The Effects of Ascorbate on Root Regeneration in Seedling Cuttings of Tomato |
| |
Authors: | Jaros?aw Tyburski Piotr Jasionowicz Andrzej Tretyn |
| |
Institution: | (1) Department of Biotechnology, Institute of General and Molecular Biology, Nicolas Copernicus University, Gagarina 9, 87-100 Toruń, Poland |
| |
Abstract: | The changes in ascorbate (ASC) and dehydroascorbate (DHA) levels and the activities of ascorbate metabolising enzymes were
examined during adventitious root formation in cuttings of tomato (Lycopersicon esculentum Mill. cv. Paw) seedlings. The effects of ASC, DHA and the immediate ascorbate precursor – galactono-γ-lactone (GalL) supplemented to the culture medium on the rooting response, ascorbate content and the activities of the ASC-metabolising
enzymes were also investigated. The cuttings treated with abovementioned compounds formed more roots then control plants.
However, in contrast to the number of regenerated organs, the elongation of newly formed roots was markedly inhibited. Treatment
with auxin (IAA) resulted in a similar phenotype. The inhibitor of auxin polar transport-TIBA (2,3,5-triiodobenzoic acid)
effectively blocked rooting. The inhibitory effect of TIBA was reversed by auxin and ASC treatments, while DHA and GalL were
ineffective. Both auxin and ASC stimulated cell divisions in an area of pericycle layer of TIBA-treated rooting zones, that
enabled cuttings to form roots in the presence of the inhibitor of auxin polar transport. It has been found that the first
stages of rooting, preceding the emergence of roots, are accompanied by an increase in endogenous content of ASC with a peak
in the 3rd day of rooting. Subsequent stages, when elongation of newly formed roots occurs, are characterised by low level
of ASC. The activities of the ascorbate peroxidase (APX), ascorbate oxidase (AOX), ascorbate free radical reductase (AFRR)
and dehydroascorbate reductase (DHR) increased in the first 3 days of root formation. The initial period of rooting was also
accompanied by the increase of the hydrogen peroxide content and the activities of catalase (CAT) and guaiacol peroxidase
(GPX) in the rooting zones. IAA, ASC, DHA as well as Gal stimulated the APX activity, however the rise of the enzyme's activity
induced by ASC, DHA and Gal was reversed by TIBA, which was found to inhibit APX. Only exogenous IAA was able to maintain
the high level of APX activity in the TIBA-treated cuttings. AOX was strongly affected by ASC and GalL – treatments, its activity
increased in the cuttings grown on the media containing ASC in the absence as well as in the presence of TIBA. On the other
hand, GalL-dependent stimulation of its activity was suppressed if TIBA was present in a rooting medium. |
| |
Keywords: | Ascorbate Auxin In vitro Rooting TIBA |
本文献已被 SpringerLink 等数据库收录! |
|