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Modification of gibberellin production and plant development in Arabidopsis by sense and antisense expression of gibberellin 20‐oxidase genes
Author(s) -
P Jeremy,
Phillips . Coles andrew L.,
Croker Stephen J.,
GarcíaLepe Raol,
Lewis Mervyn J.,
Hedden Peter
Publication year - 1999
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1999.00410.x
Subject(s) - gibberellin , arabidopsis , sense (electronics) , hypocotyl , biology , oxidase test , transgene , gene , genetically modified crops , gene expression , microbiology and biotechnology , botany , enzyme , biochemistry , chemistry , mutant
Summary Gibberellin (GA) 20‐oxidase catalyses consecutive steps late in GA biosynthesis in plants. InArabidopsis, the enzyme is encoded by a gene family of at least three members (AtGA20ox1,AtGA20ox2andAtGA20ox3) with differential patterns of expression. The genes are regulated by feedback from bioactive GAs, suggesting that the enzymes may be involved in regulating GA biosynthesis. To investigate this, we produced transgenicArabidopsisexpressing sense or antisense copies of each of the GA 20‐oxidase cDNAs. Over‐expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls; the plants flowered earlier than controls in both long and short days and were 25% taller at maturity. GA analysis of the vegetative rosettes showed a two‐ to threefold increase in the level of GA 4 , indicating that GA 20‐oxidase normally limits bioactive GA levels. Plants expressing antisense copies ofAtGA20ox1had short hypocotyls and reduced rates of stem elongation. This was reflected in reduced levels of GA 4 in both rosettes and shoot tips. In short days, flowering was delayed and the reduction in the rate of stem elongation was greater. Antisense expression of AtGA20ox2had no apparent effects in long days, but stem growth in one transgenic line grown in short days was reduced by 20%. Expression of antisense copies ofAtGA20ox3had no visible effect, except for one transgenic line that had short hypocotyls. These results demonstrate that GA levels and, hence, plant growth and development can be modified by manipulation of GA 20‐oxidase expression in transgenic plants.