Bibliography: leaves 127-152. The aim of this work is to study viroids in grapevines, particularly their vertical transmission via seeds, during meristem culture and micropropagation. There was also an attempt to produce viroid-free vines by shoot apical meristem culture (SAMC).

The meristem genes SHOOT MERISTEMLESS (STM), CLAVATA1 (CLV1) and ZWILLE (ZLL) are essential for the formation and maintenance of the shoot apical meristem (SAM). As an extension of that work, this thesis examines the function of these genes during seed oil accumulation and microspore-derived embryogenesis. Using a transgenic approach it is demonstrated that only the over-expression of BnSTM increases the percentage of total seed oil and a reduction of glucosinolate (GLS) levels achieved by transcriptional regualtion. The over-expression of BnSTM also affected in vitro embryogenesis by increasing the number and quality of microspore-derived embryos (MDEs) in contrast to the MDEs down-regulating BnSTM. The MDEs with ectopic expression of BnSTM were found to regulate embryonic SAM by altering cytokinin synthesis, catabolism, perception and signaling. Taken together, these findings provide evidence for a novel function of BnSTM in promoting desirable changes in seed oil and GLS levels and enhancing in vitro embryogenesis.

The meristem genes SHOOT MERISTEMLESS (STM), CLAVATA1 (CLV1) and ZWILLE (ZLL) are essential for the formation and maintenance of the shoot apical meristem (SAM). As an extension of that work, this thesis examines the function of these genes during seed oil accumulation and microspore-derived embryogenesis. Using a transgenic approach it is demonstrated that only the over-expression of BnSTM increases the percentage of total seed oil and a reduction of glucosinolate (GLS) levels achieved by transcriptional regualtion. The over-expression of BnSTM also affected in vitro embryogenesis by increasing the number and quality of microspore-derived embryos (MDEs) in contrast to the MDEs down-regulating BnSTM. The MDEs with ectopic expression of BnSTM were found to regulate embryonic SAM by altering cytokinin synthesis, catabolism, perception and signaling. Taken together, these findings provide evidence for a novel function of BnSTM in promoting desirable changes in seed oil and GLS levels and enhancing in vitro embryogenesis.

Bibliography: leaves 127-152. / v, 152, [42] leaves, [13] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this work is to study viroids in grapevines, particularly their vertical transmission via seeds, during meristem culture and micropropagation. There was also an attempt to produce viroid-free vines by shoot apical meristem culture (SAMC). / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Science, 1997? / Includes bibliographical references (leaves 127-152).

Halle (Saale), Univ., Diss., 2008

Universiẗat, Diss., 2004--Köln.

Vincristine and vinblastine, two closely related alkaloids are extracted from the Madagaskar Periwinkle, Vinca rosea Linn. They have been shown to be effective oncolytic agents and cause arrest of mitosis at the metaphase stage, similar to that of colchicine andcolcimid. Clinically, vincristine has been found to produce a complete remission in patients with acute leukaemia. Tumour regression in patients with Hodgkin's disease, lymphosarcoma and certain childhood solid tumours have also been reported.

Vicia faba and investigating the effects of ionizing radiation on its root system. In particular, species such as Tradescantia, Pisum, Allium and Mordeum vulgare have been extensively studied. Nevertheless an ever-increasing number of workers have used Vicia faba for explaining the basic problems of radio biology. One of the reasons is the small number of large chromosomes contained in the root meristem cells, which are particularly conducive to simple cytological analysis. The seedlings also have other attractive features.

Somatic embryogenesis can provide researchers with an important tool to study the physiological and molecular mechanisms involved in embryo development. In spruce, few lines are able to produce fully developed embryos due to the presence of malformed meristems. Genes from two families known as KNOX (knotted-like homeobox) and ARGONAUTE (AGO) have previously been found to be involved in meristem development and maintenance. This work documents the discovery of a new member of the AGO family of proteins designated as PgAGO and the further study of a KNOX gene known as HBK2. The complete coding sequence of both PgAGO and HBK2 was obtained through screening of cDNA libraries generated from white spruce (Picea glauca) somatic embryos. RNA in-situ hybridization studies showed that PgAGO mRNAs accumulate preferentially within cells of the shoot and root apical meristems in developing spruce embryos. In addition, the expression of PgAGO was low in white spruce lines unable to produce embryos in culture. Norway spruce (Picea abies) embryogenic tissue was transformed via microprojectile bombardment with an antisense construct of PgAGO. Down-regulation of PgAGO altered proper development of the apical meristems and reduced embryo regeneration. RNA in-situ hybridization studies showed that HBK2 is specifically expressed in the sub-apical and cortical regions of developing embryos. Like PgAGO, HBK2 expression was diminished in white spruce lines unable to produce embryos in culture. Transformation experiments with antisense constructs of HBK2 completely arrested somatic embryo development. This study reveals the importance of a functional meristem during embryo development. / October 2006