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Title: TRANSCRIPTIONAL RESPONSE TO GIBBERELLIN AND ABSCISIC ACID IN BARLEY ALEURONE

Author
item CHEN, KEGUI - UNIV OF WISCONSIN
item An, Yong-Qiang - Charles

Submitted to: Journal of Integrative Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2005
Publication Date: 5/1/2006
Citation: An, Y., Chen, K. 2006. Transcriptional response to gibberellin and abscisic acid in barley aleurone. Journal of Integrative Plant Biology. 48:591-612.

Interpretive Summary: Gibberellin (GA) and abscisic acid (ABA) are two plant hormones affecting many important agronomic traits. For examples, GA and ABA can determine if seeds will germinate or not, how tall plants will grow and whether plants can tolerate stressful environments such as drought. To enable us to improve those crop traits, we have to figure out how ABA and GA affect the agronomic traits at molecular levels and find the genes that can be potentially used for improving the traits. In this report, we used a specific kind of barley cells, called de-embryonated cereal aleurone, to see which genes were turned on and which were turned off after incubating the aleurone with GA and/or ABA. The changes in gene activities are likely to be responsible for ABA and GA effect on the agronomic traits mentioned above. Using traditional methods, scientists can see changes in one or several genes at one time. In this experiment, we used a new technology, called microarray technology, to see such changes for over 22,000 genes simultaneously. Since the experiment generated an extremely large amount of data, we used computer software to analyze the data. We found that many gene products were increased and decreased after GA and ABA treatments. We also found that GA and ABA have opposite effects on many genes. We generated a tremendous amount of knowledge about ABA and GA, and identified many gene candidates related to GA and ABA effects. This work will aid farmers and barley researchers to improve GA and ABA related agronomic important traits such as malting quality and lodging.

Technical Abstract: De-embryonated cereal aleurone has been established as a model system to study GA and ABA responses, and their interaction. Using Barley 1 GeneChip, we examined mRNA accumulation of over 22,000 genes in de-embryonated barley aleurone treated with GA and ABA. We observed that 1328 genes had more than a three fold change in response to GA treatment, while 206 genes had a more than three fold change in response to ABA treatment. Interestingly, approximately 2.5 times more genes were up-regulated than down-regulated by ABA. Eighty-three genes were differentially regulated by both GA and ABA. Most were subject to antagonistic regulation by ABA and GA, particularly for the genes related to seed maturation and germination, such as the genes encoding late embryogenesis abundant proteins and storage mobilization enzymes. This supports the antagonistic roles of GA and ABA in seed maturation and seed germination. Interestingly, a significant percentage of the genes were coordinately regulated by both GA and ABA. A significant interaction between ABA and GA occurred in regulating expressions of 1051 genes. Some GA responsive genes encoded proteins involved in ethylene, jasmonate and auxin metabolic and signaling transduction pathways, suggesting their potential involvement in GA response. We also identified a group of transcription factor genes such as MYB and Homeobox genes that were differentially regulated by GA. Overall, the manuscript provided a comprehensive and global view of transcript expression accompanying the GA and ABA response in barley aleurone and identified a group of genes with potential regulatory functions in GA and ABA signaling pathways for future functional validation.