Cytonuclear Coordination Is Not Immediate upon Allopolyploid Formation in Tragopogon miscellus (Asteraceae) Allopolyploids

• Published in: PloS one Vol. 10; no. 12; p. e0144339
• Main Authors: Sehrish, Tina, Symonds, V Vaughan, Soltis, Douglas E, Soltis, Pamela S, Tate, Jennifer A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08-12-2015; Public Library of Science (PLoS)
• Subjects: Allopolyploidy; Analysis; Arabidopsis; Asteraceae; Asteraceae - genetics; Base Sequence; Bias; Care and treatment; Cell Nucleus - metabolism; Chromosome abnormalities; Complications and side effects; Cytoplasm - metabolism; Deoxyribonucleic acid; DNA; DNA methylation; Evolution; Evolutionary adaptation; Gene duplication; Gene expression; Genes, Plant; Genetics; Genomes; Genomics; Hybridization; Mitochondria; Molecular Sequence Data; Museums; Natural populations; Oxygenase; Physiological aspects; Polymerase Chain Reaction; Polyploidy; Populations; Reproduction (copying); Ribulose-bisphosphate carboxylase; Sequence Homology, Nucleic Acid; Tragopogon; Tragopogon dubius; Tragopogon miscellus; Tragopogon porrifolius; New England
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0144339

Allopolyploids, formed by hybridization and chromosome doubling, face the immediate challenge of having duplicated nuclear genomes that interact with the haploid and maternally inherited cytoplasmic (plastid and mitochondrial) genomes. Most of our knowledge of the genomic consequences of allopolyploidy has focused on the fate of the duplicated nuclear genes without regard to their potential interactions with cytoplasmic genomes. As a step toward understanding the fates of nuclear-encoded subunits that are plastid-targeted, here we examine the retention and expression of the gene encoding the small subunit of Ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco; rbcS) in multiple populations of allotetraploid Tragopogon miscellus (Asteraceae). These polyploids formed recently (~80 years ago) and repeatedly from T. dubius and T. pratensis in the northwestern United States. Examination of 79 T. miscellus individuals from 10 natural populations, as well as 25 synthetic allotetraploids, including reciprocally formed plants, revealed a low percentage of naturally occurring individuals that show a bias in either gene (homeolog) loss (12%) or expression (16%), usually toward maintaining the maternal nuclear copy of rbcS. For individuals showing loss, seven retained the maternally derived rbcS homeolog only, while three had the paternally derived copy. All of the synthetic polyploid individuals examined (S0 and S1 generations) retained and expressed both parental homeologs. These results demonstrate that cytonuclear coordination does not happen immediately upon polyploid formation in Tragopogon miscellus.