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Cereal Research Communications
Authors: Hongxiang M, Jinbao Yao, Miaoping Zhou, Xu Zhang, Lijuan Ren, Giuhong Yu, and Weizhong Lu

.Z., Nichoson, P. 2003. SSR marker for Fusarium head blight resistaance QTL in three wheat populations. Scientia Agricultura Sinica 36 (10): 1150–1155 Nichoson P. SSR marker for Fusarium

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combination with the use of genetically mapped barley SSR markers. Genome (in press) Islam, A. K. M. R., Shepherd, K. W., 1992: Production of wheat-barley recombinant chromosomes through induced homeologous pairing. 1

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Garcinia . Studies on various Garcinia species involving random amplified polymorphic DNA (RAPD), inter simple sequence repeats (ISSR) and simple sequence repeats (SSR) markers were successfully used by various researchers throughout the world ( Mansyah

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Bread wheat ( Triticum aestivum L.) is an economically and nutritionally important cereal crop in the Mediterranean region. Characterization of wheat germplasm by means of DNA fingerprinting techniques provides a tool to assess genetic diversity and to identify varieties. In this study, six Tunisian bread wheat cultivars were characterized by AFLP and SSR markers. Five AFLP primer pairs showed clear different patterns and seems to be the most suitable for analysis of the bread wheat varieties. Three SSR primers were polymorphic with more than two alleles. The pairwise genetic similarities (GS) based on these molecular markers were calculated and used to construct a dendrogram that allowed the discrimination of the six cultivars. The GS among the six varieties ranged from 0.79 to 0.36. The six varieties used in this work clustered into four groups using either AFLP or SSR markers. A high GS was found between Tebecca and Vaga Varieties which have a similar pedigree.

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The use of genetic markers allows the study of polymorphism and genetic distances between maize lines in greater depth than can be achieved on the basis of phenotype and DUS traits. The analysis of polymorphism between 46 maize inbred lines with known genetic background and the classification of these lines in related groups was carried out by means of morphological description, isoenzyme analysis, RAPD analysis, and identification using gene-linked microsatellite (SSR) markers. The genetic distance or degree of relationship between the lines was determined using cluster analysis. Only a very limited extent of allele polymorphism could be detected in isoenzyme analyses; the 46 lines formed only 18 gel electrophoresis groups. Nevertheless, on the basis of RAPD and SSR markers, all the lines could be distinguished from each other. This was reflected by the PIC (polymorphism index content) values, which ranged from 0.04 to 0.55 (mean 0.27) for the various enzyme loci, while far higher values were obtained for RAPD and SSR markers (0.20–0.91, mean 0.61, and 0.54–0.90, mean 0.73, respectively). Due to the large number of lines, two lines, derived from each other or from common parents, were chosen from each related group as the basis for grouping the lines according to genetic background. It was found that, while the individual marker systems only partially reflected the actual relationships between the lines, a joint processing of the genetic markers, supplemented with morphological data, revealed a close correlation between the groups formed on the dendrogram and the genetic background.

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Availability of markers that distinguish commercially important premium Basmati rice varieties from cheaper Basmati or non-Basmati indica rice varieties is of interest to exporters, commercial suppliers and consumers to ensure the varietal purity of Basmati rice supplies. In this study, a fingerprint database of 27 rice varieties including commercially important traditional Basmati (TB), cross-bred (evolved) Basmati and some non-Basmati indica rice varieties has been prepared using 50 microsatellite markers. A total of 271 electromorphs (alleles) were detected at 50 SSR (simple sequence repeat) loci, 92 of which were observed only in 2–10 of the 16 Basmati rice varieties. Notably, 7–10 of the sixteen Basmati rice varieties had the same Basmati specific electromorphs at RM562, RM551 and RM547 loci. Alarge number of unique (22) and null (16) electromorphs were noticed in Basmati rice varieties. A combination of four SSR markers (RM224, RM248, RM547 and RM594) can be used to differentiate all the 27 rice varieties. Specific SSR markers have been identified for the authentication of Premium Basmati rice cultivars such as Taraori Basmati (RM547, RM594 and RM511), Basmati 370 (RM252, RM426 and RM527), Karnal Local (RM248, RM423 and RM488) and Pusa 1121 (RM252, RM400 and RM410), and for the detection of adulterant like Sharbati (RM215, RM423 and RM259). SSR database reported here, shall broaden the list of SSR markers already recommended for varietal identification and detection of adulteration in Basmati rice supplies.

