Euphytica 63 : 22 5-231, 1992 .© 1992 Kluwer Academic Publishers . Printed in the Netherlands .

Resistance in spelt wheat to yellow rustIII. Phylogenetical considerations

Gert H.J . KemaResearch Institute for Plant Protection (IPO-DLO), P .O. Box 9060, 6700 GW Wageningen,The Netherlands

Received 21 February 1992 ; accepted 15 July 1992

Key words : phylogeny, Puccinia striiformis, resistance, spelt wheat, stripe rust, Triticum aestivum ssp . spelta,yellow rust

Summary

Theories on the origin and dissemination of spelt wheat (Triticum aestivum ssp . spelta) are evaluated . Recentinformation on resistance to yellow rust (Puccinia striiformis Westend. f . sp . tritici) and variation for gliadinpatterns in spelt wheat accessions originating from Iran and Europe is superimposed on literature reportsconcerning the origin, status and dissemination of spelt wheat . The data support the theory on the origin ofspelt wheat in the Near East. An alternative European site of origin, albeit improbable, cannot be excluded .

Introduction

Spelt wheat, Triticum aestivum (L.) Thell. ssp .spelta (L.) Thell. (Kimber & Sears, 1983) or Tspelta L . (Kimber & Sears, 1987), is a primitivehexaploid wheat with a brittle rachis and adherentglumes, long spike internodes and non-sphericalseeds, which are controlled by the pleiotropic speltfactor (Q/q), and factors for ear compactness (Clc)and seed form (Sl/s,), respectively. Therefore, itsgenotype has been designated as ggccS,S, (McIn-tosh, 1983) . During evolutionary processes muta-tions materialized, eventually resulting in breadwheat (T aestivum L., QQCCS,S,) . The questionwhere these processes took place has been a scien-tific issue since the early thirties .

A natural site of origin of spelt wheat was discov-ered in Iran (Kuckuck & Schiemann, 1957) . Thereis not much archaeological evidence, however, forits agronomical importance in the Middle-Eastwhere emmer (T turgidum ssp . dicoccum, domes-ticated form of T turgidum ssp . dicoccoides) was

most popular (a.o . Harlan, 1981) . The area of culti-vation of the crop has been confined to Europe .According to Gradmann (1909 ; cited by Harlan,1981) the acreage of spelt wheat exceeded breadwheat in the first decade of this century . In 1930 itwas still a major constituent (40%) of the Middle-European wheat growing area, ranging from theNorth-West Alps, where its former importance isrecognized in village names like `Dinkelbuhl'('Dinkel' is the German word for spelt wheat), andparts of Austria up to the Black Forest in Germanyand North-East France, where its cultivation is al-ready known for some 900 years (Flaksberger,1930) . According to Zeven & de Wet (1982) thearea might have been much larger, reaching fromSweden to Spain or North Africa . Linguistic evi-dence includes the old Spanish word 'Escandia'(spelt wheat) for a Swedish region considered to bethe ancestral home of the 'Escandians' or Norse-men (McFadden & Sears, 1946) . According to ex-cavations in Denmark, Sweden and the UnitedKingdom, the first occurrence of spelt wheat in

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Fig . 1 . Map of Europe and western-Asia, indicating (presumed) sites of origin (shaded areas) and dissemination tracks of spelt wheat(scale 1 : 2 .10') .

Europe is dated in the late Bronze Age (ca .1000 BC; Bell, 1987) . An inventory on its prehis-toric distribution, compiled by Schultze-Motel &Kruse (1965), provides evidence for Iron Age(600 BC) and even Neolithic (5000-4000 BC) pres-ence of spelt wheat . The first reference in literatureas 'spelta' or 'scandula' was in the Edict of theRoman emperor Diocletian (301 A .D.) (a.o .Flaksberger, 1930) .The interest in spelt wheat has been recently

revived due to its reputation as a species with anatural defence against several fungal pathogens .The competitive properties of the species undermarginal cultural conditions initiated a breedingprogramme in Switzerland (Riesen et al ., 1986 ;Schmid & Winzeler, 1990) . Moreover its flour is

considered to be of an excellent quality for pastryproduction and the grains are the major constituentin the traditional German `Griinkern' dish (Bau-mann, 1984 ; Hitschfeld, 1985 ; Zullig, 1985). Thesetrends are not yet reflected in an increasing agricul-tural importance, however . Currently the cropgains most attention from ecological farmers andits total acreage in Europe is still negligible (e.g .5% of the total Swiss wheat acreage in 1985) .

