First report of shoot proliferation of bleeding heart (Dicentra spectabilis) in Poland, associated with phytoplasma infection

Dicentra spectabilis (Bleeding heart or Lady's locket; Fumariaceae) is native to Siberia and Japan. Plants have attractive flowers and are produced for temperate, partly-shaded gardens and as a cut flower crop. D. spectabilis is propagated by tuber pieces, shoot and leaf cuttings or by seeds. Symptoms of sprout and shoot proliferation, along with small reddened or chlorotic leaves, were common on D. spectabilis plants cvs. Alba and Rosea grown in a commercial nursery in Skierniewice during 2001.

Examination of ultra-thin tissue sections by electron microscopy revealed severe necrosis of phloem sieve tube elements in shoots and roots of symptomatic D. spectabilis plants. Phytoplasmas were readily observed in sieve elements and occasionally in phloem parenchyma cells of diseased plants but were not evident in asymptomatic plants. No other pathogens were observed in diseased Dicentra plants.

Nucleic acids were extracted from sprouts, roots and leaves of diseased plants (three of each cultivar) and from symptomless plants (one per cultivar), as previously described (Ahrens & Seemüller, 1992). Extracts were assessed by polymerase chain reaction (PCR) assays employing phytoplasma universal rRNA primer pair P1/P7 and resulting products were reamplified using nested 16S rRNA primer pairs fA/rA, R16mF2/R16R2 or phytoplasma group 16SrI-specific primers R16(I)F1/R1. Phytoplasma identification was accomplished by restriction fragment length polymorphism (RFLP) analysis of R16mF2/R16R2-primed PCR products digested with AluI, HhaI, MseI or RsaI endonucleases. Products were generated by direct PCR exclusively from diseased Dicentra plants and by nested PCR from both diseased and symptomless plants. RFLP patterns indicated that plants were singly infected by either aster yellows subgroup 16SrI-B or subgroup 16SrI-A phytoplasmas. In Poland, 16SrI-B subgroup strains affect several other ornamental crops including rose and magnolia plants (Kamińska et al., 2001; Kamińska et al., 2003). This is the first report of a phytoplasma disease of Dicentra plants and also the first record of a 16SrI-A subgroup phytoplasma in Poland.