Roberto Giacomini Chapola

Sugarcane improvement: how far can we go?

In recent years, efforts to improve sugarcane have focused on the development of biotechnology for this crop. It has become clear that sugarcane lacks tools for the biotechnological route of improvement and that the initial efforts in sequencing ESTs had limited impact for breeding. Until recently, the models used by breeders in statistical genetics approaches have been developed for diploid organisms, which are not ideal for a polyploid genome such as that of sugarcane. Breeding programs are dealing with decreasing yield gains. The contribution of multiple alleles to complex traits such as yield is a basic question underlining the breeding efforts that could only be addressed by the development of specific tools for this grass. However, functional genomics has progressed and gene expression profiling is leading to the definition of gene networks. The sequencing of the sugarcane genome, which is underway, will greatly contribute to numerous aspects of research on grasses. We expect that both the transgenic and the marker-assisted route for sugarcane improvement will contribute to increased sugar, stress tolerance, and higher yield and that the industry for years to come will be able to rely on sugarcane as the most productive energy crop.

Reaction of sugarcane varieties to orange rust (Puccinia kuehnii) and methods for rapid identification of resistant genotypes

Sugarcane orange rust was recently introduced into Brazil and its control is based on the use of resistant varieties. This study aimed to determine the reaction of Brazilian sugarcane varieties to the disease in the field and to compare artificial inoculation methods. Rust severity was assessed in 17 varieties at a 15-day interval. The maximum disease severity (MS%) and the area under the disease progress curve (AUDPC) were determined for each genotype. The artificial inoculation methods tested were: spraying of a spore suspension on 60-day-old plants in the greenhouse, or placing the spore suspension into the leaf whorl of 5-month-old field-grown plants. Nine out of the 17 varieties studied were resistant to the disease, including the most widely grown in new plantings, RB867515 and RB966928. Varieties RB72454, SP89-1115 and SP79-2233 were susceptible, while RB925211 and SP81-3250 were moderately susceptible. Varieties RB855156, RB92579 and SP83-2847 showed an intermediate reaction. Both inoculation methods correlated well with field results. Spray inoculation discriminates better the responses of the varieties and enables the evaluation of more disease variables. Leaf whorl inoculation allows the use of field-grown plants and generates results in a shorter time.

Breeding of Sugarcane

Sugarcane is the main source for sugar production and the most important crop for energy production, as well as for byproducts like ethanol and fibers in the world. With a complex genome, the plant has its species from crosses between species of the genus Saccharum, which were the basis for sugarcane breeding programs worldwide. The production of sugarcane has increased worldwide due to breeding programs that have developed more productive clones for specific uses and adapted to different climatic conditions. The future objective of breeding programs is to develop sugarcane with high productivity, high sucrose content, drought tolerance, and high production of ethanol and biomass, i.e., plants with high fiber content and with cell walls easily broken to favor the production of ethanol from bagasse, efficient plants with low nitrogen fertilizer use, and others, and consequently to reduce environmental impacts. Currently, the demand for products derived from sugarcane is consistently increasing; the ethanol byproduct has been pointed out as one of the important sources to feed the demand for renewable energy in fossil and nonrenewable fuel substitution programs in different countries around the world. This chapter describes the genetic improvement of sugarcane and its current goals.

Controle da podridão abacaxi da cana-de-açúcar por meio da pulverização de fungicidas em rebolos no sulco de plantio

Sugarcane pineapple disease, caused by the fungus Thielaviopsis paradoxa, can cause germination and yield decreases of up to 50% and 42%, respectively. The aim of this research was to assess the control of this disease through in-furrow fungicide application on seedpieces. Two experiments were installed in greenhouse and one under field conditions with this purpose. The substrate and the soil were infested with the pathogen before the sugarcane planting and the fungicides were sprayed on seedpieces immediately after the planting with a CO2 backpack sprayer. Seedpieces in-furrow spraying was effective in controlling the pineapple disease with certain fungicides, providing up to 12% yield recovery. Among the tested treatments, the fungicides pyraclostrobin + epoxiconazole; pyraclostrobin and propiconazole showed good potential for pineapple disease control.

RB965902 and RB965917 Early/medium maturing sugarcane varieties

The varieties RB965902 and RB965917 were developed for harvesting at the beginning to the middle of the sucrose extraction period (early/medium maturity) and released for the South-Central region of Brazil. In specific environments, the tons of Pol per area (sucrose yield) of these varieties is higher than of the commercial standard RB855453 and they are resistant to the main diseases of the crop.

Validação de marcadores moleculares associados à resistência à ferrugem marrom em cana-de-açúcar

ABSTRACT Brown rust caused by the fungus Puccinia melanocephala is an important disease affecting sugarcane ( Saccharum spp.) and is present in almost all growing areas. A major effect gene, Bru 1, was described as a durable resistance source in sugarcane against isolates of P. melanocephala . The aim of this study was to evaluate the efficiency of two molecular markers strongly associated with Bru 1 gene, R12H16 and 9O20-F4-RsaI, for prediction of genetic resistance to brown rust in sugarcane varieties. Thus, this study included 14 RB varieties, developed by RIDESA (Interuniversity Network for the Development of the Sugarcane Industry), which were among the 10 most cultivated varieties in the central-south region of Brazil in the period of 1974-2015. To evaluate the disease in the field an experiment was conducted in randomized blocks with four replicates. The severity of Barreto, F.Z.; Balsalobre, T.W.A. Chapola, R.G.; Hoffmann, H.P.; Carneiro, M.S. Validation of molecular markers associated with brown rust resistance in sugarcane.