Structural basis for specific self-incompatibility response in Brassica

Ma, Rui; Han, Zhifu; Hu, Zhongzhi; Lin, Ge; Gong, Xinqi; Zhang, Heqiao; Nasrallah, June B.; Chai, Jijie

doi:10.1038/cr.2016.129

Cited by 62 publications

(84 citation statements)

References 43 publications

(58 reference statements)

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“…Overall, we find a slightly higher number of atomic 234 contacts between the SCR and SRK molecules in the SRK03-SCR03 cognate complex (1,543 235 contacts over 91 and 62 distinct SRK and SCR amino acids respectively) than in the SRK28-236 SCR28 cognate complex (1,395 contacts over 89 and 57 distinct SRK and SCR amino acids 237 respectively, Table S1). As already noted by Ma et al (2016) Contrary to our expectation however, the non-cognate complexes did not differ substantially 252 from the cognate complexes on the basis of their total number of atomic contacts (Fig 4). 253 Specifically, the SRK03/SCR28 and SRK28/SCR03 non-cognate complexes were predicted to 254 establish a total of 1,546 and 1,328 contacts, respectively, between atoms of their SCR and 255 SRK molecules, very close to the 1,543 and 1,395 predicted contacts for the SRK03/SCR03 256 and SRK28/SCR28 cognate complexes (Table S1).…”

contrasting

confidence: 84%

Asymmetrical diversification of the receptor-ligand interaction controlling self-incompatibility in Arabidopsis

Chantreau

Poux

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et al. 2019

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150 words) 11 How two-components genetic systems accumulate evolutionary novelty and become 12 diversified in the course of evolution is a fundamental problem in evolutionary systems 13 biology. In the Brassicaceae, self-incompatibility (SI) is a spectacular example of a diversified 14 allelic series in which numerous highly diverged receptor-ligand combinations are 15 segregating in natural populations. However, the evolutionary mechanisms by which new SI 16 specificities arise in the first place have remained elusive. Using in planta ancestral protein 17 resurrection, we demonstrate that two allelic variants currently segregating as distinct 18 receptor-ligand combinations diverged through an asymmetrical process whereby one 19 variant has retained the same recognition specificity as the (now extinct) ancestor, while the 20 other has functionally diverged and now represents a novel specificity no longer recognized 21 by the ancestor. Examination of the structural determinants of the shift in binding specificity 22 suggests that allosteric changes may be an important source of evolutionary novelty in this 23 highly diversified receptor-ligand system. 24 25

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contrasting

confidence: 84%

Asymmetrical diversification of the receptor-ligand interaction controlling self-incompatibility in Arabidopsis

Chantreau

Poux

Lensink³

et al. 2019

Preprint

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“…Specifically, we searched for major-effect variants resulting in frameshifts, premature stop codons or nonconsensus splice sites, present in sequences from the SC C. orientalis and/or in the SC C. bursa-pastoris B subgenome, which is derived from C. orientalis (Douglas et al, 2015), but not in sequences from the same haplogroup found in the SI species C. grandiflora and A. halleri. For SRK we identified nonsynonymous changes in hypervariable regions important for SRK specificity (Kusaba et al, 1997;Nishio & Kusaba, 2000), based on a protein sequence alignment of Capsella SRK with Brassica rapa SRK9, which represents a different haplogroup, but whose protein structure and interaction with SCR has been resolved recently (Ma et al, 2016).…”

Section: Candidate Mutations For the Loss Of Si In C Orientalismentioning

confidence: 99%

“…SCR is a small cysteine-rich protein that is deposited on the pollen coat and acts as a ligand to the SRK receptor (Schopfer et al, 1999;Takayama et al, 2001). Direct interaction between SRK and SCR from the same S-haplotype results in inhibition of pollen germination (Takasaki et al, 2000;Takayama et al, 2001;Ma et al, 2016) through a signaling cascade involving several proteins (Nasrallah & Nasrallah, 2014). This SI response prevents close inbreeding and promotes outcrossing.…”

Section: Introductionmentioning

confidence: 99%

Genetic basis and timing of a major mating system shift in Capsella

et al. 2019

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Summary A crucial step in the transition from outcrossing to self‐fertilization is the loss of genetic self‐incompatibility (SI). In the Brassicaceae, SI involves the interaction of female and male specificity components, encoded by the genes SRK and SCR at the self‐incompatibility locus (S‐locus). Theory predicts that S‐linked mutations, and especially dominant mutations in SCR, are likely to contribute to loss of SI. However, few studies have investigated the contribution of dominant mutations to loss of SI in wild plant species. Here, we investigate the genetic basis of loss of SI in the self‐fertilizing crucifer species Capsella orientalis, by combining genetic mapping, long‐read sequencing of complete S‐haplotypes, gene expression analyses and controlled crosses. We show that loss of SI in C. orientalis occurred < 2.6 Mya and maps as a dominant trait to the S‐locus. We identify a fixed frameshift deletion in the male specificity gene SCR and confirm loss of male SI specificity. We further identify an S‐linked small RNA that is predicted to cause dominance of self‐compatibility. Our results agree with predictions on the contribution of dominant S‐linked mutations to loss of SI, and thus provide new insights into the molecular basis of mating system transitions.

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“…Self-incompatibility (SI) is a genetic mechanism in hermaphroditic flowers that prevents inbreeding by rejection of self-pollen, while allowing cross-or genetically diverse pollen to germinate on the stigma to successfully fertilize the ovules. In Brassica, SI is initiated by the allele-specific recognition of pollenencoded, secreted ligand (SCR/SP11) by the stigmatic receptor kinase S-locus receptor kinase (SRK), resulting in activation of SRK through phosphorylation [1][2][3]. Once activated, this phospho-relay converges on intracellular compatibility factors, which are immediately targeted for degradation by the E3 ligase, ARC1, resulting in the pollen rejection response [4,5].…”

Section: In Briefmentioning

confidence: 99%