Role of Liguleless (LG1) gene in sorghum defense against sap-feeding aphids

Sugarcane aphids (Melanaphis sacchari, SCA) are a major pest of Sorghum (Sorghum Bicolor L.), often leading to severe yield losses. While ligules, leaf outgrowths at the blade-sheath junction, are known for structural roles like regulating leaf angle and protecting the sheath, their function in pest resistance is unknown. Here, we infested both Wild-type (RTx430) plants and liguleless1 mutants (lg1) with SCA. Lower aphid fecundity was observed in lg1 plants, indicating reduced susceptibility. Further, qRT-PCR analysis of key defense genes showed uninfested lg1 plants with constitutively higher expression of jasmonic acid (JA) and salicylic acid (SA) marker genes. However, after infestation, JA marker gene transcripts were suppressed to levels comparable to the infested WT, while SA marker gene remained unchanged. This preliminary study highlights a previously unexplored morphological trait- ligules, as a potential contributor to sorghum–aphid interactions through modulation of phytohormonal defense signaling, warranting further downstream investigation.