Identification and incidence of Iris yellow spot virus in Allium field crops in Southwest Germany

Hospedantes alternos de Iris yellow spot virus y trips en cultivos de cebolla de Morelos y Michoacán, México

“…This has been shown in the case of onion, where its distribution of the virus in the plant is heterogenous, which can give false negatives, leading to an underestimation of its incidence (Hsu et al, 2010). On the other hand, the symptoms caused by the IYSV do not tend to be consistent and clear, therefore, when taking plant tissue samples for their analysis with RT-PCR and/or DAS-ELISA results may be inconsistent (Krauthausen et al, 2012). This expression of symptoms is influenced by the period of incubation, the phenology of the plant at the moment of infection, weather conditions, the level of stress in the plant, as well as in the cultivar (Bag et al, 2012).Likewise, Ochoa et al (1996) point out that obtaining negative samples in weeds does not imply that they are not a reservoir for the virus.…”

“…Esto se ha demostrado en el caso de la cebolla, donde su distribución del virus en la planta es heterogénea lo que puede dar falsos negativos tendiendo a subestimar su incidencia (Hsu et al, 2010). Por otro lado, los síntomas ocasionados por IYSV no suelen ser consistentes y claros, por lo que al momento de tomar muestras de tejido vegetal para su análisis por RT-PCR y/o DAS-ELISA pueden tenerse resultados inconsistentes (Krauthausen et al, 2012). Dicha expresión de síntomas es influenciado por el período de incubación, la fenología de las plantas al momento de la infección, las condiciones climáticas, nivel de estrés en la planta así como del cultivar (Bag et al, 2012).…”

First report of Iris yellow spot virus in Costa Rica

“…Six samples tested positive by RT-PCR, although; were ELISA negative. Uncertain diagnosis based on leaf symptoms and discrepancies between ELISA and RT-PCR results were reported previously (Krauthausen et al 2012). Moreover, the distribution of IYSV throughout an infected plant is uneven (Kritzman et al 2001;Smith et al 2006) and thus the pieces of tissue used for ELISA and RT-PCR may contain differential virus titer, even when extracted from the same plant.…”

“…Similarly, Krauthausen and collaborators (2012) reported no amplification for some samples with this primer pair at 60°C annealing temperature. Therefore, samples were tested with two additional primer pairs: IYSV-837/Tos-R15 ( U g a a n d Ts u d a 2 0 0 5 ) a n d J J -2 3 2 f / J J -6 9 2 r (Krauthausen et al 2012); and 14 and 13 samples were positive, respectively. In total, 89% (16/18) of the samples were confirmed to be IYSV-positive with one or (Table 1).…”

“…These results confirmed the detection of IYSV in onion samples from Costa Rica. Moreover, the IYSV partial N sequences (accession numbers KY569524 to KY569538) were aligned against a selection of IYSV sequences worldwide (Nischwitz et al 2007;Krauthausen et al 2012;Iftikhar et al 2014) with MEGA7 (Kumar et al 2016) using MUSCLE (Edgar 2004). Phylogeny was inferred in MrBayes v.3.2.6 (Ronquist et al 2012) with a mixed substitution model (lset = mixed) and gamma-shaped rate variation with a proportion of invariable sites (lset rate = invgamma).…”