Biochemical and Folk Assessment of Variability of
Andean Cultivated Potatoes l
C. F.
QUIROS,2
S. B.
BRUSH,3 D.
S.
DOUCHES,"
K. $. ZIMMERER,5 AND G. HUESTlS 2
ISQzvme markers were u cd 10 Sllrw'Y Ih" gen"lIC mria!)/!llyofnon-blller pow/OC\
10 subsistence./iRlds of Andeanfarmers al 3600-3850 In above sea level. Sixty­
Si'\"en percent oflhe "'{JnelJe.~ were /elrapfOtds corresponding 10 the 'pCClCX Solanum
tuberosum ssp. andigcna, ! 4% Iv",rc /nplolds. probably corr;;spondllJg 10 /he speCies
S. x ehaueha. and I JW) It'ere diploids corresponding 10 Ihc specics S. Slenotomum.
S. phureja. and S gOD.ocalyx. The isozymc 111!ormall0I1 served to de/ermine Ihe
consistency oflhe folk naming sySIi?m, We found a high degree ofcorrespondence
bcllvecn farmer idcl1/1jicQIIO!1 and efectrophore/lc phenolypes. The consiSli!ncy 0/
Ihe ji)lk syslO:m In deurophoreric /errns depended on Ihe farmer who was In/ef­
l'icII'cd. The mosl common Incongruity COI1SISled ofcallmg dlj}erent deClrophor~lIc
phUlo/ypes by Ihe sume \'(11'1('1.1' name. leadmg 10 a sligh I undereslimation ofgenetIC
I'anabilil\' /Jrcoenl ill Ihe jldds. The amount ofvaflabllity observed In the sample
or Ihe Andean pOlalO poplila/lon was superIOr /0 Ihal present In /\lorl17 A mencan
and l~'uropcan varieties, This was !neaswTd inlerrns ofnumbcr ofalleles, number
0/ elecrrophoreth phcnIJlypes and percelll of hcterozygosllY. This jmdlllg SUPPOriS
Ihe impressiollihal () subslanlwf ([mOun I ofyel Ulu'Ap/olled vanabtllly r~matns in
Ilndc()1I ,.·ola/o popl//alll)IlS.
in
Evaluaeion bioqllllTl ica y popular de \<:1 variabilidad interespeeifica de las papas
clIlti vadas en los Andes. Ell <'51,' traba}o se da a conoeer fos resultados de un estudlO
f(CnCl;CO subrc '·aflcdadcs d(' papa dulce en los Andes, realuuda pOI' medlO de
marcadarcs ISOenZ/I1UlliC/JS ell parcetas de subslstencia loca/izados entre 3600 y
3850 ,ilelros sobre e! nive! de! mar. 5e eneon/ra que 67% de {as variedades mues­
Ircadas ,':an IelraplOides de fa ('specie S. wberosum ssp, andigena, 14% Inpfoides
probabfemell/e de fa espeCle S. x chaucha, y I Jljlo dip/aides de las especles S.
stenolOmllm, S. phureja und S. gonioealyx. La informaCion IsoenZimallca lue (Ill!
en fa C'valuaCton de la /)I'e('lslon cle! sistema lolkforlco pam Idenllficar varu:dades.
Sc ellcontro un allO grado dl! asoClaCion ('!/Ire ef 5ls/(,ma d'" etasljtcaclon usado POl'
e! campesillo para deno/mllar sus \'ariedade~, J' los feno/lpos eleciroforell cos. La
prCClsion del "t"lema de Ic//?Iltic/ad fofklorico en lermlnos dec/roforaicos dependlo
del campeslI10 emrel'is/(jdo. La discrepanCia mas /recuen/(' entre los dos 5151('1'1'10$
de nomenclatura COnSlSlllJ en {{amar e/(ferenles jcnOI/pus c1eclroforc/icos con eI
mislllo lIombre l·aTlelal. fo que rcsuflO cn una subesllinaCIi)n de la vartab/fldad
gcnetico pre ('1/1(' ('II I(J~ campos. Ef I/II'eI de vanabIfldad observado en fa mueslro
de PQfJQ.\ de la jJob!ac/lj" ane/ma Iu;; superior a/ ohsen'ado en ,'ariedades nortea­
II1crimnas.l' curopeas, La \'ariilliitidud .Ie midlo ell bose al mimcrode aldos, I1lfrnero
dejenolipos eleclr%rellcos l' porcenlaje de heleroCigosidad. ESlos resultados es/an
de ael/erdo COil la Impri?SI{)n general de que lodal'fa e-'oste mucha vanabllidad en
rariedadcs de papa alldll1as que no ha sido alin explotada.
,
,
)
,
,
Received 10 Septtmbcr 1988: accepted 3 May 1989,
Departmenl of V,:~clablc ("rops, Un! versily of Ca', IOm'u. Dav.s, CA 95616.
Department of Applied Behavwral SCIences, University of Califomia, Davis. CA 95616.
Crop and Soil SCiences Department, M iehigan Slale Universl1y, East Lansing. MJ 48824.
