Solar UV-B radiation modulates chemical defenses against Anticarsia gemmatalis larvae in leaves of field-grown soybean.

DILLON, F; CHLUDIL, H; ZAVALA, J. A.*

PHYTOCHEMISTRY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 141 p. 27 - 36

0031-9422

Although it is well known that solar ultraviolet B (UV-B) radiation enhances plant defenses, there is lessknowledge about traits that define insect resistance in field-grown soybean. Here we study the effects ofsolar UV-B radiation on: a) the induction of phenolic compounds and trypsin proteinase inhibitors (TPI)in soybean undamaged leaves or damaged by Anticarsia gemmatalis neonates during six days, and b) thesurvival and mass gain of A. gemmatalis larvae that fed on soybean foliage. Two soybean cultivars (cv.),Charata and Williams, were grown under plastic with different transmittance to solar UV-B radiation,which generated two treatments: ambient UV-B (UVBþ) and reduced UV-B (UVB) radiation. Solar UV-Bradiation decreased survivorship by 30% and mass gain by 45% of larvae that fed on cv. Charata, but noeffect was found in those larvae that fed on cv. Williams. TPI activity and malonyl genistin were inducedby A. gemmatalis damage in both cultivars, but solar UV-B radiation and damage only synergisticallyincreased the induction of these compounds in cv. Williams. Although TPI activity and genistein derivativeswere induced by herbivory, these results did not explain the differences found in survivorshipand mass gain of larvae that fed on cv. Charata. However, we found a positive association between lowerlarval performance and the presence of two quercetin triglycosides and a kaempferol triglycoside infoliage of cv. Charata, which were identified by HPLC-DAD/MS2.We conclude that exclusion of solar UV-Bradiation reduce resistance to A. gemmatalis, due to a reduction in flavonol concentration in a cultivarthat has low levels of genistein derivatives like cv. Charata.