Alternative preservation method againstSclerotiumtuber rot of Jerusalem artichoke using natural ...

12 Pages·2016·0.47 MB·English

by  Khalid M. Ghoneem

Phytoparasitica(2016)44:341–352
DOI10.1007/s12600-016-0532-3
Sclerotium
Alternative preservation method against tuber
rot of Jerusalem artichoke using natural essential oils
KhalidM.Ghoneem&WesamI.A.Saber&
AmlA.El-Awady&YounesM.Rashad&
AbdulazizA.Al-Askar
Received:17June2016/Accepted:2August2016/Publishedonline:16August2016
#SpringerScience+BusinessMediaDordrecht2016
Abstract The Sclerotium tuber rot fungus (Sclerotium inhibitionofthefungalgrowth.Inthestorageexperiment,
rolfsii Sacc.) represents a serious problem for Jerusalem twopreservationmethodswereappliedusingcarawayoil.
artichoke (JA) tubers during storage periods. The aim of Inthefirstmethod,JAtubersweretreatedwithcarawayoil
this study was to investigate an alternative preservation at2%,keptinperforatedpolyethylenebagsandstoredat
method using a natural essential oil to inhibit the fungal 4 °C and 90 % relative humidity (RH). In the second
growth,increasestorability,andkeepnutritivevalueofJA method,JAtubersweretreatedwithcarawayoilat2%,
tubersunderstorageconditions.Invitroantifungalactivity keptbetweenpeatmosslayersandstoredatroomtemper-
wasassessedusingtwoessentialoils;carawayandspear- ature (25/10 °C, day /night) and 70 % RH. Comparing
mintatconcentrationsof2,3,4and5%.Amongthetested with the infected-untreated control, tubers infected with
treatments, caraway oil at 2 % resulted in complete S.rolfsiiandtreatedwithcarawayoilwhichkeptinpeat
moss exhibited lower severity of Sclerotium tuber rot,
sproutingpercentageandweightloss.Ontheotherhand,
thistreatmentledtothehighestdrymatterandcontentsof
K.M.Ghoneem
SeedPathologyResearchDepartment,PlantPathologyResearch carbohydrates,protein,inulinandtotalphenolsaswellas
Institute,AgriculturalResearchCenter,Giza,Egypt the activity of peroxidase and polyphenol oxidase en-
e-mail:[email protected]
zymes.Basedontheobtainedresultswerecommendthe
useofcarawayoilandpeatmosswhenstoringJAtubersat
W.I.A.Saber
MicrobialActivityUnit,MicrobiologyDepartment,Agricultural roomtemperatureduetoitseco-safetyandsavingofthe
ResearchCenter,Giza,Egypt coolingenergy.
e-mail:[email protected]
A.A.El-Awady Keywords Caraway.Carvone.Limonene.Peatmoss.
VegetableResearchDepartment,HorticultureResearchInstitute, Spearmint
AgriculturalResearchCenter,Giza,Egypt
e-mail:[email protected]
Y.M.Rashad (*) Introduction
PlantProtectionandBiomolecularDiagnosisDepartment,Arid
LandsCultivationResearchInstitute,CityofScientificResearch
andTechnologicalApplications,Alexandria,Egypt From a biorefinery point of view, Jerusalem arti-
e-mail:[email protected] choke or sunchoke (Helianthus tuberosus L.) is a
perennial plant which has a high economic value. In
A.A.Al-Askar
addition to be used traditionally as a human food
BotanyandMicrobiologyDepartment,FacultyofScience,King
SaudUniversity,Riyadh,SaudiArabia and livestock fodder due to its high nutritive value,
e-mail:[email protected] its tubers have been used for the production of
342 Phytoparasitica(2016)44:341–352
biofuels and some functional food ingredients such products,andarepotentiallysuitableforuseinintegrat-
as inulin, oligofructose and fructose. The carbohy- edpestmanagementprograms.
drates in the tubers were found to have a potential for Caraway (Carum carvi L.), also known as me-
production of platform chemicals, e.g., succinic acid. ridian fennel, is a biennial medicinal plant in the
Moreover, some bioactive metabolites from its leaves family Apiaceae. It was used in folk medicine as a
andstemshavebeenusedinsomepharmaceuticalappli- digestive, carminative and lactogenic. Different re-
cations(Johanssonetal.2015;Yangetal.2015). searches have been previously studied its antimi-
Jerusalem artichoke tubers are subjected to at- crobial, anticancer, antioxidant, antidiabetic, anal-
tack by several phytopathogenic fungi, causing gesic, gastrointestinal and many other pharmaco-
rust, southern blight, and tuber rots diseases that logical activities (Seidler-Lozykowska et al. 2013;
can limit its yield production. Under storage con- Al-Snafi 2015).
