Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Workshop: Abiotic Stress
            

FIELD EVALUATION OF MAIZE BDLs AND DERIVED HYBRIDS DIFFERING FOR A QTL WHICH AFFECTS LEAF ABA CONCENTRATION

¹ Dept. of Agroenvironmental Science and Technology, Via Filippo Re 6-8, 40126 Bologna, ITALY

Leaf abscisic acid concentration (L-ABA) influences plant responses to drought. Previous studies (Tuberosa et al. 1998, T.A.G., 97, 744-755) allowed us to identify an important QTL for L-ABA in Os420 (high L-ABA) × IABO78 (low L-ABA) on chromosome 2, between umc34 and csu4. This QTL was also described in Lebreton et al. (1995, J. Exp. Bot., 46, 853-865) who reported an associated positive effect on root pulling force. Starting from an F4 plant heterozygous at this QTL region, a marker-assisted backcross program allowed us to obtain pairs of BC5 BDLs homozygous for the (+ +) or the (- -) QTL. These BDLs were tested for L-ABA concentration at tassel appearance. The ABA means of the Os420 BDLs were 336 (+ +) and 252 (- -) ng, while the means of the IABO78 BDLs were 222 (+ +) and 184 (- -) ng. The additive effect was 31 ng, corresponding to 12.4% of the mean. In Tuberosa et al. (1998) the additive effect at this QTL was 49 ng (12.1% of the mean). Hybrids [(+ +), (- -), (+ -), (- +)] between the BDLs were evaluated for grain yield and other agronomic traits. The high L-ABA showed a significantly lower root lodging (44.6%) compared to the low L-ABA (66.1%). Two populations divergently selected for L-ABA from an Os420 x IABO78 F2 population provided similar results (Landi et al., Crop Sci. 41, 335-344). The results for L-ABA, grain yield and other agronomic traits of the hybrids are presently being analysed.