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.