Identification of sweet potato little leaf phytoplasma associated withVigna unguiculatavar.sesquipedalisandLycopersicon esculentum

Abstract

Vigna unguiculata var. sesquipedalis (snakebean) and Lycopersicon esculentum (tomato) plants with phytoplasma-like symptoms were found in the horticultural region in Broome, Western Australia. The symptoms on snakebean included ‘witches’ broom’ and proliferation of small leaves, and on tomato they varied from phyllody and ‘big bud’ to ‘witches’ broom’ and proliferation of small leaves. Using universal primers for phytoplasmas, the complete 16S rRNA gene and intergenic spacer region, and part of the 23S rRNA gene were amplified by PCR. Sequence analysis identified that the agent associated with the symptoms was a strain of sweet potato little leaf strain V4 (SPLL-V4) phytoplasma (16SrII group, strain of ‘Candidatus Phytoplasma australiense’). SPLL phytoplasma has not been reported before in snakebean or tomato in this isolated agricultural region.