Amare Assefa

Year: 2010

Exploration of potential interactions between SA signaling and lipid metabolism: characterization of two putative SA-binding proteins (pSABPs) Shaven 3(SHV3) and Shaven-Like 2(SVL2) in plant resistance

Despite the abundance of plants and their relative ease of study, defense mechanisms are still yet to be fully understood. Jasmonic acid (JA) and salicylic acid (SA) have proven to be important signals for plant defense and immunity against insect and pathogenic attack, respectively. Seeing that SA is an essential hormone in plant defense against biotrophic pathogens, the Klessig lab investigates putative salicylic acid binding proteins (pSABPs) including Shaven-3 (SHV3) and SHV3-like 2 (SVL2). These glycerophosphoryl diester phosphodiesterase- like (GPDLs) proteins have two tandem repeats similar to classified GPDs which break down glycerophosphodiesters into glycerol-3-phosphate and an alcohol. Additionally, SVL2 was found to be an NPR1-dependent SA-induced early responsive gene. Previous research shows SHV3 and SVL2 were wound induced and SA induced but their regulation was independent of MeJA. In order to understand the role of lipid metabolism in plant defense I characterized SHV3, SVL2, and SVL1, another homolog of SHV3, regulation in response to biotic stresses. Transcription analysis of the GPDLs using promoter:GUS fused plant was done. After insect herbivory the GPDLs were responsive to wounding by caterpillars represented by increased GUS activity at the wound edge. Transcriptional analysis after innoculation with Pseudomonas syringae pv. tomato DC3000 avrRpt2 resulted in an inhibition of SVL1 and SVL2 promoter activity. SVL1 and SVL2 promoter suppression in response to pathogen attack might be regulated by SA. However, SVL1 and SVL2 promoter activation in response to insect feeding might be independent of JA. Further characterization of SVL1, SVL2, and SHV3 transcripts will help to understand their direct regulation in response to biotic stress. Characterizing insect and pathogen performance on knock-out mutants of these genes will help to gain insight in their relevance during the plants’ defense response.

My Experience

Despite the abundance of plants and their relative ease of study, defense mechanisms are still yet to be fully understood. Jasmonic acid (JA) and salicylic acid (SA) have proven to be important signals for plant defense and immunity against insect and pathogenic attack, respectively. Seeing that SA is an essential hormone in plant defense against biotrophic pathogens, the Klessig lab investigates putative salicylic acid binding proteins (pSABPs) including Shaven-3 (SHV3) and SHV3-like 2 (SVL2). Further characterization of SVL1, SVL2, and SHV3 transcripts will help to understand their direct regulation in response to biotic stress. Characterizing insect and pathogen performance on knock-out mutants of these genes will help to gain insight in their relevance during the plants’ defense response.