Sucrose non-fermenting related protein kinase 1 (SnRK1) provides limited protection against fall armyworm (FAW), Spodoptera frugiperda in rice

Sucrose non-fermenting related protein kinase 1 (SnRK1) is considered as the central regulator in energy deficit signaling. In rice, SnRK1 has been shown to promote tolerance against both biotic and abiotic stresses. Among biotic stressors, the role of SnRK1 has been explored against rice pathogens; however, its role against insect herbivores is less understood. To test this, we used wild type (that express SnRK1) and snrk1 mutant lines and examined the role of SnRK1 against one of the highly destructive, polyphagous pests, Fall armyworm (FAW), Spodoptera frugiperda. First, we investigated the response of FAW by exogenous application of phytohormone, Jasmonic acid (JA), and a JA blocker (Ibuprofen). Then we evaluated the response of FAW to these lines by feeding them with leaf infused artificial diet, a fresh leaf-based feeding assay, and on intact plants by a short-term exposure to FAW. Below and above ground ecophysiological traits and surface defenses in rice as well as FAW growth and developmental traits were measured. Our results showed that the response of FAW did not vary between wild and mutants. However, phytohormonal application improved the ecophysiological traits irrespective of the rice lines, and we found no evidence linking these effects to SnRK1. Collectively our findings show that SnRK1, the central stress regulator has a limited role in protection against FAW in rice, and the defenses in rice against FAW are possibly independent of SnRK1.