Elevated CO2 concentration enhances Oryza sativa seed shattering and affects seed shattering gene expression

Abstract

AbstractWeedy rice (Oryza spp.) is widely recognised as a major constraint in cultivated rice systems globally. Seed shattering is related to the invasiveness and persistence of weedy ecotypes in field and exacerbates control of weedy rice in cultivated rice systems. Shattering traits are controlled genetically and by different environmental conditions. At present, a rapidly changing environment, including rising levels of atmospheric carbon dioxide, could alter shattering frequency, with subsequent effects on weed seed input and competition. The study aimed to evaluate the interaction between weedy rice seed shattering and transcriptional seed shattering‐regulation genes as affected by weedy rice genotypes and atmospheric CO2 concentrations. We examined seven biotypes and two levels of atmospheric [CO2]: ambient {a[CO2]} and enhanced {e[CO2]} concentrations of 400 and 700 μmol mol−1 respectively. Our results indicate that e[CO2] increases weedy rice seed shattering. The gene expression analysis demonstrates that in most genotypes the e[CO2] increased the expression of all shattering‐related genes (OsCPL1, qSH1, Sh4, SHAT1, OsXTH8, OSH15 and SH5). Atmospheric [CO2] greatly affects seed shattering in weedy rice and has a minor effect on cultivated rice, by modulation of seed shattering‐related gene expression. Weedy rice genotypes had the highest upregulation of these genes.