| 1. |
- Schrader, J., et al.
(författare)
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Cambial meristem dormancy in trees involves extensive remodelling of the transcriptome
- 2004
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Ingår i: The Plant Journal. - Malden : Wiley-Blackwell. - 0960-7412 .- 1365-313X. ; 40:2, s. 173-187
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Tidskriftsartikel (refereegranskat)abstract
- The establishment of the dormant state in meristems involves considerable physiological and metabolic alterations necessary for surviving unfavourable growth conditions. However, a global molecular analysis of dormancy in meristems has been hampered by the difficulty in isolating meristem cells. We used cryosectioning to isolate purified cambial meristem cells from the woody plant Populus tremula during active growth and dormancy. These samples were used to generate meristem-specific cDNA libraries and for cDNA microarray experiments to define the global transcriptional changes underlying cambial dormancy. The results indicate a significant reduction in the complexity of the cambial transcriptome in the dormant state. Although cell division is terminated in the dormant cambium, the cell cycle machinery appears to be maintained in a skeletal state as suggested by the continued presence of transcripts for several cell cycle regulators. The downregulation of PttPIN1 and PttPIN2 transcripts explains the reduced basipetal polar auxin transport during dormancy. The induction of a member of the SINA family of ubiquitin ligases implicated in auxin signalling indicates a potential mechanism for modulation of auxin sensitivity during cambial dormancy. The metabolic alterations during dormancy are mirrored in the induction of genes involved in starch breakdown and the glyoxysomal cycle. Interestingly, the induction of RGA1 like gene suggests modification of gibberellin signalling in cambial dormancy. The induction of genes such as poplar orthologues of FIE and HAP2 indicates a potential role for these global regulators of transcription in orchestrating extensive changes in gene expression during dormancy.
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| 4. |
- Savolainen, Peter, et al.
(författare)
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A detailed picture of the origin of the Australian dingo, obtained from the study of mitochondrial DNA
- 2004
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 101:33, s. 12387-12390
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Tidskriftsartikel (refereegranskat)abstract
- To determine the origin and time of arrival to Australia of the dingo, 582 bp of the mtDNA control region were analyzed in 211 Australian dingoes sampled in all states of Australia, 676 dogs from all continents, and 38 Eurasian wolves, and 263 bp were analyzed in 19 pre-European archaeological dog samples from Polynesia. We found that all mtDNA sequences among dingoes were either identical to or differing by a single substitution from a single mtDNA type, A29. This mtDNA type, which was present in >50% of the dingoes, was found also among domestic dogs, but only in dogs from East Asia and Arctic America, whereas 18 of the 19 other types were unique to dingoes. The mean genetic distance to A29 among the dingo mtDNA sequences indicates an origin approximate to5,000 years ago. From these results a detailed scenario of the origin and history of the dingo can be derived: dingoes have an origin from domesticated dogs coming from East Asia, possibly in connection with the Austronesian expansion into Island Southeast Asia. They were introduced from a small population of dogs, possibly at a single occasion, and have since lived isolated from other dog populations.
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| 5. |
- Beaujean, A, et al.
(författare)
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Engineering direct fructose production in processed potato tubers by expressing a bifunctional alpha-amylase/glucose isomerase gene complex
- 2000
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Ingår i: Biotechnology and Bioengineering. - 0006-3592. ; 70:1, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- Manipulation of starch biosynthesis/degradation and formation of novel molecules in storage organs of plants through genetic engineering is an attractive but technically challenging goal. We report here, for the first time, that starch was degraded and glucose and fructose were produced directly when crushed potato tubers expressing a starch degrading bifunctional gene were heated for 45 minutes at 65 degrees C. To achieve this, we have constructed a fusion gene encoding the thermostable enzymes: alpha-amylase (Bacillus stearothermophilus) and glucose isomerase (Thermus thermophilus). The chimeric gene was placed under the control of the granule-bound-starch synthase promoter. This enzymatic complex produced in transgenic tubers was only active at high temperature (65 degrees C). More than 100 independent transgenic potato plants were regenerated. Molecular analyses confirmed the stable integration of the chimeric gene into the potato genome. The biochemical analyses performed on young and old tubers after high-temperature treatment (65 degrees C) revealed an increase in the formation rate of fructose and glucose by a factor of 16.4 and 5. 7, respectively, in the transgenic tubers as compared to untransformed control tubers. No adverse discernible effect on plant development and metabolism including tuber formation and starch accumulation was observed in the transgenic plants before heat treatment. Our results demonstrate that it is possible to replace starch degradation using microbial enzymes via a system where the enzymes are produced directly in the plants, but active only at high temperature, thus offering novel and viable strategies for starch-processing industries.
