Elevated CO2 concentration enhance Oryza sativa seed shattering and affects seed-shattering gene expression

Weedy rice (Oryza sativa L.) is widely recognized 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 its control in cultivated rice systems. Shattering traits are controlled genetically and by different environmental conditions. At present, a rapidly changing environment, including rising levels of carbon dioxide [CO2], could alter shattering frequency, with subsequent effects on weed seed input and competition. The objective of the current study was to evaluate the interaction between weedy rice seed shattering and the transcriptional seed shattering-regulation genes as affected by weedy rice genotypes and atmospheric CO2 concentrations. We examined seven biotypes and two atmospheric CO2 concentrations: ambient {a[CO2]} and enhanced {e[CO2]} concentration, 400 and 700 µmol mol-1 respectively. Our results indicate that e[CO2] increases weedy rice seed shattering. The gene expression analysis demonstrates an effect of [CO2] in the expression of all gene shattering-related genes (OsCPL1, qSH1, Sh4, SHAT1, OsXTH8, OSH15, and SH5), with high variability observed between genotypes. Here we showed that increased CO2 concentration affects greatly seed shattering in weedy rice and in minor effect cultivated rice, by modulation of seed shattering-related genes and weedy genotypes showed the highest upregulation level of this genes. Thus, increased CO2 concentration positively affect panicle number and grain yield mainly in cultivated rice.