1 research outputs found
Role of Large Cabbage White butterfly male-derived compounds in elicitation of direct and indirect egg-killing defenses in the black mustard
To successfully exert defenses against herbivores and pathogens plants need to
recognize reliable cues produced by their attackers. Up to now, few elicitors
associated with herbivorous insects have been identified. We have previously
shown that accessory reproductive gland secretions associated with eggs of
Cabbage White butterflies (Pieris spp.) induce chemical changes in Brussels
sprouts plants recruiting egg-killing parasitoids. Only secretions of mated
female butterflies contain minute amounts of male-derived anti-aphrodisiac
compounds that elicit this indirect plant defense. Here, we used the black
mustard (Brassica nigra) to investigate how eggs of the Large Cabbage White
butterfly (Pieris brassicae) induce, either an egg-killing direct [i.e.,
hypersensitive response (HR)-like necrosis] or indirect defense (i.e.,
oviposition-induced plant volatiles attracting Trichogramma egg parasitoids).
Plants induced by P. brassicae egg-associated secretions expressed both traits
and previous mating enhanced elicitation. Treatment with the anti-aphrodisiac
compound of P. brassicae, benzyl cyanide (BC), induced stronger HR when
compared to controls. Expression of the salicylic (SA) pathway- and HR-marker
PATHOGENESIS-RELATED GENE1 was induced only in plants showing an HR-like
necrosis. Trichogramma wasps were attracted to volatiles induced by secretion
of mated P. brassicae females but application of BC did not elicit the
parasitoid-attracting volatiles. We conclude that egg-associated secretions of
Pieris butterflies contain specific elicitors of the different plant defense
traits against eggs in Brassica plants. While in Brussels sprouts plants anti-
aphrodisiac compounds in Pieris egg-associated secretions were clearly shown
to elicit indirect defense, the wild relative B. nigra, recognizes different
herbivore cues that mediate the defensive responses. These results add another
level of specificity to the mechanisms by which plants recognize their
attackers