title: Genotypes of Brassica rapa respond differently to plant-induced variation in air CO2 concentration in growth chambers with standard and enhanced venting.
abstract: Growth chambers allow measurement of phenotypic differences among genotypes under controlled environment conditions. However, unintended variation in growth chamber air CO2 concentration ([CO2]) may affect the expression of diverse phenotypic traits, and genotypes may differ in their response to variation in [CO2]. We monitored [CO2] and quantified phenotypic responses of 22 Brassica rapa genotypes in growth chambers with either standard or enhanced venting. [CO2] in chambers with standard venting dropped to 280 micromol mol(-1) during the period of maximum canopy development, approximately 80 micromol mol(-1) lower than in chambers with enhanced venting. The stable carbon isotope ratio of CO2 in chamber air (delta13C(air)) was negatively correlated with [CO2], suggesting that photosynthesis caused observed [CO2] decreases. Significant genotype x chamber-venting interactions were detected for 12 of 20 traits, likely due to differences in the extent to which [CO2] changed in relation to genotypes' phenology or differential sensitivity of genotypes to low [CO2]. One trait, 13C discrimination (delta13C), was particularly influenced by unaccounted-for fluctuations in delta13C(air) and [CO2]. Observed responses to [CO2] suggest that genetic variance components estimated in poorly vented growth chambers may be influenced by the expression of genes involved in CO2 stress responses; genotypic values estimated in these chambers may likewise be misleading such that some mapped quantitative trait loci may regulate responses to CO2 stress rather than a response to the environmental factor of interest. These results underscore the importance of monitoring, and where possible, controlling [CO2].
authors: Department of Botany, University of Wyoming, Laramie, WY 82071, USA. cedwar10@uwyo.edu
authors: Christine E
authors: CE
authors: Edwards
authors: Monia S H
authors: MS
authors: Haselhorst
authors: Autumn M
authors: AM
authors: McKnite
authors: Brent E
authors: BE
authors: Ewers
authors: David G
authors: DG
authors: Williams
authors: Cynthia
authors: C
authors: Weinig
mesh_terms: D000388:Air; D029741:Brassica rapa / Q000254:growth & development*; D002245:Carbon Dioxide / Q000502:physiology*; D002247:Carbon Isotopes / Q000737:chemistry; D018556:Crops, Agricultural / Q000254:growth & development*; D004780:Environment, Controlled; D005838:Genotype; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide