Molecular detection and identification of phytoplasmas associated with little leaf and witches’ broom disease of marigold (Tagetes erectaL.) in India

Abstract

Marigold (Tagetes erecta L.) is widely cultivated commercially as ornamental plant in India and worldwide. Little leaf and witches’ broom disease symptoms were observed in a number of T. erecta plants growing in garden at Lucknow and cultivated fields around Gorakhpur in the years 2007 and 2008. The phytoplasma presence was detected by direct PCR followed by nested PCR using universal phytoplasma primers which resulted into ~1.2 kbp amplicons only in symptomatic samples of T. erecta. The amplicons obtained from symptomatic samples collected from both locations were sequenced and data deposited in GenBank database under accession numbers: HM230685 (Tagetes erecta little leaf phytoplasma-Gorakhpur) and EU516321 (marigold witches’ broom phytoplasma-Lucknow). The phytoplasma-Gorakhpur shared highest 99% sequence identities and closest phylogenetic relationships with several ‘Candidatus Phytoplasma asteris’ (16SrI group), however, phytoplasma-Lucknow shared only 96% identities and distant relationships with ‘Ca. P. asteris’ (16SrI) group. Hence, ‘Ca. P. asteris’ (16SrI) group and a new ‘Ca. Phytoplasma’ species associated with little leaf and witches’ broom disease, respectively, were identified.