To contribute to our understanding of the genome complexity of sugarcane, we undertook a large-scale expressed sequence tag (EST) program. More than 260,000 cDNA clones were partially sequenced from 26 standard cDNA libraries generated from different sugarcane tissues. After the processing of the sequences, 237,954 high-quality ESTs were identified. These ESTs were assembled into 43,141 putative transcripts. Of the assembled sequences, 35.6% presented no matches with existing sequences in public databases. A global analysis of the whole SUCEST data set indicated that 14,409 assembled sequences (33% of the total) contained at least one cDNA clone with a full-length insert. Annotation of the 43,141 assembled sequences associated almost 50% of the putative identified sugarcane genes with protein metabolism, cellular communication/signal transduction, bioenergetics, and stress responses. Inspection of the translated assembled sequences for conserved protein domains revealed 40,821 amino acid sequences with 1415 Pfam domains. Reassembling the consensus sequences of the 43,141 transcripts revealed a 22% redundancy in the first assembling. This indicated that possibly 33,620 unique genes had been identified and indicated that >90% of the sugarcane expressed genes were tagged

The genome sequence of Leifsonia xyli subsp. xyli, which causes ratoon stunting disease and affects sugarcane worldwide, was determined. The single circular chromosome of Leifsonia xyli subsp. xyli CTCB07 was 2.6 Mb in length with a GC content of 68% and 2,044 predicted open reading frames. The analysis also revealed 307 predicted pseudogenes, which is more than any bacterial plant pathogen sequenced to date. Many of these pseudogenes, if functional, would likely be involved in the degradation of plant heteropolysaccharides, uptake of free sugars, and synthesis of amino acids. Although L. xyli subsp. xyli has only been identified colonizing the xylem vessels of sugarcane, the numbers of predicted regulatory genes and sugar transporters are similar to those in freeliving organisms. Some of the predicted pathogenicity genes appear to have been acquired by lateral transfer and include genes for cellulase, pectinase, wilt-inducing protein, lysozyme, and desaturase. The presence of the latter may contribute to stunting, since it is likely involved in the synthesis of abscisic acid, a hormone that arrests growth. Our findings are consistent with the nutritionally fastidious behavior exhibited by L. xyli subsp. xyli and suggest an ongoing adaptation to the restricted ecological niche it inhabits.

A study was made of the genetics of resistance to the soybean cyst nematode, race 3, in a population derived from crosses between the Brazilian soybean genotypes BR 90-4722 and FT-Cristalina. Crosses between the two parents were made, the F1 and F2 generations were obtained and the population was analyzed for the number of cysts found in each plant of each generation as well as the type of reaction to the nematode. The results showed that resistance to the cyst nematode in this soybean population is of a qualitative nature and conditioned by three genes, one dominant and two recessives. The heritability of the character was very high (0.96), with minimum environmental effect, which means that this population is suitable for the development of soybean cultivars resistant to the cyst nematode.
O presente estudo foi conduzido com o objetivo de estudar a genética da resistência de uma população de soja, derivada de cruzamentos entre os genótipos brasileiros BR 90-4722 e FT-Cristalina, ao nematóide do cisto da soja, raça 3. Foram efetuados vários cruzamentos entre os parentais, sendo obtidas as gerações F1 e F2, as quais foram analisadas considerando-se o número de cistos presentes em cada planta de cada geração, bem como a reação das plantas após as inoculações. Os resultados evidenciaram que a resistência ao nematóide do cisto nessa população de soja é de natureza qualitativa e governada por três genes, sendo um dominante e dois recessivos. A herdabilidade do caráter foi alta (0,96), com mínimo efeito ambiental, sugerindo que essa população é adequada para o desenvolvimento de genótipos de soja resistentes ao nematóide do cisto

-Stem canker caused by the fungus Diaporthe phaseolorum f. sp. meridionalis is a disease that limits soybean cultivation. Phenotypic evaluations aiming at disease resistance require labor-intensive processes, as for instance handling and transport of phytopathogens. The use of DNA markers in the selective procedures eases certain phases, besides being practical, safe and reliable. A RAPD fragment of 588pb was identified among bulks of resistant and susceptible plants in the cross BR92-15454 (R) x IAC-11 (S). Through co-segregation, the distance between the resistance locus and the fragment was estimated at 7.4 ± 2.1 cM, with a Lod max. of 23.072 (first year) and at 6.0 ± 3.4 cM with a Lod max. of 7.806 (second year). The fragment was converted into a SCAR marker and digested with enzyme

Four microsatellite sequences were tested in soybean DNA from cultivars and segregating genotypes. Three of them were close to the resistance locus rhg1 on molecular linkage group G (Satt309, Sat_168, Sat_163) and one was close to Rhg4 locus on group A2 (Sat_162). Progenies previously classified as cyst nematode (SCN) resistant and others with unknown reaction were tested, using the resistant cultivars Liderança, and Renasscença and the susceptibles 'Cristalina' and 'OCEPAR-4' as control. The best primer for resistance to SCN was Sat_162. Twenty segregant progenies tested with Sat_162 presented a 150 bp band for homozygous resistant genotypes and 200 bp for susceptible ones, and both for the heterozigous genotypes. Previous studies have shown that this microsatellite marker is efficient to select genotypes carrying Peking-derivative resistance. 'Peking' takes part in the in the genealogy of all segregant progenies evaluated in this study. Thus, the obtained results showed that Sat_162 distinguished resistant and susceptible soybean genotypes to SCN, race 3.