Symptom Remission and Specific Resistance of Pepper Plants After Infection by Pepper golden mosaic virus

Abstract

Pepper golden mosaic virus (PepGMV) is an important begomovirus infecting solanaceous crops in Mexico and Central America. Under controlled conditions for growth and inoculation with a low-pressure biolistic device, PepGMV-infected pepper plants consistently showed symptom remission or host recovery 12 to 15 days postinoculation (dpi). Inoculated plants initially developed the characteristic PepGMV symptoms; however, newer leaves presented a significant decrease or disappearance of symptoms. Younger asymptomatic, recovered leaves accumulated lower quantities of viral DNA and transcripts than the ones found in the symptomatic tissue. Nonetheless, viral DNA did not disappear during the evaluation period (up to 35 dpi), suggesting that a population of viral molecules escape from plant defensive mechanisms to maintain a subliminal, symptomless infection. Recovery was correlated with a specific resistance to PepGMV but not to Pepper huasteco yellow vein virus, a different gemi-nivirus commonly found in mixed infections with PepGMV. Virus-related small interfering RNAs were detected in practically all tissues (from symptomatic to recovered leaves) but it was not possible to establish a correlation between concentration and symptom severity. The participation of a posttranscriptional gene silencing mechanism in the recovery process and specific resistance is discussed.

Characterization of a New World Monopartite Begomovirus Causing Leaf Curl Disease of Tomato in Ecuador and Peru Reveals a New Direction in Geminivirus Evolution

“…5B). The recovery phenotype in plants infected with begomoviruses is a type of defense response and is associated with reduced levels of viral DNA (55,56). Results of DNA gel blot hybridization analyses indicated that viral DNA levels were similar and relatively high for all three genotypes at 21 dpi, when infected plants showed severe leaf curl symptoms (Fig.…”

Two Populations of Viral Minichromosomes Are Present in a Geminivirus-Infected Plant Showing Symptom Remission (Recovery)

“…Sonora Anaheim) seeds were germinated in a bioclimatic chamber at 26 to 28°C with a 16/8-h (light/dark) photoperiod. The fourth leaf on plants at the four-leaf stage (around 30 days postgermination) were inoculated with PepGMV (pepper golden mosaic virus) infectious dimeric clones or with pBluescript for mock inoculations by biolistic bombardment (20). Samples of symptomatic tissue were harvested 10 days postinoculation (dpi), whereas recovered tissue was harvested at 24 dpi.…”

“…Previous results have suggested that viral minichromosomes from symptomatic and recovered tissues could present differences in structure organization (19,20). Therefore, we decided to compare the minichromosome populations from both types of tissue using a micrococcal nuclease sensitivity assay.…”

“…Our group has reported that the recovery phenomenon observed in pepper plants infected with PepGMV is associated with a reduction of viral DNA and RNA levels, the presence of virusrelated siRNAs, and an increase in the levels of viral DNA methylation (19,20). Based on those results and additional evidence, it was suggested that viral minichromosomes in symptomatic and recovered tissues could present differences in structure organization.…”

“…TGS directed against the viral minichromosome may lead to epigenetic modifications in an attempt to stop or reduce virus replication (18). In a few documented examples, this leads to a process called host plant recovery (19,20). The natural outcome of this plantvirus interaction (host recovery) is the emergence of new asymptomatic leaves after a typical symptomatic infection.…”