Commonalities and differences between Brassica and Arabidopsis self-incompatibility

Abstract

In higher plants, the self-incompatibility mechanism is important for inhibition of self-fertilization and facilitation of out-crossing. In Brassicaceae, the self-incompatibility response is mediated by allele-specific interaction of the stigma-localized S-locus receptor kinase (SRK) with the pollen coat-localized ligand (SCR/SP11). All self-incompatible Brassicaceae plants analyzed have been found to have the SRK and SCR/SP11 genes in the S-locus region. Although Arabidopsis thaliana is self-compatible, transformation with functional SRK-SCR genes from self-incompatible Arabidopsis species confers the self-incompatibility phenotype to A. thaliana. The allele-specific interaction between SRK and SCR activates the downstream signaling cascade of self-incompatibility. Yeast two-hybrid analysis with a kinase domain of SRK as bait and genetic analysis suggested several candidate components of self-incompatibility signaling in Brassica. Recently, A. thaliana genes orthologous to the identified genes for Brassica self-incompatibility signaling were evaluated by using a self-incompatible transgenic A. thaliana plant and these orthologous genes were found not to be involved in self-incompatibility signaling in the transgenic A. thaliana. In this review, we describe common and different aspects of S-locus genomic regions and self-incompatibility signaling between Brassica and Arabidopsis.

The Papaver rhoeas S determinants confer self-incompatibility to Arabidopsis thaliana in planta

“…This demonstrates that PrsS and PrpS function as S-determinants and are the sole additional requirement to elicit SI. Intergeneric transfer of S-determinants has only been achieved between closely related species with orthologs of the Brassica S-determinants, effectively involving complementation using SRK and SCR pairs to "restore" SI (12)(13)(14). Because the Papaveraceae diverged from the Brassicaceae ~140 mya (8,15) and Arabidopsis lacks PrsS and PrpS orthologs, finding that they function in planta in A.…”

Genetic Transformation and Genomic Resources for Next-Generation Precise Genome Engineering in Vegetable Crops

“…A further constraint in vegetable breeding is the manipulation of the reproductive system (e.g., apomixis and self-incompatibility). Such traits are under the control of several candidate genes ( Hand and Koltunow, 2014 ; Yamamoto and Nishio, 2014 ) and genome editing methods could facilitate the identification of their roles, enhancing the possibility to fix desirable genotypes and accelerate the breeding rate.…”

Progress on deciphering the molecular aspects of cell-to-cell communication in Brassica self-incompatibility response

“…When there is self-pollination, the pollen ligand (SCR/SP11) and receptor (SRK) interaction from the same S haplotype induces autophosphorylation of S-receptor kinase in an S-haplotype-specific manner (Takayama et al 2001;Kachroo et al 2001Kachroo et al , 2002Watanabe et al 2012). The autophosphorylated SRK elicit a signal transduction cascade in stigma papilla cells that results in the pollen rejection and inhibition of pollen tube penetration into the epidermal cell wall of stigma and induces SI response (Kao and McCubbin 2000;Ivanov and Gaude 2009;Watanabe et al 2012;Nasrallah and Nasrallah 2014;Yamamoto and Nishio 2014). In contrast, when there is cross pollination, the pollen ligand (SCR) can neither bind nor activate SRK kinase domain and no pollen rejection signaling cascade is triggered, hence leads to development and penetration of pollen tube into the stigma papillae.…”