In addition to rice yellow dwarf (RYD) phytoplasma, several phytoplasmas infect gramineous plants, including rice orange leaf, bermuda grass white leaf, brachiaria grass white leaf and sugarcane white leaf phytoplasmas. To investigate whether the RYD phytoplasma is a discrete, species-level taxon, several isolates of the aforementioned phytoplasmas were analysed using PCR-amplified 16S rDNA sequences. Two RYD isolates, RYD-J(T) and RYD-Th, were almost identical (99.2 %), but were distinct (similarities of 96.3-97.9 %) from other phytoplasma isolates of the RYD 16S-group. The notion that the RYD phytoplasma constitutes a unique taxon is also supported by its unique insect vector (Nephotettix sp.), its unique host plant in nature (rice) and its limited geographical distribution (Asia). In Southern blot analysis, chromosomal and extrachromosomal DNA probes of the RYD phytoplasma reportedly did not hybridize with those of closely related phytoplasmas. These properties of the RYD phytoplasma clearly indicate that it represents a novel taxon, 'Candidatus Phytoplasma oryzae'.
"Bermuda grass white leaf (BGWL) is a destructive phytoplasma disease of Bermuda grass (Cynodon dactylon), which is known to occur in several countries including India, Sudan, Italy, Cuba and Australia (Jung et al., 2003). The associated agent is a member of the BGWL group (16SrXIV), 'Candidatus Phytoplasma cynodontis' (Marcone et al., 2004). "
"White leaf diseases of other grasses are associated with 'Ca. P. cynodontis' on Bermuda grass (Cynodon dactylon) and annual blue grass (Poa annua) in Italy (Lee et al., 1997; Marcone et al., 2004), Brachiaria grass (Brachiaria distachya), carpet grass (Axonopus compressus) and crowfoot grass (Dactyloctenium aegyptum) in Thailand (Wongkaew et al., 1997; Sdoodee et al., 1999; Jung et al., 2003a), and Delhi grass (Dichanthium annulatum) in India (Rao et al., 2009). Until now, no phytoplasma disease had been recorded on golden beard grass. "
[Show abstract][Hide abstract] ABSTRACT: A phytoplasma was detected in golden beard grass (Chrysopogon acicalatus) displaying white leaf symptoms near vegetative fields at the Tatkone region in Myanmar, 2011. Based on restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA genes, including the 16S-23S spacer region and part of the 23S rRNA gene, the phytoplasma was identified as a member of the Bermuda grass white leaf phytoplasma (BGWL) group. The golden beard grass white leaf phytoplasma (GBGWL) 16S rRNA gene sequence exhibited over 98.7% similarity with all members of BGWL group phytoplasmas and 99.5% similarity with Thailand Bermuda grass white leaf phytoplasma (AF248961). In addition, the GBGWL phytoplasma was confirmed to be a member of 'Candidatus Phytoplasma cynodontis' by phylogenetic analyses.
"Bermuda grass [Cynodon dactylon (L.) Pers.] white leaf (BGWL), first reported from Taiwan (Chen et al., 1972), known to occur in several Asian countries (Lee et al., 2000; Jung et al., 2003; Rao et al., 2007), from Africa (Dafalla and Cousin, 1988), Australia (Padovan et al., 1999; Tran-Nguyen et al., 2000), Europe (Marcone et al., 1997), Cuba (Arocha et al., 2005), Iran (Salehi et al., 2009) and lately reported also from Turkey (Çağlar et al., 2013). The disease causes light green to yellow streaks on the leaves, extensive chlorosis and white discolorations, proliferation of axillary shoots, bushy growing habit, small leaves, shortened stolons and rhizomes, stunting, and death of the plants. "
[Show abstract][Hide abstract] ABSTRACT: Bermuda grass white leaf phytoplasma (BGWL) was previously reported in Turkey. In the study, transmission of agents from Bermuda grass to wheat (Triticum spp.) plants was experimentally investigated by a root-bridge system in August 2012, Adana. Twelve Bermuda grass plants, infected with Candidatus Phytoplasma cynodontis, strain M6 from Turkey and showing symptoms of light green to yellow streaks on the leaves and bushy growth, were taken out from soil separately and transplanted to two plastic pots. Two hundred of wheat seeds were sown in to each pot between diseased Bermuda grass plants. After two months under net screen, wheat plants in the pots started to turn into yellow color, compared with healthy control plants. All infected wheat plants were positive when 16S rDNA-amplifying primers were used in nested PCR, contrarily to the healthy ones used as negative controls. Restriction fragment length polymorphism (RFLP) assays conducted on the 16S primed-DNA of BGWL-phytoplasma PCR-positive samples yielded a uniform profile and similar to the strain M6 of the BGWL-phytoplasma used as an inoculum. This information was further confirmed by sequence analyses. To our knowledge, this is the first report of transmission of BGWL disease to another host, different from Bermuda grass plants, by root-bridge.
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