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The use of volatile organic compounds to control postharvest potato pathogens               Elisabeth M. Wood            ...
Agenda Introduction     Potato Storage Diseases     Volatile Compounds Objectives     Will plant derived volatile org...
Introduction Potatoes are a food source for millions of people Can be processed and utilized in a variety of ways   maki...
Potato Storage Diseases    Controlled by carefully monitoring storage     temperature, humidity, and sanitation    Sprea...
Blemish diseases of        P. atrosepticum is the causal                               agent of potato soft rot and potat...
 C. coccodes is the causal Blemish diseases of           agent of blackdotpotatoes caused by 3         Symptoms on stems...
Blemish diseases of         H. solani is the causal agent of                               silver scurfpotatoes caused by...
 P. erythroseptica is the causal    Storage rots of           agent of pink rot potatoes caused by 3       Stolons infec...
 P. ultimum is the causal agent   Storage rots of                 of pythium leakpotatoes caused by 3             Infect...
 P. infestans is the causal agent                                    of late blight   Storage rots ofpotatoes caused by 3...
 F. sambucinum is a causalOther potato diseases,          agent of dry rot   3 more pathogens:                           ...
 A. solani is the causal agent ofOther potato diseases,           potato early blight  3 more pathogens:                 ...
 S. sclerotiorum is the causalOther potato diseases,                 agent of white mold  3 more pathogens:              ...
Agenda Introduction     Potato Storage Diseases     Volatile Compounds Objectives     Will plant derived volatile org...
Volatile compounds to                     control disease              2E-hexenal is a naturally produced                ...
Volatile compounds to                       control disease                Acetaldehyde is a naturally produced          ...
Agenda Introduction     Potato Storage Diseases     Volatile Compounds Objectives     Will plant derived volatile org...
Objectives Which volatile compound is the most   effective and at what concentration in vitro? Can this volatile compoun...
In vitro methods
Results: Acetaldehyde least effective       Acetaldehyde Did not inhibit the growth of    None of the treatment   any of...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L2.5 µL/L                    Results: P. atrosepticum ...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L2.5µL/L 5 µL/L                    Results: C. coccode...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L2.5 µL/L                    Results: H. solani       ...
Objectives Which volatile compound is the most effective and at Which volatile compound is the most   what concentration...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L                                                     ...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L                                                     ...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L                                                     ...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L                                                     ...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L                                                     ...
() UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L                                                     ...
Objectives Which volatile compound is the most effective and at Can this volatile compound control other   what concentr...
 Blemish pathogen C. coccodes and   H. solani    Microscopy experiments were      completed to understand the      relat...
2.5 µL/L                    C. coccodes germination in vitro                    2.5 µL/L capable of completely inhibiting ...
2.5 µL/L                    C. coccodes hyphal elongation in vitro                    2.5 µL/L 2E-hexenal capable of signi...
2.5 µL/L                    H. Solani germination in vitro                    2.5 µL/L capable of strongly inhibiting coni...
2.5 µL/L                    H. Solani hyphal elongation in vitro                    2.5 µL/L 2E-hexenal capable of somewha...
C. acutatum untreated cell                                                        Results: Mode of Action                 ...
Objectives   What is the mode of action of this volatile Which volatile compound is the most effective and at what    co...
Large Scale Trials                            In vivo methods  (C. Coccodes)                                              ...
Results: C. coccodes large-scale trialThe amount of C. coccodes present on naturally infected potatoes increased over time...
Results: in vivo large-scale trial Results indicate that 2E-         Poor circulation of 2E-   hexenal was not effective...
In vivo methodsSmall Scale Trials                                                     Un-inoculated Tubers                ...
50 µL/L                    Results: C. coccodes small scale                    Under small-scale experimental conditions, ...
Pit Rot Symptoms                                            Bacterial Soft Rot Symptoms50 µL/L                            ...
0                                                                          All replications                               ...
10                 All replications                                                     0                                 ...
50 µL/L                    Results: H. solani                    Under experimental conditions, 2E-hexenal inhibited the g...
Results: in vivo small-scale trial                                   Low oxygen conditions (P. Results indicate that 2E-...
Objectives Whichthis volatile compoundeffective and at what Can volatile compound is the most control these    concentra...
Agenda Introduction     Potato Storage Diseases     Volatile Compounds Objectives     Will plant derived volatile org...
Overall Conclusions:            Acetaldehyde was not              effective            2E-hexenal was effective         ...
 Low treatment volumes                                                    Fumigation                 Applications:      ...