ditions, approximately 20 pathogens causing stor- Spearmint (Mentha spicata L.), also known as
age rots have been isolated from JA tubers, which bush mint, is a perennial plant that grows in tem-
vary in their disease potentiality and economic perate climates. Its essential oil is used in perfume,
significance (Kays and Nottingham 2008). Tuber cosmetics, air fresheners, drink flavorings, candies
and stem rot, caused by Sclerotium rolfsii Sacc., is and medications. It has been reported to possess
one of the most important diseases of JA infecting antibacterial, antifungal, antiviral, insecticidal and
the tubers during field and/or storage stages. It can antioxidant properties (Hussain et al. 2010)
be a serious disease causing a severe yield loss, The present work was planned to investigate the
especially under higher storage temperatures most important rot causing fungal pathogens af-
(Sennoi et al. 2010). Although fungal spoilage of fecting JA tubers, find out an alternative preserva-
tubers can start in the field, actual proliferation tion method for controlling tuber and stem rot
and substantial spoilage occur in the postharvest disease of JA under storage conditions, with keep-
period when the main plant defenses are reduced ing the nutritive value and quality of the tubers
or eliminated (Jin et al. 2013). Therefore, simple using the combinations of essential oils of caraway
and economic storage technologies of JA to reduce and spearmint at room temperature and cooling
losses are demanded. conditions.
Storage JA tuber rots can be controlled by various
meansincluding;lowtemperature,removalofdiseased
tubers and minimizing mechanical damage or applica-
tionofchemicalfungicides.Anotherappliedmethodin Materialsandmethods
the high cold climatic regions which is the over-
wintering (keeping tubers in the soil). Unfortunately, Isolationoftuberrotassociatedfungi
many fungi can grow at low temperatures and cause
substantial damage, especially when storage extended Rotted JA tubers obtained from the refrigerated storage
forlongperiods(Tesioetal.2011).Acommonsolution, were separately washed, surface-disinfected for 3 min in
is the use of synthetic chemical fungicides, however, 0.5 % sodium hypocholorite and rinsed with sterilizing
their use is accompanied by threatening human health water.Sections(1cm)ofthetuberswereplacedonpotato
and the environment by supporting the emergence of dextrose agar (PDA) plates (Difco, USA), supplemented
resistant pathogens and by contaminationoffoodwith with antibacterial agent(L-chloramphenicol;5 mg/L and
thepesticidedeposits(Zhangetal.2013). streptomycinsulphate;5mg/L)andincubatedat25°Cfor
Recently,thenaturalalternativessuchasplantessen- 5–7days.Hyphaltip and singlespore techniqueswere
tial oils provide a promising control of plant diseases usedtoobtainpureculturesoftheisolatedfungalpath-
becausetheyvirtuallyconstitutearichsourceofbioac- ogens. The recovered isolates were maintained onto
tive chemicals such as phenols, flavonoids, quinones, slants of potato, carrot agar medium and kept at 4 °C
tannins, alkaloids, saponins and sterols (Combrinck for further studies. The isolated fungi were identified
et al. 2011). Moreover, these natural alternatives can according to their cultural, morphological and
also maintain the biochemical constituents of tubers microscopical characteristics as described by Domsch
during storage, they are biodegradable to nontoxic etal.(1980)andWatanable(2002).
Phytoparasitica(2016)44:341–352 343
Pathogenicitytest flaskswereincubatedinadarkat25±2°Cfor7days.
Untreated medium was used as a control. Triplicate
Pathogenicity test was conducted to determine the rot- flasks were used for each treatment. At the end of the
ting potential of the isolated fungi. Disease-free tubers incubation period, the mycelial mats were harvested,
of Fuseau cultivar, obtained from Vegetable Research washed several times with distilled water, and oven
Department,HorticultureResearchInstitute,Agricultur- driedtoconstantweightat80°C.Theantifungalactivity
alResearchCenter,Giza,Egypt,werewashedandsur- wasexpressedasthereductionpercentageinthemyce-
face disinfested as described. Inoculation was carried lialdryweight.
