Identification of novel inhibitors of 1-aminocyclopropane-1-carboxylic acid synthase by chemical screening in Arabidopsis thaliana.

Ethylene is a gaseous hormone important for adaptation and survival in plants. To further understand the signaling and regulatory network of ethylene, we used a phenotype-based screening strategy to identify chemical compounds interfering with the ethylene response in Arabidopsis thaliana. By screening a collection of 10,000 structurally diverse small molecules, we identified compounds suppressing the constitutive triple response phenotype in the ethylene overproducer mutant eto1-4.

Alkaline alpha-galactosidase degrades thylakoid membranes in the chloroplast during leaf senescence in rice.

Here, we studied the functional role of a chloroplast alkaline alpha-galactosidase (OsAkalphaGal) in the breakdown of thylakoid membranes during rice (Oryza sativa) leaf senescence. We assayed the enzyme activity of recombinant OsAkalphaGal with different natural substrates and examined the effect of ectopic OsAkalphaGal expression in rice plants. Recombinant OsAkalphaGal showed at least a two-fold greater substrate-binding affinity and a 10-fold greater turnover rate to galactolipid digalactosyl diacylglycerol than the raffinose family of oligosaccharides (verbascose, stachyose, raffinose) and melibiose.