these H+ pumped to the cell wall. This decreases pH in the cell wall as protons are pumped across which activates expanding proteins. This increases cell wall extensibility and thus stimulates cell wall extension. This happens because the loosening of the cell wall allows for turgor pressure to extend the length of the cell, resulting in overall root growth. It is important to note however that there are no significant differences in growth of the leaves when they were exposed to different AHLs, even C6-HSL. That being said, other AHLs may have different functions in quorum sensing such as inducing defense related transcriptional changes. The defense-inducing AHLs in A. thaliana showed different characteristics in contrast to the growth-inducing AHLs in A. thaliana. When A. thaliana treated with C14-HSL and C12-HSL are compared in Pseudomonas syringae bacteria exposure, A. thaliana treated with C14-HSL derivatives exhibited smaller colony-forming unit numbers, conferring stronger bacterial resistance in A. thaliana. This shows that long-chain AHLs induce pathogen resistance while growth-inducing short-chain AHLs don't. However, it is important to note that resistance induced from long-chain AHL was only effective against the biotrophic and hemibiotrophic pathogens. It is speculated that mitogen-activated protein kinase (MAPK) plays a role in the resistance by transducing the external stimuli to extracellular responses. Nevertheless, more study is needed to further speculate the precise mechanism of AHL-induced resistance. A prominent QS molecule (autoinducer) as discussed before is the AHL which is produced proportionally to the number of cells in the bacteria colony. Once produced, A. thaliana has receptors that are precise to different AHL in order to induce different interactions which are dependent on the recognition of lactone ring, amide group, and fatty acid chain length. The defense that can be induced through the sensing of AHL by its cognate receptor are the production of ethylene, salicylic acid, and jasmonic acid. Although the mechanism/pathway of these responses are not understood as of yet completely for A. Thaliana, the response of production of jasmonic acid and salicylic acid and alongside ethylene allows for a shifting of focus from plant growth to the defense against bacteria. Production of jasmonic acid, salicylic acid, and ethylene production works on the defense against bacteria and jasmonic acid for the root and shoots, salicylic acid for the induction of local and systemic acquired resistance against different bacteria, and ethylene modulates the plant's immune responses. Overall, it is obvious how