The AtPP gene of the Brassica napus S locus region is specifically expressed in the stigma and encodes a protein similar to a methyltransferase involved in plant defense
N. Brugiere et al., The AtPP gene of the Brassica napus S locus region is specifically expressed in the stigma and encodes a protein similar to a methyltransferase involved in plant defense, SEX PLANT R, 13(6), 2001, pp. 309-314
Self-incompatibility (SI) in Brassica is controlled by the S locus. The spe
cificity of the Sl response is controlled on the stigma side by the S recep
tor kinase (SRK) and on the pollen side by the SCR (S locus cysteine-rich)
protein, but other proteins might be involved in the process of self-pollen
rejection. In this study, we show that the AtPP gene linked to the S locus
of Brassica napus is expressed in the stigmas of Sl lines. AtPP has a deve
lopmental pattern of expression similar to the SRK gene. The AtPP protein h
as similarity with members of an Arabidopsis protein family and with an S-a
denosyl-L-methionine:salicylic acid carboxyl methyltransferase, which is a
plant defense-related protein of Clarkia breweri representing a new class o
f methyltransferases. A member of the AtPP gene family is present in the ho
meolog region of the S locus in Arabidopsis. Therefore, this gene might hav
e co-evolved with S genes from an ancestral S locus of Brassicaceae. Possib
le functions of the AtPP protein in the self-recognition process are discus
sed.