The whitefly
Bemisia tabaci
(Gennadius, 1889) is a major plant pest of horticultural crops from the families Solanaceae,
Fabaceae and Cucurbitaceae in Neotropical areas. The exploration of host plant resistance and their biochemical
mechanisms offers an excellent alternative to better understand factors affecting the interaction between phytophagous
insect and host plant. We evaluated the survival of
B. tabaci in landrace genotypes of
Capsicum annuum
L., and the
activity of plant defense-related enzymes (chitinase, polyphenoloxidase, and peroxidase). The landrace genotypes Amaxito,
Tabaquero, and Simojovel showed resistance to
B. tabaci, as we observed more than 50% nymphal mortality, while in the
commercial susceptible genotype Jalapeño mortality of
B. tabaci nymphs was not higher than 20%. The activities of plant
defense-related enzymes were significantly different among pepper genotypes (P < 0.05). Basal activities of chitinase,
polyphenoloxidase and peroxidase were significantly lower or equal in landrace genotypes than that of the commercial
genotype Jalapeño. The activity of plant enzymes was differential among pepper genotypes (P < 0.05). For example,
the activity of chitinase enzyme generally was higher in non-infested plants with
B. tabaci than those infested. Instead
polyphenoloxidase (‘Amaxito’ and ‘Simojovel’) and peroxidase enzymes activities (‘Tabaquero’) increased in infested
plants (P < 0.05). We conclude that basal activities of plant defense-related enzymes could be act through other mechanism
plant induction, since plant defense-related enzymes showed a different induction response to
B. tabaci. We underlined the
role of polyphenoloxidase as plant defense in the pepper genotype Simojovel related to
B. tabaci.
