2012 Annual Report
1a.Objectives (from AD-416):
The long-term objective of this project is to reduce the impact of diseases on the productivity of the domestic sugarcane (Saccharum hybrids) industry by providing assistance to sugarcane breeders in identifying parental clones with resistance, improving the efficiency of selection for disease resistance traits, and providing the industry the information needed to guard against more virulent strain shifts and/or new pathogens. Our primary objectives will be to identify and develop germplasm with resistance to the major diseases affecting sugarcane, to identify the genetic variability among endemic pathogen populations, and to monitor the Louisiana sugarcane industry for the emergence of new pathogens. Disease resistant germplasm will be sought from among different taxa of Saccharum and related genera. Molecular markers that are linked to genes for disease resistance will be identified. Molecular approaches will be used to enhance the studies of host and pathogen genetics.
1b.Approach (from AD-416):
To identify and develop germplasm with resistance to the major diseases affecting sugarcane in the United States, highly domesticated and wild clones of sugarcane and near relatives will be evaluated for resistance to the major sugarcane diseases following either natural and infections or artificial inoculation. To identify molecular markers that are linked to genes for disease resistance, polymerase chain reaction (PCR) based methods such as AFLP, SSR, or TRAP will be used to identify genetic markers closely linked to the resistance genes. Priority will be given to finding markers for smut, then ratoon stunting disease (RSD) and mosaic. Genotypic and phenotypic expressions of variability within populations of pathogens will be used to identify the genetic variability among pathogen populations and determine the distribution of races, strains, or other biotypes. The domestic sugarcane industry will be monitored for the introduction of exotic pathogens.
This is the final report for the project 6410-22000-013-00D, which expired in January 2012. There was 3 months between the beginning of FY 2012 and the expiration of this project. Milestones for this project were met prior to the start of FY 2012; some continuing field experiments with FY 2012 milestones were initiated between October 1, 2011 and the initiation of the new project. See details of new research project (6410-22000-016-00D).
Progress on this project focused on identifying and developing germplasm with resistance to the major diseases of sugarcane, the identification of genetic variability among endemic pathogen populations, and the monitoring of the sugarcane industry for the emergence of new pathogens. Following screening of clones in the field by artificial inoculation and observations of variety trials, pathology recommendations were made annually at the variety advancement and variety release meetings. Screening protocols were improved to make them more accurate and efficient.
A visual representation, known as a linkage map, of the genes in sugarcane and how they are organized was constructed using a population of progeny from seed produced by the selfing of the sugarcane variety, LCP 85-384. The map was improved each year of the project by adding details with specialized markers. By analyzing the map, geneticists will be able to associate regions of the map with genes that control resistance or susceptibility to several important sugarcane diseases.
Genetic variability of Sorghum mosaic virus (SrMV), the virus causing sugarcane mosaic in Louisiana, was analyzed each year. Following the discovery of orange rust in Florida in 2007, surveys were made of the Louisiana sugarcane industry to determine if the pathogen was present in the state using spore traps and sentinel plots.
Disease symptoms not typically produced by diseases present in Louisiana were investigated to determine if they were produced by a new disease previously unreported in Louisiana.