Depal1 men I of Geograph y. Un i versi ly of North Carohna, Chapel HIli. NC 275 14.
BOIOIIF. 44(2), 1990. DP 254-266
'.. 1990, by lht' .'\Iew York l30lanlcal Garden. Bron,\, NY 10458
Fcollumiz
1')')0\
QU1ROS ET Al.: ANDEAN POTATOI:S
255
Great intraspecific diversity of cultivated plants is one of the hallmarks of
agricultural evolution, bUI this diversity presenlS numerous scientific issues. Why
is there so much intraspecific diversity of cultivated species, and why is this
exaggerated in certain regions? What is the contribution of ecologicaL agronomic.
and human factors 10 the origin and maintenance of this diversity? What is the
best way to describe and analyze this diversity? How is diversity affected by
agricultural, economic and other changes?
Two primary steps in answering these questions are to understand the genetic
base of the crop and to describe the ways in which fanners perceive and select
crops so as to affect diversity. Investigating how and why farmers in centers of
crop evolution maintain oiversity can usefully begin with folk taxonomies and
thei r relation to the genetics of the crop (Brush 1986). For whatever reason that
diversity is mallllained, farmers must have a specific means to accomplish this,
and a folk nomenclature and taxonomy can be helpful toward this end. Folk
nomenclature and taxonomies create labels and keys to distinguish morphological
differences. The work of Boster (1985) on Aguaruna taxonomy of AlanihOI es­
culenlQ Cranz shows that folk taxonomy of great intraspecific variability can be
understood as a means to maintain diversity and that diversity is sought for its
own sake and not for a sped fie reason. Folk taxonomy allows Aguaruna culti vators
to make distinctions that have no apparent utility, although culinary and phar­
macological differences are noted between some folk varieties. Most important,
there are no recognized agronomic characteristics incorporated into the Aguaruna
folk ta,'\.onomy.
The ract that folk taxonomies are designed to satisfy cultural rather than ag­
ronomic reasoning forces the question of their utility for understanding the bio­
logical dynamic~ of a crop. It has been repeatedly shown that interspecific folk
taxonomIes are biologically accurate (Alcorn 1984; Berlin et al. 1974), but does
thiS accuracy extend to the II1traspecific level? Do folk identification and classi­
fication provide us with guides to estimating genotypic diversity? These questions
are importantoeeause crop germ plasm collections are often based to some degree
on folk taxonomies. Gen~ticists at the International Potato Center have reduced
the ll:.Jmber of accessions in the Center's don ally propagated collection because
of their conviction that extensive duplication existed. The idea of duplication
derives. in part, from the notion that the folk taxonomies that underlie the original
accessIOn list are unreliable and tend toward overclassification.
Our article examines the identification of the cultivated potato (Solanum lube­
rosurn L., Sole.:~aceae) in reference to its cultivation in the Andes, its center of
doneS1lCation. It reviews the means to classify the great intraspecific diversity of
potatoes employed by fanners and geneticists. The article presents the use of
biochemical narkers as a way lO cope with the great intraspecific diversity en­
countered in the Andean potato crop, and it correlates the identification of folk
varieties and those determined by biochemical means.
VARIETAL CLASSlFlCAT10N OF THE CULTIVATED POTATO
The diversity orthe cultivated potato has posed an intriguing and challenging
taxonomic problem for several generations of potato geneticists (Correll 1962;
Hawkes 1979). Four ploidy levels (2n = 2x = 24 to 2n = 5x = 60) comprise the
256
ECONOMIC 110' ,\NY
[VOL. 44
cultivated potatoes. Under the taxonomic system of Hawkes (1979), which is
currently the most widely used. these four ploidy levels divide into eight cultivated
species (four diploids, two triploids. one tetraploid, and one pentaploid). In An­
dean potato fields, the tetraploid S. tuberosum ssp. andigena (JUl. et Buk.) Hawkes
is by far the most prominen t, accoun ti ng for more than two thirds of the planted
pota toes (Brush et a!. 1981).
Ploidy and species level classification are of somewhat limited value for treating
intraspecific diversity at the field lcvel. WIllie some plants in a typical field may
he of different species or ploidy levels, most of them are of a single subspecies
(andigena). Visual and agronomic distinctiveness may be greater within this sub­
species than across the eIght cultivated Solanum species. Because of the potato's
predominantly asexual propagation. clonal distinctiveness is particularly impor­
tant. This propagation works against the survival of products of genetic exchange
and hybridization both between and within species. Somatic mutation is common
and will not be revealed at the species or ploidy level. Polyploidization and
hybridization may create different species and ploidies out of morphologically
similar potatoes.