Acknowledgements:Committee:Phillip WhartonNora OlsenJoe KuhlRafael AurasPotato Pathology Crew:Tim MilesLaura MilesKatie Fa...
Questions? Thank you for your time 
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Elisabeth wood defense seminar final

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Elisabeth wood defense seminar final

  1. 1. The use of volatile organic compounds to control postharvest potato pathogens Elisabeth M. Wood Aberdeen Research and Extension Center Department of Plant, Soil and Entomological Sciences University of Idaho Major Professor: Dr. Phillip Wharton
  2. 2. Agenda Introduction  Potato Storage Diseases  Volatile Compounds Objectives  Will plant derived volatile organic compounds work to control postharvest potato pathogens? Results  in vitro studies  Mode of action studies  in vivo studies Conclusions
  3. 3. Introduction Potatoes are a food source for millions of people Can be processed and utilized in a variety of ways making them a highly desirable crop Able to be stored for many months after harvest Time spent in storage can lead to loss from disease
  4. 4. Potato Storage Diseases Controlled by carefully monitoring storage temperature, humidity, and sanitation Spread easily and quickly through storage, especially if potatoes are damaged during harvest In storage, one of the only defense mechanisms available to potatoes is their impermeable skin Only a few fungicides approved for direct use on edible product Expensive control measures and losses from disease can be costly to producers There is a need for better disease control methods
  5. 5. Blemish diseases of  P. atrosepticum is the causal agent of potato soft rot and potatoes caused by 3 pit rot main pathogens:  Infected in wet soils• Pectobacterium (anaerobic conditions), high humidity and warm atrosepticum temperatures in field and• Colletotrichum coccodes storage• Helminthosporium solani  The bacterium contains pectolytic enzymes
  6. 6.  C. coccodes is the causal Blemish diseases of agent of blackdotpotatoes caused by 3  Symptoms on stems and main pathogens: roots, and senesce prematurely (early die off)• Pectobacterium atrosepticum  Infected tubers have sooty lesions (microsclerotia)• Colletotrichum coccodes  Does not spread in storage• Helminthosporium solani
  7. 7. Blemish diseases of  H. solani is the causal agent of silver scurfpotatoes caused by 3  Infected by soil-borne main pathogens: inoculum• Pectobacterium atrosepticum  Storage spread via air-borne conidia• Colletotrichum coccodes  Infected potatoes show• Helminthosporium silvery raised lesions and solani rough skin
  8. 8.  P. erythroseptica is the causal Storage rots of agent of pink rot potatoes caused by 3  Stolons infected in water- main pathogens: saturated soils. In storage, infection spreads in• Phytophthora warm and humid conditions via zoospores. erythroseptica• Pythium ultimum  Softened tuber tissue turns pink when exposed to air• Phytophthora infestans
  9. 9.  P. ultimum is the causal agent Storage rots of of pythium leakpotatoes caused by 3  Infected during harvest main pathogens: through wounds when humidity and temperatures• Phytophthora erythroseptica are high• Pythium ultimum  Infected potatoes have• Phytophthora infestans soft, discolored tuber tissue and watery discharge
  10. 10.  P. infestans is the causal agent of late blight Storage rots ofpotatoes caused by 3  Infected by plant material or soil, high humidity and warm main pathogens: temperatures in field and storage. Infection can spread• Phytophthora erythroseptica quickly in storage• Pythium ultimum  Infected potatoes show rust• Phytophthora colored tissue and darkened infestans lenticels
  11. 11.  F. sambucinum is a causalOther potato diseases, agent of dry rot 3 more pathogens:  Infected by soil-borne• Fusarium inoculum, in storage spreads quickly and is able to infiltrate sambucinum wounded skin• Alternaria solani  Infected potatoes have visible• Sclerotinia sclerotiorum mycelia in tuber wounds  Dry rot infection is often followed by soft rot infection (P. atrosepticum)
  12. 12.  A. solani is the causal agent ofOther potato diseases, potato early blight 3 more pathogens:  Infected when tuber skin is• Fusarium sambucinum wounded during harvest• Alternaria solani  Typically a foliar pathogen,• Sclerotinia sclerotiorum but infected potatoes have sunken, corky, lesions that extend into tuber tissue
  13. 13.  S. sclerotiorum is the causalOther potato diseases, agent of white mold 3 more pathogens:  Potato stems and leaves• Fusarium sambucinum infected in the field at flowering, kills stems and can• Alternaria solani cause early senesce• Sclerotinia  Not typically a tuber sclerotiorum pathogen in the USA, but has been shown to infect tubers under specific conditions resulting in tuber tissue decay Infected potato images courtesy of Queensland Government Department of Agriculture, Fisheries, and Forestry
  14. 14. Agenda Introduction  Potato Storage Diseases  Volatile Compounds Objectives  Will plant derived volatile organic compounds work to control postharvest potato diseases? Results  in vitro studies  Mode of action studies  in vivo studies Conclusions
