ avocado fruit. These edible coatings could therefore be an alternative organic postharvest coating treatment and could potentially be commercialized as a new organic biofungicide for the avocado fruit industry.

scholarly journals Combined Treatments Reduce Chilling Injury and Maintain Fruit Quality in Avocado Fruit during Cold Quarantine

PLoS ONE ◽  
2015 ◽  
Vol 10 (10) ◽  
pp. e0140522 ◽  
Author(s):  
Velu Sivankalyani ◽  
Oleg Feygenberg ◽  
Dalia Maorer ◽  
Merav Zaaroor ◽  
Elazar Fallik ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Chilling Injury ◽  
Combined Treatments ◽  
Avocado Fruit

Avocado diseases affecting fruit quality.

2020 ◽  
Vol 15 (016) ◽  
Author(s):  
Kerry R. Everett
Keyword(s):  
Fruit Quality ◽  
Cold Storage ◽  
Persea Americana ◽  
The Body ◽  
Human Consumption ◽  
Post Harvest ◽  
Avocado Fruit ◽  
High Calcium ◽  
Environmental Requirements ◽  
Very High

Abstract The avocado (Persea americana Mill.) is from an ancient plant lineage, the Lauraceae. Although evidence for human consumption dates back 15,000 years, commercialisation has occurred only over the last 150 years. The most commonly traded variety was first the green-skin 'Fuerte' (green as it ripens), and more recently 'Hass', on which skin darkens when ripe. Production has been increasing worldwide, and currently about 64 countries produce avocados. The range of climates is from arid to very high rainfall and from tropical to temperate. The minimum daily temperatures are above 5°C in all avocado-growing regions because of frost sensitivity. Apart from avocado sunblotch viroid (ASBVd), most avocado fruit diseases are caused by fungi. Some fungi cause visible symptoms resulting in unmarketable fruit, and other infections in the orchard are symptomless. These symptomless infections express as rots after harvest during cold storage, transport and ripening. Most post-harvest pathogens infect through both the body of the fruit and the stem-end wound, while a few infect only through the stem-end wound. The geographic distribution of these fungi varies possibly because of differences in environmental requirements and effective quarantine measures during trade. Fungal rots can be reduced by the application of fungicides in the orchard, removing inoculum residing in dead branches and mummified fruit in the canopy, ensuring high-calcium levels in the fruit flesh are maintained, careful post-harvest handling and selling fruit as soon after harvest as possible. Some post-harvest fungicides can be effective.

scholarly journals Use of a Plastic Rain Shield Reduces Fruit Decay and Need for Fungicides in Sweet Cherry

Plant Disease ◽  
2003 ◽  
Vol 87 (5) ◽  
pp. 523-528 ◽  
Author(s):  
Jorunn Børve ◽  
Arne Stensvand
Keyword(s):  
Fruit Quality ◽  
Sweet Cherry ◽  
Colletotrichum Gloeosporioides ◽  
Prunus Avium ◽  
Monilinia Laxa ◽  
Fruit Cracking ◽  
Fruit Decay ◽  
Mucor Piriformis ◽  
The Mean ◽  
Covering Times

It has been shown previously that covering sweet cherry trees (Prunus avium L.) with rain shields made of polyethylene or other waterproof, light-transmitting material prior to harvest to prevent fruit cracking will reduce fruit decay by various fungi. In the present work, the effects of extending the covering period on fruit decay, fruit quality, and the potential reduction in number of fungicide applications were investigated. In six of eight trials, there were significant reductions in fruit decay in covered fruit compared with fruit that were not covered. The most prevalent fruit-decaying fungi were Monilinia laxa and Botrytis cinerea. Mucor piriformis and Colletotrichum gloeosporioides occurred in high amounts in one trial each. The treatments included covering during rain periods until harvest was over from (i) bloom (bloom-cover), (ii) 6 to 7 weeks prior to harvest (early-fruit-cover), (iii) 3 to 4 weeks prior to harvest (late-fruit-cover), and (iv) not covered. In two trials, the number of fungicide applications was similar between different covering times (bloom-cover not included), and in one trial no fungicides were applied at all (all treatments included). There was a significant effect of covering on fruit decay in all three trials, but there was no difference between covering 6 to 7 and 3 to 4 weeks prior to harvest. In the sprayed fields, the incidence of decay was 48% in fruit that were not covered compared with from 6 to 11% in covered fruit. In the unsprayed field, covering from bloom resulted in 14% fruit decay compared with 23 to 26% in the other two cover treatments. In five trials, all covering regimes were included, and the number of fungicide applications varied with time of covering. The number of fungicide applications for the different treatments were: bloom-cover, 0; early-fruit-cover, 1 to 4; late-fruit-cover, 2 to 5; uncovered, 3 to 6. The mean incidence of fruit decay at harvest for the five trials (range in parentheses) was 3.4 (2.0 to 4.3), 1.8 (0.4 to 4.0), 3.8 (1.8 to 7.7), and 16.5% (2.5 to 39.7), respectively, for the covering times listed. There were no significant differences in decay after storage (3 to 7 days at 4°C followed by 2 to 4 days at 20°C) among the different covering times in the six experiments where fruit were stored. The results indicate that fungicide applications were not needed if fruit were covered during rainy periods from bloom until the end of harvest, and it was possible to omit 1 fungicide application if the covering period was increased from 3 to 4 weeks to 6 to 7 weeks. The fruit quality was not reduced by increasing the covering period from the normal 3 to 4 weeks in any of the experiments.

scholarly journals Relationship between skin color and some fruit quality characteristics of 'Hass' avocado.

1969 ◽  
Vol 95 (1-2) ◽  
pp. 15-23
Author(s):  
Jorge A. Osuna-García ◽  
Gilles Doyon ◽  
Samuel Salazar-García ◽  
Ricardo Goenaga ◽  
Isidro J. L. González-Durán
Keyword(s):  
Fruit Quality ◽  
Skin Color ◽  
Dry Matter ◽  
The United States ◽  
Quality Characteristics ◽  
Matter Content ◽  
Dry Matter Content ◽  
The European Union ◽  
Avocado Fruit ◽  
Hass Avocado

Mexico is the main 'Hass' avocado exporter in the world. More than 300,0001 are exported every year. The United States of America, Japan, the European Union, and Canada are the main importer countries. Recently, 'Hass'avocado shipments to Canada containing fruit with skin blackening have been rejected since this characteristic is associated with low pulp firmness and short shelf life. The objective of this study was to determine the relationship between skin color of 'Hass' avocado fruit with quality characteristics. Fruit varying in black skin color (from 0 to 100%, categories 1 to 5) were collected from two different packinghouses in Michoacán, Mexico. Treatments were arranged in a split-plot design with five replications. Significant differences were detected between packinghouses for weight, length, skin color ('a', ‘b’, chroma and hue) and pulp firmness but not for width, dry matter content or the Avocado Maturity Index (AMI). As color skin category increased towards more blackened fruit, AMI value increased, firmness decreased but dry matter content did not change. These results provide evidence that fruit skin blackening is not associated with lower fruit quality, but it did lower pulp firmness at fruit packing.

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