ISSN:0192-253X    

DOI:10.1002/dvg.1020160402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have identified 188 embryo mutants of rice and characterized them into six groups based on their phenotypes: (1) embryoless in mature seed, (2) deletion of embryonic organ(s), (3) abnormal position of embryonic organs, (4) abnormal embryo size, (5) defect in organ morphology, and (6) variable abnormal phenotypes in spite of single mutations. Three types of organless mutants are obtained: small globular embryo, club‐shaped embryo, and large embryo. Although 12 shootless mutants derived from at least three loci are identified, only three radicleless mutants are recovered, which produce normal adventitious roots after germination. In reduced embryo mutants, every embryonic organ is reduced, in contrast to giant embryo mutants in which only scutellum is enlarged. Considerable number of mutants are categorized into (5) and (6) in the above. These diverse embryo mutants would serve as promising materials for genetic study of embryogenesis. © 1995 Wiley‐Liss,

ISSN:0192-253X    

DOI:10.1002/dvg.1020160403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTheembryo‐defective(emb) mutants ofArabidopsisconstitute a large and diverse group of mutants disrupted in a broad range of embryonic processes, including morphogonesis, cell differentiation, and maturation programs. This report describes a subset of these mutants, the lateembryo defectives, which develop beyond the globular stage of embryogenesis but fail to complete normal morphogenesis. A representative sample of 12 late mutants was chosen for this study, patterns of morphogenesis were characterized, the germination potential of mutant seeds was investigated, and additional mutant alleles within the collection were identified. Morphological defects in mutant embryos became apparent during the heart stage of development, when embryos normally begin the rapid cell division and expansion required for the completion of morphogenesis. Despite their morphological abnormalities, mutant embryos often germinated from dry seed, demonstrating that genetic programs required for the establishment of desiccation tolerance remained intact. Mutant seedlings displayed a wide range of developmental abnormalities, including altered morphology, lack of pigmentation, dwarfism, and disorganized vegetative growth. One late mutant was found to be allelic to an earlyembryo defectivethat arrests at the globular stage. These results suggest that a number of lateEMBgenes encode basic cellular and metabolic functions needed for cell division, enlargement, and embryonic growth. The rapid growth and metabolic changes that occur at the heart stage may present a barrier to normal development in the late mutants, resulting in altered embryo morphology and other developmental defects. It is proposed that manyArabidopsismutants with abnormal embryo and seedling morphology are not defective in the regulation of pattern formation or morphogenesis, but rather in fundamental physiological and cellular processes required for the completion of normal growth and development. © 1995 Wiley‐Liss,

ISSN:0192-253X    

DOI:10.1002/dvg.1020160404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractEmbryogenesis in higher plants requires the precise regulation of cell division, orientation of cell elongation and specification of cell differentiation. The division plane is determined by the position of a new cell plate at cytokinesis. A mutant of pea has been isolated in which both the embryo pattern and surface morphology is altered. The phenotype of the mutant is manifest primarily in the cotyledons where cell plates only partially form, generating cell wall stubs and multinucleate cells. Some cotyledonary cells of the mutant proceed through nine DNA replication cycles, including nuclear division, but not cytokinesis, producing nuclei with a DNA content of ca. 1000C. The cytological phenotype of the mutant could be mimicked by the treatment of wild‐type cells with caffeine. We have termed this mutantcytokinesis‐defective(cyd). © 1995 Wiley‐Lis

ISSN:0192-253X    

DOI:10.1002/dvg.1020160405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAt the nonpermissive temperature, somatic embryos of the temperature‐sensitive (ts) carrot (Daucus carotaL.) cell variantts11only proceed beyond the globular embryo stage in the presence of medium conditioned by wild‐type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium fromts11embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect onts11embryo development could be detected between the 32 kD chitinase purified from wild‐type cultures and the chitinase fromts11cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in ats11embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature‐sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype ofts11is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that thets11phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley

