Articles
TRANSFORMATION OF RHODODENDRON WITH GENES FOR ABIOTIC STRESS TOLERANCE
Article number
572_13
Pages
113 – 120
Language
English
Abstract
An Agrobacterium tumefaciens – mediated gene transfer technique was established for large flowering evergreen Rhododendron hybrids and used for the transfer of target genes.
The transformation protocol was based on pre-cultured leaves taken from in vitro shoots.
Transformation rates between one and two percent were obtained.
Two different strate-gies have been followed.
In an unspecific approach rol genes from Agrobacterium rhizo-genes were used.
Fourteen rol-transgenic rhododendron lines were created.
Eleven lines have been transformed with the rolABC gene combination under the control of the native promotor, and the remaining 3 lines with the 35S-rolB construct.
Severe growth retarda-tion was only observed in two of the 35S-rolB– transgenic lines.
The other lines showed morphological alterations and often strong root systems.
Even on lime enriched culture media in vitro rooting was significantly enhanced in some lines.
We assume that an improved rooting performance could be obtained that may contribute to a better adap-tation of Rhododendron to calcareous soils.
In a second approach a gene coding for the enzyme ferric-chelate reductase (Fro2) was introduced in 30 different lines.
This enzyme is also in Rhododendron responsible for a better iron uptake under low iron stress soil conditions and should be increased by using a constitutive promotor.
Transfer and expres-sion of rol genes as well as the Fro2 gene in different rhododendron rootstock genotypes was proved by molecular analysis of DNA and RNA.
The transformation protocol was based on pre-cultured leaves taken from in vitro shoots.
Transformation rates between one and two percent were obtained.
Two different strate-gies have been followed.
In an unspecific approach rol genes from Agrobacterium rhizo-genes were used.
Fourteen rol-transgenic rhododendron lines were created.
Eleven lines have been transformed with the rolABC gene combination under the control of the native promotor, and the remaining 3 lines with the 35S-rolB construct.
Severe growth retarda-tion was only observed in two of the 35S-rolB– transgenic lines.
The other lines showed morphological alterations and often strong root systems.
Even on lime enriched culture media in vitro rooting was significantly enhanced in some lines.
We assume that an improved rooting performance could be obtained that may contribute to a better adap-tation of Rhododendron to calcareous soils.
In a second approach a gene coding for the enzyme ferric-chelate reductase (Fro2) was introduced in 30 different lines.
This enzyme is also in Rhododendron responsible for a better iron uptake under low iron stress soil conditions and should be increased by using a constitutive promotor.
Transfer and expres-sion of rol genes as well as the Fro2 gene in different rhododendron rootstock genotypes was proved by molecular analysis of DNA and RNA.
Publication
Authors
F. Dunemann, R. Illgner, I. Stange
Keywords
Rhododendron spp., iron chlorosis, gene transfer with Agrobacterium tume-faciens, rol genes, rooting ability, iron uptake, Fro2 gene
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