Poster: Intercellular Signaling

Abs # 802: Identification of components in the signaling pathway for a cell wall-associated receptor kinase through a suppressor screening

Presenter:	Lally, David , wlkgene@yahoo.com
Authors	Lally, David  (A)   Cavazos, Alexandra  (A)   Tong, Hong-Yun  (A)   He, Zheng-Hui  (A)
Affiliations:	(A): San Francisco State University

Our prior studies have shown glucocorticoid-induced antisense expression of an Arabidopsis cell wall-associated kinase (WAK4) inhibits cell elongation and leads to early developmental arrest (Lally, et al., 2001 Plant Cell 13:1317-1331). Plants homozygous for the WAK4 antisense gene die in early stages of development if WAK4 antisense expression is turned on by the inducer dexamethasone (DEX, 30mM). This dramatic DEX-inducible lethal phenotype provides an excellent system to genetically dissect the WAK4 signaling pathway through a suppressor screening. WAK4 antisense (W4A) seeds were mutagenized with EMS. A saturated screening was carried out on the M2 population to identify mutants capable of surviving on media containing 30 mM DEX. Thirty-seven such survived mutants have been identified. Among these survivors, plants with impaired W4A expression have been ruled out through genetic analyses. Since the lethality caused by W4A expression is dominant, backcrosses of these candidate mutants into both the wild-type and the W4A parental plants have allowed us to differentiate true suppressor mutants from mutants with impaired W4A expression. Seven true suppressors have been identified, and all seven appear to be recessive. These seven suppressors are currently being isolated through positional cloning. Characterizing these suppressors will allow us to gain valuable insight into how WAKs function in communication between the cell wall and the cytoplasm.