outundersterilizedconditionsbymakingasmallholein
thetuberusingasterile5mmCork-borerandinsertinga Gas-liquidchromatography–massspectrometry
5mmdiscof5-days-oldcultureofthetestedfungusin (GLC-MS)
thehole.Inoculatedtuberswerethenplacedundermoist
conditionsincoveredglasscontainersat25°C.Latter, After extraction, the most efficient antifungal essential
selectedpathogenicisolatesweretestedfortheirrotting oilwasanalyzedtoidentifyandquantifyitsbasiccon-
potentialityat4,15and25°C. stituents.Identificationoftheconstituentsoftheessen-
Theseverity(%)ofthetuberrotwasevaluatedbased tial oil was performed by gas-liquid chromatography
onourproposedscale;where:0=nosymptomsofrot,1 coupled to mass spectrometry (Schimadzu QP-5000
=1–10%oftuberrot,2=11–20%oftuberrot,3=21– GCMS), using an Autosystem XL, equipped with a
30%oftuberrot,4=31–40%oftuberrot,5=41–50% DB-1fusedsilicacolumn(30m×0.25mmfilmthick-
oftuberrot,6=51–60%oftuberrot,7=61–70%of ness0.25m;J&WScientificInc.)connectedtoaPerkin-
tuberrot,8=71–80%oftuberrotand9≥81%oftuber Elmer Turbomass. The oven temperature was pro-
rot.Theseveritywasthencalculatedusingtheformula; grammed from 50 to 200 °C in increments of
3 °C min−1. On reaching 200 °C, the temperature was
S¼ ∑n (cid:2)100 keptisothermalfor10min,thetemperatureofthetrans-
N(cid:2)9 ferline,230°C;thetemperatureoftheionizationcham-
Where;S =severityoftuberrot(%);Σn=sumofthe ber 200 °C, helium carrier gas, adjusted to a linear
velocity of 30 cm s−1; split-flow ratio 1:40, ionization
individual ratings; N = total number of potato tubers
energy70eV,ionizationcurrent,60A;massrange,40–
assessedand9isthehighestscoreontheseverityscale.
300U,scantime1s.Astandardsolutionofn-alkanes
(C9-C21)wasusedtoobtaintheretentionindices.The
Essentialoilsextraction
compounds were identified by comparison of their re-
tentionindiceswiththosereportedinliteratureandalso
Essentialoilswereextractedseparatelyfrom(200g)of
intheWileyRegistryofMassSpectralData,6thEdition
carawayseedsandspearmintdryleaves.Extractionwas
(WileyInterscience,NewYork).(Andradeetal.2015).
done by hydro-distillation of the plant materials for
150minusingClevengerapparatusasdescribedCharles
Evaluationofthecarawayessentialoilandpeatmoss
andSimon(1990).Thepurifiedextractedessentialoils
applicationunderstorageconditions
werethenstoredincleandarkglassbottlesat4°Cuntil
used.
HealthyJAtubers(~20geach)werewashedbywater,
surface disinfected in0.5 % (v/v) sodiumhypochlorite
Invitroassessmentforantifungalactivity for3min,thenrinsedinsterilizedwaterandlefttodry.
For essential oil application, JA tubers were soaked in
Antifungalactivity ofthetwoessentialoilswasevalu- caraway essential oil at 2 % concentration for 20 min,
ated. Suitable volumes of the plant essential oils were thenlefttodryabout2hbeforethestorage.Forinocu-
separately added to100 mlErlenmeyerflaskscontain- lum preparation, 250 ml Erlenmeyer flask containing
ing 20 ml sterilized PD broth and 0.5 % Tween-20 to 50 ml of sterilized PD broth medium and inoculated
obtaintheproposedconcentrationsof2,3,4and5%(v/ withadisc(5mmdiameter)from5-days-oldcultureof
v). Discs (5 mm diameter) from 5-days-old culture of S. rolfsii was incubated in the dark at 25±2 °C for
S.rolfsiiwereusedtoinoculatetheflasks,andthenthe 10 days. The mycelial mat was then harvested and
344 Phytoparasitica(2016)44:341–352
washedgentlywithsteriledistilledwater.Twentygrams are illustrated in Fig. 1. Seventeen fungal species be-
of the fungal mat were taken, mixed thoroughly and longing to 12 genera were isolated and identified with
blended with 1000 ml of distilled water to produce a variedoccurrence percentages.The highest occurrence
homogenized suspension and adjusted at a concentra- wasrecordedforS.rolfsii(61.7%),followedbyFusar-
tion of5×104 cfu mL−1. Artificial infection was done iumincarnatum(22%),whereasGeotrichumcandidum
bysprayingthetuberswiththefungalsuspensionuntil was the lowest recovered fungus, recording 2.7 %. A
run-off. thin, easily penetrated surface layer and high sugar
Theexperimentwasdividedintotwogroupsaccord- content make JA tubers more susceptible to infection
ingtothestoragemethod.Inthefirstgroup,thetubers byawiderangeoffungi.Severalfungiassociatedwith
were kept in 10-kg capacity perforated polyethylene rottedJAtubershavebeenreportedintheliteraturee.g.
bags (0.075 mm thickness), and stored at 4 °C at a S.rolfsii,Sclerotiniasclerotiorum(Snowden2010),Bo-
relativehumidity(RH)of90–95%.Intheothergroup, trytis cinerea, Rhizopus stolonifera, Penicillium and
thetuberswerestoredat25±2°Cincartonboxes(50× Fusarium species (Kays and Nottingham 2008) and
30×20 cm) with moistened peat moss layers (SAB Rhizoctoniasolani(Ezzatetal.2015).