  15. 15. Volatile compounds to control disease  2E-hexenal is a naturally produced volatile compound (lipoxygenase pathway)  Previous studies show anti-fungal and anti-bacterial properties  Approved by the FDA as a food/flavor2E-hexenal additive  Volatile nature allows for highly effective control methods such as fumigation or headspace treatment
  16. 16. Volatile compounds to control disease  Acetaldehyde is a naturally produced volatile compound (pyruvic acid and pyruvate decarboxylase)  Previous studies show slowing of the ripening process of fruit  Previous studies show anti-fungalAcetaldehyde properties  Volatile nature allows for highly effective control methods such as fumigation or headspace treatment
  17. 17. Agenda Introduction  Potato Storage Diseases  Volatile Compounds Objectives  Will plant derived volatile organic compounds work to control postharvest potato diseases? Results  in vitro studies  Mode of action studies  in vivo studies Conclusions
  18. 18. Objectives Which volatile compound is the most effective and at what concentration in vitro? Can this volatile compound control other potato pathogens in vitro? What is the mode of action of this volatile compound? Can this volatile compound control these pathogens in vivo?
  19. 19. In vitro methods
  20. 20. Results: Acetaldehyde least effective Acetaldehyde Did not inhibit the growth of  None of the treatment any of the blemish volumes of acetaldehyde pathogens were significantly different from the untreated control
  21. 21. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L2.5 µL/L Results: P. atrosepticum 2.5 µL/L of 2E-hexenal was capable of inhibiting growth of P. atrosepticum completely in vitro.Untreated Control
  22. 22. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L2.5µL/L 5 µL/L Results: C. coccodes 2.5 µL/L of 2E-hexenal was capable of slowing C. coccodes growth, but 5 µL/L completely inhibited growth in vitro.Untreated Control
  23. 23. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L2.5 µL/L Results: H. solani 2.5 µL/L of 2E-hexenal was able to inhibit the growth of H. solani completely in vitro.Untreated Control
  24. 24. Objectives Which volatile compound is the most effective and at Which volatile compound is the most what concentration in vitro? effective and at µL/L forconcentration in vitro?  2E-hexenal at 5 what potato blemish pathogens  2E-hexenal at 5 µL/L for potato blemish Can this volatile compound control other pathogens potato pathogens in vitro? What is the mode of action of this volatile compound? Can this volatile compound control these pathogens in vivo?
  25. 25. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L P. erythroseptica in vivo 60 50 40 Diameter in mm Diameter (mm) 30 202.5µL/L 5 µL/L 10 0 -10 0 1 2 3 4 7 8 Days Post Inoculation Results: P. erythroseptica 2.5 µL/L was capable of slowing P. erythroseptica growth, 5 µL/L capable of inhibiting growth completely in vitro.Untreated Control
  26. 26. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L P. ultimum in vitro 60 50 40 Diameter in mm Diameter (mm) 30 202.5 µL/L 10 0 -10 0 1 2 3 4 7 8 Days Post Inoculation Results: P. ultimum 2.5 µL/L was capable of capable of inhibiting P. ultimum growth completely in vitro.Untreated Control
  27. 27. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L P. infestans in vitro 60 50 40 Diameter in mm Diameter (mm) 30 202.5 µL/L 10 0 -10 0 1 2 3 4 7 8 Days Post Inoculation Results: P. infestans 2.5 µL/L was capable of capable of inhibiting P. infestans growth completely in vitro.Untreated Control
  28. 28. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L F. sambucinum in vitro 60 50 40 Diameter in mm Diameter (mm) 30 202.5µL/L7.5 µL/L 5 10 0 -10 0 1 2 3 4 7 8 Days Post Inoculation Results: F. sambucinum 7.5 µL/L was capable of inhibiting F. sambucinum growth completely in vitro, with 2.5 and 5 µL/L able to slow the growth of the pathogen in vitro.Untreated Control
  29. 29. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L A. solani in vitro 60 50 40 Diameter (mm) Diameter in mm 30 202.5 µL/L5 µL/L 10 0 -10 0 1 2 3 4 7 8 Days Post Inoculation Results: A. solani 5 µL/L was capable of capable of inhibiting A. solani growth completely in vitro, although 2.5 µL/L did slow the growth of the pathogen in vitro.Untreated Control
  30. 30. () UTC () IS Check () 2.5 µL/L () 5 µL/L () 7.5 µL/L () 10 µL/L S. sclerotiorum in vitro 60 50 40 Diameter in mm Diameter (mm) 30 202.5 µL/L 10 0 -10 0 1 2 3 4 7 8 Days Post Inoculation Results: S. sclerotiorum 2.5 µL/L was capable of inhibiting S. sclerotiorum growth completely in vitro.Untreated Control
  31. 31. Objectives Which volatile compound is the most effective and at Can this volatile compound control other what concentration in vitro? potato pathogens in vitro?  2E-hexenal at 5 µL/L for potato blemish pathogens  7.5 µL/L 2E-hexenal toxic to all tested Can pathogens in vitro control other potato this volatile compound pathogens in vitro?  7.5 µL/L 2E-hexenal toxic to all tested pathogens in vitro What is the mode of action of this volatile compound? Can this volatile compound control these pathogens in vivo?
