Abstract:

Free air carbon dioxide enrichment (FACE) technique is capable of providing a means by which the environment around growing plants may be modified to realistically simulate future concentrations of atmospheric CO2. The plant growth and development, as well as its height, biomass, and yields can be accelerated and enhanced under FACE. Identifying genomic regions influencing the response of plant height and its components to elevated CO₂ will be useful for us to understand the genetic response to changed CO₂ environment and select materials or cultivars adapting to future elevated CO2 atmospheric environment in plant height characteristics. A mapping population of 65 indica (IR24) chromosome segment substitution lines (CSSLs) with japonica (Asominori) background was used to detect quantitative trait locus (QTL) for plant height and its components containing panicle length and various internode lengths under ambient atmosphere CO₂ concentration (Ambient, about 370 µmol CO2 mol^-1) and FACE (exceed ambient CO₂ concentration about 200 µmol mol^-1). The main results indicated that plant height and its components of Asominori and IR24 under FACE were significantly different from these of Ambient at 1% probability level. Both positive and negative responses to elevated CO₂ in plant height and its components of CSSLs were observed under FACE. Among them, eight CSSLs largely responded to elevated CO₂, they were AI63 (increased 14.2 cm) and AI44 (reduced 4.54 cm) in plant height, AI9 (increased 3.56 cm) and AI12 (reduced 2.39 cm) in panicle length, AI39 (increased 15.74 cm) and AI27 (reduced 1.49 cm) in the first internode, AI32 (increased 8.09 cm) and AI53 (reduced 3.00 cm) in the second internode. Fourteen QTLs and 15 QTLs were detected under FACE and Ambient, respectively. Among them, 5 QTLs, named qPH6^-4, qPH8^-4, qPL8^-4, qPL12^-4, and qLFN6^-4, were simultaneously detected under FACE and Ambient, the others were detected only under one CO₂ level. Three QTLs, named qPH6^-4QE, qPH8^-4QE and qLSN5^-4QE were found to have gene x environment interaction effects significantly. It is suggest that some new QTLs for plant height and its components can be detected under elevated CO₂ condition, the QTLs being detected under unitary CO₂ condition, natural ambient atmosphere or FACE are sensitive to CO₂ concentration, plant height is controlled by the interaction effect between genotype and CO₂ concentration.

Key words: CO2 concentration, Chromosome segment substitution lines (CSSLs), Plant height, Quantitative trait loci (QTLs), Rice