SykerAgrarberatungsundHandelsGmbH&Co.,Ger-
many,pH3.5andRH75%)attherateofpeatmoss:JA Pathogenicitytest
tubers (1.5: 1, Kg/Kg). The treatments applied to each
groupcanbesummarizedasfollows:untreatedcontrol Allisolatedfungalstrainsweresubjectedtothepatho-
(C),infectedwithS.rolfsii(P),treatedwithcarawayoil genicitytestatdifferenttemperatures(4,15and25°C)
(O), and treated with caraway oil and infected with todetermine the most aggressivefungus causing tuber
S. rolfsii (O + P). For each treatment, 30 kg of tubers rot and its best growth temperature (Table 1). Great
wereused. variation inthe pathogenicpotential ranged between 0
Monthly and along 120 days of storage, tuber rot and100%wasrecordedforthetestedfungiaccording
severity, percentage of sprouting, weight losses and to the temperature and the fungal species. Some fungi
dry matter of tubers were evaluated. The stored tubers havethe pathogenicpotential evenunder cooling tem-
werealsoanalyzedforcarbohydrate,inulinandprotein perature.Thepathogenicpotential,ifpresent,increased
contentsaccordingtoandDuboisetal.(1956),Winton withthetemperatureincrement.Amongthetestedfungi,
and Winton (1958) and Robinson (1973),respectively. S. rolfsii was the only pathogen that recorded 100 %
The defense related enzymes (peroxidase and disease severity at25 °C. However, its pathogenic po-
polyphenoloxidase) were assessed according to the tentialremainedrelativelyhighat4and15°C(53.3and
methodsdescribedbyMariaetal.(1981)andMaxwell 73.3 %, respectively). Sclerotinia sclerotiorum came
and Bateman (1967). Totalphenolwas determined ac- nextwithdiseaseseverityof70,93.3and25.7%at4,
cordingtoDiaz,andMartin(1972). 15and25°C,respectively.Ontheotherhand,sixfungal
speciesshowedlowtomoderatepathogenicpotentials,
Statisticalanalysis while, nine fungi recorded no pathogenic potential at
anytemperature.
All experiments were arranged in randomized block The obtained results are in accordance with that of
design. Statistical analysis, including, analysis of vari- Koike(2004)andSennoietal.(2013)whoreportedthat,
anceandDuncantest,aswellasthestandarddeviation S.rolfsiiisconsideredasaseriouspathogenofJAtubers
wereperformedusingCoStat(CoHortSoftware,U.S.A) inbothfieldandstorage.Jerusalemartichoketuberrot
version6.4atlevelofprobability(P)≤0.05. causedbyS.rolfsiiwasreportedtooccurintemperature
range of 2 to 20 °C. The pathogen sclerotia have the
abilitytosurviveatlowtemperature(−10°C),andcan
Resultsanddiscussion germinateunderawiderangeofrelativehumidity(Kays
and Nottingham 2008; Snowden 2010). On the other
Tuberrotassociatedfungi hand, watery soft rot of JA tubers caused by
S.sclerotiorumwasreportedtodevelopatlowtemper-
Occurrencepercentagesofthefungalspeciesassociated ature(Snowden2010).BluemoldrotandFusariumrot,
withrottedJAtuberswhichstoredundercoldconditions caused by several Penicillium and Fusarium species,
Phytoparasitica(2016)44:341–352 345
Fig.1 Occurrenceoffungiassociatedwithrottedtuberstoredundercoldconditions.Columnssuperscriptedwiththesameletterarenot
significantlydifferentatP≤0.05(Duncantest)
respectively, were reported to infect JA tubers only at Invitroassessmentforantifungalactivity
relatively high temperatures (Kays and Nottingham oftheessentialoils
2008). Based on the obtained results, S. rolfsii was
selectedforthenexttests. In vitro antifungal activity of the caraway and spearmint
essentialoilswasevaluatedagainstS.rolfsii(Fig.2).The
obtaineddatarevealedthat,carawayessentialoilcomplete-
Table1 Diseaseseverity(%)causedbytheisolatedfungiunder lyinhibitedthegrowthofthepathogenevenatthelowest
differentstoragetemperatures concentration(2%),while,spearmintessentialoilshowed
aslightreductionofthefungalgrowth.Theseresultsarein
Fungus Temperature(°C)
agreement with those of Abdel-Kader et al. (2011) who
4 15 25 reported the inhibitory effects of caraway oil against the
mycelial growth of F. solani, R. solani, S. rolfsii and
Alternariaalternata 0k* 0k 0k
Macrophominaphaseolinaunderinvitroconditions.The
Aspergillusflavus 0k 0k 0k
antifungalactivityofcarawayessentialoilmaybeattrib-
A.glaucus 0k 0k 0k
uted to some antifungal phytochemicals that constitute a
A.niger 0k 0k 0k large fraction of the oil like carvone, limonene, carveol,
Cladosporiumsp. 0k 0k 0k pinen and thujone (Seidler-Lozykowska et al. 2013;
Cunninghamellasp. 0k 0k 0k Daroughehetal.2014).
