Journal of Plant Pathology Archive

Abstract:

During February-April 2013, symptoms of yellowing, chlorosis and mosaic were observed in approximately 50% of the surveyed jack bean [Canavalia ensiformis (L.) DC.] plants in Las Tunas province (Cuba). Twenty-one leaf samples of plants with symptoms and 10 without symptoms were col- lected. Total DNA was extracted and used as a template in a nested PCR assay to amplify the phytoplasma 16S rDNA gene with primer pairs R16mF1/R16mR1 and R16F2n/ R16R2. Products of the expected size (1,246 bp) were amplified for all symptomatic but not from symptomless plants. Restric- tion profiles after amplicon digestion with HaeIII, HhaI and KpnI endonucleases were all identical to each other and to those of reference phytoplasma strains related to ‘Candida- tus Phytoplasma asteris’ (16SrI-B subgroup) (Lee et al., 1998). Three selected PCR products were cloned into the pGEM-T Easy Vector (Promega, USA) and three inserts of each clone were further sequenced in both directions (Macrogen, South Korea). The sequences of the clones were identical and one of them was deposited in GenBank under accession No. KR232799). BLASTN search and alignment of related phyto- plasma sequences using the MUSCLE algorithm implemented in MEGA v. 5.0 showed that Canavalia yellows phytoplasma (CPY) had the highest nucleotide sequence identity of 99.8% with several sequences of phytoplasma strains related to ‘Ca. P. asteris’ [Aster yellows group (16SrI-B subgroup)] in different hosts. In Cuba, ‘Ca. P. asteris’ has been also reported affecting other legumes such as broad bean (Vicia faba L.) (Arocha et al., 2007) and common bean (Phaseolus vulgaris L.) (Zamora et al., 2012). To our knowledge, this is the first evidence of a phy- toplasma associated with jack bean in Cuba and worldwide.