Poster: Hormones
Abs #
595: The effect of BRīs on ripening and composition of the tomato fruit
|
|
Presenter: |
Lisso, Janina , lisso@mpimp-golm.mpg.de |
Authors | Lisso, Janina (A) Altmann, Thomas (B) (A) | | Affiliations: |
(A): Max-Planck-Institute of Molecular Plant Physiology, Department I
(B): Unversity of Potsdam, Institute of Biochemistry and Biology
|
|
|
Brassinosteroids (BRs) comprise a group of polyhydroxysteroids and represent a recently identified class of phytohormones showing structural similarities to steroid hormones from mammals and arthropods. They occur ubiquitously in plants and control various developmental and metabolic processes. They are integrated into a complex regulatory network including several other plant hormones. A number of mutants affected in BR-metabolism have been isolated, including crinkled and cabbage-2, the BR-deficient mutants dumpy and dwarf, and the BR-insensitive curl-3. The Dwarf gene (D) encodes a cytochrome P450 enzyme (P450) (Bishop et al., 1999). Plants homozygous for extreme dwarf, the postulated null-allele of the D-gene, show the most extreme phenotype with all parts of the plant foreshortened and dark, rugose leaves.
Fruits of wildtype and dx- tomato-plants were analysed at different ripening stages. Despite higher growth rates, dx-fruits on the plants reached the respective ripening stages later in comparison to wildtype-fruits. Dramatically reduced levels of most carbohydrates resulted into a decreased dry mass leading to lower fruit yield. In contrast levels of amino acids were elevated in dx-fruits, most probably due to enhanced protein degradation. All observed effects could be partially complemented by BR treatment. The activity of acid invertases was lower in dx-fruits in comparison to wildtype fruits. The organic acids analysed did not show a common response after BR deficiency or treatment. Several other parameters of fruit development displayed no obvious BR-related changes.
It can thus be concluded, that BR deficiency leads to alterations in some processes during fruit development with consequences on both the time of ripening and the tomato fruit composition.
