Current knowledge and practices related to seed transmission of sugarcane pathogens and movement of seed

Abstract

Sugarcane breeding programs benefit from sharing genetic resources. Traditionally, this has been accomplished by exchanging vegetative planting material of clones of interest. Diseases can be spread during this process, and quarantines were established to enable continued sharing of germplasm while minimizing the risk of pathogen introduction. The inclusion of sensitive pathogen assays in quarantine operations has greatly reduced this risk, but sugarcane quarantines are expensive and time consuming. The exchange of seed offers another means to obtain genes of interest. There has been minimal movement of seed because plant growth, crossing and selection are required to introgress new genes, and there is uncertainty about the threat of seed transmission of pathogens. A survey of different sugarcane industries was undertaken to determine the current practices and experience with seed movement and pathogen transmission. Some industries have decided that the potential benefits of seed exchange outweigh the risks of seed transmission of pathogens. Levels of precautions being taken to attempt to prevent pathogen introduction vary widely. There is currently no evidence of seed transmission of pathogens in sugarcane. Most pathogens detected have been external contaminants. The morphology of sugarcane seed facilitates external contamination by microorganisms. Research is attempting to expand knowledge about the potential for actual seed transmission by different viruses and bacteria.