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Summary Distyly is an intriguing floral adaptation that increases pollen transfer precision and restricts inbreeding. It has been a model system in evolutionary biology since Darwin. Although theS‐locus determines the long‐ and short‐styled morphs, the genes were unknown inTurnera. We have now identified these genes.We used deletion mapping to identify, and then sequence,BACclones and genome scaffolds to constructS/shaplotypes. We investigated candidate gene expression, hemizygosity, and used mutants, to explore gene function.Thes‐haplotype possessed 21 genes collinear with a region of chromosome 7 of grape. TheS‐haplotype possessed three additional genes and two inversions.TsSPH1was expressed in filaments and anthers,TsYUC6in anthers andTsBAHDin pistils. Long‐homostyle mutants did not possessTsBAHDand a short‐homostyle mutant did not expressTsSPH1.Three hemizygous genes appear to determine S‐morph characteristics inT. subulata. Hemizygosity is common to all distylous species investigated, yet the genes differ. The pistil candidate gene,TsBAHD, differs from that ofPrimula, but both may inactivate brassinosteroids causing short styles.TsYUC6is involved in auxin synthesis and likely determines pollen characteristics.TsSPH1is likely involved in filament elongation. We propose an incompatibility mechanism involvingTsYUC6andTsBAHD.
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RNase‐based self‐incompatibility in cacti
Summary Approximately one‐half of all flowering plants express genetically based physiological mechanisms that prevent self‐fertilisation. One such mechanism, termed RNase‐based self‐incompatibility, employs ribonucleases as the pistil component. Although it is widespread, it has only been characterised in a handful of distantly related families, partly due to the difficulties presented by life history traits of many plants, which complicate genetic research. Many species in the cactus family are known to express self‐incompatibility but the underlying mechanisms remain unknown.We demonstrate the utility of a candidate‐based RNA‐seq approach, combined with some unusual features of self‐incompatibility‐causing genes, which we use to uncover the genetic basis of the underlying mechanisms. Specifically, we assembled transcriptomes fromSchlumbergera truncata(crab cactus or false Christmas cactus), and interrogated them for tissue‐specific expression of candidate genes, structural characteristics, correlation with expressed phenotype(s), and phylogenetic placement.The results were consistent with operation of the RNase‐based self‐incompatibility mechanism in Cactaceae.The finding yields additional evidence that the ancestor of nearly all eudicots possessed RNase‐based self‐incompatibility, as well as a clear path to better conservation practices for one of the most charismatic plant families.
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- Award ID(s):
- 1655692
- PAR ID:
- 10446928
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 231
- Issue:
- 5
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- p. 2039-2049
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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