Characterization of Aster Yellows Phytoplasma Affecting Cycas revoluta in Egypt

In 2015, Pale yellowing symptoms were observed on Cycas revoluta (family: Cycadaceae) leaves rachis and lamina grown as ornamental plant in gardens of the Alexandria Governorate, Egypt. Since the symptoms were suggestive the phytoplasma presence, samples were tested by PCR amplification of 16S rRNA gene nucleotide sequences using phytoplasma universal primers P1/P7 in direct, and in nested R16F2n/R16R2 PCR. RFLP-PCR product of the nested primer with MseI restriction enzyme and phylogenetic analyses of 16S rRNA gene nucleotide sequences suggested that the phytoplasma of Aster yellows designated in 16SrI group. Various 16Sr groups of phytoplasmas, e.g. 16SrI, 16SrII, 16SrX, 16SrXII, and 16SrXVII, are recognized to be associated in abnormalities of ornamental plants in many regions.However, this study reports for the first time the incidence of  16SrI phytoplasma in association with aster yellows disease in Cycas revoluta grown in Egypt.