ABSTRACTtechniques used to characterize wheat cultivars (Vaccino et al., 1993) and assess genetic diversity (Kim andCharacterization of germplasm by means of DNA fingerprinting Ward, 1997; Paull et al., 1998 Tautz and Renz, 1984) and AFLP (Vos et al., 1995).cation Matrix that allowed the discrimination of the 105 cultivars.The SSR technique gained rapid acceptability be- Data obtained from SSR markers were complemented by informationcause of its codominant nature, reproducibility, and high derived from AFLPs. Molecular data were used to quantify genetic information content (De Loose and Gheysen, 1995). than RFLP were found between bread wheat cultivars released in the 1970sand prompted the development of more than 400 SSR 1998; Stephenson et al., 1998). The first SSR markers available were used to characterize eight European cultivars (Devos et al., 1995) and 11 Canadian cultivars I dentification and registration of bread wheat culti-(Lee et al., 1995) of wheat bread. In a more comprehenvars is mainly based on morphologic and physiologic sive study of 40 European bread wheat cultivars using characteristics. Even though these descriptors are use-23 SSR, Plaschke et al. (1995) concluded that a relative ful, they are limited in number and may be affected by small number of SSR was sufficient to discriminate this environmental factors. Molecular markers are a useful set of cultivars. complement to morphological and physiological characThe AFLP technique combines the RFLP reliability terization of cultivars because they are plentiful, indewith the power of PCR to amplify simultaneously many pendent of tissue or environmental effects, and allow restriction fragments (Vos et al., 1995). This technique cultivar identification early in plant development. Mowas used successfully to evaluate genetic diversity and lecular characterization of cultivars is also useful to evalgenetic relationships in wheat (Salamini et al., 1997; uate potential genetic erosion, defined here as a reduc- Barrett and Kidwell, 1998;Domini et al., 2000), bean tion of genetic diversity in time.(Phaseolus vulgaris L.) (Tohme et al., 1996), rice (MacRestriction fragment length polymorphism (RFLP, kill et al., 1996;Virk et al., 2000), tea (Camellia sinensis Bostein et al., 1980) was one of the first DNA marker Kuntze) (Paul et al., 1997), barley (Hordeum vulgare L.) (Qi and Lindhout, 1997), and soybean (Maughan et al., 1996).M.M. Manifesto, A.R.

Peanut smut caused by Thecaphora frezii Carranza & Lindquist has been an issue for farmers and the peanut industry (Arachis hypogaea L.) in Argentina since the mid‐1990s. This disease causes pod malformation due to hypertrophy of seed tissues; in addition, colonized cells filled with teliospores give seeds a smutted mass appearance. Incidence may reach up to 52% in commercial plots, with up to 35% yield losses. Cultural management strategies and chemical treatment have not been effective; therefore, growing resistant varieties is likely to be the most effective control method for this disease. This study is aimed to identify sources of resistance in wild Arachis and to develop pre‐breeding materials for transferring the trait to cultivated peanut. After 3 yr of field trials using a randomized complete block design, the seven accessions of wild species assayed were resistant to smut. An amphidiploid [A. correntina (Burkart) Krapov. & W.C. Greg. × A. cardenasii Krapov. & W.C. Greg.] × A. batizocoi Krapov. & W.C. Greg.)4× was obtained and subsequently crossed with and experimental line of A. hypogaea for the development of a recombinant inbred line (RIL) population (89 lines). The RIL population showed a high phenotypic variability for resistance to peanut smut. The amphidiploid and 22 RILs were highly resistant, illustrating the effective transmission of resistance to peanut smut from the wild diploids into A. hypogaea. The development of RILs with resistance derived from wild species is a significant step towards the development of new peanut cultivars with different sources of resistance to peanut smut.

Quinoa (Chenopodium quinoa Willd.), one of the main crops domesticated in the Andean highlands 1,000 of years ago, played an important role as a protein source. 35 germplasm accessions collected along the Northwest Argentina (NWA) region were studied using 22 microsatellite (SSR) markers. Results showed a great level of genetic diversity, differing from previous reports about the geographical distribution of quinoa variability. All SSR loci analysed were highly polymorphic detecting a total of 354 alleles among all populations, with an average of 16 alleles per locus. Cluster analyses grouped the accessions into four main clusters at the average genetic distance level (0.80), each of which represented a different environment of the NWA region: Puna (UHe = 0.42, ±0.07 SE), Dry Valleys (UHe = 0.27, ±0.05 SE), Eastern Humid Valleys (UHe = 0.16, ±0.04 SE) and a transition area with high altitudes between the last two environments (UHe = 0.25, ±0.03 SE). An eastward decreasing genetic diversity gradient was found. AMOVA analyses showed a strong genetic structure: a high population subdivision relative to the grouping by region (Fsr = 0.47) together with a high genetic differentiation among populations (Fst = 0.58) and a heterozygous defect (Fis = 0.63) in each of them. The variability structure, a reflection of the structure of the NWA landscapes, is discussed in connection with environmental variables.

