Plant Biology 2001

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Abstract
Jan A.D. Zeevaart (Michigan State University–Department of Energy Plant Research Laboratory, East Lansing, MI) was awarded the 2000 Steven Hales Prize for his work during the last four decades on plant hormones and the regulation of plant growth. The award honors the Reverend Stephen Hales for his pioneering work in plant biology published in his 1727 book Vegetable Staticks. Zeevaart's many contributions to plant biology include elucidation of the biosynthetic pathways of abscisic acid (ABA) and gibberellins (GA), the roles of ABA in stomatal closure and seed germination, and the role of GA in photoperiodism. Currently, his laboratory is interested in the environmental regulation of ABA and GA biosynthesis. ABA accumulation is induced very rapidly by drought. Although the mechanism of stress perception is not known in this case, likely targets of this signaling cascade include the genes that regulate the oxidative cleavage of a carotenoid precursor to yield ABA. Zeevaart's group has shown that this point of regulation is the limiting step in ABA biosynthesis (Qin and Zeevaart, 1999). His laboratory also is working to understand how long-daylength increases GA biosynthesis in long day Arabidopsis accessions and in spinach (Xu et al., 1997). They have demonstrated that the expression of 20-oxidase, a key GA biosynthetic enzyme, naturally increases in these plants upon induction by long-days. Overexpression of this gene in the long day rosette plant Nicotiana sylvestris promotes stem elongation under short- day conditions.