Dissecting out the Role of Beta-Aminobutyric Acid in Plant Immunity against Bacterial Pathogen Pst DC3000
Date Issued
2010
Date
2010
Author(s)
Chu, Po-Wei
Abstract
The non-protein amino acid beta-aminobutyric acid (BABA)has been known for years to be an effective inducer of resistance against pathogen infection. When BABA-pretreated Arabidopsis plants are challenged with the pathogenic bacteria Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), a strong potentiation of PR1 expression is observed. PR1 is the marker gene for salicylic acid (SA)-related defense response. Here, we report that BABA-mediated bacterial resistance acts in a partly SA-independent manner to prime the early Arabidopsis defense response. Upon Pst DC3000 infection, mitogen-activated protein kinase (MAPK) cascade genes, ethylene (ET) and other signaling pathways were potentiated by BABA pretreatment in both Col-0 wild type and in the SA biosynthetic sid2 mutant. Callose deposition in response to Pst DC3000 inoculation was also primed by BABA. In addition, RNAi-mediated PR2 gene silencing in sid2 mutant demonstrated BABA-induced resistance (BABA-IR) to Pst DC3000 similar to sid2 indicating that PR2 is not critical for BABA-induced resistance in sid2.
To further investigate how BABA regulates Arabidopsis immunity, members of Zimmerli’s laboratory tested over 70 T-DNA knock-out mutant lines for their sensitivity towards BABA and Pst DC3000 infection. Two T-DNA knock-out lines of a leucine-rich repeat protein kinase (LRR-PK) demonstrated enhanced bacterial susceptibility, reduced callose deposition, as well as impaired BABA sensitivity. This LRR-PK localizes to the plasma membrane. Upon Pst DC3000 infection and PAMPs treatment, this LRR-PK gene was rapidly induced. Hence, our preliminary data suggest that this gene is involved in Arabidopsis early defense responses. In addition, one gene was found important for plant resistance to necrotrophic pathogens. Mutation of AtNUDX25, one Ap4A hydrolase, led to enhanced susceptibility to Botrytis cinerea and Erwinia carotovora subsp. carotovora strain WPP14 (Ecc WPP14).
Subjects
Arabidopsis
Pseudomonas syringae
SA
early defense response
callose deposition
leucine-rich repeat protein kinase
Ap4A hydrolase
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