VARIANCE FOR WATER-USE EFFICIENCY AMONG ECOTYPES AND RECOMBINANT INBRED LINES OF ARABIDOPSIS-THALIANA (BRASSICACEAE)

Knowledge of natural variation among ecotypes and recombinant inbred l ines of Arabidopsis thaliana L. Heynh for season-long water-use effici ency (WUE, moles of carbon accumulated per mole of water used) is usef ul in the design of experiments to understand the genetic control of t his phenomenon. Water-use efficiency among 31 container-grown Arabidop sis ecotypes ranged from a high of 2.40 to a low of 1.86 mg/g (grams o f dry aerial biomass per gram of water used). Genetic variance for WUE was observed among 80 F-5 recombinant inbred lines (RILs) derived fro m a cross between the highest (Lip-0) by the lowest (Edi-0) ecotype. T he heritability of WUE was calculated as 0.18 +/- 0.07. The mean WUE f or the ten highest and ten lowest RILs was 2.42 and 1.05 mg/g, respect ively. A significant difference was observed in the composition of sta ble isotopes of plant carbon (delta(13)C) between the mean of the ten highest (-31.23 parts per thousand) and the mean of the ten lowest (-3 1.96 parts per thousand) RILs based on WUE. Characterization of the 80 RILs provides a structured population for further genetic and physiol ogic study of WUE.