PCR analysis of phytoplasma associated with 'Maize bushy stunt' disease in tropical maize genotypes cultivated in Southeastern Brazil. In: Agrotrópica v. 18 p. 57-62, 2006.

Abstract

The ‘maize bushy stunt’ (MBS) is a phytoplasma-based disease that has become a serious problem for tropical maize genotypes in Brazil. Universal-modified (16S rDNA) and MBS-specific primer-pairs were used in PCR experiments to verify the possibility of developing a simple and fast procedure to reliably detect MBS phytoplasma among field-sampled maize plants. Overall, the pattern of amplification was not consistently associated with disease phenotypes. Nevertheless, one-round PCR with these primers showed practical usefulness, as it was able to detect the presence of phytoplasma in symptomless plants, which would be otherwise miscored by phenotypic assessment. Interestingly, distinct patterns of amplification by these primers in the same set of samples indicated the simultaneous presence of at least two different phytoplasmas in some symptomatic plants; this was further suggested by direct partial sequencing of the Universal-primed amplicons and comparison with other phytoplasma sequences from GenBank, including a maize entry. Positive amplification was also obtained from embryo-derived tissue-cultured maize plantlets and from symptomatic and symptomless field-collected sorghum plants. The consequences of these findings for maize breeding programs and other research directions are discussed.