Assistant Professor (fixed-term) Michigan State University East lansing, Michigan
Body of Abstract: Chloroplast membranes are characterized by an extensive photosynthetic membrane uniquely composed of galactolipids. The plastid lipase 3, PLIP3, cleaves 18:3 acyl groups (number of carbons: number of double bonds) from Arabidopsis chloroplast membrane lipids and can be subsequently oxygenated by enzymatic reactions or chemical oxidation to yield oxylipins such as jasmonic acid (JA). Overexpression of PLIP3 resulted in stunted plant growth with altered leaf morphology and accumulation of JA and other oxylipin metabolites, redirecting the metabolism from growth to defense. Moreover, the expression of PLIP3 is responsive to abiotic stressors and ABA, suggesting a possible PLIP3-based mechanism connecting JA and ABA signal transduction pathways in Arabidopsis.
To gain a deeper understanding of how chloroplast membrane lipid-derived signals are involved in coordinating biotic or abiotic stress responses, we have conducted a genetic suppressor screen in the PLIP3-OX (PLIP3 overexpression) background to query the information chain from the origin of the lipid-based signal to its transduction, perception, and modification by other signaling pathways. Following mutagenesis of the PLIP3-OX overexpression lines, plants exhibiting (partially) restored growth or reversion of morphological phenotypes such as petiole length were selected. Part of the mutant screen effort was conducted during a Course-based Undergraduate Research Experience (CURE), and promising M2 generation suppressor mutants were further studied in the research lab. The M3 generation of plants showing suppressor phenotypes were backcrossed with PLIP3-OX, and the F2 generation of segregating mutants was analyzed for their morphological traits, genotype, and lipid profiles. We have identified two promising mutants and will perform bulk sequencing to determine the mutated loci.
This work will extend our understanding of the integration of biotic and abiotic stress responses about the roles of individual signaling molecules such as JA or ABA and ultimately will inform novel strategies in efforts to make plants more resilient to environmental insults.