Biology Reference
In-Depth Information
for the HAMPs At Pep1, At Pep2, At Pep3, At Pep4, At Pep5, and At Pep6 and PEPR2
is a receptor for At Pep1 and At Pep2 (Yamaguchi et al. 2010 ).
The pepr1 and pepr2 mutants affected in PEPR1 and PEPR2 and the wild type
Arabidopsis plants were sensitive to AtPep1, but the double mutant pepr1 / pepr2
was completely insensitive. At Pep1 triggers a receptor-dependent transient depolar-
ization through activation of plasma membrane anion channels. This effect was
absent in the double mutant pepr1 / pepr2 (Krol et al. 2010 ). These results suggest
that a receptor complex consisting of two PRRs (PEPR1 and PEPR2) acts as recep-
tor for At Pep1. The double mutant also fails to respond to At Pep2 and At Pep3, the
homologues of At Pep1, suggesting that the receptor complex PEPR1 and PEPR2 is
responsible for the perception of all three HAMPs (Krol et al. 2010 ).
Both PEPR1 and PEPR2 were transcriptionally induced by the HAMP Pep
peptides (Yamaguchi et al. 2010 ). Methyl jasmonate induced transcription of both
PEPR1 and PEPR2 expression within 30 min, whereas methyl salicylate and
1-aminocyclopropan-1-carboxylic acid, an ethylene precursor, did not induce
either PEPR1 or PEPR2 (Yamaguchi et al. 2010 ). The results suggest that JA sig-
naling system may be involved in activation of PEPRs. The receptors may be
involved in amplifi cation of the innate immune response in Arabidopsis induced
by Pep peptides (Yamaguchi et al. 2006 ).
2.11.15
WAK1 as a Receptor for the HAMP
Oligogalacturonides
Oligogalacturonides (OGs) released from the plant cell wall are active as
damage-associated molecular patterns (DAMPs) or host-associated molecular
patterns (HAMPs) for activation of the plant immune response (Brutus et al.
2010 ). The wall-associated kinase 1 (WAK1) has been identifi ed as a receptor of
OGs (Brutus et al. 2010 ). WAK1 belongs to the huge family of 610 receptor-like
kinases identifi ed in the Arabidopsis thaliana genome (Shiu and Bleecker
2001a , b ). WAKs display a typical plant Ser/Thr kinase signature and an extra
cytoplasmic domain (ectodomain) containing several EGF (Epidermal Growth
Factor)-like repeats. WAK1 binds in vitro to OGs through the N-terminal non-
EGF portion of the ectodomains (Decreux et al. 2006 ; Cabrera et al. 2008 ).
WAK1 is induced by wounding, bacterial infection, and salicylic acid treatment
(He et al. 1998, 1999 ; Wagner and Kohorn 2001). WAK1 is up-regulated in
response to OGs, whereas it is slightly down-regulated by fl g22 (Denoux et al.
2008 ). WAK1 was capable to sense OGs in vivo and trigger a defense response
(Brutus et al. 2010 ). The role of WAK1 as a receptor of the HAMP OGs was
demonstrated by constructing chimeric receptors carrying EFR and WAK1.
Upon stimulation with OGs, the WAK1 ectodomain was capable of activating
the EFR kinase domain. Transgenic plants over expressing WAK1 are more
resistant to Botrytis cinerea (Brutus et al. 2010 ).
 
Search WWH ::




Custom Search