Solar UV‐B radiation and ethylene play a key role in modulating effective defenses against Anticarsia gemmatalis larvae in field‐grown soybean

• Published in: Plant, cell and environment cell and environment, 2018-02, Vol.41 (2), p.383-394
• Main Authors: Dillon, Francisco M., Tejedor, M. Daniela, Ilina, Natalia, Chludil, Hugo D., Mithöfer, Axel, Pagano, Eduardo A., Zavala, Jorge A.
• Format: Article
• Language: English
• Subjects: Abscisic Acid - metabolism; Animals; Anticarsia gemmatalis; Carboxylic acids; Crops; Cultivars; Cyclopentanes - metabolism; Ethylene; Ethylenes - metabolism; Flavonoids; Flavonols; Gene expression; Glycine max; Glycine max - physiology; Glycine max - radiation effects; Herbivory; Insects; Isoflavonoids; Jasmonic acid; Larva; Larvae; Leaves; Moths; Oxylipins - metabolism; Pathogenesis; Plant Growth Regulators - physiology; Plant Leaves - physiology; Plant resistance; plant‐insect interactions; Priming; Protease inhibitors; Proteinase; Radiation damage; Salicylic acid; Salicylic Acid - metabolism; Solar radiation; Soybeans; Species; Trypsin; Ultraviolet radiation; Ultraviolet Rays
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.13104

Solar UV‐B radiation has been reported to enhance plant defenses against herbivore insects in many species. However, the mechanism and traits involved in the UV‐B mediated increment of plant resistance are unknown in crops species, such as soybean. Here, we studied defense‐related responses in undamaged and Anticarsia gemmatalis larvae‐damaged leaves of two soybean cultivars grown under attenuated or full solar UV‐B radiation. We determined changes in jasmonates, ethylene (ET), salicylic acid, trypsin protease inhibitor activity, flavonoids, and mRNA expression of genes related with defenses. ET emission induced by Anticarsia gemmatalis damage was synergistically increased in plants grown under solar UV‐B radiation and was positively correlated with malonyl genistin concentration, trypsin proteinase inhibitor activity and expression of IFS2, and the pathogenesis protein PR2, while was negatively correlated with leaf consumption. The precursor of ET, aminocyclopropane‐carboxylic acid, applied exogenously to soybean was sufficient to strongly induce leaf isoflavonoids. Our results showed that in field‐grown soybean isoflavonoids were regulated by both herbivory and solar UV‐B inducible ET, whereas flavonols were regulated by solar UV‐B radiation only and not by herbivory or ET. Our study suggests that, although ET can modulate UV‐B‐mediated priming of inducible plant defenses, some plant defenses, such as isoflavonoids, are regulated by ET alone. Solar UV‐B radiation has been reported to enhance plant defenses against herbivore insects in many species. However, the mechanism and traits involved in the UV‐B mediated increment of plant resistance are unknown in crops species, such as soybean. In this study, we show that in field‐grown soybean isoflavonoids were regulated by both herbivory and solar UV‐B inducible ET, whereas flavonols were regulated by solar UV‐B radiation only and not by herbivory or ET. Although ET can modulate UV‐B‐mediated priming of inducible plant defenses, isoflavonoid are regulated by ET alone.