Patterns of gene expression during carrot somatic embryogenesis /

Bibliographic Details
Main Author:	Wilde, Henry Dayton, 1957-
Other Authors:	Nessler, Craig L. (degree committee member.), Park, William D. (degree committee member.), Smith, Roberta H. (degree committee member.)
Format:	Thesis Book
Language:	English
Published:	1988.
Subjects:	Gene expression. Developmental genetics. Carrots > Genetics. Major biology. Academic theses
Online Access:	ProQuest, Abstract Link to OAKTrust copy

Description
Abstract:	When a carrot (Daucus carota) cell suspension is transferred from auxin-containing to auxin-free medium, somatic cells develop into embryos through a process termed somatic embryogenesis. The pattern of expression of individual mRNA transcripts and the general mRNA population indicates that early events of carrot somatic embryogenesis take place in auxin-containing medium. Several embryo-regulated cDNA recombinants were isolated by differential hybridization of λgt10 and λgt11 somatic embryo libraries. The developmental regulation of these clones was examined and two cDNAs, Dc3 and Dc5, were characterized in terms of nucleotide sequence and gene copy number. In plants, Dc3 is expressed in reproductive (seeds, flowers), but not vegetative, tissues. In tissue culture, Dc3 expression correlates with the development of embryogenic cell clusters, termed proembryogenic masses (PEMs), from nonembryogenic cells. General patterns of gene expression were examined by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and by hybridization analysis with single-stranded cDNA of different mRNA populations. A model of somatic embryogenesis is presented that incorporates these results and recent data from other laboratories (Choi and Sung, 1984; Nomura and Komamine, 1985a, deVries et al., 1988). The acquisition of "embryogenic potential" in PEMs was found to require exogenous auxin. Auxin-dependent cell cluster development may be necessary for orienting the morphogenesis of the somatic embryo. The ability of the PEM to function as a surrogate suspensor has been recognized for some time (Halperin,1966). The possiblity that embryonic determination and the acquisition of "embryogenic potential" are separate events is discussed. Developmental regulation of cytoskeletal proteins and their mRNAs may play a role in plant embryo morphogenesis.
Item Description:	Typescript (photocopy). Vita. "Major subject: Biology."
Physical Description:	ix, 82 leaves : illustrations ; 29 cm
Bibliography:	Includes bibliographical references (leaves 69-81).