Articles
MOLECULAR ANALYSES OF CAROTENOID-ASSOCIATED PROTEINS FROM CHROMOPLASTS OF CUCUMIS SATIVUS COROLLAS
Article number
447_111
Pages
575 – 578
Language
Abstract
Chromoplasts are carotenoid-accumulating plastids found in the corollas and fruits of many higher plants.
In most cases the pigment in these plastids is accumulated within unique structures with the aid of carotenoid-associated proteins.
We isolated and characterized the cDNA (CHRC) from Cucumis sativus corollas which encodes the chromoplast-specific carotenoid-associated protein CHRC. Analysis of CHRC transcript level in Cucumis sativus revealed its temporal and tissue-specific regulation: the transcript was detected only in corollas, where its level increased in parallel to flower development, peaking just before anthesis.
A CHRC fragment that includes the potential active site of the protein was used as a probe in northern blot analyses of floral and fruit tissues from various plants containing chromoplasts of different types: CHRC homologues of similar sizes were revealed in all cases.
To further study chromoplast biogenesis in floral tissues, a minor (in abundance) protein of ca. 14 kD (CHRD) was isolated from cucumber corolla chromoplasts.
Immunological characterization revealed it to be chromoplast-specific, and its steady-state level in corollas increased in parallel to flower development.
The protein was not detected in cucumber leaves or fruits.
Using an in vitro bud-culture system, the effect of phytohormones on CHRD expression was found to be similar to that on CHRC. GA3 very rapidly enhanced, whereas ABA and paclobutrazol downregulated the steady-state level of CHRD. Ethylene also downregulated the protein’s steady-state level and etiolation increased CHRD accumulation.
It is suggested that hormonal control of chromoplastogenesis is tightly regulated at the tissue/organ level and that mainly developmental signals control carotenoid accumulation in non-photosynthetic tissues.
In most cases the pigment in these plastids is accumulated within unique structures with the aid of carotenoid-associated proteins.
We isolated and characterized the cDNA (CHRC) from Cucumis sativus corollas which encodes the chromoplast-specific carotenoid-associated protein CHRC. Analysis of CHRC transcript level in Cucumis sativus revealed its temporal and tissue-specific regulation: the transcript was detected only in corollas, where its level increased in parallel to flower development, peaking just before anthesis.
A CHRC fragment that includes the potential active site of the protein was used as a probe in northern blot analyses of floral and fruit tissues from various plants containing chromoplasts of different types: CHRC homologues of similar sizes were revealed in all cases.
To further study chromoplast biogenesis in floral tissues, a minor (in abundance) protein of ca. 14 kD (CHRD) was isolated from cucumber corolla chromoplasts.
Immunological characterization revealed it to be chromoplast-specific, and its steady-state level in corollas increased in parallel to flower development.
The protein was not detected in cucumber leaves or fruits.
Using an in vitro bud-culture system, the effect of phytohormones on CHRD expression was found to be similar to that on CHRC. GA3 very rapidly enhanced, whereas ABA and paclobutrazol downregulated the steady-state level of CHRD. Ethylene also downregulated the protein’s steady-state level and etiolation increased CHRD accumulation.
It is suggested that hormonal control of chromoplastogenesis is tightly regulated at the tissue/organ level and that mainly developmental signals control carotenoid accumulation in non-photosynthetic tissues.
Authors
M. Vishnevetsky, M. Ovadis, Y. Libal-Weksler, A. Vainstein, H. Itzhaki
Keywords
cucumber, CHRC, CHRD, GA3, ethylene, paclobutrazol, ABA
Online Articles (132)