Fusariumincarnatum 0k 0k 0k
F.verticillioides 0k 0k 3.3k
Constituentsofcarawayessentialoil
F.oxysporum 0k 6.7jk 16.7ghi
F.solani 3.3K 13.3hij 26.7ef
GLC analysis of caraway oil revealed that, mono-
Geotrichumcandidum 0k 0k 0k
terpenes is the main component of the oil. Ten
Mucorindicus 0k 3.3k 10Ijk
compounds were determined in caraway essential
Penicilliumsp. 20fgh 46.7d 63.3c
oil. The main components were carvone and lim-
Rhizopusstolonifer 16.7ghi 26.7ef 33.3e
onene (57.7 and 35.5 %, respectively). According
Sclerotiniasclerotiorum 70bc 93.3a 25.7efg
to other researchers, the percentage of carvone and
Sclerotiumrolfsii 53.3d 73.3b 100a
limonene in caraway essential oil ranges from 92.2
Trichodermaviride 0k 0k 0k to 99.8 %. The overall quality of caraway fruits is
* Means followed by the same letter(s) are not significantly considered to correlate with its carvone / limonene
differentatP≤0.05(Duncantest) ratio; the higher the ratio, the better the quality
346 Phytoparasitica(2016)44:341–352
Fig.2 InhibitioninmycelialdryweightofS.rolfsiiasafunctionofthetestedoils.Columnssuperscriptedwiththesameletterarenot
significantlydifferentatP≤0.05(Duncantest)
(Seidler-Lozykowska et al. 2010). In addition, the trans -carvol, perilla alcohol, carvacrol and β-
essential oil contains myrcene, α-Terpinolene, caryophyllene. In this study, these constituents
trans-limonene oxide, trans -dihydro carvone, were present in small amounts.
Table2 Meanrotseverity(%)ofJAtuberstreatedwithcarawayessentialoilandinfectedwithS.rolfsiiusingtwostoragemethods
Storagemethod* Treatment** Storageperiod(day)
30 60 90 120
1 C● 28.5b*** 73.3a 100.0a NA
P 100.0a NA NA NA
O 0.0e 0.0e 0.0d 0.0d
O+P 8.9d 24.4d 37.5b 53.6b
2 C 20.1c 33.6c 40.0b 66.5a
P 20.0c 47.2b 100.0a NA
O 0.0e 0.0e 0.0d 0.0d
O+P 0.0e 0.0e 8.9c 13.3c
*1=storageinpolyethylenebagsat4°Cand2=storageinpeatmosslayerat25°C
**C=untreatedcontrol,P=infected,O=treatedwithcarawayessentialoilandO+P=infectedandtreatedwithcarawayessentialoil.NA
=notapplicableduetofulldeterioration
***Meansineachcolumnfollowedbythesameletter(s)arenotsignificantlydifferentatP≤0.05
● Tubersrotintheuntreatedcontrol(C)treatmentwasduetoreasonsotherthanthetargetfungus
Phytoparasitica(2016)44:341–352 347
Evaluationofthecarawayessentialoilandpeatmoss even after 120 days of storage. Storage of the
applicationunderstorageconditions infected-untreated JA tubers (P) in peat moss layer
at 25 °C significantly reduced the disease severity
Diseaseseverity for 60 days of storage compared with the storage
under cooling method, after which, the tubers were
The mean data of rot disease severity of JA tubers fully deteriorated. On the other hand, storage of the
treated with caraway essential oil and infected with untreated-uninfected JA tubers (C) in peat moss
S. rolfsii using the two storage methods are present- layer at 25 °C significantly reduced the disease
ed in Table 2. Although the disease severity in- severity (caused by reasons other than S. rolfsii)
creased with the increase of storage period using compared with the storage under cooling method.
the two storage methods, the storage of the infected These results are in accordance with those obtained
JA tubers treated with caraway essential oil (O + P) by Al-Mughrabi et al. (2013) against potato storage
in peat moss layer at 25 °C significantly reduced the pathogens (F. coeruleum, F. sambucinum,
disease severity compared with the cooling method F. avenaceum, F. oxysporum, Alternaria solani,
Table3 Meansprouting,weightlossanddrymatterweight(%±2SD)ofJAtuberstreatedwithcarawayessentialoilandinfectedwith
S.rolfsiiusingtwostoragemethods.
