Identification of aster yellows phytoplasma in garlic and green onion by PCR-based methods

Abstract

In the summer of 1999, typical yellows-type symptoms were observed on garlic and green onion plants in a number of gardens and plots around Edmonton, Alberta, Canada. DNA was extracted from leaf tissues of evidently healthy and infected plants. DNA amplifications were conducted on these samples, using two primer pairs, R16F2n/R2 and R16(1)F1/R1, derived from phytoplasma rDNA sequences. DNA samples of aster yellows (AY), lime witches'-broom (LWB) and potato witches'-broom (PWB) phytoplasmas served as controls and were used to determine group relatedness. In a direct polymerase chain reaction (PCR) assay, DNA amplification with universal primer pair R16F2n/R2 gave the expected amplified products of 1.2 kb. Dilution (1/40) of each of the latter products were used as template and nested with specific primer pair R16(1)F1/R1. An expected PCR product of 1.1 kb was obtained from each phytoplasma-infected garlic and green onion samples, LWB and AY phytoplasmas but not from PWB phytoplasma. An aliquot from each amplification product (1.2 kb) with universal primers was subjected to PCR-based restriction fragment length polymorphism (RFLP) to identify phytoplasma isolates, using four restriction endonucleases (AluI, KpnI, MseI and RsaI). DNA amplification with specific primer pair R16(1)F1/R1 and RFLP analysis indicated the presence of AY phytoplasma in the infected garlic and green onion samples. These results suggest that AY phytoplasma in garlic and green onion samples belong to the subgroup 16Sr1-A.

Molecular Characterization of Aster Yellows Phytoplasma Associated with Valerian and Sowthistle Plants by PCR–RFLP Analyses

“…The similarity between the RFLP patterns of AY-27 (reference control) and AY phytoplasma in valerian and sowthistle suggests that a similar AY strain infected these host plants. These results are in agreement with previous studies that demonstrate AY-27 phytoplasma, which is also called western strain, is most commonly found in Alberta, Canada (Wang and Hiruki, 2004;Khadhair et al, 2002;Chang et al, 2004;Hwang et al, 1997a;Khadhair et al, 1998;Ceranic-Zagorac and Hiruki, 1996).…”

Molecular Characterization of 16S Ribosomal DNA and Phylogenetic Analysis of Two X‐disease Group Phytoplasmas Affecting China‐tree (Melia azedarach L.) and Garlic (Allium sativum L.) in Argentina

“…It would be interesting to compare the symptoms of these diseases and to study their vectors and the possibility of mixed infections by these two phytoplasmas and the ChTDIII. Other phytoplasmas from the Aster Yellows group have been reported to be infecting garlic crops (Khadhair et al, 2002). We made a wide survey in garlic fields over the main production areas in Argentina, and the only phytoplasma we could find up to now was GDIII.…”

Detection and molecular characterization of phytoplasmas associated with vegetable and alfalfa crops in Qassim region

“…Phytoplasma group 16SrI was associated with alfalfa plants in Bolivia, Lithuania and the USA (Peters et al 1999;Jomantiene et al 2000;Jones et al 2005). Although there are many reports about onion infection by phytoplasma group 16SrI around the world (Khadhair et al 2002;Lee et al 2003;Jomantiene et al 2010), the association of 16SrII phytoplasma with onion is considered as the first report not only in Saudi Arabia, but also in the world. While information about the association of phytoplasma with green mustard is very limited, it is hereby demonstrated to be a host for 16SrII phytoplasma.…”

“…Phytoplasmas were detected in faba bean plants in many countries, such as India, Saudi Arabia, Sudan, Spain, Cuba and Egypt, showing phyllody, witches' broom, and mild yellow symptoms (Castro and Romero 2004;Arocha et al 2007;Alfaro-Fernández et al 2012;Omar & Foissac 2012;Singh et al 2013;Hamed et al 2014). It was reported in particular countries including Japan, Lithuania, Canada, Pakistan, Mauritius, Iran and Tonga that onion is susceptible to phytoplasma with diverse symptoms including yellows, stunting, twisting and proliferation of flowers (Oshima et al 2001;Khadhair et al 2002;Lee et al 2003;Davis et al 2006;Gungoosingh-Bunwaree et al 2010;Jomantiene et al 2010;Sichani et al 2014;Ahmad et al 2015). Green mustard was surrounded by infected plants of faba bean and onion at the experimental station of College of Agriculture, so it was infected by phytoplasma with an incidence of 4.5%.…”