‘Self’ Pollen Rejection Through the Intersection of Two Cellular Pathways in the Brassicaceae: Self-Incompatibility and the Compatible Pollen Response

Comparative transcriptome analysis of self-incompatible flower stigmas and self-compatible bud stigmas following self-pollination in broccoli

“…The results of this study revealed that THL had inhibitory effect in SI reaction of broccoli, and that stigmas of buds were self-compatible, which might be related to the high expression of THL and low expression of SRK, SLG, and ARC1. Exo70A1 was a potential substrate for ARC1 and was required for compatible pollenstigma interactions (Samuel et al, 2008). However, in this study, the expression levels of EXO70A1 in SBs were far lower in SFs and pollination had little to no effect on its expression levels both in SBs and SFs, which indicates that EXO70A1 could not be the negative regulator of SI.…”

“…When incompatible pollen landed on stigma, SRK interacted specifically with SCR, and was released from THL and activated. It was then directed with ARC1 to re-localize to the proteasomes, where ARC1 targets EXO70A1 (Kachroo et al, 2001;Takayama et al, 2001;Samuel et al, 2008;Wang et al, 2014). A complex SI signal pathway was activated in the stigma, which ultimately led to rejection of self-pollen.…”

Proteomic Analysis of Brassica Stigmatic Proteins Following the Self-incompatibility Reaction Reveals a Role for Microtubule Dynamics During Pollen Responses

“…In species of Brassicaceae (canola, broccoli, cabbage, Arabidopsis), which are characterized by dry stigmas, this recognition occurs at the earliest stages of pollen adhesion and hydration. Only compatible pollen is capable of inducing the stigma to release its resources such as water and other factors necessary for pollen growth, whereas incompatible pollen is blocked either prior to hydration or during attempts to penetrate the stigmatic barrier (3). Although multiple genetic screens have identified various compatible pollen factors necessary for the initial recognition mechanisms, the molecules or mechanisms behind delivery of stigma factors necessary to support pollen growth remain largely unknown (3,4).…”

“…Only compatible pollen is capable of inducing the stigma to release its resources such as water and other factors necessary for pollen growth, whereas incompatible pollen is blocked either prior to hydration or during attempts to penetrate the stigmatic barrier (3). Although multiple genetic screens have identified various compatible pollen factors necessary for the initial recognition mechanisms, the molecules or mechanisms behind delivery of stigma factors necessary to support pollen growth remain largely unknown (3,4). The lipids of the stigmatic cuticular layer are proposed to interact with the lipids from pollen coat to form a hydraulic conduit for passage of water from the stigma to pollen.…”

Evaluation of genetic diversity in self-incompatible broccoli DH lines assessed by SRAP markers

“…The SSI system has been best characterized in the genus Brassica, and is primarily controlled by a receptorligand system encoded in two tightly linked and multiallelic genes: the S receptor kinase (SRK), and the small cysteine-rich secreted protein, SP11/SCR (Samuel et al, 2008). SRK is the sole determinant of specificity in the stigma, and encodes a membrane-associated receptor protein kinase with extracellular, transmembrane and cytoplasmic kinase domains (Takasaki et al, 2000;Silva et al, 2001).…”