Characterization of 16SrII-D subgroup associated phytoplasmas in new host plants in Egypt

Abstract

Samples of three plant species displaying phytoplasma symptoms were collected from Kafrelsheikh and Al-Gharbia governorates during 2014. Witches’ broom and virescence symptoms were observed in periwinkle (Catharanthus roseus). Onion (Allium cepa) plants showed yellowing, streaks and twisting and Opuntia abjecta with proliferation and cylindrical of cladodes. Total DNA was extracted from symptomatic and asymptomatic plants, and phytoplasma were detected in all 12 symptomatic plants collected through direct and nested PCR assays with primers P1/P7 and R16F2n/R16R2. The results of phylogenetic analysis revealed that the phytoplasma isolates belong to 16SrII group. With a nucleotide identity greater than 98.7% with three members of 16SrII group, Papaya yellow crinkle, Y10097; “Ca. P. aurantifolia”, U15442; and peanut witches’ broom, Al33765, the strains identified in this study are “Ca. P. aurantifolia”-related strains. Virtual RFLP analysis of the 16S rRNA gene sequences with 17 restriction enzymes confirmed that the phytoplasma isolates belong to the “Candidatus Phytoplasma australasia” 16SrII-D subgroup. To the best of our knowledge, periwinkle, onion and Opuntia abjecta are considered new hosts for 16SrII group in Egypt.

Keywords:

• 16SrII group phytoplasma
• Egypt
• onion
• Opuntia abjecta
• periwinkle

Acknowledgement

The authors would like to thank Prof. Dr Yasser M. Hafez (Department of Plant Pathology, Plant Pathology and Biotechnology Laboratory, Faculty of Agriculture, Kafrelsheikh University, 33516 Kafrelsheikh, Egypt) for his help to collect onion samples and to Dr Perez Lopez (Phytoplasma specialist, Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA) for the editions made and English corrections.