  32. 32.  Blemish pathogen C. coccodes and H. solani  Microscopy experiments were completed to understand the relationship between 2E-hexenal and the two fungal blemish pathogens  Germination rate  Hyphal elongation
  33. 33. 2.5 µL/L C. coccodes germination in vitro 2.5 µL/L capable of completely inhibiting C. coccodes conidial germination in vitro.Untreated Control
  34. 34. 2.5 µL/L C. coccodes hyphal elongation in vitro 2.5 µL/L 2E-hexenal capable of significantly decreasing hyphal elongation of C. coccodes in vitro.Untreated Control
  35. 35. 2.5 µL/L H. Solani germination in vitro 2.5 µL/L capable of strongly inhibiting conidial germination in vitro. H. solani has a notably slower rate of germination than C. coccodes.Untreated Control
  36. 36. 2.5 µL/L H. Solani hyphal elongation in vitro 2.5 µL/L 2E-hexenal capable of somewhat decreasing hyphal elongation of H. solani in vitro. However, with low germination rates and very slow rates of growth the results are more modest.Untreated Control
  37. 37. C. acutatum untreated cell Results: Mode of Action C. acutatum : 2E-hexenal  C. coccodes  2E-hexenal inhibits C. coccodes and H. solani conidial germination and  Blackdot significantly reduces hyphal elongation  H. solani  Silver Scurf  Other research has shown that 2E- hexenal scrambles cellular membranes disrupting organellesC. acutatum untreated cell and important cellular functions C. acutatum : 2E-hexenal Arroyo, F. T., Moreno, J., Daza, P., Boianova, L., and Romero, F., 2007. Antifungal activity of strawberry fruit volatile compounds against Colletotrichum acutatum. Journal of Agricultural and Food Chemistry. 55:5701–5707
  38. 38. Objectives What is the mode of action of this volatile Which volatile compound is the most effective and at what concentration in vitro? compound? 5 µL/L for potato blemish pathogens  2E-hexenal at  2E-hexenal inhibited conidial Can this volatile compound control other potato pathogens in germination as well as hyphal elongation vitro?  7.5 the 2E-hexenal toxic to all tested pathogens in vitro in µL/L blemish pathogens C. coccodes and H. solani What is the mode of action of this volatile compound?  2E-hexenal inhibits conidial germination as well as hyphal elongation in the blemish pathogens C. coccodes and H. solani Can this volatile compound control these pathogens in vivo?
  39. 39. Large Scale Trials In vivo methods (C. Coccodes) Small Scale Trials Molecular and Visual Quantification
  40. 40. Results: C. coccodes large-scale trialThe amount of C. coccodes present on naturally infected potatoes increased over time in storageover 5 monthsUnder large-scale experimental conditions, 2E-hexenal did not inhibit the growth of C. coccodes on thein storage.untreated control.
