We have developed a new DH mapping population for oilseed rape, named TNDH, using genetically and phenotypically diverse parental lines. We used the population in the construction of a high stringency genetic linkage map, consisting of 277 loci, for use in quantitative genetic analysis. A proportion of the markers had been used previously in the construction of linkage maps for Brassica species, thus permitting the alignment of maps. The map includes 68 newly developed Sequence Tagged Site (STS) markers targeted to the homologues of defined genes of A. thaliana. The use of these markers permits the alignment of our linkage map with the A. thaliana genome sequence. An additional 74 loci (31 newly developed STS markers and 43 loci defined by SSR and RFLP markers that had previously been used in published linkage maps) were added to the map. These markers increased the resolution of alignment of the newly constructed linkage map with existing Brassica linkage maps and the A. thaliana genome sequence. We conducted field trials with the TNDH population at two sites, and over 2 years, and identified reproducible QTL for seed oil content and erucic acid content. The results provide new insights into the genetic control of seed oil and erucic acid content in oilseed rape, and demonstrate the utility of the linkage map and population.

BackgroundFlax (Linum usitatissimum L.) has been cultivated for around 9,000 years and is therefore one of the oldest cultivated species. Today, flax is still grown for its oil (oil-flax or linseed cultivars) and its cellulose-rich fibres (fibre-flax cultivars) used for high-value linen garments and composite materials. Despite the wide industrial use of flax-derived products, and our actual understanding of the regulation of both wood fibre production and oil biosynthesis more information must be acquired in both domains. Recent advances in genomics are now providing opportunities to improve our fundamental knowledge of these complex processes. In this paper we report the development and validation of a high-density oligo microarray platform dedicated to gene expression analyses in flax.ResultsNine different RNA samples obtained from flax inner- and outer-stems, seeds, leaves and roots were used to generate a collection of 1,066,481 ESTs by massive parallel pyrosequencing. Sequences were assembled into 59,626 unigenes and 48,021 sequences were selected for oligo design and high-density microarray (Nimblegen 385K) fabrication with eight, non-overlapping 25-mers oligos per unigene. 18 independent experiments were used to evaluate the hybridization quality, precision, specificity and accuracy and all results confirmed the high technical quality of our microarray platform. Cross-validation of microarray data was carried out using quantitative qRT-PCR. Nine target genes were selected on the basis of microarray results and reflected the whole range of fold change (both up-regulated and down-regulated genes in different samples). A statistically significant positive correlation was obtained comparing expression levels for each target gene across all biological replicates both in qRT-PCR and microarray results. Further experiments illustrated the capacity of our arrays to detect differential gene expression in a variety of flax tissues as well as between two contrasted flax varieties.ConclusionAll results suggest that our high-density flax oligo-microarray platform can be used as a very sensitive tool for analyzing gene expression in a large variety of tissues as well as in different cultivars. Moreover, this highly reliable platform can also be used for the quantification of mRNA transcriptional profiling in different flax tissues.

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1994, Carbohydrates are not the sole factor determining desiccation tolerance in seeds of Arahidopsis liwliana. AB-Vdcficient iahti-l) and ,'\BA-insensitive iahi?-!) double mutant -seeds oi Ayahidapsis thaHaua are desiccation-intolerant-Carbohydrates are supposed lo fulfill a role in membrane protection during dehydration-Desiccation tolerance can be induced in double mutant seeds in \ ivo by supplying the -^BA-analog L.' VB 17,^ 711 to the pianl root system-Howe%er, this does noi lead to signiticant changes in the carbohydrate composition-In contrast, in vitro incubation of dissected immature seeds with ,AB.A induced desiccation tolerance concomitant with an increase in the seed raftlnose content. Thus, ditierent desiccation tolerance-inducing treatments show contradictor} effects on seed carbohydrate composition and accumulalion. ll is concluded that, although carbohydrates might be involved in membrane protection or giass formation during dehydration, it is nnlikeK that they are the sole factor determining desiccation toleiiince in Arahifhfp\is seeds Key wnrd.y -AB,-\-.Arahidopsis ihallatia. cai'bohydrates, desiccation tolerance-./-J. .1. Chillis Icorrcspcndini^ ainhor I and C. M. Karssen. Depl of Pianl Physiology. Wageniugeii .Ai^iicuhura! Univ.. .Arhoyeniinlaau 4. 6703 BD Wugcniiigeii. The !\'erhei'laiids: J. A. Wilmer. Center far Agnihlological Research. P.O. 14. 67iX) AA Wagentngt'ii. The Netherlands.