ISSN:0192-253X    

DOI:10.1002/dvg.1020160406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe formation of shoot and root meristems that ultimately give rise to all tissues of the plant body occurs for the first time during embryogenesis. Meristem formation has traditionally been defined in terms of the appearance of histological features of meristems; this approach has led to varying interpretations of the timing of meristem formation relative to other events in embryogenesis. Markers that would provide more objective criteria for the analysis of meristem formation have not been widely available. The maize homeobox gene,knotted1(kn1), is expressed in shoot meristems throughout postembryonic stages of shoot development. In order to determine whether this gene is expressed in the shoot meristem from its earliest inception, we examined the expression of kn1 in embryos at a series of stages by in situ hybridization tokn1mRNA and immunolocalization of KN1 protein. Our results show that the onset of kn1 expression is temporally and spatially coincident with the earliest histologically recognizable signs of shoot meristem formation in the embryo, and thus provides a valuable marker for this process. © 1995 Wiley‐Liss, I

ISSN:0192-253X    

DOI:10.1002/dvg.1020160407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractFourZea mayshomeobox (ZmHox) genes have been analyzed in their spatial expression pattern during development of the maize plant. TheZmHox1a or bandZmHox2a or bgene pairs encode putative plant transcriptin factors; the mRNA transcripts belong to the rare class of mRNA molecules. Expression of theZmHox1and 2 genes is activated very early in embryonic development and restricted to the embryo proper in the proembryo stage. After establishment of the root/shoot axis, transcripts are prevalent in the embryonic root and shoot apical meristems but later are also found in provascular tissues and young leaf primordia. In the vegetative plant body the transcription of theZmHoxgenes marks several types of meristems of the shoot and root system, the descending proliferating regions and provascular strands. Expression persists in the developing reproductive organs, but results obtained in the male flower indicate that transcription ofZmHoxgenes here may become confined to specific cell types. The data obtained during this study show that these fourZmHoxgenes are expressed very specifically in cells where developmental decisions contribute to the ontogeny of the maize plant. The overall expression pattern suggests that theZmHoxclass of maize homeobox genes will be involved in transcriptional control during maize development from the embryonic to the reproductive phase. © 1995 Wiley‐Liss, I

ISSN:0192-253X    

DOI:10.1002/dvg.1020160408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe primary shoot apical meristem of angiosperm plants is formed during embryogenesis. Lateral shoot apical meristems arise postembryonically in the axils of leaves. Recessive mutations at thePINHEADlocus ofArabidopsisinterfere with the ability of both the primary shoot apical meristem as well as lateral shoot apical meristems to form. However, adventitious shoot apical meristems can form in pinhead mutant seedlings from the axils of the cotyledons and also from cultred root explants. In this report, the phenotype ofpinheadmutants is described, and a hypothesis for the role of the wild‐typePINHEADgene product in shoot meristem initiation is presented. © 1995 Wiley‐Liss,

ISSN:0192-253X    

DOI:10.1002/dvg.1020160409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractMetatherian (marsupial) mammals possess a non‐random form of X‐chromosome inactivation in which the paternally‐derived X is always the one inactivated. To examine the progression of X‐linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encodedGpdgene products in heterozygous female Virginia opossums (Didelphis virginiana) across a moior portion of the developmental period. Panels of tissues obtained from fetuses, newborns, and pouch young were examined via polyacrylamide gel electrophoresis of the G6PD protein. As in adults, G6PD phenotypes in these developmental stages were highly skewed in favor of the maternal allele product, but in some tissues there was a marked increase in paternal allele expression with advancing developmental age. However, even by 42 days of post‐partum development, expression of the paternal Gpd allele had not attained the adult, tissue‐specific activity pattern. Our findings indicate remarkable developmental changes in the activity of the paternal allele in several tissues/organs continuing well into mid pouch‐life stages and beyond. Specifically we found that 1) a substantially repressed paternal Gpdgene is present in the cells of female stage 29 fetuses and later developmental stages, 2) the activity state of the paternal Gpd gene is not fixed during early embryonic development in this species, 3) maior changes in paternal Gpd expression occur in advanced developmental stages and comprise a maturation of the gene expression pattern during ontogeny, and 4) alterations of paternal Gpd allele activity during development occur in a tissue‐specific manner. © 1995

ISSN:0192-253X    

DOI:10.1002/dvg.1020160410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020160401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY