Sang Wook Park - profile information

Research

Modus operandi of phytodefense hormone 12-oxophytodienoic acid (OPDA) in plant disease resistances: OPDA binds and reduces a receptor, cyclophilin (CYP)20-3, by stimulating its interaction with thioredoxin (TRX)F2 that delivers electrons (e⁻) from the photosystem (PS)I. The activated CYP20-3 then splits serine acetyltransferase (SAT)1 (dimeric trimers) in half to bring about the recruitment of O-acetylserine(thiol)lyase (OASTL)-B dimer, forming a hetero-oligomeric cysteine (Cys) synthase complex (CSC) that assimilates sulfurs and generates Cys and glutathione (GSH), which in turn coordinates (i) the S-glutathionylation (activation) of 2-Cys peroxiredoxinA (2CPA, a recycler in the water-water cycle) in peroxide detoxification, while (ii) triggering the retrograde regulation of the expression of defense OPDA-responsive genes in the nucleus. This regulatory interface between growth and defense responses shapes the optimal growth plasticity and survival potential of plants under various environmental pressures. Chl, chloroplasts; Fd, ferredoxin; FTR, ferredoxin-thioredoxin reductase; 2CPA^GS, S-glutathionylated 2CPA; Nuc, nucleous; ox, oxidized; TCA, tricarboxylic acid cycle; Thyl, thylakoid.

Engineering of for-profit drought tolerant crops: The cost of defense, referred to as the growth and defense tradeoffs, appears to be a major pitfall in the process of genetically engineering/improving defense capacity in plants (PMPP 95:55). In an effort to search for feasible approaches to enhance defense responses, many studies including ours have highlighted plant growth-promoting rhizobacteria (PGPR)-mediated Induced Systemic Tolerance (IST), unique mechanisms capable of priming drought and/or abiotic stress tolerance without growth. A caveat is that PGPR applications often display little reproducibility in the field, because a variety of endo/exogenous factors cause them to be unable to colonize plant roots (Biotechnol Lett 32: 1559). Thus, we have identified two PGPR-responsive genes, RD29s, that play critical roles in equipping plants with IST.