Symptom remission and specific resistance of pepper plants after infection by Pepper golden mosaic virus

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 geminivirus 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.