Science and Technology Journal,
Vol. 3
Issue: 1
ISSN: 2321-3388
DifferentialEffectsofCeO2andZnONanoparticles
onChlorophyllandSecondaryMetabolitesin
Alfalfa(Medicagosativa)
SusmitaBandyopadhyay1,3,ArnabMukherjee1,3,CyrenM.Rico2,3,JoseR.PeraltaVidea1,2,3,andJorgeL.Gardea-Torresdey1,2,3,*
1
500WestUniversityAve.,ElPaso,TX79968USA
500WestUniversityAve.,ElPaso,TX79968USA
UniversityofCaliforniaCenterforEnvironmentalImplicationsofNanotechnology(UCCEIN),
E-mail:*jgardea@utep.edu
Abstract—Littleisknownabouttheeffectsofengineerednanoparticles(ENPs)onplantmetabolites.Inthisstudy,
alfalfa(Medicagosativa
ENPs(n
andn
-1
. Atharvest,total leafchlorophyll, chlorophylla&b, carotenoids,and
750mgkg-1,n
andn
aby60%and40%,respectively,comparedtocontrol.Inaddition,
-1
,andby
chlorophyllbwasreducedby64%,48%,and60%,respectively,withn
-1
40%withn
n
at
-1
-1
, n
500mgkg-1,butreducedby49%withn
n
n
onsecondarymetabolites
andchlorophyllproductioninalfalfaplant.
Keyword:
INTRODUCTION
Alfalfa (Medicago sativa L.) is widely used as forage crop
and nutritional supplement in human diet owing to its
high protein content [1]. In addition to protein, it also
containscarbohydrates,vitamins,nutrients,andnumerous
carotenoids[4],whichareofattentioninhumannutrition.It
lavonoidsproducedbyrootsofalfalfa
are signaling molecules for nodulation process, acting as
chemoattractants [5–7]. Flavonoid and phenolics also
inducenodgeneforthesymbioticRhizobiumassociationin
contentswilldirectlyimpactalfalfa’snutritionalvalue,and
willbedistressed.
The widespread use of engineered nanoparticles
(ENPs) is of great concern due to the possibility of their
environmentalreleaseandeffectsonecosystemcomponents.
of food crops, like alfalfa. Interactions of ENPs with food
cropsarewidelystudied[8-16]intermsofbioaccumulation
–
at lesser scale, trophic transfer [17]
thatn
andn
–14],
ButtheunderstandingofENP-plant
interactionstowardscellularmetabolicprocesses,interms
of secondary metabolites
still in its rudimentary stage. The interaction of phenolic
grainsize.Theoriginalsoiltypewasfoundtobesandyloam
few studies have reported the interaction of ENPs with
–
et al
radish(Raphanussativus
n
.Krishnarajetal.
-1
of the medicinal plant Bacopa monnieri (Linn.) Wettest
preparedwithsoilamendedwithdesiredamountofn
and n
750mgkg-1
treatedwithn
(50seedsperpot).Threereplicateswerepreparedforeach
treatment.
.
have beenreported on the interaction of n
andn
n
metabolites. These metabolites play very important role
by maintaining physiological functions that protect plants
n
e
The above and below ground plant parts were carefully
followed by washing with CaCl ,
andn
metabolitecontents.Plantstreatedwithn
forfurtheranalysis.Later,rootsandshootswereseparated
and digested by microwave-assisted acid digestion with
andn
a,b,andtotal)
microwaveaccelerationreactionsystem(CEM,Mathews,NC)
accumulatedinrootandshoottissues.Leafchlorophylland
(spinachleavesandpeachleavesNIST1547and1570)were
MATERIALSANDMETHODS
eO2
n
n
and n
wereobtainedfromtheUniversityofCalifornia Center for
EnvironmentalImplicationsofNanotechnology(UC-CEIN).
TheseNPswerepreviouslycharacterizedandpublishedby
Bandyopadhyayetal
etal
amountsofENPsweresuspendedinMilliporewater(MPW)
-1
ofsoil.
n
andn
aandbwereestimated
etal.
followingPorraetal.
withsoil.
