EcoRI or HindIII-restricted DNA from phytoplasmas associated with tomato big bud (TBB) and sweet potato little leaf (SPLL-V4) was cloned into pBluescript and the recombinant plasmids were screened by reciprocal DNA hybridization with TBB- and SPLL-V4 DNA. Most of the recombinant plasmids hybridized to DNA of both phytoplasmas. Southern hybridization analysis of EcoRI- or HindIII-restricted TBB- and SPLL-V4 DNA with two TBB probes (pTBB32 and pTBB87) gave identical restriction patterns. Southern hybridizations of HindIII- or EcoRI digested DNA from 10 phytoplasma-positive field samples revealed a different restriction fragment pattern in two phytoplasmas from sweet potato. Three TBB probes which did not hybridize to SPLL-V4 were selected for Southern blot analysis of samples. The pTBB42 and pTBB78 hybridized to nine of the 10 TBB-symptomatic held samples producing identical patterns. pTBB88 contained extrachromosomal DNA and hybridized with two phytoplasmas from diseased sweet potato and perennial phlox;. The SPLL-V4-specific probe pH 21 hybridized to five field samples generating different restriction patterns. About 80 held samples were subjected to the polymerase chain reaction using primers deduced from pH21, pTBB32 and pTBB88, These phytoplasmas had been previously characterized and grouped by their 16S/23S spacer region restriction fragment pattern but this classification was in most cases different to the results obtained with these primers.
|Number of pages||10|
|Journal||Journal of Phytopathology|
|Publication status||Published - Jan 1999|