First report of Streptomyces acidiscabies causing potato scab in China

Abstract

In spring 2004, potato scab disease was observed on potato tubers (Solanum tuberosum cv. Favorita) at approximately 5–10% incidence in fields in Shandong province, China. Scabby tubers had brown, superficial or pitted corky lesions that were somewhat different from typical symptoms (for example, superficial, raised or pitted lesions) of potato scab caused by Streptomyces scabies. Both traditional and PCR-based methods were employed to identify the causal agent. A Streptomyces sp. strain CPS-3 was isolated from the lesion of a scabby potato tuber on oatmeal agar. It produced rectiflexuous spore chains, and the spores were white with smooth surface and 0AE4–0AE5 · 0AE9–1AE1 lm in size. The strain did not produce melanin on tyrosine-peptone-yeast extract agar medium, but produced diffusible yellow pigments, utilized all the International Streptomyces Project (ISP) sugars as single carbon sources (Shirling & Gottlieb, 1966), and L-hydroxyproline, L-histidine as sole nitrogen sources but not L-methionine. It grew at pH 4AE0 and was susceptible to phenol (0AE1%) and crystal violet (0AE5 lg ⁄ mL), but not to penicillin (10 IU ⁄ mL) and streptomycin (20 lg ⁄ mL). It did not produce H2S. The 16S rRNA sequence of the strain was amplified using the primers S1 (5¢CATTCACGGAGAGTTTGATCC-3¢) and S2 (5¢-AGAAAGGAGGT GATCCAGCC-3¢). The resulting 1460 bp sequence (GenBank Accession No. AY621376) had the highest similarity (99AE8%) with S. acidiscabies type strainATCC 49003 (AB026220). The strain is identical to S. acidiscabiesbasedon theabovecharacteristics (LambertL Loria et al., 1997) but this is the first report of S. acidiscabies causing potato scab in China.