Criterion Storagemethod* Treatment** Storageperiod(day)
30 60 90 120
Sprouting 1 C 40.0±10.0 70.0±4.0 90.0±4.0 NA
P NA*** NA NA NA
O 0.0 0.0 0.0 0.0
O+P 3.8±0.1 3.9±0.1 4.0±0.4 4.3±0.2
2 C 50.0±10.0 80.0±14.0 95.0±6.0 98.0±2.0
P 3.6±0.4 4.8±0.4 NA NA
O 0.0 0.0 0.0 0.0
O+P 0.0 0.0 0.0 0.0
Weightloss 1 C 20.5±2.9 35.7±5.3 59.9±8.0 NA
P NA NA NA NA
O 0.0 0.0 0.0 0.0
O+P 2.9±0.2 3.0±0.2 3.8±0.6 4.6±0.5
2 C 7.1±0.2 21.7±3.3 50.9±5.8 70.9±8.2
P 30.7±4.0 39.5±9.9 NA NA
O 0.0 0.0 0.0 0.0
O+P 0.0 1.0±0.1 1.0±0.2 1.7±0.4
Drymatterweight 1 C 17.2±0.5 18.0±0.7 19.2±1.5 NA
P NA NA NA NA
O 22.5±0.4 22.9±0.6 23.6±0.3 24.9±0.6
O+P 22.0±0.2 22.3±0.4 23.3±0.9 23.5±0.8
2 C 22.6±0.4 23.0±0.3 21.0±0.5 21.5±1.1
P 18.6±0.6 17.0±0.5 NA NA
O 23.6±0.5 24.6±0.8 24.9’±0.5 25.8±0.5
O+P 23.5±0.4 23.7±0.6 24.2±0.4 25.5±0.3
*1=storageinpolyethylenebagsat4°Cand2=storageinpeatmosslayersat25°C
**C=untreatedcontrol,P=infected,O=treatedwithcarawayessentialoilandO+P=infectedandtreatedwithcarawayessentialoil
***NA=notapplicableduetofulldeterioration
348 Phytoparasitica(2016)44:341–352
R. solani, Phytophthora infestans, P. erythroseptica resistance build up against chemicals because they
and Phoma exigua). The antimicrobial effects of contain two or more stereo-isomers that may be
monoterpenes, carvone and limonene, presented in targeted on multi-sites on the pathogen’s cell mem-
the caraway essential oil may be due to the increase brane (Lambert et al. 2001).
of the permeability of the fungal cell membrane, One of the valuable applications for peat moss is the
inactivation of some structures and energy produc- traditional use in food preservation (Taskila et al. 2016).
tion enzymes and/or the reduction of conidial ger- Theantifungalpropertyofpeatmosseshasbeenreported
mination, ultimately resulting in death of the fungus by many researchers against Candida albicans, Crypto-
(Maetal.2015).Inaddition,theuseofessentialoils coccusalbidus,Aspergillusniger,A.flavus,A.terreus,A.
in managing JA storage diseases may provides sev- nidulans, A. spinulosus, and Trichophyton rubrum
eral positive advantages, including, they are eco- (Zaitseva 2009). The antimicrobial activity in peat moss
friendly, biodegradable, multifunctional, and non- maybeattributedtosomeofitsbioactivecomponentslike
persistentnaturalproducts.Moreover,theseessential sphagnan, a pectin-like polymer, that inhibit microbial
oils may tend to reduce the risk of pathogen growth via electrostatic immobilization of extracellular
Table4 Meancontentsofcarbohydrates,inulin(mg/g±2SD)andprotein(%±2SD)ofJAtuberstreatedwithcarawayessentialoiland
infectedwithS.rolfsiiusingtwostoragemethods
Criterion Storagemethod* Treatment** Storageperiod(day)
30 60 90 120
Carbohydrates 1 C 42.5±1.4 41.7±1.5 38.4±4.3 NA
P NA*** NA NA NA
O 44.6±1.3 44.2±1.3 43.3±1.3 43.0±1.0
O+P 42.7±1.7 42.0±0.7 41.6±1.1 41.3±0.3
2 C 42.0±0.3 40.2±1.4 37.7±1.0 36.0±0.5
P 36.7±1.4 36.0±0.3 NA NA
O 46.0±0.3 46.9±0.5 47.0±0.8 47.7±0.9
O+P 42.0±0.8 41.9±0.7 41.5±1.2 41.0±1.4
Inulin 1 C 14.2±0.6 13.6±0.7 12.8±1.2 NA
P NA NA NA NA
O 15.6±0.8 15.0±0.3 16.7±0.6 15.0±0.2
O+P 14.9±0.6 14.0±0.1 14.0±0.0 13.9±0.4
2 C 14.3±0.5 14.0±0.4 13.8±0.6 13.0±0.2
P 13.0±0.4 12.0±0.3 NA NA
O 18.9±0.5 18.0±0.4 17.9±0.2 17.6±0.6
O+P 17.9±0.5 17.6±0.8 17.0±0.2 17.0±0.0
Protein 1 C 12.2±0.4 12.0±0.2 11.9±0.4 NA
P NA NA NA NA
O 12.8±0.3 12.7±0.3 12.7±0.4 12.6±0.4
O+P 12.6±0.5 12.6±0.2 12.4±0.1 12.0±0.1
2 C 12.5±0.3 12.3±0.4 12.0±0.4 11.9±0.2
P 9.9±0.2 9.0±0.4 NA NA
O 13.0±0.3 13.0±0.6 12.7±0.5 12.7±0.2
O+P 12.6±0.5 12.4±0.5 12.3±0.4 12.0±0.4
