UTILIZING GENE EXPRESSING PROFILES TO INVESTIGATE MAIZE RESPONSES TO ABIOTIC STRESS

Trait & Technology Development; Pioneer Hi-Bred Int., Inc.; 7250 N.W. 62nd Ave., Johnston, IA 50131

Drought induced yield losses in maize can be substantial and researchers have been attempting to improve the tolerance of this crop to limiting supplies of water for decades. We believe that one key to improving drought tolerance is the identification of critical genes whose expression modulates the plant phenotype. With the advent of functional genomic technologies, it is now possible to efficiently analyze transcript levels of hundreds of genes simultaneously. We are using our maize ESTs in conjunction with the MD/Amersham DNA microarray system to determine transcript levels of genes in maize ears. We conducted a replicated study in which we exposed a Pioneer hybrid (3732) to a drought stress, at a time immediately prior to pollination. Ears were collected at various times during the stress period. In addition, ears from another subset of plants were harvested after the plants had been re-watered. RNA was extracted from whole ears, converted into cDNA and the cDNA was labeled with fluorescent dyes. DNA from over 350 genes was spotted onto glass slides, and the labeled DNA was allowed to hybridize with the spotted DNA. The amount of fluorescence emitted was determined, and the data were used to ascertain changes in steady-state transcript levels. We identified several genes that have significantly altered message levels when exposed to drought, and that may play a critical role in helping us identify rate limiting pathways in ears exposed to water-stress conditions.