Differential gene expression during germination and after the induction of adventitious bud formation in Norway spruce embryos

Abstract

A pulse treatment of embryos of Norway spruce with cytokinin suppresses germinative development and induces the coordinate formation of adventitious buds from subepidermal cell layers. To analyse the patterns of gene expression associated with germination and the alterations induced by the bud induction treatment, we have isolated cDNA clones corresponding to genes that are differentially expressed in cytokinin-treated and untreated in vitro germinating embryos. One category of 14 clones hybridized to transcripts that were abundant specifically during germination. The expression of 8 of these genes was reduced by the bud induction treatment. Four clones, including one identified as a histone H2A gene, recognized transcripts that showed an increased abundance in bud-induced versus in vitro germinating embryos. A second category of 13 clones hybridized to transcripts that increased in abundance during post-germinative development of the seedling. Among these a subset of 8 clones, including an alpha-tubulin clone, corresponds to genes suppressed by the bud induction treatment, whereas 5 clones, including a gene with sequence similarity to polyubiquitin, were unaffected by the treatment. One clone hybridized to a message abundant in the seed, during early germination as well as in the vegetative bud, and showed 60% partial sequence identity to a barley (1----3)-beta-glucanase gene. Genes expressed exclusively in bud-induced or in vitro germinating embryos were not found. The results show that a major difference in gene expression between treated and untreated embryos is related to the shift from extensive cell proliferation to elongation and differentiation that occurs at the transition from germination to post-germinative development, and which is suppressed in the bud-induced embryos.

A homeobox gene with potential developmental control function in the meristem of the conifer Picea abies

“…A spruce cDNA library constructed from zygotic embryos, induced to form adventitious meristems by a treatment with the hormone cytokinin (27), was screened with a fragment of the maize Kn1 cDNA. Plaques (200,000) were screened and four clones representing two different sequences were isolated.…”

“…Clones (200,000) of a cDNA library constructed from spruce embryo RNA (27) were screened with a BamHI-XhoI fragment of the Knotted1 cDNA clone pBSKN1 containing the homeobox but excluding the 5Ј end of the clone encoding the histidine-rich region. A partial cDNA was isolated and used subsequently to isolate a fulllength cDNA by the screening of 200,000 clones of a spruce female strobilus cDNA library (28).…”

“…A partial cDNA was isolated and used subsequently to isolate a fulllength cDNA by the screening of 200,000 clones of a spruce female strobilus cDNA library (28). Labeling, hybridization, and washing were performed as described (27). Positive clones were subcloned into the EcoRI site of pBS SK ϩ (Stratagene).…”

Molecular characterization of a phosphoenolpyruvate carboxylase in the gymnosperm Picea abies (Norway spruce)

“…Despite its enormous ecological and economic importance very few studies of the molecular biology of Norway spruce have been carried out so far [4,10,20,33,57].…”

Differential water uptake kinetics in axes and cotyledons during seed germination of Vigna radiata under chilling temperature and cycloheximide treatment

“…Water uptake by the axes attached to cotyledons was always somewhat higher than for detached axes, difference being more prominent in the case of scarified seeds. This is possibly because cotyledons supplemented the water supply to the axes possibly through vascular connection that might have differentiated by that time (Sundås et al, 1992) or through diffusion. Chilling treatment prevented water uptake by both attached and detached axes, again suggesting some problem in entry of water through membranes.…”