While the geneticist may be interested in describing potato populations, where
species and ploidy level are meaningful, the farmers who actually manage the crop
are concemed with the individual plant and variety. The selection, exchange, and
maintenance of tubers is done at the variety level. This suggests that an under­
standing of population dynamics of the Andean potato must somehow include a
more sophisticated treatment of the crop at the variety level than is allowed in
the current taxononlic tools. Howevn, varietal identification is plagued by such
problems as somatic mutation, hybridization, and a daunting amount of data to
:)c 2.nalyzed. The elabora te nam ing system of farmers is often viewed with skep­
ticism by g('neticists, partly because the specific knowledge base that determines
folk classification is not formalized. and there is no easy way to estimate how
consistent folk taxonomies are between indiVidual farmers or between commu­
nities.
Nevertheless, we ignore varietal di versi ty and its identification· by farmers at
our own scientific peril since the actual dynamics of the potato crop are signifi­
cantly determined at thc varietallewl. It has been firmly established for the potato
and for other crops that folk identification and taxonomy are the keys to under­
standing the behavioral patterns that affect crop evolution (Boster 1984; Brush
ct al. 1981; Johns 1985). The Andean folk classification system for potatoes is
based on tuber characteristics, cultivation, edibility, processing and frost resis­
tance. Potato folk taxonomy helps determine cultivation practices that make the
Andean potato fields dynam ic evol utionaI)' systems where new varieties and
perhap~ new speCIes are generated by cross hybridization and introgression from
related wild species (J ac~son et al. 1977; Johns and Keeo 1986).
Concern for the varietal level requires that new taxonomic techniques be mo­
bilized, since the conventional ones used for the species and ploidy level descrip­
tion miss most of the intraspecific diversity. Further, the data requirements of
using conventional morphological markers for variety identification are so large
as to be essentially impossible. We have found that biochemical markers, spe­
cifically isozymes, provide effective tOols for describing this great diversity.
Ql'IROS ET AL.. ANDEAN POTATOES
19901
257
APPL'"iNG BIOCBEMICAL MARKERS TO ANDEAN POTATOES
Recent research in the Peruvian Andes by Brush indicates that a high degree
of diversity is still maint<iJiled by peasant cultivators. Inventories of potatoes
stored in households after harvest revealed that households in the Paucartambo
area east of euseo maintain an average of 9.6 distinct named varieties: Some
households were found to maintain as many as 26 varieties, while others kept as
few as a single variety. The traditional planting procedure in southern Peru fields
is to sow as many as five small tubers in a single hole opened by the footplow.
These tubers might comprise different varieties and even species of different
ploidies. One reason for planting heterogeneous fields is to enhance the diet by
having a mixture of flavors, textures, shapes, and colors. The great diversity and
heterogeneity of these fields pose interesting problems of variety identification
and classification by the farmers in order to maintain and conserve the original
variability. A folk nomenclature based primarily on tuber morphology has been
pre viousl)' descn bed (Brush et al. 1981).
In the last ~c:w years a number of biochemical markers useful for potato clone
identifical;on have been reported (Oliver and Zapater 1984; Quiros and McHale
1985; Stegfmann and Loeschcke 1977). In particular, isozyme markers are most
useful as bio~;l~mical markers because of their known genetic basis and co-dom­
inant expression (Quiros and McHale 1985). These have been used to follow up
segregatIOns in interploidy matings and to generate experimental data on the
transmission of heterozygosity by Ihe diploid strains with the ability to produce
2n gametes (Douches and Quiros 1987, 1988).
The objective oflhis article is 10 survey with isozyme markers the actual genetic
variability of non-bitter potatoes in subsistence Andean fields at 3600-3850 ill
above sea level. ThIS information serves to determine the accuracy of the folk
classification system for potalOes in the Andes.
MATERIALS AND METHODS
held sampling
Ten fields in a radIUS of 30 km and located between 3600 to 3850 m above sea level were sampled
the ProvInce of Paucartamho. Depanmcill of Cusco, Peru (Table l). After we sampled a single
tukr from 200 plants in each fIeld chosen 31 random, the lubers were bulked togelher m a pile
accordtng \0 tuber s,mJlarily. Th.e farmer was asked to examine each pile, to regroup piles accordmg
to h.JS critcria. and h) name each unique group or mdlvldual tuber. Then, the tubers were washed and
placed in paper bags idclllified by variety and by field, The only exception was Ihe fieJd at Maqopala
(field number (0) where 11", farmer classified the tubers as they were harvesled.
Because of the IMger number of tubers. when a vaflcty had more Ihan 30 tubers per bag, a repre­
sCn131iv(' sample of 10--25 tubers wa~ taken for the electrophoretic determination dcpendmg on the
level of morpholO:;JcaJ helerogenel1y presenl in lhe bag.
in
fsoz.vmr analYSIS
Honwnlal Slillch gel ;;:Ie<:trophoresis was empJoyed to assay for nine enzyme systems disclosing 12
loci useful for gcnotyping the lubcrs of each variety (Douches and QUIroS 1987: Quiros and McHale
1985). These are phosphoglucoisomerase I (PC I-I). phosphogJucomulase I and 2 (PGM- I and PGM­
2). 6 phosphoglucooase dehydrogenase 3 (6PGD-3), lsocitrale dehydrogenase J (J DH-I), malate de­
hydrogenase I and 2 (M DH-I and MDH-2), acid phosphal3se I (APS-I), g1utamale oxaloacetate
[VOL. 44
ECONOMIC BOTANY
258
TABLE I.
