Resistance to geminivirus mixed infections in Mexican wild peppers

Screening for resistance to mixed infections with pepper huasteco virus (PHV) and pepper golden mosaic virus (PepGMV) was carried out on plants representing wild pepper accessions collected in different states of Mexico. One accession collected in Yucatan (BG-3821) corresponded to Capsicum chinense Jacq., and three collected from Michoacan (BG-3818), Tamaulipas (BG-3820), and Sinaloa (BG-3819) were identified as C. annuum L. Forty-eight plants were initially inoculated with a 1:1 mix of PHV and PepGMV DNAs by a biolistic method. Those plants that did not show typical symptoms after the biolistic method, were inoculated by grafting. Half of the plants (24) were highly susceptible, while the other half expressed different degrees of resistance. Of the resistant individuals, eight plants were asymptomatic and viral DNA of both viruses was detected in low levels. Two individuals showed delayed symptoms 34 days after symptom expression in the control plants. This delay was correlated with an increase in PHV DNA levels when plants became symptomatic. The remaining 14 plants showed symptom remission in newly developed leaves at 31 days postinoculation, and this asymptomatic effect was correlated diminished PHV DNA within the plants. Our results suggest that the resistance shown by some individuals to geminivirus mixed infections (PHV and PepGMV) is likely due to constrains in viral movement.