Expression ofBrassica napusGLO1 is sufficient to breakdown artificial self-incompatibility inArabidopsis thaliana

Abstract

Members of the Brassicaceae family have the ability to regulate pollination events occurring on the stigma surface. In Brassica species, self-pollination leads to an allele specific interaction between the pollen small cysteine-rich peptide ligand (SCR/SP11) and the stigmatic S-receptor kinase (SRK) that activates the E3 ubiquitin ligase ARC1 (Armadillo repeat-containing 1), resulting in proteasomal degradation of various compatibility factors including Glyoxalase I (GLO1) which is necessary for successful pollination. Suppression of GLO1 was sufficient to reduce compatibility, and overexpression of GLO1 in self-incompatible Brassica napus stigmas resulted in partial breakdown of the self-incompatibility response. Here, we verified if BnGLO1 could function as a compatibility factor in the artificial self-incompatibility system of Arabidopsis thaliana expressing AlSCRb, AlSRKb and AlARC1 proteins from A. lyrata. Overexpression of BnGLO1 is sufficient to breakdown self-incompatibility response in A. thaliana stigmas, suggesting that GLO1 functions as an inter-species compatibility factor. Therefore, GLO1 has an indisputable role as a compatibility factor in the stigma in regulating pollen attachment and pollen tube growth. Lastly, this study demonstrates the usefulness of an artificial self-incompatibility system in A. thaliana for interspecific self-incompatibility studies.

The Brassica mature pollen and stigma proteomes: preparing to meet

“…Deletion or inactivation of one or both of these genes is believed to underlie the evolutionary switch from an outbreeding to an inbreeding mating system within the Brassicaceae (Kitashiba and Nasrallah, 2014). However, the self‐compatibility exhibited by B. carinata could also result from defects with other proteins affecting the SI response, such as Armadillo repeat‐containing 1 (ARC1), M locus protein kinase (MLPK) and glyoxalase 1 (GLO1) (Kenney et al., 2020), with GLO1 detected in the stigma (Table S1).…”