FIELD lOCATION, AlTiTUDE, fARMER NAME AND NUMBER Of TUBERS FOR SOLAj\'"UM
SPECIES SAMPLED PER fiELD (PAUCARTAM80. CUSCO, PERU).
F:armcr
I Jesus Amao
2 Julio AmaQ
3 Sebaslian Maun
4 Trinidad Sandi
5 Gomercindo ClJampt
6 Augustin Turpo
7 Santos Chipa
8 Hipolito Mamani
9 Pablo Mamani
10 FauslinQ I1la
UXUllOn
Colquepata
Colquepata
SipasC'ancha Alta
MollomarC'3
Moll,'marca
Mollomarca
Sispacancha Alta
Carpapampa
Carpapampa
Moqopata Alw.
Al!Hllde- (m)
Tuber!=;
3650
3600
3750
3680
3720
3750
3700
3830
3780
3850
70
47
JOI
135
45
37
76
72
62
185
lranS<Lr'I;;[ase I and 2 (GOT-l and GOT-2), peroxidase 3 (PRX-3), and shikimic aCid dehydrogenase
(SKI)-I ).
For the e]cctrophorellc assay a tuber eye was e,'C1sed from a tuber and crushed in 75 )JI of 0.1 M
Tfls-HCl ,,:{ 7,0 bu:kr ('onlaln\n,~ 2% giulalhlone as anlioxidant. The extract was soaked mlo 3M
(lller paper wIcks and subJecled 10 electrophoresis.
Other tuber detemlinations
The foil< lW'lng Luber charaClensl'cs :\'\. recorded: skm and flesh color. tuber eyes (color. depth, shape),
si.,n lexlUrc, and shape. Afler the eleclrophoretic survey, chromosome counls were made for a rep­
resentative tuber ofclcClrophorctic phenotype. For lhls purpose Ihe tubers were wrapped in mOlslened
towels and inlroduced inl" covned plastIC shoe boxes. Smce most of lhe tubers were already sprouted,
til,'y (o""ed roots readJly at Ihe base of the sprouts. The root tips were collecled, fixed In alcohol­
acetic ac,d (3' I). and slained With feulgen.
G('II('IIC
paramelNs
Three parameters were detenmned In the Andean luber populallon, percenl helerozygosity (H),
tOlal number of alleles, ~:,nd total number e!ectrophoretl<: phenotypes 111 a per locus baSIS. These values
were compared to those recorded in 24 North American and European pow.to cultivars: 'Russet
Burbank', 'Norc'''p', 'Red Ponltac', 'Gold Rush', 'l(athadin', 'Rosa', 'BintJe', 'Sangre', 'Bel Rus',
'Pu;meer'. 'Alianllc', 'Monona', 'Targee', 'Nooksack', 'Shepody', 'Superior', 'Agassiz', 'Red Norland',
·Alpha'. 'CentenmaJ Russet', 'BIson', 'LemhI'. 'Sebago', and 'Red La Soda'.
Spew·.\ idcm IjiCClt/() 11
In an aHcm!'! to clectrophorellcaJly Identify by specific allozymes the various spcCJes cultivated in
the l1elds, six to 18 aCCl'»ions of the specIes S. ,lfnO(Omum Juz, el Buk.. S. gOlllvcalyx Juz, et 8uk..
S phur<'jG JUl:. et Buk .. S x c!rauc!lG JUl:. eL Bul; .. and S. wbNosl.lm ssp. Glldlgena were eleclropho­
""Ically surveyed. Also, 16 aeceSS,Olls of the biller species S. x juz('pzukll Buk. (3 x) and 4 of S. x
curtdohum Juz, CI Buk. (5 x) were mcluded in Ihe survey.
Comparison between fall.. and iso:ym(' Identification
An agreement inde>. was developed 10 express a ratio of the proportion of tubers represenled by
the most numerous elecirophoretlc phenotype mulliphed by Ihe propOnlon of farms in Ihe sample
whose namwg agrees with this ph,·clotypc. It 1$ arrived at by comparing the number of tubers ill the
dominant sub-group With Ihe 101al number of tubers in the group and the number of farmers agreeing
Oil name with th<: lotal number of fanne., who had that eleclrophorelJc phenotype. A score of one
indicates perfect C"ongruence (s)" cases) and a score of zero wd\C3tes that there was no congruence
across (arms for the elcctrophoretic phenotypes found under a common name (II cases).
QUIROS ET AL: ANDEAN POTATOES
1990j
TABLE
2.
259
NUMBER OF VARIETIES REPORTfOD AND ACTUAL NUMBER OF ELECTROPHORETIC
PHENOTYPES OBSERVED FOR SOLANUM SPECIES SAMPLED (PAUCARTAMBO. CUSCO. PERU).
