A Cytosolic Phosphoglucose Isomerase, OsPGI1c, Enhances Plant Growth and Herbivore Resistance in Rice

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, <i>Nilaparvata lugens</i>) 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, <i>OsPGI1c</i>, which is ubiquitously expressed in rice plants; the highest transcript levels are found in leaves, outer leaf sheaths, and seeds. The expression of <i>OsPGI1c</i> was induced by infestation by gravid females of the BPH, mechanical wounding, and treatment with jasmonic acid (JA). Overexpressing <i>OsPGI1c</i> 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 <i>OsPGI1c</i> 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.