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Pre-harvest sprouting (PHS) in bread wheat (Triticum aestivum L.) is one of the major abiotic constraints influencing production of high quality grain. Selection for pre-harvest sprouting (PHS) resistance in bread wheat (Triticum aestivum L.) in early generations is difficult because it is expressed as a quantitatively inherited trait and subject to environmental effects. The objectives of this study were to validate a major quantitative trait locus (QTL) for PHS resistance on chromosome 4A in bread wheat and to isolate near-isogenic lines for this QTL using marker-assisted selection. A total of 60 Canadian wheat cultivars and experimental lines were screened with three SSR markers in a QTL region for PHS resistance. The SSR markers DuPw004, barc170 and wmc650 explained 67%, 75% and 60% of total variation in germination (%), respectively, among different wheat genotypes. Marker assisted back crossing with DuPw004 reduced the population size in BC1F1 and BC2F1 generation by 41% and 59%, respectively. A survey of pedigrees of different genotypes revealed that the parental line RL4137 is a major source of increased PHS resistance in a number of western Canadian wheat cultivars. Microsatellite markers (DuPw004, barc170 and wmc650) will be useful for plant breeders to pyramid QTL from different PHS resistance sources.

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Aegiolops kotschyi cytoplasmic male sterile system often results in part of haploid plants in wheat (Triticum aestivum L.). To elucidate the origin of haploid, 235 wheat microsatellite (SSR) primers were randomly selected and screened for polymorphism between haploid (2n = 3x = 21 ABD) and its parents, male-sterile line YM21 (2n = 6x = 42 AABBDD) and male fertile restorer YM2 (2n = 6x = 42 AABBDD). About 200 SSR markers yielded clear bands from denatured PAGE, of which 180 markers have identifiable amplification patterns, and 20 markers (around 8%) resulted in different amplification products between the haploid and the restorer, YM2. There were no SSR markers that were found to be distinguishable between the haploid and the male sterile line YM21. In addition, different distribution of HMW-GS between endosperm and seedlings from the same seeds further confirmed that the haploid genomes were inherited from the maternal parent. After haploidization, 1.7% and 0.91% of total sites were up- and down-regulated exceeding twofold in the shoot and the root of haploid, respectively, and most of the differentially expressed loci were up/down-regulated about twofold. Out of the sensitive loci in haploid, 94 loci in the shoot, 72 loci in the root can be classified into three functional subdivisions: biological process, cellular component and molecular function, respectively.

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A reborn interest has occurred during the last decade toward wheat landraces for broadening genetic basis of modern wheat cultivars. The investigation of molecular traits within and between existing landraces of wheat can help scientists to develop appropriate strategies for their efficient maintenance and exploitation. The present study dealt with the gliadin characterization of forty-seven wheat landraces collected from wheat mainly planted areas of China, each of which was represented by a sample of at least 43 individuals. Twelve accessions selected on the basis of gliadin analysis were investigated further using 21 SSR markers. The results proved that landraces of wheat are a mixture of variable individuals genetically distinguishable from each other. Twelve of the analyzed 47 accessions were observed to be homogeneous, while 35 (74.5%) of them were heterogeneous in their gliadin composition. In total, 122 gliadin pattern were observed. On average, 10.1% (Gst) of the total variation arose from differentiation among regions, and 89.9% was attributed to within-region variation. Furthermore, nineteen of the 21 SSR markers were polymorphic across all the populations. The total number of the amplified DNA products was 110, with a mean of 6.11 alleles per locus. The values of genetic diversity within each landrace population varied from 0.006 to 0.351. Implications for the management of this valuable genetic resource are discussed.

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A quick and reproducible tool for cultivar identification is useful to assess in certified seed production programs and to resolve legal conflicts. Simple Sequence Repeats (SSRs) have been the elected markers to carry out cultivar identification studies. The main aim of this research was to define the minimum number of SSR markers to distinguish 80 durum wheat cultivars. Preliminary, an analysis of 11 SSRs informativeness was carried out on a subset of 28 durum wheat cultivars. The discriminating ability of each primer was estimated both with Polymorphism Information Content (PIC) and with Resolving power (Rp). Rp resulted the best parameter for assessing the discriminatory power of SSR primers (r=0.94***; P≤0.001). The marker Xwmc597 was able to discriminate all the 28 cultivars. Successively, 80 genotypes were analysed using three SSR markers with the higher Rp value. Two SSRs were able to distinguish all the 80 genotypes. Particularly, Xwmc597 was able to distinguish 69/80 genotypes while Xwmc415 identified the other cultivars. An identification key was obtained combining the data of these two markers.

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