Elevationof1144above sealevel,top10cm). Theplants
total phenolic content was estimated as per Dewanto
et al.
etal.
(Scotts,premiumpottingsoiltoenhance soilfertility)and
8
DifferentialEffectsofCeO2andZnONanoparticlesonChlorophyll
hevarianceoftriplicatetreatments wascalculated with
forthepairwisecomparisonofmeans,usingSPSSstatistical
based ona probabilityofp
chlorophyll and carotenoids. Four replicates were used to
RESULTSANDDISCUSSION
Zn
e
Figure1Ashowstheconcentrationofzincindryalfalfaroot
500,and750mgkg-1 n
respectively.Incaseofn
treatments,Celevelsincreased
and 9 times more Ce than control, respectively (Fig. 1B).
In green pea (Pisum sativum
-1
of n
-1
Fig.1:CeriumConcentration(Top)andZnConcentration
(Bottom)inRootsandShootsofAlfalfaPlantsExposed
to Either nCeO2 or nZnO at 0 (control) to 750 mg kg-1.
Data are means ± Standard Error of Four Replicates
and Bars with Different Symbol/ Letters Show
p
Respectively
accumulation from n
also accumulated higher Ce in roots compared to other
plants[8,11].Translocationfactors(TF),calculatedthrough
-1
-1
750 mg kg
almost the same at all n
-1
, respectively). The
shows the chlorophyll content in leaves of alfalfa
n
andn
withthephysiologicalfunctionsofbothelementsinplants.
kg-1
functions, while there is no known function for Ce. Thus,
chlorophyllawasreducedby40%and60%at750mgkg-1
of n
with previously reported literature, where the majority of
kg-1 n
n
n
b
, respectively, but remained the same in n
theCespeciesaccumulatedinroots,comparedtostemand
-1
that showed a 40%
Raphanussativus
to n
andn
at concentrations < than 500 mg kg-1, there was
higherconcentrationofCeinleaves,comparedtoroots[19].
-1
9
n
b
n
750 mg kg-1 treatments, respectively. The effects of n
andn
-1
of n
,
n
the photosyntheticapparatus andlight harvestingprocess
n
n
didnotappeartoimpactchlorophyllthroughtheireffectson
n
substituted the central magnesium atom of chlorophyll
decay and ultimately, interrupting the photosynthetic
.
followed by n
to interrupt chlorophyll production are
notwellunderstood.Wehypothesizethatsmallamountsof
n
might reduce the photosynthetic pigments
Fig.2:(A)Chlorophylla,(B)Chlorophyllb,and(C)Total
Chlorophyll Content in Leaves of Alfafa Plants Grown
for 30 Days in Soil Amended with Either nCeO2 nZnO
at 0 (control), 250, 500, and 750 mg/kg. Error Bars
StandforStandardErrors(n=3)andBarswithDifferent
p
nZnO and nCeO2 Treatments are
MutuallyIndependent
Table 1: Total Leaf Carotenoids Represented as mg
g-1 of Fresh Alfalfa Leaves from Plants Grown for
30DaysinSoilAmendedwithEithernCeO2ornZnOat0
(Control),250,500,and750mgkg-1.Dataaremeans±
StandardErrorofThreeReplicates
Treatments
pigments.
Control
250
mg kg-1
4.98a
1.45a
500
mg kg-1
750
mg kg-1
n
n
4.98a
nCeO2
6.81a
nZn
Phenolic an
effectofn
andn
n
-1
at500mgkg
At500mgkg-1,n
by86%,whileat750mgkg-1
mg kg-1 n
by 77%, while at 750 mg kg-1
49%,comparedwithcontrol.Krishnarajetal.
an increase in leaves, phenol content of Bacopa monnieri
10
DifferentialEffectsofCeO2andZnONanoparticlesonChlorophyll
Oryza
sativa)treatedwith500mgn
kg-1sho
high n
n
protectiveroleinmetalchelationandscavengingofreactive
NPs might correlate to
the increased enzymatic activities, suggesting ‘de novo’
ofalfalfawithincreasingdoseofn
a negative effect in the nutritional value of alfalfa shoots.
