malfunction |
the rice mutant of KAO (oskao-1) has low levels of GA53, GA20, and GA1, OsWOX3A-OX downregulates KAO expression, which causes significantly reduced levels of GA53, GA20, and, finally, bioactive GA1. Quantitative analysis of gibberellic acid intermediates reveals significantly reduced levels of GA20 and bioactive GA1 in transgenic rice overexpressing OsWOX3A-OX, due to downregulation of the expression of KAO. The mutant OsWOX3A-OX exhibits severe dwarfism with very short and wide leaves, a phenotype that resembles that of gibberellic acid (GA)-deficient or GA-insensitive mutants. Loss of OsWOX3A function in narrow leaf2 (nal2) nal3 double mutants (termed nal2/3) causes pleiotropic effects, such as narrow and curly leaves, opened spikelets, narrow grains, more tillers, and fewer lateral roots, but almost normal plant height. Loss-of-function nal2/3 mutants show increased expression of KAO, changes in gibberellic acid contents are consistent with the expression levels of KAO and GA20ox2 in nal2/3 mutants |
Oryza sativa Japonica Group |
additional information |
OsWOX3A acts as a transcriptional repressor, generation of transgenic rice overexpressing OsWOX3A, OsWOX3A-OX, the mutant consistently exhibits severe dwarfism with very short and wide leaves, a phenotype that resembles that of gibberellic acid (GA)-deficient or GA-insensitive mutants. OsWOX3A expression is drastically and temporarily upregulated by gibberellin GA3 and is downregulated by paclobutrazol, a blocker of gibberellic acid biosynthesis |
Oryza sativa Japonica Group |
physiological function |
ent-kaurenoic acid oxidase, encoded by gene KAO, is a gibberellin biosynthetic enzyme. WUSCHEL-related homeobox 3 in Oryza sativa, OsWOX3A, is a gibberellic acid-responsive gene and functions in the negative feedback regulation of the gibberellic acid biosynthetic pathway for gibberellic acid homeostasis to maintain the threshold levels of endogenous gibberellic acid intermediates throughout development. OsWOX3A interacts directly with the KAO promoter to repress KAO expression. Changes in gibberellic acid contents are consistent with the expression levels of KAO and GA20ox2 in nal2/3 mutants. OsWOX3A directly downregulates the expression of KAO as a trans-repressor or upregulates the expression of GA20ox2 as a trans-activator |
Oryza sativa Japonica Group |