=========================. ­
Famu'r
Vd","',etLes
Phcnoty~~
n:poncd
ot1strY.ed
15
16
31
34
/0
]csus ,'-\mao
70
[1
2 Julio Amao
47
)4
lOI
135
22
45
8
IJ
3 Sebastian Mauri
4 Trinidad Sandi
5 Gomercindo Champ,
17
DJffercnC\:
4
2
9
/7
6 Augustin Turpo
37
7 Santos Chipa
76
72
/5
24
3
-1
9
14
20
6
62
16
[7
t
185
43
36
-7
8 Hipolito Mamani
9 Pablo Mamanj
10 Faustino Ilia
10
RESULTS AK"l) DISCUSSION
("Irrespondence
qr.rolk names and electrophorellc phenotype
Two major :'esults are evident from this research. First. there is an overall high
degree 01 correspondence between farmer identification and electrophoretic phe­
notypl:. Second, :he accuracy of the folk naming system in electrophoretic terms
depended on the farmer doing the classification.
'iWO types of incongruity were evident within each field. The first type consisted
in calling differenl electrophoretic phenotypes by the same variety name while
the second type consisted in calling the same electrophoretic phenotypes by more
Ihan one variety name. The most com man error of inconsistency was of the first
type, leadi ng to a general underesti mation of the genetic variability presen 1 in the
fields. In only twO farms (numbers 6 and 10) more varieties than genotypes were
observed. "fable 2 summarizes the data on tuber identification from the 10 fields.
The range or inconsistency in tuber identification went from 3% to 22%. The
highest nUI"'bcr of underestimated varieties (17 or 50%) was also observed in the
same fie!u (Trinidad Sandi, #4), while the lowest was observed for Pablo Mamani
(#9) (I or 5.9%), excluding the fields of Augustin Turpo (#6) and Faustino lIla
(# (0) where the number of varieties was overestimated. This wide variation
represents, in par'·., lack of enthusiasm or desire by the farmer to spend the time
to do an accurate identification. but it also indicates the wide range of skill and
knowledge among larmers. Nevertheless, the inconsistency was justifiable in cases
where the lubers were mOJTlhologically very similar as far as skin color and shape
was concerned. However. slicing of the tubers revealed flesh color differences,
wheh were further substantiated by electrophoretic differences.
A good example of this situation was observed for the variety Yana Imilla
where three phenotypes were detected (Fig. 1-3). Although the distinction to us
j,', enough to separate the three as different varieties, it is possible that the range
of variation within Yana Imilla was not enough for the Andean farmer to consider
them different entities. The consistency of variety names among fields was much
lower than within fields, but the level of agreement is still about half. That is in
cases where two farmers give the same name for tubers, they are naming similar
260
IVOL.44
ECONOMIC BOTANY
3
2
cur .aj stn
juz
<
Fig.l 1.
Ande~<)
cultivated pot::lloes. Fig. 1. Example ofmconslslent classification within Solanum
Paucarlambo. Cuseo. Peru. Morphologically similar tubers clas·
s,(,ed as Yana Imi/la ~:i$\. 2. Example Orilleonsistent clasSification within S. IUberosum ssp. andlgrfla
collected in Paucartambo, Cuseo, Peru Sample Yana Imdla tubers disclosing three different pheno­
t yp~s for Ilesh color J od for tile enzy me M D H. Fig. 3. Exam ple of Inconsistency in classification across
three Jiclds lor the variety Yana Suv(u Three dllT'clcnt morphotypes of Solanum speCIes from Pau­
cartam boo Cusco, Peru. WI t h sa me name. Fig. 4. Diseri m I nation of biller from non- bi Iter pota to species
on the basis of the enzyme Ivi DH _The blller species S x juupzukll (luz) and S. x cumlDbum (cur)
carry lhe unique enzyme Mdh-2-\ also presenl to lhe,r ancestral species S. at:aulc (ad) (arrows). Tne
non-bllter cullivatcd species and olh"" wl1d species lack thiS unique isozyme (mga l11eglSlacrolobllln,
tor - loralGparulli. rap = ro.pn aIIi!O IIU ill , spi = sparsipdl./m, aJ ;: aiannl/in, SIn' SII?IIOlOI11um (Huaman
and l{oss 1985)] Thl c.;: accessions per species are displayed, excepl ror GjGnhUiri. which includes only
one acceSSLon
lubNo.~um ssp. amil~{'na collected In
electrOphorelic phenotypes 50% of the time. Comparison between farms is difficult
because of the common presence of different electrophoretic phenotypes within
a single name. Among 32 named varieties that were found on more than one
farm, 19 had more than one electrophoretic phenotype on at least one farm. The
average for these multiple electrophoretic phenotypes was 2.9. A common pattern
of inconsistency between nums was for agreement on a dom inant electrophoretic
261
QUIROS ET AL.: ANDEAN pOTATOes
1990J
3.
TABLE
AGREEMENT ACROSS FARMS ON lDE/'ITIACATION OF LIKE ELECTROPHORETIC
PHE OTYPES OF SOLANUM SPECIES SAMPLED (PAUCARTAMRO,
Cuseo,
PERU).
