Caracterización del Viroide exocortis de los cítricos en diferentes condiciones de indexado

Abstract

Resumen. Citrus exocortis viroid (CEVd) es unfitopatógeno regulado en la citricultura de México. El diagnóstico por indexado para detectar la presencia y transmisión de CEVd en material propagativo de bancos de germoplasma es de aplicación oficial. El objetivo de este estudio fue caracterizar al CEVd en condiciones de indexado in vitro e in vivo comparando la eficiencia de transmisión y la rapidez con que se generan los síntomas para establecer su aplicación en el diagnóstico biológico. Characterization of Abstract. Citrus exocortis viroid (CEVd) is aregulated pathogen in Mexican citriculture. The diagnosis by indexing to detect the presence and transmission of CEVd in propagative material of germplasm banks is of official application. The aim of this study was characterizing to CEVd by in vitro and in vivo indexing to analyzing the efficiency of the transmission and the speed with which the symptoms are generated to establish their application in the biological diagnosis. The height, incidence, area under the disease progress curve (ABCP) and transmission efficiency were evaluated in etrog citron indicator plants, cultivated in vivo inoculated by grafting and in buds cultivated in vitro inoculated with callus. The mean height of buds and infected plants was 7.5 mm and 56.3 mm less than the control, incidence, ABC and regression model were 81.2%, 10.7, y= 0.0009x 2 + 0.0693x-0.0057, R 2 = 0.99 in vitro y 70.8%, 9.84, y= 0.0004x 2 -0.0048x-0.0061, R 2 = 0.94 in vivo, respectively. The efficiency

A Current Overview of Two Viroids Prevailing in Citrus Orchards: Citrus Exocortis Viroid and Hop Stunt Viroid

“…It has been proved that the in vitro indexing of CEVd is efficient as well as the in vivo diagnosis, and requires between 20 and 40 days less to reach the maximum incidence after inoculation. Epinasty, growth reduction, and rugged leaves with dry tips, and reduced size are the main symptoms observed on the sprouts planted in vitro and grafted with CEVd-infected callus [59]. The same symptoms have been reported for sprouts grafted with CEVd infected cortex [62].…”

“…CEVd and HSVd are viroid diseases present in citrus orchards around the world [11]. The biological diagnosis through indexing method is considered as an efficient tool to test the health status of a plant, regarding a disease by inoculation with the grafting of the budwood or any other infected tissue in indicator plants that allow viroid replication, symptoms expression [11,58], and the enhancement of viroid concentration [59]. However, bioassays for CEVd and HSVd detection and identification may require a panel of indicator host plants [60].…”

“…The citron test is a very sensitive and diagnostic index for determining the presence of CEVd [9]. However, indexing, in vivo for CEVd diagnosis is time-consuming, labor-intensive, and requires technician greenhouses [59]. It can take 90 days after inoculation or grafting onto indicator plants [61][62][63].…”

“…It can take 90 days after inoculation or grafting onto indicator plants [61][62][63]. Symptoms of slight to severe epinasty leaves wrinkled and twisted to the reverse with light to dark brown cracks in petiole and branches, blisters in the petiole, corking of the midrib, and reduced growth are the main symptoms observed on Etrog citron Arizona 861-S indicator plants graft-inoculated with CEVd-infected budwoods [28,29,59,63]. An in vitro indexing procedure has been developed to minimize the risks of epidemics caused by viroids including CEVd.…”