Additionally, it is hypothesized that there is a probability
of increasing plant stress due to accumulation of reactive
contentsuggeststhatalfalfaplantsareaffectedfromsevere
stressconditionsimposedbyn
andn
Fig. 4: Changes in Flavonoid Content Expressed
as µg catechin/g of Freeze Dried (A) Root and
(B) Shoot of Alfalfa Plants Grown for 30 Days in
Soil Amended with Either nCeO2 or nZnO at 0
(Control), 250, 500, and 750 mg/kg. Error Bars
Stand for Standard Errors and Bars with Different
TreatmentsareMutually
Independent
2
CONCLUSION
Thisstudyhasshownthatalfalfaabsorbsandtranslocates
n
and n
a butn
also affected
chlorophyll b and total chlorophyll production. n
n
areaffected bysevere stressconditions imposedby n
andn
ACKNOWLEDGEMENT
This material is based upon work supported by the
National Science Foundation and the Environmental
Protection Agency under Cooperative Agreement Number
Fig.3:TotalPhenolicContent(RepresentedasµgGAE/g)
in(A)Rootsand(B)ShootsofFreezeDriedAlfalfaPlant
Grownfor30DaysinSoilAmendedwithEithernCeO2or
nZnOat0(Control),250,500,and750mg/kg.ErrorBars
Stand for Standard Errors and Bars with no Symbols
GAE=GallicAcidEquivalent,n=3
11
of the National Science Foundation or the Environmental
ProtectionAgency. ThisworkhasnotbeensubjectedtoEPA
Coriandrum
J.Agric.FoodChem.
sativum
laboratoryforspectroscopicmeasurements.
14.
REFERENCES
J.
Agriculture”,Ind.Biotechnol,
15.
1.
Solanum
lycopersicum L.) and its Implications for Food Safety”,
Metallomics,
Medicago sativa L.)
Parts”,J.Agric.FoodChem,
16.
”, J. Agric. Food
Environ. Sci. Pollut. Res.,
Chem,
17.
Alfalfa by Stop-and-go Counter-Current Chromatography
Nanomaterials in Terrestrial Environments”, Environ. Sci.
Technol
J.ChromatogrA
18.
Protein (Pro-Xan) and Dehydrated Meals”, J. Agric. Food
Chem
19.
4.
Stress”,Pol.J.Environ.Stud.,
.
5.
but do not Impact Tuber Ionome in Raphanus sativus (L)”,
PlantPhysiol.Biochem
the Sinorhizobium–Medicago Model”, Nat. Rev. Microbiol,
6.
of Rhizobium meliloti
Appl. Environ. Microbiol,
7.
Synthesized Silver Nanoparticles on Bacopa monnieri
(Linn.) Wettst. Plant Metabolism”, Process Biochem
pp.651–658.
Nodulation”,NewPhytol,
8.
Nanoparticles in Cucumber Plants”, Environ. Sci. Technol,
Oryzasativa
J.Agric.FoodChem.
9.
10.
SusceptibilitytoManufacturedNanomaterials:Evidencefor
P.Natl.Acad.Sci.
USA,
In Situ
Nanoparticles towards Sinorhizobium meliloti, a Symbiotic
Alfalfa Associated Bacterium: Useof Advanced Microscopic
J. Hazard. Mater,
Media”,Environ.Sci.Technol.,
(Glycinemax)”,ACSNano,
11.
J.Sediment.Res.,
andToleranceofZeamays
Nanoparticles:CrossTalk
ACS
inDifferentSolvents”,Biochem.Soc.T.,
Nano,
Metallomics,
12
Determination of Chlorophylls a and b. Photosynth”, Res.,
DifferentialEffectsofCeO2andZnONanoparticlesonChlorophyll
J.Agric.FoodChem.,
J. Agric. Food Chem.,
synthesizing glutamate 1-semialdehyde aminotransferase
metabolisminalfalfa(MedicagosativaL.).PlantPhysiol.106:
relevanceofheavymetalsubstitutedchlorophyllsusingthe
BIOGRAPHY
Dr. Jorge Gardea-Torresdey
Gardea-Torresdey is the Dudley Professor of Chemistry and Environmental Science and
phytoremediation, novel methods for the bioproduction of nanoparticles and study of the fate of
13