Rice sucrose non-fermenting related protein kinase (SnRK1) has a limited role in defense against Fall armyworm (Spodoptera frugiperda)

Abstract

Sucrose non-fermenting (SNF) related protein kinase 1 (SnRK1) is a master regulator of energy deprivation signaling, has also been implicated in abiotic and biotic stress regulation. SnRK1 promotes stress tolerance through metabolic and transcriptional changes and plays important roles in innate immunity against various pathogens. However, whether it plays a role against insect herbivory is not understood. To test this, using the wild type (with SnRK1) and snrk1 mutant lines in rice, we examined the potential role of SnRK1 in rice against the ruinous pest, Fall armyworm (FAW), Spodoptera frugiperda. We also investigated the response of FAW towards these lines at different time intervals after exogenous application of plant hormone, Jasmonic acid (JA), and a JA blocker (Ibuprofen). Additional experiments by feeding FAW with leaf infused diet, fresh leaves, and a short-term exposure of FAW to the lines were also carried out. FAW mass gain, growth and development, and host ecophysiological traits were observed. In addition, we also quantified the major surface defenses- trichomes, and wax before and after herbivory. Our results show that FAW response did not vary between mutants and wild type rice. Meanwhile, we found plant hormonal application influenced the ecophysiological traits regardless of mutants and wild type rice. Collectively, we show that while defense against FAW in rice is JA mediated, SnRK1 has a limited role as observed through manipulative experiments with the wild type and snrk1 mutant rice lines.