Carotenoids play essential biological roles in plants, and genes involved in the carotenoid biosynthesis pathway are evolutionarily conserved. Orange sweetpotato is an important source of β-carotene, a precursor of vitamin A. In spite of this, only a few research studies have focussed on the molecular aspects of carotenoid genes regarding their specific sequence and structure. In this study, we used published carotenoid gene sequences from Ipomoea and other species for "exon-primed intron-crossing" approaches. Fifteen pairs of primers representing six carotenoid genes were designed for different introns, eleven of which amplified scorable and reproducible alleles. The sequence of PCR products showed high homology to the original ones. Moreover, the structure and sequence of the introns and exons from five carotenoid structural genes were partially defined. Intron length polymorphism and intron single nucleotide polymorphisms were detected in amplified sequences. Marker dosages and allelic segregations were analysed in a mapping population. The developed markers were evaluated in a set of Ipomoeas batatas accessions so as to analyse genetic diversity and conservation applicability. Using CG strategy combined with EPIC-PCR technique, we developed carotenoid gene markers in sweetpotato. We reported the first set of polymorphic Candidate Gene markers for I. batatas, and demonstrated transferability in seven wild Ipomoea species. We described the sequence and structure of carotenoid genes and introduced new information about genomic constitution and allele dosage.

TitleMolecular markers associated with differences in bread-making quality in a cross between bread wheat cultivars with the same high M-r glutenins ABSTRACTThe association between molecular markers and bread-making quality (BMQ) was investigated in a cross between two wheat cultivars with the same high J,1,-glutenin subunits but significantly different BMQ A segregant F1 population was generated after crossing Klein 32 and Chinese Spring, and the BMQ of each F 1 -derived F3 family was estimated using sodium dodecyl sulfate (SDS) sedimentation and mixograms. The same families were characterized for II polymorphic loci using restriction fragment length polymorph isms (RFLP) and single sequence repeats (SSR). These loci were specifically selected for their complete or close linkage to storage protein gene families. No significant differences in BMQ were detected at XClu-Bl and XClu-Alloci using RFLP markers. Highly significant (P<0'01) differences in all BMQparameters were detected for XCli-Bl and XClu-B310ci on chromosome arm I BS. The increase in the number of Klein 32 alleles at these loci determined a linear increase in sedimentation and mixogram values. It was not possible to differentiate the effect of XClil from that of XClu3 because of the close linkage between these two loci. These two loci, considered together, explained from II to 15% of the ~ariation in BMQ observed in this cross. The inclusion of the protein content of each sample as a covariable in the model increased thr proportion of variation in SDS sedimentation explained by the analysis up to 46'Yo and the precision of the statistic analysis up to 180%. Mixing paramrters showed a lowrr correlation with protein content than SDS sedimentation parameters, and the increase in precision obtained by the use of the protein content as a covariab1e was non-significant.

History and environment shape crop biodiversity, particularly in areas with vulnerable human communities and ecosystems. Tracing crop biodiversity over time helps understand how rural societies cope with anthropogenic or climatic changes. Exceptionally well preserved ancient DNA of quinoa (Chenopodium quinoa Willd.) from the cold and arid Andes of Argentina has allowed us to track changes and continuities in quinoa diversity over 18 centuries, by coupling genotyping of 157 ancient and modern seeds by 24 SSR markers with cluster and coalescence analyses. Cluster analyses revealed clear population patterns separating modern and ancient quinoas. Coalescence-based analyses revealed that genetic drift within a single population cannot explain genetic differentiation among ancient and modern quinoas. The hypothesis of a genetic bottleneck related to the Spanish Conquest also does not seem to apply at a local scale. Instead, the most likely scenario is the replacement of preexisting quinoa gene pools with new ones of lower genetic diversity. This process occurred at least twice in the last 18 centuries: first, between the 6th and 12th centuries—a time of agricultural intensification well before the Inka and Spanish conquests—and then between the 13th century and today—a period marked by farming marginalization in the late 19th century likely due to a severe multidecadal drought. While these processes of local gene pool replacement do not imply losses of genetic diversity at the metapopulation scale, they support the view that gene pool replacement linked to social and environmental changes can result from opposite agricultural trajectories.

The South American Transition Zone (SATZ) is a biogeographic area in which not only orogeny (Andes uplift) and climate events (aridification) since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species’ range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2–1.2) Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity.

KeywordsIpomoea batatas; morphological descriptors; skin and flesh colour; sweetpotato. Correspondence M.M. Manifesto, Instituto de Recursos Biológicos CIRN-INTA-Argentina, N Repetto y Los Reseros s/n., AbstractThe knowledge about the distribution of descriptors of a collection constitutes a useful tool for the management of genetic resources. The object of this work was to evaluate the composition and morphological characterisation of the 'in vitro' collection kept at the Gene Bank of the Biological Resources Institute (IRB), INTA Castelar, Argentina, to establish conservation criteria and make available useful data for breeding programmes. This collection, comprising 310 sweetpotato clones, includes landraces, worldwide clones, commercial varieties and breeding material. The descriptors, which presented the highest correlation values, were leaf lobe types, the shape of central leaf lobes and general leaf outline. Cluster analyses showed eight major groups with an average similarity of 0.42 (SE ± 0.005). About 76% of the clones presented unique morphology, whereas 34% of them were distributed in 22 groups that could not be distinguished with this technique. Worldwide germplasm formed a separate group with values of diversity higher than those of the Argentinean clones and no duplicates. A projection of the phenotypic variation among cultivars was obtained through Principal Coordinate Analysis (PCoorA), which confirmed the results obtained by UPGMA analysis, predominant skin colour, secondary skin colour, number of leaf lobes, general leaf outline, petiole pigmentation and predominant colour of vine were the variables that made the highest contribution. Collection composition in reference to flesh and skin colour was also analysed.