To keep genetic diversity, flowering plants have developed a self-incompatibility system, which can prevent self-pollination.
It has been reported that calcium concentration in pistil papilla cells was increased after self-pollination
in transformed self-incompatible Arabidopsis thaliana. In this study, we found that CML27 changed its expression
level for both mRNA and protein when compared to transcriptome and proteome. At the same time, CML27 was
expressed in the anther and pistil at a high level and reached up to 5-fold up-regulated expression in the pistil
at 1 h post-pollination when compared to 0 min. In order to find out potential proteins that may interact with
BoCML27, BoCML27 was expressed in and isolated from E. coli. After its co-incubation with Brassica oleracea
pistil proteins, the products were separated on SDS-PAGE gels. We found a specific band at the position between
130–180 kDa. Through LC-MS-MS (Q-TOF) analysis, eight proteins were identified from the band. The proteins
include 26S proteasome non-ATPase regulatory (26S), Phospholipase D, alpha 2 (PLDα2) involved in Ca2+ binding
and Coatomer subunit alpha-2-like (Coatomer) involved in vesicle mediated transport. All of these identified
proteins provide new insights for the self-incompatibility response in B. oleracea, specific for increasing Ca2+
concentration in pistil papilla cells.