SolarUV‐Bradiation and ethylene play a key role in modulating effective defenses againstAnticarsia gemmatalislarvae in field‐grown soybean

Abstract

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.

Ultraviolet radiation exposure time and intensity modulate tomato resistance to herbivory through activation of jasmonic acid signaling

“…post-herbivory) jasmonate levels, resulting in reinforced chemical defenses (Đinh et al ., 2013; Qi et al , 2018). Recently, Dillon et al (2018) reported enhanced induction of ET by combined solar UV-B and herbivory, and highlighted its possible role in soybean defenses. Less is known about the roles of SA, auxin, and ABA in UV-mediated induction of plant defenses.…”

Ultraviolet radiation enhances salicylic acid-mediated defense signaling and resistance to Pseudomonas syringae DC3000 in a jasmonic acid-deficient tomato mutant

“…In particular, increases in the JA and ethylene burst has been described after combined UV-B exposure and aboveground herbivory, resulting in enhanced plant resistance. [9][10][11][12][13][14] Recently, we have demonstrated that supplemental UV (A + B) (λ 280-400 nm) can enhance tomato (Solanum lycopersicum) resistance to thrips (Frankliniella occidentalis),…”

Digestive activity and organic compounds of Nezara viridula watery saliva induce defensive soybean seed responses

“…N. viridula herbivory phosphorylated and activated the mitogen-activated protein kinase (MAPK) pathway and induced an early peak of jasmonic and salicylic acid accumulation and ethylene emission in developing seeds of field-grown soybean; this up-regulated plant defenses and reduced stink bug preference 21 . Ethylene emission in soybean pods induced isoflavonoids, which are an effective defense against stink bugs 32 , 37 . Moreover, N. viridula feeding led to seed cell wall thickening as well as to increased expression of genes coding for expansine, xyloglucan endo-transferase, pectate lyase and polygalacturonase, all involved in the relaxation and restructuration of the cell wall 24 .…”