Heterologous array analysis in Pinaceae: hybridization of Pinus taeda cDNA arrays with cDNA from needles and embryogenic cultures of P. Taeda, P. Sylvestris or Picea abies.

Hybridization of labelled cDNA from various cell types with high-density arrays of expressed sequence tags is a powerful technique for investigating gene expression. Few conifer cDNA libraries have been sequenced. Because of the high level of sequence conservation between Pinus and Picea we have investigated the use of arrays from one genus for studies of gene expression in the other.

Comparison of standard exponential and linear techniques to amplify small cDNA samples for microarrays.

Background: The need to perform microarray experiments with small amounts of tissue has led to the development of several protocols for amplifying the target transcripts. The use of different amplification protocols could affect the comparability of microarray experiments.

Results: Here we compare expression data from Pinus taeda cDNA microarrays using transcripts amplified either exponentially by PCR or linearly by T7 transcription.

Microarray analyses of gene expression during adventitious root development in Pinus contorta.

In order to investigate the gene expression pattern during adventitious root development, RNA of Pinus contorta hypocotyls, pulse-treated with the auxin indole-3-butyric acid and harvested at distinct developmental time points of root development, was hybridized to microarrays containing 2,178 cDNAs from Pinus taeda. Over the period of observation of root development, the transcript levels of 220 genes changed significantly. During the root initiation phase, genes involved in cell replication and cell wall weakening and a transcript encoding a PINHEAD/ZWILLE-like protein were up-regulated, while genes related to auxin transport, photosynthesis, and cell wall synthesis were down-regulated.

Up, down and up again is a signature global gene expression pattern at the beginning of gymnosperm embryogenesis.

Somatic embryogenesis of a gymnosperm, Picea abies, represents a sequence of specifically regulated developmental stages including proembryogenic mass (PEM), PEM-to-embryo transition, and early and late embryogeny. Here, we report cDNA array analysis of expression patterns of 373 genes in the beginning of P. abies embryo development.

Requirement for far-red light to maintain secondary needle extension growth in northern but not southern populations of Pinus sylvestris (Scots pine).

Extension growth of secondary needles is under photoperiodic control in Pinus sylvestris. To test for the effects of far-red light on maintaining this extension growth, seedlings of six populations originating from latitudes between 57 degrees and 67 degrees N were raised for 11 weeks in continuous incandescent (metal halogen) light at 300 &mgr;mol m-2 s-1 and 20 degrees C and then transferred at the same temperature to a daily regime of 8 h incandescent light (230 &mgr;mol m-2 s-1) followed by a 16 h day extension with cool white fluorescent light (40 &mgr;mol m-2 s-1, R/FR ratio 7.5) or with incandescent lamps (20 &mgr;mol m-2 s-1, R/FR ratio 2.

Latitudinal cline of requirement for far-red light for the photoperiodic control of budset and extension growth in Picea abies (Norway spruce).

To test for the effects of far-red light on preventing budset in Picea abies, seedlings of six populations originating from latitudes between 67°N and 47°N were grown for 4-8 weeks in continuous incandescent (metal halogen) light at 300 µmol m s and 20°C and then transferred, at the same temperature, to a daily regime of 8 h incandescent light (300 µmol m s ) followed by 16 h cool white fluorescent light (40 µmol m s ). (Cool white lamps are deficient in far-red light, with a R/FR ratio of 7.5 compared with 2.