B
o. lUOe.cs In
dommant
C
D
No. rnnns in
"Ub~group
T 0\31 no. lUbe.rs
agreement
w'/pheno(yPC'
I
11\
6
30
21
2
2
2
2
2
4
2
3
4
5
6
7
2
0
0
2
2
0
3
2
2
2
2
2
2
3
2
2
3
3
A
VanC't}'
12
2
13
3
17
8
2
2
~
10
II
JJ
J
J'
19
7
11
12
13
14
15
16
17
18
19
20
21
;n
23
24
25
26
27
28
29
30
31
32
JI
J
10
17
1
29
10
10
7
I
10
10
43
33
\6
51
2
A vg. agreement lOdex
SI. Dev.
:~
4
13
9
21
5
2
II
2
22
17
12
14
21
3
II
23
3
45
13
10
14
2
II
16
54
34
16
70
3
a
2
2
2
0
0
3
0
6
E
Total
OQ
5
2
3
2
2
2
3
2
6
0
2
2
0
2
2
0
2
2
3
5
2
0
2
5
2
fann'"
5
4
2
6
a
2
F
Agreement
Lndc~'
0.300
0,114
1.000
0.333
1.000
0.333
0.000
0.000
1.000
1.000
1.000
0.864
0.000
0.917
0.571
0.347
0.000
0.000
0.739
0.000
0.644
0.000
1.000
0.000
0.000
0.909
0.000
0.319
0.319
1.000
0.486
0.000
0.43279304
0.41865658
. ,"&n·."',n' Ind<X IF) ­ IB/Olo/E).
phenolype bUI disagreement on less dominant tubers. Eleven names with acces­
sions Crom different farms had no multiple electrophoretic phenotypes, and in
these cases rhere was congruence between the name and electrophoretic phenotype
on six. Table 3 gives the results of a comparison between names and 32 electro­
phoretic phenotypes found across our sample offanns. This comparison expresses
the dominance of a single electrophoretic phenotype and congruence between
farms. An agreement index of one means that the same electrophoretic phenotype
was given the same name On all farms where it was found. An index of zero
indicates that a differen t name was gi ven on each farm. Scores between zero and
one l't:sult when only some farmers agreed on the name or when some electro­
phoret;c phenotypes were given two or more names by the same farmer.
ECONOMJC BOT ,\NY
262
TABLE
4.
[VOL. 44
TUBER NAMES fW ELECTROPHORETIC PHENOTYPE FOR SOLANUM SPECIES SAMPLED
(PAUCARTAMBO, CUSCO, PERU).
Name
No lube"
Skin (aJor
Yllraq (' 'while' ') K'lIsi
Yana ("black "j K'usi
Hllrl.\'fo
YIII"q Kusi
76
34
1
10
while
black
Phenotype 1
farm 10
Farm 8
black
Phenotype 1
Farm 10
Farm 3
Farm 4
Farm 6
SoqowaqolO
Soqnwaqmo
Ya na Cht'qcpphoro
Yllraq Ch 'eqepphoro
Wallidw
Ch 'fqfpphoro
4
2
while
6
10
black
white
Yana
29
I
whl1e
~
1
Phenotype :3
Farm 10
K'IIS1
blaek
Phenotype 1
Farm 10
Farm 4
Yllmq Waqoro
"Iqa Qompis
Qompls
1
4
7
?
red
red
Phenotype 5
Farm :3
Farm
~
Farm
J
Filrm 6
Onor Qompis
Alqa Warml
All/a Qompis
Qomp/S
QomplS
8
2
9
6
10
red
red
red
red
red
In the comparison of names and electrophoretic phenotypes across farms, two
types of inconsistencies Wff';:, again, evident: the calling of different varieties by
the same name and naming a variety by more than two names. This lalter in­
consistency may be hard 10 distinguish from synonymy, which is not an error.
Synonyms are recognized by farmers and cannot be considered misclassifications.
The previous discussion began with a potato name found on more than one
farm and then examined the electrophoretic phenotypes associated with that name.
By beginn I ng with the electrophoretic phenotypes and looking for associated names,
a pa1tel'll of synonymy and some splilling is revealed. Table 4 shows the names
for five electrophoretic phenotypes. For phenotype 2, for instance, the names
Soqowaqoto and Yuraq Ch 'eqepphoro appear to be synonyms. Farmer 4 split this
phenotype into two names according to color, and he apparently erred in the
Wallicha case.
Our examinatiOfl of naming in comparison to electrophoretic phenotypes both
on s: ILgie farms and between farms clearly indicates that farmers err in naming
principally by underestimating the degree of genetic diversity in their collections.
There is far more lumping of different genotypes than splilting of like ones.
However, an unexplained fact is that, although we found 104 electrophoretic
phenotypes, farmers gave 100 names. Th is list ineludes synonyms and overesti­
QUIROS ET AL. ANDEAN POTATOES
19901
TABLE
5_
263
PLOIDY DISTRIBUTION AND SPEC! ES OF THE ELECTROPHORETIC PHENOTY'PES OF
SOLmUM SPECIES SAMPLED (PAUCARTAMBO, CI.JS(_X). PERU).
