Abstract
<jats:title>Abstract</jats:title> <jats:p> The rejection of self-incompatible (SI) <jats:italic>Brassica</jats:italic> pollen is mediated by three signaling branches that function in parallel in the stigma. The recognition of SI pollen by the stigma S-Receptor Kinase (SRK) results in activation of the ARM-Repeat-Containing 1 E3 ubiquitin ligase (ARC1) which mediates the degradation of compatibility factors, the FERONIA (FER) and ANJEA (ANJ) receptor kinases that induces ROS accumulation to inhibitory levels and the <jats:italic>M</jats:italic> Locus Protein Kinase (MLPK) which may also be connected to ROS production. <jats:italic>Arabidopsis</jats:italic> self-incompatibility is regulated by SRK as well, but the signaling events downstream of SRK following SI pollen perception are less well-understood. In this study, we evaluated the requirements of <jats:italic>FER, ANJ</jats:italic> and <jats:italic>HERCULES RECEPTOR KINASE 1</jats:italic> ( <jats:italic>HERK1</jats:italic> ) for SI pollen rejection in the transgenic <jats:italic>Arabidopsis thaliana</jats:italic> SI-Col-0 <jats:italic>ψsrka-1</jats:italic> line. The <jats:italic>ψsrka-1</jats:italic> T-DNA disrupting the expression of the endogenous <jats:italic>ψSRKA</jats:italic> gene was crossed into SI-Col-0 to prevent any potential <jats:italic>SRK</jats:italic> transgene silencing. T-DNA mutants for <jats:italic>FER</jats:italic> and <jats:italic>ANJ/HERK1</jats:italic> were then crossed into the SI-Col-0 <jats:italic>ψsrka-1</jats:italic> line. Using standard assays for pollen-stigma interactions, the SI phenotypes were assessed for the SI-Col-0 <jats:italic>fer</jats:italic> , SI-Col-0 <jats:italic>anj-1</jats:italic> and SI-Col-0 <jats:italic>anj-1 herk1-1</jats:italic> lines. Our results presented here indicated that <jats:italic>FER</jats:italic> and <jats:italic>ANJ</jats:italic> are not required in the stigma for <jats:italic>Arabidopsis</jats:italic> SI pollen rejection, further providing evidence for a divergence in the SI downstream signaling pathway in <jats:italic>Arabidopsis</jats:italic> . </jats:p>