Several spelt wheat accessions have been studiedwith respect to resistance to the fungal yellow rustpathogen of wheat (Puccinia striiformis Westend .f. sp . tritici) and variation for gliadin patterns (Ke-ma, 1992; Kema & Lange, 1992) . In addition tohaving similar gliadin patterns, European and Ira-nian accessions were found to carry an identical

allele for resistance, designated Yr5, which wasinitially discovered in T spelta var . album (Macer,1963). European accessions generally carriedeither this allele or none (Kema, in press ; Kema etal., 1986). One Iranian accession was found to car-ry Yr10 (Kema & Lange, 1992), a resistance allelefirst reported in P1178383 (Lewellen et al ., 1967), abread wheat specimen from the Turkish Hakkariprovince, which was collected by Harlan in 1948(Harlan, 1976) .

The present contribution is an evaluation of theliterature on the origin and dissemination of speltwheat. Resistance to yellow rust and variation ingliadin patterns (Kema et al ., 1986; Kema, 1992 ;Kema & Lange, 1992) will be compared with de-scribed linguistic, archaeological and genetic evi-dence for hitherto conflicting theories on the estab-lishment and distribution of spelt wheat .

Origin and dissemination of spelt wheat

Background. The dispute on the origin and dis-persal of spelt wheat was beset with conflictingarchaeological, genetical, taxonomical and linguis-tic argumentations. Flaksberger (1930) absolutelydenied the vague information about the occurrenceof the species in South-Western Asia, Egypt andEthiopia on questionable taxonomical reasons. Herestricted the appearance of spelt wheat entirely toEurope, and considered the Alpine region to be thesite of origin, where it should have been derivedfrom T aestivum . Involvement of amphiploidiza-tional processes leading to an allopolyploid speltwheat was rejected . Schiemann (1931) mentionedboth hypotheses and stressed the possibility ofcrosses between T turgidum ssp. dicoccum and Taestivum which could have resulted in the so-calledT antiquorum (Heer, 1865; cited by Schiemann,1931) . This was the first naked wheat with short`club' ears (CC), also referred to as 'Pfahlbauwei-zen', which occurred in excavations of dwellingsites of Neolithic peoples in Switzerland . Thiswheat was considered to be the ancestor of speltwheat. Archaeological evidence indicated theSwiss Alps as the probable site of origin (Fig . 1 ;Flaksberger, 1930; Schiemann, 1931, 1947). The

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cultivation area of spelt wheat was believed to beconfined to the ancient Rhine valley .The establishment of a synthetic hexaploid,

through amphiploidization of the tetraploid T tur-gidum ssp. dicoccum and the diploid Aegilopssquarrosa, which was barely distinguishable fromspelt water (McFadden & Sears, 1946) initiatedinvestigations and discussions until the late seven-ties. According to McFadden & Sears (1946), speltwheat originated from the Fertile Crescent (thearea where the putative parents T turgidum ssp .dicoccoides and Aegilops squarrosa occur) and mi-grated to Europe either via Poland to Germany orvia a southern route following the Danube, reach-ing the Alps and ultimately progressing via theRhine valley (Fig . 1) . This hypothesis was support-ed by linguistic evidence (see citations by McFad-den & Sears, 1946; Andrews, 1964) . However,Schiemann (1947) emphasized the lack of archae-ological data on the occurrence of spelt wheat inthe Fertile Crescent and stressed the possibility of aEuropean origin which was also left open byMcFadden & Sears (1946). The discovery of speltwheat in Iran (Fig . 1 ; plateau of Shahr-Kord, in thearea of the Baktiari tribe, collection sites usuallyover 3000 m; Kuckuck & Schiemann, 1957), com-plicated the dispute about its status, centre of ori-gin and possible dispersion tracks to Europe, sinceit accentuated McFadden & Sears' hypothesis .Hence, additional theories were developed on (1)the genetic origin, considering either a primaryorigin of spelt wheat as the first hexaploid wheat ora secondary origin as a derivative of T aestivumand on (2) the geographical origin, considering twoindependent sites of origin of spelt wheat, viz . Eu-rope and Iran, or a single site in the Near Eastfollowed by migration to Europe .