Frequency %
Diploids
Triploids
Tetraploids
13%(16/12))
14% (17/125)
67% (84/125)
SlenOiomum, gOllycolyx. phureja
choucho
alldigena
mati on errors of farmers #6 and 10. Our estimate of the actual number of discrete
farmer names would be between SO and 90. This suggests that there is less lumping
than indicated in Table :'.
The system affalk identi ficati on is expected to be somewhat am biguous because
it is based in part On subjeclive descriptions. For example, lhe variety Yana Kuwl
Sullu means lilerally "black gu inea pig felus." So depending on the criteria and
Imagination of the farmer, many of the black skinned tubers could be classified
under the same variety name. A good example of this type of inconsistency can
be appreciated in the variety Yana Suyt'u (Fig. 2). The prefix "yana" refers to
jlack skin color, so Jesus Amao (# 1) and Sebastian Mauri (#3) might have been
right when they classi tied the tubers in the figure as Yana Suyl'u, although the
:norphological differences between the two are very distinct. The third farmer,
Augustin (#6), might have been truly mistaken since he classified a pink skin
tuber as black. However, "suyt'u," means long, which was an accurate description
for all three tubers. This second name, ofcourse, migh t have been used by Augustin
as the main criterion to classify his tubers under this variety.
The chromosome count$ revealed that the majority of the genotypes culti vated
in the fields sampled at Paucartambo were tetraploids, most likely corresponding
to S. luber05um ssp. andlgena. Cultivated diploid and triploid genotypes shared
about the same frequency (Table 5). Although it was not possible to find specific
allozymes to diAhentiate the species of the group tuberosum, it is safe to assume
tl-:at the diplOids included the species S. stenotomum, S. phurejo" and S. gonia­
cdyx. while the triploids corresponded exclusively to S. x chaucha. On the other
hand, specific allozymes were observed for the bitter species S. acaule Bitt., S. x
juzepzu.kii, and S. x curlilobum. For example, the allozyme Nfdh· 2J was observed
:n These three sp::cies supporllng the hypothesis that the former species is ancestral
to both the triploid S. x juzepzukii and the pentaploid S. x curti/ovum (Hawkes
1979) (Fig. 4). So, on the basis orthis unique marker, il was possible to conclude
that non-bitter triploids were present in the fields sampled at Paucartambo.
No sludies :Iave been done in potatoes on the possible associations of speci hC
isozyme loci and genes determining morphological traits such as tuber flesh or
skin color. We did not observe in our survey any evidence of these associations
for the isozyme loci and traits investigated. These traits include skin and Aesh
color and tuber shape. For example, the varieties Yuraq Kusi and Yana K'usi in
Maqopata (# J 0) had the same electrophoretic phenotype for eight loci tested;
however. the hrst is triploid and its skin is white, and the second is black and
tetraploid. Therefore, it is likely thal one might have been derived from the other
jy somatic m~tation and chromosome doubling. A similar situation was observed
ror Yuraq Ch'eqepphoro and Yana Ch'eqepphoro, where the first one is a white
[VOL 44
ECONOMIC BOT ANY
264
TABLE
6.
GENETIC VARIABILITY IN THE ANDEAN POPULATION AND lN NORTH AMERICAN!
EUROPEAN CULTIVARS OF SOLANl,',I{ SPECIES.
Nonh Amem,"an/l urOoea,O cullivars
Andean population
LocI
Pgi-I
Pgm-I
Pgm-2
6pgdJ
Idh-I
Mdh-I
/vfdh-2
Aps-}
Go!-I
Aueles
Pbf:ootypc:s
3
1
3
3
3
4
2
3
3
5
%H
4
36
2
74
4
4
81
5
3
Ii
2
94
25
4
39
4
3
7
2
3
4
58
Sdh-I
4
')
64
Total"
23
t'I(.I.!.'/' (11.1(-2, :JIld
33
%H
Phcn.olypes
2
20
3
2
2
46
52
4
2
6
SO
2
8
2
3
24
3
3
52
2
2
3
2
92
44
GOI-2
Prx-3
• Excludmg /dh. J,
All").,
47%
20
0dh-l II'I 11K Andc.an popula1l0n smCt" th.. .'~"-, JOCl wert 001
24
~LJ ...... e)\'d jn
44%
.he NOl1J1 Amenrean/
EurODC,. I rJOpulatloll
tetraploid, and ,he second one is 3 black diploid. Another case was observed in
two tetraploids of identical electrophoretic phenotype. Y Gila Ruki wi th black skin
and Yuraq Rukl with white skin. "Ruki" is the local term for bitter varieties,
probably indicating that these samples were misidentified. These observations
indicate that skir. color is independent of the eight isozyme loci studied.