  41. 41. Results: in vivo large-scale trial Results indicate that 2E-  Poor circulation of 2E- hexenal was not effective in hexenal controlling C. coccodes in vivo, why?  Respiring potatoes may interact with 2E-hexenal and Improvements decrease concentration Small-scale trials designed to  Broad sample collection over come these possible times issues  C. coccodes does not spread in storage, symptoms worsen
  42. 42. In vivo methodsSmall Scale Trials Un-inoculated Tubers Potatoes tuber peel (2 2E-hexenal Both the treated with mm) and tuber absorbed the volatile compound for up tissue absorbed 2E-hexenal, absorption to 5 independent of treatment volume was days after treatment and tuber surface areaMolecular and Visual Quantification
  43. 43. 50 µL/L Results: C. coccodes small scale Under small-scale experimental conditions, 2E-hexenal did not inhibit the growth of C. coccodes In vivo.Untreated Control
  44. 44. Pit Rot Symptoms Bacterial Soft Rot Symptoms50 µL/L All replications Results: P. atrosepticum small-scale trial Under small-scale experimental conditions, 2E-hexenal did not inhibit the growth of P. atrosepticum in vivo, and in fact may have increased disease severity due to anaerobic conditions.Untreated Control
  45. 45. 0 All replications 121 UTC 25 uL/L IS check 5 uL/L 50 uL/L 100 a. Phytophthora erythroseptica 90 Percentage of infected tissue 80 70 60 5050 µL/L 40 30 20 10 0 All replications 100 Results: P.ultimum 90 b. Pythium erythroseptica of infected tissue Under small-scale experimental conditions, 2E-hexenal did not inhibit the 80 growth of P. erythroseptica in vivo. 70Untreated Control 60 50
  46. 46. 10 All replications 0 UTC 25 uL/L IS check 5 uL/L 50 uL/L 100 b. Pythium ultimum 90 Percentage of infected tissue 80 70 60 50 4050 µL/L 30 20 10 0 All replications UTC 25 uL/L IS check Results: P. ultimum 50 uL/L 5 uL/L Under experimental conditions, 2E-hexenal did not inhibit the growth of P. ultimum in vivo.Untreated Control
  47. 47. 50 µL/L Results: H. solani Under experimental conditions, 2E-hexenal inhibited the growth of H. solani in vivo at the minimum treatment volume of 5 µL/L.Untreated Control
  48. 48. Results: in vivo small-scale trial  Low oxygen conditions (P. Results indicate that 2E- atrosepticum) due to hexenal controlled H. solani increased treatment in vivo but nothing else, concentrations why?  Anoxic conditions lower Improvements potato defense mechanisms Decrease treatment volumes  Rot pathogens penetrate tuber tissue deeper than Decrease treatment time volatile Increase oxygen presence  C. coccodes microsclerotia and volatile circulation  H. solani rapid sporulation on Treat prior to inoculation tuber surface
  49. 49. Objectives Whichthis volatile compoundeffective and at what Can volatile compound is the most control these concentration in vitro? pathogens in 5 µL/L for potato blemish pathogens  2E-hexenal at vivo?  2E-hexenal inhibited H. solani in vivo at 5 Can this volatile compound control other potato pathogens in µL/L vitro?  7.5 µL/L 2E-hexenal toxic to all tested pathogens in vitro What is the mode of action of this volatile compound?  2E-hexenal inhibits conidial germination as well as hyphal elongation in the blemish pathogens C. coccodes and H. solani Can this volatile compound control these pathogens in vivo?  2E-hexenal inhibited H. solani in vivo at 5 µL/L
  50. 50. Agenda Introduction  Potato Storage Diseases  Volatile Compounds Objectives  Will plant derived volatile organic compounds work to control postharvest potato diseases? Results  in vitro studies  Mode of action studies  in vivo studies Conclusions
  51. 51. Overall Conclusions:  Acetaldehyde was not effective  2E-hexenal was effective  7.5 µL/L of 2E-hexenal inhibited growth of all tested pathogens in vitro  Mode of action: inhibition of conidial germination and prevention of hyphal elongation in fungal blemish pathogens at 2.5 µL/L  This shows promise for in vivo control, but more to work is needed for commercialization
  52. 52.  Low treatment volumes  Fumigation Applications:  Active packaging With further research, 2E- hexenal could be used to  Further research control the growth of  Improved In vivo studies postharvest potato  Inclusion complexes and pathogens, and an alternative polymeric plastic films to postharvest fungicides. (packaging)Almenar, E., Auras, R., Wharton, P., Rubino, M.,& Harte, B. (2007). Release of acetaldehydefrom β-cyclodextrins inhibits postharvest decayfungi in vitro. Journal of Agricultural and FoodChemistry, 55, 7205–7212.
  53. 53. Acknowledgements:Committee:Phillip WhartonNora OlsenJoe KuhlRafael AurasPotato Pathology Crew:Tim MilesLaura MilesKatie FairchildDarrah RicardEquipment Support:Joe KuhlPamela HutchinsonLouise-Marie Dandurand Thank you for your time.
  54. 54. Questions? Thank you for your time 

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