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| 6. |
- Denoyes-Rothan, B, et al.
(författare)
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QTL analysis for resistances to Colletotrichum acutatum and Phytophthora cactorum in octoploid strawberry (Fragaria x ananassa)
- 2004
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Ingår i: Proceedings of the XIth Eucarpia Symposium on Fruit Breeding and Genetics, Vols 1 and 2. - : INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE. ; , s. 147-151
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Konferensbidrag (refereegranskat)abstract
- Colletotrichum acutatum and Phytophthora cactorum are two of the most important pathogens of strawberry in Europe, and particularly in France. The characterization of quantitative trait loci (QTL) controlling resistances to these two pathogens would allow a better knowledge of the genetic architecture of these resistances in order to develop durable resistance. A pseudo-testcross strawberry population derived from the cross between Capitola and CF1116 was used for detecting QTLs associated with C. acutatum and P cactorum resistances. One hundred and eighty five individuals were inoculated with C. acutatum by dipping cold stored plants in a conidial suspension adjusted to 2.10(6) conidia per ml. They were also inoculated separately with P cactorum by inserting an agar disk containing mycelium into the crown. Each inoculation was conducted twice. Putative QTLs for resistance to C acutatum and P cactorum were identified by Interval Mapping (Mapmaker-QTL) using a LOD threshold of 2.
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| 7. |
- Gavrilets, Sergey, et al.
(författare)
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The evolution of female mate choice by sexual conflict
- 2001
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Ingår i: Proceedings of the Royal Society of London Series B. - London : The Roylal Society. - 0080-4649 .- 0962-8452 .- 1471-2954. ; 268:1466, s. 531-539
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Tidskriftsartikel (refereegranskat)abstract
- Although empirical evidence has shown that many male traits have evolved via sexual selection by female mate choice, our understanding of the adaptive value of female mating preferences is still very incomplete. It has recently been suggested that female mate choice may result from females evolving resistance rather than attraction to males, but this has been disputed. Here, we develop a quantitative genetic model showing that sexual conflict over mating indeed results in the joint evolution of costly female mate choice and exaggerated male traits under a wide range of circumstances. In contrast to traditional explanations of costly female mate choice, which rely on indirect genetic benefits, our model shows that mate choice can be generated as a side–effect of females evolving to reduce the direct costs of mating.
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| 8. |
- Lerceteau, Estelle, et al.
(författare)
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AFLP mapping and detection of quantitative trait loci (QTLs) for economically important traits in Pinus sylvestris : a preliminary study
- 2000
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Ingår i: Molecular breeding. - : KLUWER ACADEMIC PUBL. - 1380-3743 .- 1572-9788. ; 6:5, s. 451-458
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Tidskriftsartikel (refereegranskat)abstract
- We have applied a two-way pseudo-testcross strategy in an analysis of Pinus sylvestris for genetic mapping and detection of quantitative trait loci (QTLs) associated with economically important traits targeted in the Swedish tree-breeding programme. Based on 94 full-sib progeny of a cross between two plus-trees from northern Sweden we generated two parental maps using AFLP markers. The female map was comprised of 94 markers assigned to 15 linkage groups giving a size of 796 cM. On the male map 155 markers were assigned to 15 linkage groups, giving a total size of 1335 cM. The recombination frequency was found to be sex-dependent, being 29.3% higher in male than in female gametes. On the female map, 12 QTLs were detected (but none for branch diameter or wood density). Three QTLs for tree height accounted for 25.8% of the total phenotypic variation of this trait. When the QTLs detected for all the traits were taken independently, the percentages of phenotypic variance ranged from 9.3% to 22.7%. The highest value was observed for frost hardiness, an important trait in northern Sweden for which a major gene seemed to be involved. A cluster of QTLs for tree height, trunk diameter and volume was located on one linkage group. On the male map, four QTLs for trunk diameter and volume were detected. Due to the reduced number of individuals under study, the results are preliminary and have to be validated on more trees.
