Maize bushy stunt phytoplasma affects native corn at high elevations in Southeast Mexico

In the 2013–2014 growing season, field surveys were conducted in native corn fields located in high altitude agricultural communities in the ‘Sierra Norte de Puebla’ in Mexico. Symptoms typical of maize bushy stunt (MBS) disease were observed and DNA extracted from symptomatic native corn plants was used as template to confirm the presence of phytoplasmas. Amplification and sequencing of 16S rRNA-encoding sequences and chaperonin 60 universal target ( cpn 60 UT) sequences followed by in vitro restriction fragment length polymorphism and phylogenetic analyses revealed that the phytoplasma detected belongs to the subgroup 16SrI-B, ‘ Candidatus Phytoplasma asteris’. Based on 16S rRNA-encoding gene sequence analysis and on a single nucleotide polymorphism within the cpn 60 UT sequence, two MBS strains, MBS-Puebla and MBS-Veracruz, were identified. This is the first detection of MBS phytoplasma (MBSP) affecting native corn and the first molecular survey made in corn fields in Mexico to detect and characterize MBSP. We discuss these results in light of the potential evolutionary relationship between corn and MBSP.