Internal amplification control of PCR for the Glu1-Dx5 allele in wheat.

One of the limiting factors in using dominant markers is the unique amplification of the target fragment. Therefore, failures in polymerase chain reaction (PCR) or non-amplifications can be interpreted as an absence of the allele. The possibility of false negatives implies in reduced efficiency in the selection process in genetic breeding programs besides the loss of valuable genetic material. Thus, this study aimed to evaluate the viability of a microsatellite marker as an internal amplification control with a dominant marker for the wheat Glu1-Dx5 gene. A population of 77 wheat cultivars/breeding lines was analyzed. Fourteen microsatellite markers were analyzed in silico regarding the formation of dimers and clamps. The biplex reaction conditions were optimized, and the Xbarc117 marker was selected as the internal amplification control with a Glu1-Dx5 marker in wheat. It was concluded that the Xbarc117 microsatellite marker was effective in the simultaneous amplification with a dominant Glu1-Dx5 marker, making biplex PCR viable in wheat for the studied markers.

High molecular weight glutenin subunits and the classification used in Brazilian wheat industry.

Industrial wheat quality flour is related to gluten amount in grain. This study aimed to evaluate the relationship between high molecular weight (HMW) glutenins obtained by SDS-PAGE and gluten strength (W) obtained by the alveograph test and cropping environmental effect on wheat flour quality for Brazilian industry. Fifty-one cultivars/breeding lines were evaluated in three environments. The W value and HMW glutenin score were evaluated by SDS-PAGE. The environment effects on wheat flour were also evaluated. There was a relationship between the W value used in wheat flour industrial classification and score 10 of HMW glutenins, but there was no relation with scores 9 or lower. Cultivars/breeding lines with score 10 of HMW glutenin are less susceptible to environmental effects and produce breeding type wheat flour (W value ≥300) of interest for industry. The cultivars/breeding lines with score 10 for HMW glutenins is the main choice for a wheat breeding program.

Genetic diversity in elite inbred lines of maize and its association with heterosis.

The objective of the current study was to apply molecular markers (microsatellites) in the analysis of genetic diversity of 48 lines of the elite maize germplasm stored in the bank of the Cooperativa Central de Pesquisa Agrícola - Coodetec, PR, Brazil, and estimate the correlation between genetic distance and heterosis and hybrid performance from the crosses among these maize lines. Forty-four random primers were used and amplification of 124 polymorphic fragments was obtained. The expected findings from the correlation of the yield and heterosis with the genetic distance were non-significant. However, the results suggested that data from the extreme distances could be used in breeding for more productive crosses and heterotic hybrids. Thereby, molecular markers are efficient tools for predicting hybrid performance.

Construction of a molecular database for soybean cultivar identification in Brazil.

The narrow genetic base of soybean makes cultivar characterization based on morphological descriptors difficult; this characterization is mainly done for registration and protection. Correct characterization of cultivars could be achieved through molecular markers, since the frequencies of each allele in the population are known. Consequently, we developed a molecular characterization method and initiated the construction of a molecular database for soybean cultivar identification. Thirty-two soybean cultivars were analyzed with 48 fluorescent-labeled microsatellite markers. The reactions were carried out in singleplex, and genotyping in quadriplex, using a capillary electrophoresis system in an automated sequencer. Probabilities of random identity and probabilities of random identity exclusion were calculated through estimated allele frequencies. A characterization profile was considered when the probability of random identity exclusion was equal or superior to 99.9999%. All steps of the experiment were doubled, using two independent sets of the same cultivar to evaluate the reproducibility of the method. A set of 13 microsatellite markers identified all 32 cultivars with 99.9999% certainty. The method was efficient and precise, with high reproducibility for cultivar characterization. These data are the beginning of a molecular database for soybean, and they can be used for cultivar characterization for registration and protection purposes and for cultivar identification in cases of intellectual property enforcement.

Heterotic groups in tropical maize germplasm by test crosses and simple sequence repeat markers.

The objectives of the present study were to determine heterotic groups of germplasm lines of tropical maize by test crosses and by simple sequence repeat (SSR) markers and to compare five grouping methods of heterogeneous maize. Sixteen lines of nine populations in the S5 generation were evaluated in test crosses with three testers. The results of four experimental trials over two years were used to group the lines by five methods: evaluation based on the hybrid mean in top-cross tests, hybrid index, genetic diversity by the Mahalanobis distance, genetic diversity by the Euclidean distance, and genetic diversity by SSR markers. The concordance of grouping by the Mahalanobis and Euclidean distance amounted to 87.50%, and the concordance of these methods and grouping by SSR markers was 56.25%. Grouping by SSR markers was consistent with the genealogy of the lines and is a useful procedure for the formation of heterotic groups of tropical maize lines.