Characterization of a Phytoplasma Associated with Cabbage Yellows in Iran

Abstract

In 2001, a disease tentatively named Iranian cabbage yellows (ICY) was observed in cabbage fields of Zarghan (Fars Province, Iran). The major symptoms of the disease were yellowing, little leaves, plant stunting, opening of the head, and proliferation of the buds at the base of the stem into a witches'-broom. Among leafhoppers collected in cabbage fields, only Circulifer haematoceps transmitted the ICY agent. The disease agent was transmitted by the leafhopper from cabbage to cabbage, cauliflower, rape, and periwinkle, causing phytoplasma-type symptoms in these plants. Polymerase chain reaction (PCR) using phytoplasma-specific primer pair P1/P7 and nested PCR using P1/P7 and R16F2n/R16R2 primer pairs amplified products of expected size (1.8 and 1.2 kb, respectively) from symptomatic cabbage plants. Both restriction fragment length polymorphism (RFLP) of nested PCR products (1.2 kb) and phylogenetic analyses of 16S–23S rDNA spacer region sequence indicated that the ICY phytoplasma had the closest relationship to subgroup A members of the clover proliferation group, including beet leafhopper-transmitted virescence agent, ‘Candidatus Phytoplasma trifolii’, Columbia Basin potato purple top phytoplasma, and vinca virescence phytoplasma. Cabbage is reported as a new natural host to the 16SrVI group of phytoplasmas.

Failure of Flower Bud Formation in Brassica Plants Associated with Phytoplasma Infection

“…These results are in disagreement with our previous findings concerning phytoplasma infection in Brussels sprout (Kamiński et al, 2010) as well as with the results of Wang & Hiruki (2001) and Olivier et al, (2006), who were not able to detect the aster yellows phytoplasma in tested canola plants by direct PCR in Canada. On the contrary to those results, in Italy and Greece (Bertaccini et al, 1998;Marzachi et al, 1999;Maliogka et al, 2009), the USA (Lee at al., 2003) and Iran (Salehi et al, 2007) the titre of phytoplasmas in Brassica spp. plants was high and they were detectable by direct PCR.…”

“…In 2000, in southwestern Texas, about 5% of cabbage plants displayed symptoms of purple leaf discoloration and sprouts proliferation characteristic of phytoplasma (Lee et al, 2001;2003). Very recently, in Iran, cabbage disease yellows damaged cabbage up to 50% in certain fields (Salehi at al., 2007).…”

“…Most phytoplasmas associated with yellows-type symptoms of canola plants in Canada belong to subgroup 16SrI-A or 16SrI-B (Wang & Hiruki, 2001;Olivier et al, 2006), while phytoplasma associated with Iranian cabbage disease is related to 'Ca. Phytoplasma trifolii', subgroup 16SrVI-A (Salehi at al., 2007). Very recently, Kamiński et al (2010) reported the new disease of stunting, severe leaf malformation and failure of flower buds in Brussels sprout plants in Poland, associated with aster yellows phytoplasma infection.…”

Identificação molecular de fitoplasmas associados ao enfezamento do repolho e análise epidemiológica da doença

“…Salehi et al (2007) conduziram estudos sobre transmissão por cigarrinhas (Circulifer haematoceps) e conseguiram transmitir a doença do repolho para outras plantas de repolho e para plantas de outras espécies, incluindo a vinca (Catharantus roseus). Através de PCR utilizando os pares de primers R16 P1/P7 e R16F2n/R2 em PCR duplo, obtiveram amplificação de fragmentos de 1,2 kb, típicos de fitoplasmas.…”

“…Outros relatos sobre a ocorrência de vetor do fitoplasma associado ao enfezamento foram feitos mais recentemente nos Estados Unidos e no Oriente Médio (LEE et al, 2003; SALEHI et al, 2007). Um trabalho interessante foi desenvolvido por Lee et al (2003), no qual o mesmo fitoplasma detectado em repolho foi encontrado em cenoura em áreas próximas das quais havia ocorrido epidemia.…”