First report of a new grapevine yellows disease in Peru and its association with infection by a ‘candidatus phytoplasma brasiliense’-related phytoplasma strain

W. Wei, E. Pérez-López, L. Bermúdez-Díaz, R. E. Davis, C. Granda-Wong, Y. Zhao

Producción científica: Contribución a una revistaArtículorevisión exhaustiva

4 Citas (Scopus)

Resumen

Grapevine (Vitis vinifera L.) is one of the most economically valuable horticultural crops in the world, especially to the wine industry. Native to the Mediterranean region, V. vinifera is now cultivated on every continent and covers nearly eight million hectares of land (The Statistics Portal 2016). However, the health of grapevine is threatened by several diseases collectively referred as grapevine yellows (GY). Typical symptoms of GY include downward rolling of leaves, yellowing or necrosis of leave veins, uneven lignification of stems, and shriveling of grape clusters; in sensitive cultivars, GY can cause premature plant death (Davis et al. 2015). All known types of GY to date are attributed to infection by phloem-inhabiting, insect-transmitted, cell wall-less bacteria known as phytoplasmas, although the species of phytoplasma involved in an individual GY differs. In the fall of 2015, grapevine plants exhibiting symptoms of leaf discoloration (yellowing), veinal necrosis, and in some cases fruit shriveling, were observed in a vineyard located in Piura, northwestern Peru. Since the symptoms were indicative of possible GY, molecular diagnostics for phytoplasmal infection was deployed. Total DNA was extracted from leaf samples of five symptomatic plants and served as templates in PCRs primed by phytoplasma universal primer pair P1A/16S-SR (Lee et al. 2004). An amplicon of 1.5 kb was obtained from DNA samples of the three symptomatic plants exhibiting fruit shriveling. In parallel diagnostic assays, nested PCRs were performed using primer pair P1/P7 followed by R16F2n/R16R2 (Lee et al. 2004 and references therein). A 1.25-kb genome segment was amplified from DNA samples of the same three symptomatic plants. The amplicons were cloned and nucleotide sequences determined. The DNA sequence data showed that the 1.5-kb amplicon contained a near-full length 16S rRNA gene (16S rDNA) and the 1.2-kb amplicon encompassed the full F2nR2 segment of the 16S rDNA. All six 16S rDNA sequences derived by the two PCR methods from the three independent samples were mutually identical in common regions and possessed a conserved block (5′-CAAGACGATGATGTGTAGCTGGACT-3′) that is characteristic of ‘Candidatus Phytoplasma’ species (5′-CAAGAYBATKATGTKTAGCYGGDCT-3′), confirming that phytoplasmal infection occurred in the vineyard. To our knowledge, this is the first report of a phytoplasmal GY disease in Peru. The phytoplasma was designated as PeruGY1. The 16S rDNA sequences of the three PeruGY1 strains were deposited in the GenBank (KX670807, KX670808, and KX670809). An iPhyClassifier (Zhao et al. 2009) operation, using the 16S rDNA sequences of three PeruGY1 strains as queries, revealed that PeruGY1 is closely related to the reference strain of ‘Ca. Phytoplasma brasiliense,’ with 99.1% sequence similarity. Prior to this work, ‘Ca. Phytoplasma brasiliense’ had never been implicated in a GY disease, and ‘Ca. Phytoplasma brasiliense’ was known only in Brazil (Montano et al. 2001) and Costa Rica. Results from our present study clearly indicate that the phytoplasma has spread to a new geographic region, and that its host range has extended to an important horticultural crop, signaling a need for surveillance for this phytoplasma in grapevine as well as other crop plants.

Idioma originalInglés
Páginas (desde-hasta)502
Número de páginas1
PublicaciónPlant Disease
Volumen101
N.º3
DOI
EstadoPublicada - mar. 2017

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