*1=storageinpolyethylenebagsat4°Cand2=storageinpeatmosslayersat25°C
**C=untreatedcontrol,P=infected,O=treatedwithcarawayessentialoilandO+P=infectedandtreatedwithcarawayessentialoil
***NA=notapplicableduetofulldeterioration
Phytoparasitica(2016)44:341–352 349
enzymesand/ornitrogendeprivation,phenolicsthatinhibit highest dry mater weight percentage along the storage
theactivityofextracellularenzymesofmicrobesorother period compared with the untreated-uninfected control
constituents like sterols and polyacetylenes (Borsheim usingthetwomethods.Evenafter4monthsofstorage,
etal.2012). the treatment of the infected JA tubers with caraway
essentialoilledtoalowersproutingandweightlossand
Sprouting,weightlossanddrymatterofJAtubers higher dry matter weight for JA tubers stored in peat
mossat25°Cthanthosestoredinpolyethylenebagsat
Themeandataofsprouting,weightlossanddrymatter 4°Cwhencomparedwiththeinfected-untreatedtubers.
weight of JA tubers treated with caraway essential oil On the other hand, storage of the untreated-uninfected
and infected with S. rolfsii using the two storage JAtubersinpeatmossat25°Cincreasedthesprouting,
methodsarepresentedinTable3. decreasedtheweightlossandloweredthereductionof
Results indicated that, the treatment of healthy JA dry matter weight of the tubers compared with the
tuberswithcarawayessentialoilcompletelyprevented storage inpolyethylenebagsat4 °C. Theseresults are
the tubers sprouting and weight loss, but recorded the in agreement with those obtained by Gomez-Castillo
Table5 Meanactivitiesofperoxidase,polyphenoloxidaseenzymesandphenolcontent(%±2SD)ofJAtuberstreatedwithcaraway
essentialoilandinfectedwithS.rolfsiiusingtwostoragemethods
Criterion Storagemethod* Treatment** Storageperiod(day)
30 60 90 120
Peroxidase 1 C 0.40±0.02 0.30±0.0 0.28±0.05 NA
P NA*** NA NA NA
O 0.40±0.03 0.38±0.01 0.38±0.01 0.37±0.02
O+P 2.67±0.16 2.69±0.26 2.73±0.04 2.74±0.03
2 C 0.23±0.01 0.22±0.02 0.21±0.01 0.20±0.06
P 1.90±0.02 1.92±0.03 NA NA
O 0.33±0.02 0.34±0.02 0.34±0.02 0.34±0.03
O+P 1.77±0.03 1.86±0.04 1.87±0.02 1.87±0.26
Polyphenoloxidase 1 C 0.39±0.01 0.36±0.01 0.35±0.02 NA
P NA NA NA NA
O 0.47±0.03 0.47±0.02 0.45±0.03 0.42±0.06
O+P 1.46±0.02 1.57±0.05 1.47±0.02 1.57±0.03
2 C 0.40±0.04 0.40±0.03 0.37±0.03 0.35±0.03
P 1.49±0.03 1.50±0.04 NA NA
O 0.46±0.02 0.43±0.01 0.41±0.06 0.40±0.01
O+P 1.46±0.02 1.57±0.02 1.57±0.03 1.67±0.02
Totalphenol 1 C 0.29±0.02 0.28±0.01 0.27±0.01 NA
P NA NA NA NA
O 0.32±0.03 0.32±0.03 0.32±0.02 0.31±0.02
O+P 0.52±0.02 0.52±0.02 0.51±0.02 0.52±0.01
2 C 0.35±0.02 0.35±0.02 0.35±0.02 0.34±0.03
P 0.57±0.04 0.57±0.04 NA NA
O 0.26±0.01 0.26±0.01 0.26±0.02 0.26±0.02
O+P 0.55±0.02 0.55±0.02 0.55±0.01 0.56±0.01
*1=storageinpolyethylenebagsat4°Cand2=storageinpeatmosslayersat25°C
**C=untreatedcontrol,P=infected,O=treatedwithcarawayessentialoilandO+P=infectedandtreatedwithcarawayessentialoil
***NA=notapplicableduetofulldeterioration
350 Phytoparasitica(2016)44:341–352
et al. (2013) on potato tubers. The active compounds, Peroxidase,polyphenoloxidaseenzymesandphenol
limoneneandcarvone,incarawayoilareknowntosup- contentinJAtubers
presssproutingoftubersbytheinhibitionofmitochondrial
respiration and reducing carbohydrate degradation sugar. Data presented in Table 5 show the mean activities of
Carvonemayplayamorespecificroleinthesproutgrowth peroxidase, polyphenoloxidase enzymes and phenol
ofpotatotubers,suchastheinhibitionofkeyenzymein content of JA tubers treated with caraway essential oil
the mevalonate pathway, which is the main pathway of and infected with S. rolfsii using the two storage
