Variations among races of Arabidopsis thaliana (L.) heynh for survival in limited carbon dioxide.

Races of a C3 plant species, Arabidopsis thaliana, were screened for time of survival when enclosed in an air-tight chamber with a C4 plant species (Zea mays L.). This has been suggested as a method of detecting and selecting for increased photosynthetic efficiency among C3 genotypes. The C4 plant should, in such conditions, reduce the atmospheric CO2 concentration below the compensation point of the C3 plant, resulting in its eventual death. Significant differences were found among the A. thaliana races for survival time; some races survived only one week in competition with corn while others survived more than two weeks. Two races, chosen for contrasting survival in closed chambers, were hybridized and compared to their F2 progeny for survival time. Substantial genetic segregation occurred among the F2, and a number of transgressive segregates having survival times superior of both parents were identified. Also significant heterosis was observed in the F2 population.