Genetic origin of spelt wheat. Investigations on thegenetics of the pleiotropic spelt factor (Q/q) in-dicated that multiple dosages of q revealed 'square-head' wheats and eventually free-threshing ears,like T aestivum (Kuckuck, 1959; Muramatsu,1963), which accentuated a primary origin of speltwheat . The recognition of accessions without trans-locations relative to the primitive genome structureof `Chinese Spring', was a cytological evidence sup-

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porting the primary origin of spelt wheat (Riley,1969), though other accessions did show transloca-tions (Kema & Lange, 1992) . On the other hand,synthetic hexaploids of T turgidum ssp . dicoc-coides and Ae. squarrosa, which resemble speltwheat very closely, showed an identical genomestructure as `Chinese Spring' as was exemplified bythe absence of translocations during meiosis andthus also supported a primary origin of this wheat(Lange & Jochemsen, 1992) .

Initially, archaeological data suggested a second-ary origin of spelt wheat since its first occurrence inexcavations was dated ca . 1000 years later than thecarbonized remains of the predominate precedingstaple crop, the afore-mentioned T antiquorum(Schiemann, 1931, 1947) . However, successive ex-cavations indicated a much older spelt wheat culti-vation in Europe (see Schultze-Motel & Kruse,1965), thus providing evidence for a possible simul-taneous cultivation of both species and as suchleaving open the conceivability of a primary origin .Moreover, it is still unclear whether the non-speltseeds in European excavations were of hexaploidorigin since they also resembled those of the tetra-ploid T durum (Zeven, 1980) . Although typicalspelta and intermediate phenotypes have been ob-tained in segregating populations of crosses be-tween tetraploid emmer (T turgidum ssp . dicoc-cum) and hexaploid bread wheats, hybrid necrosisgenotypes of such emmer wheats (Ne,) and Alpinebread wheats (generally non-carriers), which areconsidered to be direct descendants of T antiquo-rum, do not favour the latter species as the ancestorand thus do not support the secondary origin ofspelt wheat (Zeven, 1980). Whenever emmerwheat was involved in the establishment of speltwheat, Ne,-genotypes might have been expectedamong European accessions . However, those ac-cessions are generally non-carriers (sporadicallyNee) and hence a European origin of spelt wheatwas considered to be unlikely (Zeven, 1980) .

Geographical origin of spelt wheat . Mac Key (1963)doubted the value of linguistic evidence to supporteither of the possibilities concerning the site oforigin of spelt wheat since local, traditional namesfor it, such as the Russian 'polba' or the Polish

`orkiss', often referred to mixtures of cereal crops .He also stressed the limited archaeological supportfor migration from Iran to Europe . Since then how-ever, substantial quantities of spelt wheat havebeen discovered in ancient (± 5000 BC) farmingsettlements Yarym-Tepe I and Yarym-Tepe II inNorthern Iraq (Bakhteyev & Yanushevich, 1980 ;Renfrew, 1984) . Some descriptions of this materialare similar to descriptions of European materialfrom much more recent origin .

The occurrence of Ne,-genotypes in spelt wheatis restricted to Iranian and Asian accessions where-as non-carrier (ne,ne2 ) accessions can be either ofEuropean or Asiatic origin (Tsunewaki, 1971 ; Tsu-newaki & Nakai, 1973 ; Zeven, 1981) . Tsunewaki(1971) considered two independent sites of originto be most plausible . In his opinion European speltwheat (gne,Ne2 ) was derived from Asian nakedwheats (QNe,Ne, or Qne,ne,), while the alternativecourse, from Asian spelt wheat (gNe,ne, orgne,ne2 ) to European naked wheats (Qne,Ne, orQne,ne,), was considered to be improbable . Thisinference, however, is based on the Ne-genotype ofonly two Iranian spelt wheat accessions which wereconstituents of Kuckuck's collection (Tsunewaki,1968,1969 ; K . Tsunewaki - Kyoto University, pers .comm .), and disregards the presence of non-carri-ers in either the European and the Iranian pop-ulation .

