D3096: (2nd Place) Elucidating the role of silicon in constitutive and herbivory-induced defense responses in rice using OsLsi1 mutant rice lines

Silicon (Si) has been associated with enhanced plant resistance against various insect pests. However, it is not well understood how Si uptake in rice (Oryza sativa L.) enhances rice resistance against insects. Therefore, the goal of this study was to evaluate the influence of Si uptake in rice on the resistance of rice to Spodoptera frugiperda Smith, the fall armyworm (FAW), and to examine morphological and biochemical correlates of resistance. To examine this, we have utilized three silicon transporter mutants (one >95% deficient in the uptake of Si, a second ~55% deficient in the uptake of Si, and a third with uptake similar to WT) with varying levels of Si uptake and compared them to the wild-type rice Nipponbare. An in situ, long-term feeding assay was carried out in which FAW neonates (< 6 h old) were reared to pupation on mutant and WT plants in pots. Higher levels of Si in tissues were associated with reduced larval and pupal weights. Larval and pupal durations as well as time to emerge were also prolonged in plants with higher Si contents. Induced resistance, phenolic content, and activities of oxidative enzymes were assayed in mutant and WT plants to determine whether the deficiency in Si affects these biochemical traits. The results of initial experiments show that Si negatively affects the growth of FAW and deficiency in silicon transporter OsLsi1 compromises rice constitutive resistance to FAW.