Functional analysis of Lecrk-a1, a lectin receptor kinase involved in pathogen resistance
Date Issued
2010
Date
2010
Author(s)
Chen, Wei-Yen
Abstract
β-aminobutyric acid (BABA) is an artificial, non-protein amino acid. BABA-treated plants mount a faster and stronger resistance against biotic and abiotic stress. However, the mode of action of BABA is poorly understood. Through a reverse genetic approach, we discovered the lecrk-a1 mutant that showed an altered response to BABA, including loss of BABA-mediated protection, indicating that this gene could be involved in BABA signalling pathway. This knockout lecrk-a1 mutant possesses a T-DNA insertion in the kinase domain of the lectin receptor-like kinase a1 gene (LecRK-a1).
Inactivation of LecRK-a1 causes distinct responses to biotrophic and necrotrophic pathogens. lecrk-a1 was more susceptible to Botrytis cinerea and more resistant to Pseudomonas syringae pv. tomato DC3000, possibly due to lower PDF1.2 and higher PR-1 expression after pathogen inoculation, respectively. Without any treatment, lecrk-a1 demonstrated high SA-related PR-1, PR-2 and PR-5 gene expressions. On the other hand, expression of PDF1.2 gene and other secondary JA/ET marker genes was low in lecrk-a1. Together, it suggests that the SA-defense response is constitutively activated and the JA/ET signaling is reduced in the lecrk-a1. The PR-1 expression strongly increases as the lecrk-a1 ages, while in wild type Col-0, increase in PR-1 expression is arrested at 4 weeks after germination. LecRK-a1 might be involved in age-related resistance. Introducing a wild type copy of the LecRK-a1 coding sequence in the lecrk-a1 background restored a normal PR-1 gene expression and the susceptibility to B. cinerea, confirming that the observed phenotypes are caused by a mutation in LecRK-a1.
Subjects
Arabidopsis thaliana
lectin receptor-like kinase
pathogen resistance
Type
thesis
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