PLANT PHYSIOLOGY , Vol 106, Issue 1 173-178, Copyright © 1994 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Differential Accumulation of Manganese-Superoxide Dismutase Transcripts in Maize in Response to Abscisic Acid and High Osmoticum
D. Zhu and J. G. Scandalios
Department of Genetics, Box 7614, North Carolina State University, Raleigh, North Carolina 27695
The plant growth regulator abscisic acid (ABA) has multiple physiological
effects during embryogenesis and seed formation. Although a number of genes
induced by ABA have been characterized, the functions of the encoded
proteins remain, for the most part, obscure. In this paper we demonstrate
that members of the manganese-superoxide dismutase (MnSod) gene family
encoding antioxidant isozymes of known function during development and
oxidative stress respond differentially to ABA and high osmoticum in
developing maize (Zea mays L.) embryos. Expression of the maize Sod3.1 does
not respond to ABA or high osmoticum, whereas the steady-state levels of
the maize Sod3.2, Sod3.3, and Sod3.4 transcripts are induced by ABA. Total
SOD-3 protein and enzymatic activity, however, remain constant.
Additionally, we examined the requirement for ABA in the accumulation of
MnSod transcripts in response to high osmoticum in wild-type and mutant
embryos of an ABA-deficient line (M1A4; vp5). RNA blot analyses show that
multiple Sod3 transcripts are also found in line M1A4, and ABA increases
the accumulation of the Sod3.2, Sod3.3, and Sod3.4 transcripts in both
wild-type and vp5 mutant embryos. Interestingly, although accumulation of
the Sod3.3 and Sod3.4 transcripts in the vp5 mutant embryo was induced by
ABA, it was not induced by high osmoticum. Both superoxide dismutase and
ABA have been implicated in plant tolerance to environmental stress;
results from this study demonstrate a connection between the action of ABA
and oxidative stress during embryo maturation in maize.
