Poster: Intercellular Signaling

Abs # 806: Analysis of a knockout mutant for a cell wall associated receptor kinase reveals its role in Arabidopsis heavy metal responses

Presenter:	Jackson, Angela , ajackson1love@msn.com
Authors	Jackson, Angela  (A)   Chae, Lee  (A)   Verica, Joseph  (A)   Tong, Hongyun  (A)   Selby, Jessie  (A)   He, Zheng-Hui  (A)
Affiliations:	(A): San Francisco State University

A family of genes with sequence similarity to the cell wall-associated kinase (WAK) genes in Arabidopsis has recently been identified (Verica and He, Plant Physiology 129:455-459, 2002). The WAK and the WAK-Like Kinase (WAKL) genes encode receptor protein kinases that may serve as signaling molecules physically linking the cell wall to the cytoplasm of a plant cell. WAK/WAKL proteins thus may play important roles in cell-cell and cell-environment communications. Our previous molecular and genetic studies have shown that WAK/WAKL genes are required for various cellular processes including pathogenesis and cell elongation (Lally et al., Plant Cell 13:1317-1331, 2001). In this study, the functional roles for one of the newly discovered WAKL members, WAKL14, were examined. WAKL14 gene was found to encode a protein that has auto-phosphorylation activities indicating WAKL14, as predicted, encodes an active kinase. The WAKL14 antibody localized WAKL14 protein to the cell surface suggesting, like other WAK proteins, WAKL14 is also a plasma membrane localized receptor kinase. WAKL14 promoter-GUS analyses revealed that WAKL14 was highly expressed in roots and its expression are responding to various abiotic stresses. A T-DNA knockout mutant for WAKL14 was isolated. Southern and Northern analyses showed that the isolated wakl14 mutant is a true knockout mutant. The wakl14 growth analyses on media containing various heavy metals have revealed that wakl14 mutant is hypersensitive to heavy metals including zinc and nickel. Based on our biochemical, molecular and genetic analyses of WAKL14, we conclude that WAKL14 gene encodes a receptor kinase that may play an important role in plant heavy metal responses.