Poster: Lipids & Related Molecules

Abs # 863: Deciphering the signaling molecules during programmed cell death induced by Yariv reagent in tobacco BY-2 cells

Presenter:	Chen, Ming , mc341189@ohio.edu
Authors	Chen, Ming  (C)   Showalter, Allan M (A)
Affiliations:	(A): Ohio University

Arabinogalactan-proteins (AGPs) are a group of highly glycosylated, hydroxyproline-rich glycoproteins that are widely distributed in the plant kingdom. Recent studies [Gao and Showalter (1999) Plant J. 19, 321-331; Chaves et al. (2002) Physiologia Plantarum 116, 548-553] suggest a role for AGPs in plant programmed cell death (PCD). Here, (â-D-galactosyl)3 Yariv phenylglycoside (Yariv reagent), a synthetic chemical which specifically interacts with AGPs and perturbs their functions, was used to induce PCD in tobacco BY-2 cells. The following observation were made with respect to this Yariv-induced PCD: 1) Both hydrogen peroxide and cytosolic calcium regulate this cell death with calcium acting prior to H2O2 as indicated by calcium channel blocker experiments; DAB staining also revealed the marked accumulation of H2O2 preceding PCD. BY-2 cells were stably transformed with the apoaequorin gene and will now be used to measure changes in cytosolic calcium following Yariv treatment. 2) Hsr203, a tobacco serine hydrolase gene expressed during PCD as part of the hypersensitive response, was found to be up-regulated in response to Yariv treatment. 3) A 38 KD protease was detected by an in gel protease assay following Yariv treatment. These findings indicate that AGPs, once perturbed by Yariv reagent, can activate a PCD pathway, which likely involves a number of factors including calcium, hydrogen peroxide, hydrolase and protease.