There were also several cases where identical electrophoretic and morphological
phenotypes for tubers of different ploidies were observed, indicating that these
varieties migh t ha ve origi nated directly by self polyploidization. Other situations
included almOSl identical tubers and very similar electrophoretical phenotypes,
making it very difficult to distinguish two or three varieties. For example, the
lubers of Qompis. Alqa Qompis. and Alqa Wanm are very similar, and their
genotypes are identical for 10 loci but different forthe Prx-l or Sdh- J loci. Qompis
andf/qa Qompis are heterozygous while Alqa Warmi is homozygous for these
loci. Often the tubers of these varieties were classified as a single variety that was
deSIgnated by one of the three names, indicating that the farmers understand them
as synonyms.
In general we observed that morphologically distinguishable tubers differed in
at least one isozyme locus, except in situations where somatic mutations for skin
color or polyploidization were evident. In these situations, of course the isozyme
technique was sup<.:rfluous as an identification tool. However, the electrophoretic
technique was useful to distinguish tubers that otherwise could be classified as
belonging to the same variety. It provided an additional criterion for variety
identification. The capability of the technique is expected to increase with the
number of isozyme loci surveyed.
Genetic vanabilllY
1/1
Andean versus North American/European varieties
Although the sample size for both populations was highly unequal-24 North
American/European clones against 830 Andean clones-it allowed us to obtain
QUIROS
I-.T
AL.e ANDEAN POTATOES
265
a rough estimate of the variability in both populations. Furthermore, it is likely
that the cultivars from the North American/European population covers pretty
much the variahility existi:~g in thai group. while the Andean population in spite
of the larger sample covers only a fraction of all the variability present in the
Andes. In any event, the amount of variability observed in the Andean population
was superior for the three parameters measured: total number of alleles, total
number of electrophoretic phenotypes, and percent of heterozygosity (% H) (Table
6). The largest difference was observed for the number of electrophoretic phe­
notypes. This increased variability in the plimitive population was evident even
when considering that 33% was composed by diploid and triploid tubers, while
the other population was formed exclusively by tetraploids. An interesting finding
in the Andean population was the high frequency of specific alleles at loci Pgm-2
(allele 2), GOI-l (allele 3), and Gol-2 (allele 4), reflected in a large num ber of
homozygous genotypes. On the other hand, this was only observed for allele 3 of
GOI-l in {he North American/European population. Additional research including
a larger survey will be necessary to understand the significance of this observation.
The larg-.:r number of alleles and electrophoretic phenotypes in the Andean
popula tion, some of which arc not represen ted in the North American/European
populations, supports the impression that a substantial amount of yet unexploited
variability remains in the primitive pOlato populations.
CONCLUSIONS
Thl use of isozymes as a basis for potato classification is advantageous 10
conventional taxonomies using plant morphological and general protein in several
ways. [I morc closely approximates the genetic base of the potato. It is more ea:;i1y
quantified_ It allows for a fuller treatment of intraspecific diversity. It provides a
clearer picture of the relation between cultivated species and between cultivated
and nOll-cultivated species.
Folk naming systems of the Andean potato are based on tuber charact~ristjcs
and rarely include keys from other plant markers. The use of isozyme electro­
phoresis as a classification tool indicates that farmer identdkation corresponds
wit h a high degree of accuracy to the actual biological di versity of Andean potato
fields. There is, of course. a range of consistency among different farmers, de­
pending on their interest and devotion to knowledge about their potato collection.
W:jle consistency within a particular household in classifying its potato collection
has been uemonstrated previously (Brush et al. 1981), this research suggests that
interhousehold confusion over duplicate potatoes is nOt a major problem. Out of
a rdati vely small sample of 10 fields, we iden ti fied 104 electrophoretic phenotypes.
an d am ong the I0 d ifreren t co lIect ions there were I 00 d ifferen t names gi yen by
our informants. A comparison of electrophoretic and folk identification both
within anC:; between fields reveals that farmers may slightly underestimate the
divnsi ty ofthei r fields. This finding bears on the debate of the degree ofduplication
found in the accessions collected from Andean potato fields. Our work leads us
to conclude that duplication among accessions is not common. When duplication
is found, it might be tl';1': result of sampling methods that are less proximate to
the uillmate source of Andean potatoes. For instance, collections in markets,
ra~hel than in Oelds or in farmers' storage bins, might produce more duplication
ECONOMIC BOTANY
[VOL 44
and lead to an underestimation of the actual amount of diversity still extant
Andean potato agriculture.
In
ACKNOWLEDG M ENT$
Research for thlS projeCt was done with suppon from the Nahon'll SCIence FoundatIon (ENS
84]6714) to Stephen Brush. the USAID Strengthening Grant to the University of Cali fomi a-Davis
~.nd the California Genctic Resource Conservallon Program and thc USAID grant DPE-I 0680G-SS­
.;003 \0 Carlos Quiros and Stephen Brush. AssIstance In Peru for this research was provided by
Leonidas Concha, Edgar Gudiel. Teresa Inca Roca. and Alfredo CarbajaL In Davts. we were asststed
by Ana Tarquis.
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