Molecular Detection of Diverse Leifsonia Strains Associated With Sugarcane

Abstract

Leifsonia xyli subsp. xyli, causal agent of ratoon stunting disease (RSD) of sugarcane (Saccharum interspecific hybrids), is the most well-known member of the Microbacteriaceae genus Leifsonia. However, the presence of other Leifsonia strains associated with sugarcane has not been reported. A total of 697 Australian and 40 Indonesian sugarcane fields were screened by leaf sheath biopsy (LSB) PCR using primers specific for L. xyli subsp. xyli, in addition to primers designed to amplify DNA from other members of the genus Leifsonia. While L. xyli subsp. xyli was detected in 126 fields, a total of 37 distinct and novel Leifsonia and non-Leifsonia strains were detected in 116 fields. Representatives of these strains were also detected in multiple samples of expressed xylem sap. Sequencing and phylogenetic analyses demonstrated the presence of a broad complex of novel Leifsonia strains, in addition to strains closely related to the recently erected Cnuibacter genus. Attempts to isolate Leifsonia strains were unsuccessful; however, one strain related to Cnuibacter was recovered from expressed xylem sap. Among the genetically diverse lineages discovered, identical genotypes were present in multiple sugarcane varieties growing in disparate regions in different years, strongly suggesting an ongoing association with sugarcane. The epidemiological significance of these strains is unknown, but there is evidence that they can interfere with serological and microscopic RSD diagnostics, and there is the potential that they may represent new and distinct pathologies of sugarcane.

Impact of Leifsonia xyli subsp. xyli titer on nutritional status, and metabolism of sugar cane

“…Pots were watered daily throughout the experiment to the eld capacity. At 60 DAP bacterial titers were quanti ed from a leaf sheath according to Young et al (2017). Bacterial titers in the plant was performed by qPCR according to Carvalho et al (2016).…”

Turning a Blind Eye to Ratoon Stunting Disease of Sugarcane in Australia

“…xyli, or related bacteria that can infect the xylem vessels. The discovery of a range of other Leifsonia strains associated with sugarcane should be of significant concern to the sugar industry (Young and Nock 2017). Although their pathogenicity has not yet been established, there is evidence that they are resistant to thermotherapy and have been transmitted throughout the existing plant improvement and variety release program.…”

“…It is likely that the proportional losses to RSD are higher in industries that lack the management infrastructure available in Florida or Australia. For example, although only 40 fields were surveyed, the minimum inferred RSD rate in East Java was 50% (Young and Nock 2017). The insidious nature of the disease led respected Bureau of Sugar Experiment Stations (BSES) pathologist Graham Hughes to conclude that RSD is the most economically significant disease of sugarcane (Hughes 1974).…”