Soybean plants under simultaneous signals of drought and Anticarsia gemmatalis herbivory trigger gene expression and metabolic pathways reducing larval survival

Abstract

Climate changes are promoting increases in global temperatures, variability in precipitation, and more frequent insect pest outbreaks. Understanding the molecular mechanisms for the tolerance of both, biotic and abiotic stresses, is critical for the development of improved genotypes and sustainability of productivity under climate change. Thus, we examine the regulatory cascades and metabolic pathways triggered by both drought and insect attack signals. Profiles from the genotypes drought-tolerant (EMBRAPA 48) and resistant to A. gemmatalis infestation (IAC17) were compared with one sensitive to drought/insect attack (BR16). EMBRAPA 48 and IAC17 plants under drought were less susceptible to insect attack, promoting lower caterpillar survival. Survival reductions were not dependent on the drought-tolerance or insect-resistance phenotypes, despite being more pronounced for IAC17. Furthermore, metabolites profiles, gene expression and enzymatic assays lead us to conclude that drought signal by itself was not enough to explain the survival reductions. Protease inhibition activities and expressions of LOX and PI genes correlated with ABA levels, indicating that JA-signalling was potentialized by ABA to enhance the production of deterrent metabolites. Thus, increased ABA levels during drought treatment may be acting synergistically to induce cascades responsive to JA. Thus, regulatory molecular hub(s) integrating signals may be a target to the genetic engineering of plants with multiple tolerances to environmental stresses.