Glucose-6-phosphate isomerase (PGI), a key enzyme that catalyzes the reversible conversion of glucose-6-phosphate and fructose-6-phosphate, plays an important role in plant growth, development, and responses to abiotic stresses and pathogen infections. However, whether and how PGI modulates herbivore-induced plant defenses remain largely unknown. The Brown planthopper (BPH, Nilaparvata lugens) is a devastating insect pest of rice, causing significant damage to rice plants through feeding, oviposition, and disease transmission, resulting in great yield losses. Here, we isolated a rice cytosolic PGI gene, OsPGI1c, which is ubiquitously expressed in rice plants; the highest transcript levels are found in leaves, outer leaf sheaths, and seeds. The expression of OsPGI1c was induced by infestation by gravid females of the BPH, mechanical wounding, and treatment with jasmonic acid (JA). Overexpressing OsPGI1c in rice (oePGI) enhanced both the masses of plant shoots and roots and basal levels of trehalose; however, when infested by gravid BPH females for 2 days, trehalose levels were significantly lower in oePGI plants than in wild-type (WT) plants. Additionally, the overexpression of OsPGI1c increased the BPH-induced levels of JA, jasmonoyl-L-isoleucine, and abscisic acid, but decreased the levels of ethylene and H2O2. Bioassays revealed that gravid BPH females preferred WT plants over oePGI plants for laying eggs; moreover, BPH eggs exhibited lower hatching rates and required longer developmental durations on oePGI plants than WT plants. These results indicate that OsPGI1c positively modulates both rice growth and BPH resistance.
Keywords: Oryza sativa; OsPGI1c; brown planthopper; cytosolic phosphoglucose isomerase; growth; herbivore-induced defenses.