Flower-specific jasmonate signaling regulates constitutive floral defenses in wild tobacco

Significance Plants are at the base of most food chains and hence are frequently attacked by herbivores. Leaves are the dominant aboveground tissues of most plants and their defense responses against folivores are well studied and known to be regulated by jasmonate (JA) phytohormone signaling. As the most fitness-valuable and frequently the most nutritious tissues, flowers are also commonly attacked by florivores. However floral defense, compared with leaf defense, is rarely studied, and the signaling systems that regulate these defenses are unknown. Here we show that flowers of the wild tobacco, Nicotiana attenuata , constitutively accumulate large amounts of defensive compounds, trypsin proteinase inhibitors, ( E )-α-bergamotene and defensins, and that a flower-specific sector of JA signaling regulates these constitutively expressed floral defenses.