Constitutive expression of two endochitinases from root nodules ofElaeagnus umbellata confers resistance on transgenicArabidopsis plants against the fungal pathogenBotrytis cinerea

Abstract

Plant chitinases have been known as pathogenesis-related (PR) proteins, but recent studies suggest that they play functional roles during normal plant growth and development. We previously isolated two cDNA clones encoding endochitinases, EuNOD-CHT1 and .CHT2, from the root nodules of Elaeagnus umbellata. These genes show differential expression patterns, with the EuNOD-CHT1 gene being active in the root nodules and meristems, while EuNOD-CHT2 is preferentially expressed in the infected cells of those nodules. To elucidate the functional roles of these two endochitinases, we have now constitutively expressed each gene in a heterologous plant system, Arabidopsis thaliana. Stable inheritance and expression of the transgenes were confirmed by genomic Southern hybridization and RT-PCR. Our transgenic plants did not differ morphologically from the wild types. However, constitutive expression of EuNOD-CHT1 and -CHT2 in Arabidopsis resulted in increased resistance against a fungal pathogen, Botrytis cinerea, but not against a bacterial agent, Pseudomonas syringae pv. Tomato DC3000. Expression levels were enhanced by both wounding and jasmonic acid treatments (for EuNOD-CHT1), or by jasmonic acid only (for EuNOD-CHT2). These data suggest that EuNOD-CHT1 and -CfiT2 primarily play defensive roles during root nodule development in E. umbellata.

Characterization of four defense-related genes up-regulated in root nodules of Casuarina glauca

“…Additionally, the predicted vacuolar localization of CgCHI1 might be related to the rapid release of large quantities of protein during pathogen infection, as suggested by Neuhaus et al (1991). Supporting our data are the results from Kim et al (2005), pointing to the involvement of EuNOD-CHT1 and -CHT2 in defense during root nodule development in E. umbellata.…”

Protein extraction/solubilization protocol for monocot and dicot plant gel-based proteomics

“…Our current study focuses on protein extraction from various model plants: rice, Arabidopsis (Kim et al, 2005), maize, wheat, and cucumber. One of our objectives has been to develop an extraction protocol that can accommodate at least all the mode[ plants, and be coupled with the improved extraction and sohbilization of proteins for downstream 2-DGE.…”