Solar UV-B inducible ethylene alone induced isoflavonoids in pods of field-grown soybean, an important defense against stink bugs

CHLUDIL, HUGO D.; DILLON, FRANCISCO M.; ZAVALA, JORGE A.; MITHÖFER, AXEL

ENVIRONMENTAL AND EXPERIMENTAL BOTANY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2020 vol. 178

0098-8472

Solar UV-B radiation enhances constitutive and inducible plant defenses against herbivore insects. Althoughinducible defenses in leaves damaged by lepidotperan larvae and other chewing insects are well known, almostnothing is noted for the response of reproductive organs in response to stink bug attack. Here we measured theinduction of phytohormones and flavonoids in undamaged and damaged pods by stink bug (Piezodorus guildinii)adults. We compared two different soybean cultivars grown under two levels of solar UV-B radiation. Stink bugand mechanical damage increased isoflavonoid content in pods of both cultivars and solar UV-B tended toenhance induction, without affecting isoflavonoids in undamaged pods. While pod flavonols levels did notchange by stink bug attack, mechanical damage or to solar UV-B, herbivory and mechanical damage increasedseed isoflavonoids, and solar UV-B did not affect seed isoflavonoid content. Although stink bug damage inducedethylene (ET) from pods of cv. Charata, herbivory did not affect ET emission in cv. Williams. Solar UV-B radiationincreased ET emission in mechanically damaged pods of cv. Charata, but did not affect other phytohormones.Both mechanical and stink bug damage induced jasmonates in seed of both cultivars. Application ofthe ET precursor ACC alone, but not MeJA or SA increased isoflavonoid content in pods of cv. Charata. Our fieldexperiments suggest that herbivory- and solar UV-B radiation-induced ET by itself is sufficient to increase thelevel of defensive isoflavonoids in pods against stink bugs.