McFadden & Sears (1946) mentioned the typicalrachis fracture of their synthetic hexaploid, whichleft a segment of the rachis attached to the individu-al spikelets (T turgidum ssp . dicoccoides-type) .Pohlendt (1958) attributed two types of rachis frac-ture (T turgidum ssp. dicoccoides and Ae. squarro-sa type) to anatomical structures being specific forthe majority of either Iranian or European acces-sions . This specificity has been questioned latersince both types of rachis fracture were found insingle ears (A.C. Zeven, Agricultural University -Wageningen, the Netherlands, pers . comm.). Inspite of this finding it remains interesting that twoIranian accessions, including 417' which was alsostudied by Kema (1992) and was found to carryYr5, showed a rachis fracture which was identicalto the one of European accessions, while the acces-sions 77, 411 6 and 415, which were also included in

previous studies (Kema, 1992 ; Kema & Lange,1992), happened to have a typical Iranian rachisfracture (Pohlendt, 1958) .Kuckuck & Schiemann (1957) and Gokgol

(1961) reported the absence of awnless accessionsin the Iranian spelt wheat population . Kuckuck(1964), however, described collection site 417 as aheterogeneous population, being a mixture of vul-gare and transient type hexaploids, including plantswith less developed awns . Whether the awnlessphenotype of accession 417a, as observed by Kema(1992), was the result of progressive introgressionof inhibitors from European cultivars during suc-cessive multiplications, is unknown, but conceiv-able .

The status of the Ethiopian accession 81, whichprobably also carries Yr5, is not clear (Kema,1992). It might be an introduction from Europe toEthiopia as suggested previously (Zeven, 1971) .

Significance of yellow rust resistance data and con-cluding remarks . The similarity with respect to ne-crosis genotypes, rachis fracture, gliadin patternsand especially the duplication of Yr5 in the Iranianaccessions 41l b and 417 a and 19 European acces-sions (Kema et al ., 1986; Kema, 1992), is strongevidence favouring earlier hypotheses suggestingthat ancient (trade) contacts between the two re-gions, may have facilitated the migration of speltwheat to Europe via a southern or north-westernroute (McFadden & Sears, 1946) . Ancient recog-nition of resistance to yellow rust, currently knownto be due to Yr5, and observed by 19th centuryscientists (KUhn, 1858 ; Eriksson & Henning,1896), may have contributed to unconscious selec-tion (Heiser, 1988), and thus to the rapidity of itsdistribution . The Yr5 and Yr10 alleles for resist-ance to yellow rust of wheat are currently consid-ered to be originally indigenous to the spelt wheatpopulations of Western-Asia (Kema et al., 1986 ;Kema, 1992 ; Kema & Lange, 1992) . Europeanspelt wheat accessions that differ significantly withrespect to gliadin patterns but which collectivelybear Yr5 (Kema, 1992), could therefore be theresult of multiple introductions . Although theTranscaucasian hexaploid T macha has been con-sidered as a direct progenitor of spelt wheat (Kuck-

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uck & Peters, 1964; Dorofejev, 1971), their hybridchlorosis genotypes (Chl, and Ch12 , respectively)do not support this hypothesis .

The yellow rust data, and the presence of non-carriers in both regions severely weaken Tsunewa-ki's argument for two distinct sites of origin (Tsune-waki, 1968, 1969). Although the Middle-East ispresently considered to be the most probable site oforigin, European ancestry of spelt wheat cannot becompletely ignored as some accessions carry hybridnecrosis alleles (Ne2 ) which are confined to thisregion (Zeven, 1981) . However, introgression ofthese alleles from bread wheat could explain theirpresence since bread wheat and spelt wheat areinterfertile .

Acknowledgements

I wish to thank prof. dr J.E . Parlevliet and DrRobert P. Baayen and Dr Cor H. van Silfhout forcritically reading and useful comments on the man-uscript and Harry H . Kema for preparing the map .Dr Colin R. Wellings (NSW Agriculture - Uni-versity of Sydney, Australia) kindly checked theEnglish text .

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