Leaf-, Panel- And Latex-expressed Sequenced Tags From The Rubber Tree (hevea Brasiliensis) Under Cold-stressed And Suboptimal Growing Conditions: The Development Of Gene-targeted Functional Markers For Stress Response.

Hevea brasiliensis is a native species of the Amazon Basin of South America and the primary source of natural rubber worldwide. Due to the occurrence of South American Leaf Blight disease in this area, rubber plantations have been extended to suboptimal regions. Rubber tree breeding is time-consuming and expensive, but molecular markers can serve as a tool for early evaluation, thus reducing time and costs. In this work, we constructed six different cDNA libraries with the aim of developing gene-targeted molecular markers for the rubber tree. A total of 8,263 reads were assembled, generating 5,025 unigenes that were analyzed; 912 expressed sequence tags (ESTs) represented new transcripts, and two sequences were highly up-regulated by cold stress. These unigenes were scanned for microsatellite (SSR) regions and single nucleotide polymorphisms (SNPs). In total, 169 novel EST-SSR markers were developed; 138 loci were polymorphic in the rubber tree, and 98 % presented transferability to six other Hevea species. Locus duplication was observed in H. brasiliensis and other species. Additionally, 43 SNP markers in 13 sequences that showed similarity to proteins involved in stress response, latex biosynthesis and developmental processes were characterized. cDNA libraries are a rich source of SSR and SNP markers and enable the identification of new transcripts. The new markers developed here will be a valuable resource for linkage mapping, QTL identification and other studies in the rubber tree and can also be used to evaluate the genetic variability of other Hevea species, which are valuable assets in rubber tree breeding.

CARACTERÍSTICAS DE QUALIDADE DO CONTRAFILÉ (m. L. dorsi) DE TOUROS JOVENS DA RAÇA NELORE

Quality traits of boneless rib cut (L. dorsi muscle) from Nelore young bulls. To study the meat quality traits of Nelore breed young bulls, and the effect of age (690-780 days) on them, 113 animals were slaughtered after 109 days of intensive feeding with 20% concentrate and 80% roughage. All the carcasses were graded at the slaughter floor by the Federal Inspection and chilled for 24 hours (Tinitial=5°C, Tfinal=2°C). Fifty one half carcasses (right side), type B - B R A S I L `s grading system - from animals of 23 to 26 months were boned and separated into commercial cuts. Two steaks (2.5cm thick) were removed from each boneless rib cut (m. L. dorsi), vacuum packaged and aged for 7 days (0-2°C). The pH varied from 5.44 to 5.83 and only two samples had pH ³ 5.70. The L* (brightness) average value was 34.85. The water and fat content were 75.65% and 1.71%, respectively. The average WB shear force was 6.70kg, and it was not affected by age (690-734 days), but presented a trend (t test, p=0.22) for increasing values between 735 and 780 days. Animal age did not affect other quality traits (t test, p>0.20). It was concluded that the rib cut from Nelore young bulls may not have a good acceptability in exigent markets, and that carcasses graded B, presumed to be the best grade, do not necessarily present the best meat quality characteristics.