João Messias dos Santos

Genetic similarity among genotypes of sugarcane estimated by SSR and coefficient of parentage

The aim of this study was to analyze the genetic similarity in commercial cultivars of sugarcane from the breeding program cultivars RB (Republic of Brazil), using SSR markers and coefficient of parentage. Eighteen microsatellite markers were used to estimate genetic similarity in 30 genotypes and coefficient of parentage was estimated in 28 accessions. Eighteen primer pairs produced an average of 3.2 alleles, the level of polymorphism (PIC value) ranged from 0.34 to 0.78 in SMC248CG and SCC2 primers, respectively. The parentage coefficient was high among cultivars, with a mean of 0.14, suggesting high relationship among the cultivars. The results here suggest that to analyzed accessions, there is a high genetic similarity which could reduce the genetic gain in breeding. However, crosses among genotypes of sugarcane produce a high variability in the progenies, suggesting a combination between the genomes of species that originated the current cultivars.

The potential of the energy cane as the main biomass crop for the cellulosic industry

The last century was the scene of an extraordinary social and economic development of mankind. This development had the fossil energy as one of its pillars. The discovery of petrol led the society to shape a development model highly dependent on this source of energy, which has finite resources and also promotes a big increase on the greenhouse gases, with unforeseeable consequences for the human beings as well as the entire life. It is imperative that we change the pillars of energy from fossil to renewables that will be more sustainable and less aggressive to the environment. One of the sources of this new energy platform, probably the best, is biomass. Fibrous plants bring several advantages and fit well within the requirements deemed important to be elected as producers of biomass. Among these characteristics we have the high processing capacity of solar energy into biomass, fast growth, long-term canopy, possibility of large-scale production. Despite of that this plants are adapted to suboptimal environments that allows its production not compete with food production because it requires less energy input, bringing marginal lands into production with its all social-benefit consequences. Among the fibrous plants, SUGAR CANE or, better, ENERGY CANE has one of the biggest potential for biomass productions. Results from several breeding programs has showing the high biomass potential of energy cane over other biomass crops like sorghum, elephant grass and eucalyptus.

New Polymorphic EST-SSR Markers in Sugarcane

New polymorphic SSR markers in sugarcane has potential usefulness to studies genetic diversity, genetic mapping, DNA fingerprinting and determination offspring as true hybrids, selfing or contaminant in germplasm from breeding program. SSR markers can be obtained in several ways, and the search for SSR-EST sequences an alternative with significant results. The aim of this study was to develop highly polymorphic SSR markers for germplasm studies in sugarcane. Di- tri- and tetra-nucleotide sequences were mined in the TGI bank and 53 EST-SSR markers developed. These markers were analyzed in five genotypes and showed to be highly polymorphic, with the PIC ranging between 0.48 and 0.95 with a mean of 0.86. The discriminatory power ranged from 0.35 to 0.94 with a mean of 0.82 and the genetic similarity was high in the accessions evaluated.

Production and performance of sugarcane seeds (caryopses) from different hybridizations involving RB92579

A major challenge in sugarcane breeding program is the obtaining of enough number of seeds (caryopses) for the development of new improved cultivars. Genotypes differ in their function as pollen recipient and pollen donor, which also affect the seed performance. Thus, the aim of this study was to verify the production and performance of sugarcane seeds from different hybridizations involving RB92579 as pollen recipient and pollen donor. Twelve bi-parental crossings were carried out involving RB92579 and other different genotypes randomly chosen. Seed production potential was evaluated by percentage of fertile spikelets and caryopsis fresh weight. The seed physiological potential was determined by evaluating germination and vigor (index of germination rate, number of normal seedlings per gram of fuzz, and seedling dry weight). The results showed better performance for RB92579 as pollen donor for all characteristics studied. Therefore, RB92579 sugarcane cultivar should be used as pollen donor during hybridizations, condition that permits a greater production and physiological performance of seeds for the sugarcane breeding programs.