Definitive identification of orange rust of sugarcane caused by Puccinia kuehnii in Cuba

Abstract

During a survey of Streptomyces infecting potato (Solanum tuberosum) in the UK, two strains were isolated which were distinct from S. scabiei, which is already known to occur in the UK. Amplification with speciesspecific PCR primers (Wanner, 2006) identified these strains as S. turgidiscabies (Miyajima et al., 1998) and S. acidiscabies (Lambert & Loria, 1989), and the same PCR assay indicated presence of these species in several fields in England and Scotland. Representative strains were deposited in the UK National Collection of Plant Pathogenic Bacteria as NCPPB4444 and NCPPB4445 respectively. Strain NCPPB4444 was isolated from cv. Desiree tubers, grown in South Yorkshire, England, with large erumpent lesions. A majority of tubers from the same seed stock in the same field exhibited similar symptoms. Strain NCPPB4445 was isolated from cv. Maris Piper, grown in Aberdeenshire, Scotland, on soil of pH 5AE4, where disease incidence was high and dry flaky scab symptoms typically covered almost 100% of the tuber surface. Both strains were isolated on NPPC medium (Schaad et al., 2001), producing small white sporulating colonies.Inoculation of radish seedlings with both strains resulted in severe necrosis within 2 weeks. Potato minitubers (cv. Maris Piper) grown in pots containing sterilized compost were inoculated with 250 mL suspensions of Streptomyces (approx. 10 7 cfu mL )1 ) when leaves first emerged. After 12 weeks, lesions were observed on tubers in each of five replicate pots. Uninoculated controls were free from symptoms. Bacteria recovered from lesions were confirmed by PCR to be the same species as the inocula. To confirm species identity, a portion of the 16S rDNA of each original strain was sequenced. The sequence from strain NCPPB4444 (GenBank Accession No. FJ817424) was 100% identical to that of S. turgidiscabies type strain ATCC700248. The sequence from strain NCPPB4445 (FJ804480) was 100% identical to that of the S. acidiscabies type strain ATCC49003. Although several Streptomyces spp. are known to cause common scab of potato, the species identity is of significance as different diagnosis and control methods may apply. This is the first report in the UK of common scab of potato caused by S. turgidiscabies or S. acidiscabies. Acknowledgements

Morphological and molecular characterization of Puccinia kuehnii, the causal agent of sugarcane orange rust, in Cub

“…Orange rust is a relatively new disease in Cuba (Pérez-Vicente et al, 2010), where environmental conditions, such as frequent alternation between rainy and dry days with prolonged dew periods, favor infection, spore production and disease spread. In addition, the diverse varietal composition of sugarcane planted on the island could favor pathogen variability, although no previous study has evaluated pathogen diversity in Cuba.…”

Spectral signature of brown rust and orange rust in sugarcane

“…The orange rust of sugar cane (Puccinia kuehnii (W. Krüger) E. J. Butler) is a parasite that infects only species and hybrids of the genus Saccharum. The orange rust is one of the most important at present, since it causes the decrease in the agricultural yield of the plant, with the consequent economic losses for the producers [8][9][10][11][12].…”

Foliar application of manganese increases sugarcane resistance to orange rust

“…Orange rust, caused by Puccinia kuehnii, is a widespread fungal disease (Chavarr ıa et al, 2009;Perez-Vicente et al, 2010) that leads to significant reductions in sugarcane (Saccharum spp.) yields and profits.…”