Identifying novel sources of resistance: Sorghum- sugarcane aphid interaction

Sorghum is considered as one of the world’s most important monocot crops grown for food, feed, and/or fuel. Simultaneously, sorghum is highly susceptible to insect pests that cause dramatic decreases in yields. Even though there is extensive natural variation for resistance against insect pests in sorghum, much of it remains undiscovered and under-utilized. From our preliminary insect bioassay screen using founder lines of sorghum nested association mapping populations, we have identified SC265 as resistant and SC1345 as susceptible lines, to sugarcane aphids (SCA) compared to the RTx430, (wild-type) plants. Electrical penetration graph suggested that SCA spent lesser time in phloem phase and more time in pathway phase on SC265 as compared to RTx430. Furthermore, phytohormone analyses revelated the higher constitutive and induced levels of salicylic acid (SA) in SC265 at day 1 and day 7 post-infestation, compared to wild-type and susceptible lines. Also, SCA feeding also triggers the Jasmonic acid (JA) levels at early time points in RTx430 and SC265 at 1-hour and 1-day post-infestation. These preliminary results suggest that SC265 provides resistance to SCA, which could be driven by the induction of JA and SA.