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An expanded role for the TWN 1 gene in embryogenesis: defects in cotyledon pattern and morphology in the twn 1 mutant of Arabidopsis (Brassicaceae)
Author(s) -
Ver Daniel M.,
Han Michael J.,
Le MyPhuong,
Forsthoefel Nancy R.
Publication year - 2001
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2657055
Subject(s) - suspensor , biology , cotyledon , arabidopsis , microbiology and biotechnology , embryo , mutant , botany , embryogenesis , morphogenesis , arabidopsis thaliana , genetics , gene , somatic embryogenesis
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 TWIN 1 ( TWN 1) gene, which suppresses embryogenic development in suspensor cells: twn 1 mutants produce supernumerary embryos via suspensor transformation. To better understand mechanisms of suspensor development and further investigate the function of TWN 1, we have characterized late‐embryo and post‐embryonic development in the twn 1 mutant, using seedling culture, microscopy, and genetics. We report here that the twn 1 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, TWN 1 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, amp 1, 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 TWN 1 functions in cell communication pathways that convey local positional information in both the apical and basal regions of the Arabidopsis embryo.