An expanded role for the TWN1 gene in embryogenesis: defects in cotyledon pattern and morphology in the twn1 mutant of Arabidopsis (Brassicaceae)
The suspensor is a specialized basal structure that differentiates early in plant embryogenesis to support development of the embryo proper. Suspensor differentiation in Arabidopsis is maintained in part by the TWIN1 (TWN1) gene, which suppresses embryogenic development in suspensor cells: twn1 muta...
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Published in | American journal of botany Vol. 88; no. 4; pp. 570 - 582 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
Botanical Soc America
01.04.2001
Botanical Society of America Botanical Society of America, Inc |
Subjects | |
Online Access | Get full text |
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Summary: | The suspensor is a specialized basal structure that differentiates early in plant embryogenesis to support development of the embryo proper. Suspensor differentiation in Arabidopsis is maintained in part by the TWIN1 (TWN1) gene, which suppresses embryogenic development in suspensor cells: twn1 mutants produce supernumerary embryos via suspensor transformation. To better understand mechanisms of suspensor development and further investigate the function of TWN1, we have characterized late-embryo and postembryonic development in the twn1 mutant, using seedling culture, microscopy, and genetics. We report here that the twn1 mutation disrupts cotyledon number, arrangement, and morphology and occasionally causes partial conversion of cotyledons into leaves. These defects are not a consequence of suspensor transformation. Thus, in addition to its basal role in suspensor differentiation, TWN1 influences apical pattern and morphology in the embryo proper. To determine whether other genes can similarly affect both suspensor and cotyledon development, we looked for twinning in Arabidopsis mutants previously identified by their abnormal cotyledon phenotypes. One such mutant, amp1, produced a low frequency of twin embryos by suspensor transformation. Our results suggest that mechanisms that maintain suspensor identity also function later in development to influence organ formation at the embryonic shoot apex. We propose that TWN1 functions in cell communication pathways that convey local positional information in both the apical and basal regions of the Arabidopsis embryo. |
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Bibliography: | fax: 509‐527‐5904). The authors thank Brady Hamilton and Marianne Brady for assistance in the laboratory, Dr. M. Tasaka (Kyoto University) and the Author for correspondence (e‐mail stock center for providing seeds from mutant lines, Dr. Jane McConnell for advice on SEM, and Drs. David Meinke and Frans Tax for critical reading of the manuscript. This work was supported by NSF grant IBN‐9604344 to DMV and by Whitman College. vernondm@whitman.edu Arabidopsis ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0002-9122 1537-2197 |
DOI: | 10.2307/2657055 |