DETECTION OF 'CANDIDATUS PHYTOPLASMA ASTERIS' INFECTION IN BRASSICA SPP. PLANTS WITH FLOWER BUD FAILURE IN POLAND

Two type of symptoms of unknown origin were observed in glasshouse grown Brassia spp. plants in Poland. The affected Brussels sprout (Brassica oleraceae L. var. gemmifera DC) plants were stunted, with severely malformed leaves and flower bud failure, while the interspecific crosses of B. oleracea x B. napus exhibited production of green foliage and complete flower bud failure. The presence of phytoplasma in Brassica hybrids showing failure of flower buds was demonstrated by direct PCR assay employing phytoplasma universal rRNA primer pair - P1/P7. The presence of phytoplasma in Brussels sprout plants was demonstrated by nested PCR employing primer pairs - P1/P7 followed by R16F2n/R16R2. Sequences of phytoplasmas found in the tested Brassica spp. plants were identical and they showed more than 98.5% similarity with the corresponding fragments of sequence of phytoplasmas classified in phylogenetic group 16SrI, ‘Candidatus Phytoplasma asteris’.