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| 9. |
- Lerceteau, Estelle, et al.
(författare)
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Detection of quantitative trait loci in Pinus sylvestris L. across years
- 2001
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Ingår i: Euphytica. - : KLUWER ACADEMIC PUBL. - 0014-2336 .- 1573-5060. ; 121:2, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- In an earlier study, we reported the characterisation of quantitative trait loci (QTLs) for economically important traits related to wood production for a specific year of measurement. However, validating the detected QTLs across years is important for any strategy for marker-assisted selection (MAS). Therefore, we evaluated the consistency of the QTLs across four years in 9 to 12 year-old trees. Data related to tree height were analysed in two ways. The total height was used to characterise QTLs likely to be useful in MAS, and the increment values to evaluate growth regulation. Among the 11 QTLs detected, 4 were found in both the 1996 and 1997 evaluations. QTL numbers and locations related to total height were found to be highly stable. However, the QTL effects progressively changed in successive years, following either an increasing, decreasing or curvilinear trend. Depending on their specific trends, some QTLs may not be expressed at all later in maturity, or they may be expressed at a higher level. This will have direct consequences on the applicability of molecular markers in early screening programs, since a study at the mature stage may also be required. More variation in QTL number and effect was observed relating to height increment than to total height, indicating significant differences in gene expression during the growth periods involved.
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| 10. |
- Lerceteau-Köhler, Estelle, et al.
(författare)
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Characterization of mixed disomic and polysomic inheritance in the octoploid strawberry (Fragaria x ananassa) using AFLP mapping
- 2003
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Ingår i: Theoretical and Applied Genetics. - : SPRINGER-VERLAG. - 0040-5752 .- 1432-2242. ; 107:4, s. 619-628
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Tidskriftsartikel (refereegranskat)abstract
- A two-way pseudo-testcross strategy, combined with Single Dose Restriction Fragment (SDRF) marker analysis, was used for genetic mapping in the octoploid cultivated strawberry Fragaria x ananassa (2n=8x=56). Based on a 113 full-sib progeny from a cross between the variety Capitola and the clone CF1116, we generated two parental maps using Amplified Fragment Length Polymorphism (AFLP) markers. Ninety two percent of the markers (727 out of 789) showed ratios corresponding to simplex markers (the majority being SDRF markers), and 8% (62 out of 789) fitted a multiplex ratio. Linkage maps were first established using SDRF markers in coupling phase. The female map comprised 235 markers distributed among 43 co-segregation groups, giving a map size of 1,604 cM. On the male map, 280 markers were assigned to 43 co-segregation groups, yielding a map size of 1,496 cM. Once the co-segregation groups were established, their association was tested using repulsion-phase markers. In total, taking into account associations representing the same linkage groups, 30 linkage groups were detected on the female side and 28 on the male side. On the female map, 68.3% of the pairwise marker linkages were in coupling versus 31.7% in repulsion phase, and the corresponding figures on the male map were 72.2% and 27.8%, respectively. In addition, both groups linked only in the coupling phase and groups linked in the repulsion phase were characterized. The observations suggest that the meiotic behavior of the F. x ananassa genome is neither fully disomic nor fully polysomic, but rather mixed. The genome may not be as completely diploidized as previously assumed.
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