gibberellinbiosynthesis(Oosterhavenetal.1995).Onthe methods. Results revealed that infection with S. rolfsii
otherhand,peatmosshasarelativelyhighwaterretention ledtohighertotalphenolandtheactivityofperoxidase
capacity;theircellscanhold16–25timestheirdryweight andpolyhenoloxidaseenzymesinJAtubersthanthose
of water (Taskila et al. 2016). This property gives an oftheuninfectedcontrolinthetwostoragemethods.On
advantage for its use in the preservation of JA tubers by theotherhand,thetreatmentwithcarawayessentialoil
providing a relative humidity around the tubers and of infected/uninfected JA tubers increased these en-
blockingheattransferwithinthepeatmossleadingtothe zymes and phenol content compared with the
decrease of the water loss even at 25 °C. Cabezas et al. untreated-uninfected tubers in both methods. These re-
(2002) reported that dry matter content in JA tubers de- sultsareinagreementwiththoseobtainedbyAfifyetal.
pends on many factors, such as storage conditions, and (2012) who reported an increase in peroxidase and
keepingtubersfor30daysat18°C,thisleadstoloosing polyhenoloxidase activities in potato tubers when treated
waterabove20%. withcarawayessentialoil.Althoughmostenzymaticreac-
tionsaredrasticallyreducedatlowtemperature,JAtubers
metabolism could continue at a slow rate even at 2 °C
BiochemicalcharactersofJAtubers duringstorage(SaengthobpinitandSajjaanantakul2005).
The enzymatic activation due to caraway essential oil
Mean data of carbohydrates content, inulin and pro- treatmentcouldbedirectlyrelatedtoitscontentofcarvone.
tein of JA tubers treated with caraway essential oil In conclusion, this study has presented an eco-safe
and then infected with S. rolfsii using the two stor- andenergysavingmethodforpreservingJAtubersfor
age methods are shown in Table 4. The obtained 120daysofstorage.Fromtheobtainedresults,itcanbe
results showed that the treatment of the uninfected concluded that caraway oil contains bioactive com-
JA tubers with caraway essential oil recorded the poundsabletoinhibitthegrowthofthepathogenunder
highest total carbohydrates, inulin and protein con- laboratoryandstorageenvironmentsaswellasimprove
tentscomparedwiththeuntreated-uninfectedcontrol the quality parameters of JA tubers and its storability.
in both methods. Along 120 days of storage, the TreatmentofJAtuberswithcarawayoilandpreserving
treatment of infected JA tubers with caraway essen- theminbetweenpeatmosslayerscanprovideaneffec-
tial oil effectively lowered the reduction of carbohy- tiveprotectionagainsttuberrotfor120daysofstorage
drate, inulin and protein contents compared with the even at 25 °C (the favored growth temperature by the
infected-untreated tubers in both methods. A fresh pathogen).
JA tuber contains 80 % water, 15 % carbohydrates,
mainly in the form of inulin, and about 2 % protein Acknowledgments Theauthorswouldliketoextendtheirsin-
cereappreciationtotheDeanshipofScientificResearchatKing
(Brkljaca et al. 2014). For long term storage of JA
SaudUniversityforitsfundingofthisresearchthroughtheRe-
tubers, there are various changes, i.e. microbiologi-
searchGroupProjectNo.RGP-VPP-327.
cal, enzymatic and biochemical which may lead to
tuber damage. To inhibit these biochemical activities,
natural or artificial drying products are widely used References
(Norkulova and Safarov 2015). Davies (1990) reported
thatthebasicconstituentsofcarawayoil(monoterpenes) Abdel-Kader,M.,El-Mougy,N.,&Lashin,S.(2011).Essential
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Afify,A.M.R.,El-Beltagi,H.S.,Aly,A.A.,&El-Ansary,A.E.
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