Background The role of hybridization or admixture in the biological invasion has been recognized in many invasive species. S ubgenome dominance was reported to occur instantly following the hybridization of divergent genomes, however, investigations on their consequences on physiological response were still scarce . For invasive species, thermotolerance was critical to their range expansions. In this study, a F1 weed between a chilling sensitive invasive S. trilobata and the tolerant native S. calendulacea were treated with consecutive chilling stress, Using physiological assay and RNA-sequencing, differential physiological response and transcriptome profile s were compared with a n emphasis on the patterns of the expression dominance and homeolog expression bias in the F1 hybrids.
Results P hysiological assay including content of Malondialdehyde content, superoxide dismutase activity and et al. demonstrated these F1s resembled the chilling tolerant maternal parent S. calendulacea . For both parents and the F1, the numbers and categories of the enriched pathways or gene ontology terms showed extensive divergence, and an overall resemblance between F1s and S. calendulacea w as observed. For the homeologs with altered expression, expression level dominance was the most prominent pattern. With increased chilling stress, the increased magnitude of up-regulations and decreased magnitude of down-regulations of the Spc- homeologs in the F1s were jointly contributed to the ir resemblance to chilling tolerant parent S. calendulacea . Irrespective of the total homeolog expressive level, increased magnitude of homeolog expression bias toward the chilling tolerant parent S. calendulacea in the F1s also provided another line of evidence for their physiological resemblance.
Conclusion The two Sphagneticola species showed significant differential response upon chilling stress. expression dominance and persistent S. calendulacea homeolog bias in the F1s were attributed to the overall resemblance to the tolerant native species S. calendulacea. Given their vigorous growth, it cations us that the F1 hybrid have great potential to expand northwards and become an awesome weed in the future.