Poster: Environmental physiology

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Abs # P01011: Abscisic acid up-regulates genes involved in lipogenesis and lignin biosynthesis in rice roots

Presenter:	Hong, Chwan-yang       Contact Presenter
Authors	Hong, Chwan-yang  (A)   Sun, Shiou-Jen  (A)   Ho, Tuan-hua David  (A)
Affiliations:	(A): Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
Web Site:	http://ipmb.sinica.edu.tw/

Abscisic acid is known to regulate a diverse set of physiological and developmental processes in plants. To investigate the role of ABA in different tissues, we conducted gene expression profile analysis in two-week old rice plants. Rice plants were treated with ABA for 0.5 to 3 days before roots and shoots were separated for RNA isolations followed by microarray analyses using Agilent 22K rice chips. The profile of ABA regulated genes in roots was quite different from that in shoots with twice as many genes up-regulated by ABA in roots than in shoots. In contrast, there were many more genes down-regulated by ABA in shoots than in roots. Among the root-specific ABA up-regulated genes were those related to lignin biosynthesis. In addition, the expression of genes encoding key enzymes related to lipid biosynthesis were also enhanced by ABA in roots specifically, including those encoding a subunit of pyruvate dehydrogenase for the production of acetyl CoA, a malic enzyme for the generation of NADPH, and two dehydrogenases in the fatty acid synthase complex. This root specific ABA up-regulation of genes involved in lipogenesis and lignin biosynthesis could be related to the ABA/stress enhanced growth in roots in cereals when treated with ABA/stress. Promoters of ABA up-regulated genes were further screened for their tissue specific activities. Several of them have been found to be active only in roots but not in shoots and seeds. These promoters could be useful in up-regulating the expression of beneficial genes only in roots but not in seeds, thus enhancing food safety for transgenic plants. This work was supported by grants from Academia Sinica, NSC and NSTP.AB in Taiwan.