cotyledon expansion

Michael M. Neff mneff at AIM.SALK.EDU
Tue Apr 9 23:36:04 EST 1996


>Dear Netters,
>I would like to find informations and/or references concerning the
>expansion of the cotyledons in germinating Arabidopsis : is it only due to
>cell expansion or cell division and expansion?
>Thank you for your help.
>Michel Herzog

Michel and netters,
        I too am interested in cotyledon development.  As a graduate
student I was involved in studying cotyledon expansion in the
photomorphogenic mutants phyB and hy4.
        One study showed that phytochrome B regulates cotyledon expansion
in bright-red light.  Cotyledons of phyB mutants fail to expand to
wild-type levels on intact seedlings.  Epidermal cell measurements have
show that both cell division and cell expansion are under the control of
PHYB with the primary influence being cell expansion.  Furthermore, when
phyB mutant cotyledons are excised from the rest of the seedling, they
maintain their mutant phenotype indicating the organ autonomous nature of
this control.  This work was published in the following article:

Neff MM and Van Volkenburgh E, (1994) Light-stimulated cotyledon expansion
in Arabidopsis  seedlings:  The role of phytochrome B.  Plant Physiology
104: 1027-1032

        Another study that I was involved with demonstrated the role of
CRY1 in bright-blue light stimulated cotyledon expansion.  In this case,
hy4 mutants have small cotyledons in bright blue light.  However, when
these cotyledons are excised from the rest of the seedling they expand as
well as the wild type.  This suggests that the CRY1's control of cotyledon
expansion involves other parts of the seedling.  This reference for this
work is:

Blum DE, Neff MM and Van Volkenburgh E, (1994) Light-stimulated cotyledon
expansion in the blu3 and hy4 mutants of Arabidopsis thaliana.  Plant
Physiology 105:  1433-1436

        I hope this helps in your quest for information about cotyledon
expansion in developing Arabidopsis seedlings.

Michael M. Neff



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