| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
What's this? |
Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
Received for publication November 17, 1997. Accepted for publication August 11, 1998.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Key Words: Arabidopsis • Brassicaceae • ecotypes • flowering • germination • vernalization • stratification
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
). By planting A. thaliana throughout the year in a common greenhouse, he found that flowering time (the time from germination to flowering) was strongly influenced by day length and that there was considerable variation among plants from different regions of Europe. He further concluded that A. thaliana is a facultative long-day plant; even though flowering time is decreased by long days, plants flower eventually at any day length. Finally, he found that cold treatment of the seed could significantly decrease flowering time, especially in late-flowering plants. Late-flowering plants that responded strongly to cold treatment were designated "winterannuelle" (winter annual), whereas early-flowering plants were designated "sommerannuelle" (summer annual), and it was noted that almost all plants belonged to the latter category; only a few plants originating in Scandinavia were winter annual.
Laibach's categorizations were purely ad hoc and do not correspond to standard ecological usage where a "summer annual" plant is one that overwinters as a seed and completes its life cycle in a single growing season, whereas a "winter annual" germinates in the fall and overwinters as a rosette before flowering the following spring. This choice of terminology has led to quite a bit of confusion in the literature. Ratcliffe (1961
, 1965
) investigated the life cycles of several British and French populations of A. thaliana and found that they all, with the possible exception of some Scottish Highlands and Islands populations, overwintered as a rosette. He contrasted his findings with those of Laibach, suggesting that the difference in life cycle between Britain and Central Europe could be due to differences in rainfall pattern. The problem here is that the difference was one of definitions only, and all of Laibach's plants were probably winter annual as well [the comments by Laibach and the discussion following Ratcliffe (1965)
is illuminating in this respect; see also Napp-Zinn (1969
, p. 292) and Rédei (1970
, p. 15)]. It seems that much of the early confusion regarding the life cycle of A. thaliana (Cetl, Dobrovolna, and Effmertova, 1965
; Effmertova, 1967
; Rédei, 1970
) can be explained by inconsistencies in the terminology used by the different authors. Interestingly, a description of the life history difference between British and Continental A. thaliana, as well as Ratcliffe's explanation for it, is still to be found in floras (e.g., Grime, Hodgson, and Hunt, 1988
).
In summary, the early literature indicates that almost all populations overwinter as rosettes, but a few populations from mountainous areas are reported to overwinter as seeds (Ratcliffe, 1965
, 1976
; Usmanov et al., 1978
). Further studies are clearly needed.
Today, A. thaliana has become a primary model organism for studying the induction of flowering, and much effort is being devoted to elucidating the molecular basis of the flowering response to day length and cold treatment (Martínez-Zapater et al., 1994
; Coupland, 1995
; Wilson and Dean, 1996
). At least some of the variation for response to cold treatment in European A. thaliana is likely to be due to polymorphism at the FRI locus (Burn et al., 1993
; Lee, Bleecker, and Amasino, 1993
; Clarke and Dean, 1994
; Clarke et al., 1995
; Sanda, John, and Amasino, 1997
). Given the intensity of efforts focused on the molecular genetics of flowering time, it is remarkable that we still know very little about the ecology of flowering and natural variation for this trait. From the point of view of ecological genetics, we may find ourselves in the unusual situation of understanding the genetic basis of a trait that is probably adaptive, but that has not been studied in the field. The natural life history may also be of interest to researchers interested primarily in the mechanistic aspects of the transition to flowering. For instance, if A. thaliana is a winter annual, then it would naturally experience cold as a rosette, whereas standard practice in modern studies is to cold-treat plants at the seed stage.
In a recent study, Karlsson, Sills, and Nienhuis (1993)
surveyed the variation in flowering response to cold treatment and day length for a number of A. thaliana ecotypes. We carried out a similar study to gain further insight into the existing natural variation in cold treatment responses. In particular, we investigated whether there were ecotypes that were sensitive to cold treatment at one life stage (seed or rosette) but not at the other. We additionally explored whether particular ecotypes require cold treatment to germinate. Such a requirement might perhaps be expected in a summer annual plant because it would inhibit premature germination. A winter annual, in contrast, should germinate in the fall and should therefore show no such requirement.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
|
For each replicate, ten seeds (four seeds for Kondara and Shakhdara because not enough seed was available) were sown directly into a pot. After germination was complete, all pots were thinned to a single plant. All pots were randomly placed in flats, which rotated through positions in the incubators.
Cold treatment and growing conditions
Three different seed cold treatment regimes were used and sowing thus occurred in three phases. First, the two lots that were to be subject to long seed cold treatment were sown and placed in a 4°C growth chamber with constant low illumination. Twenty-four days later the two lots that were to be subject to short seed cold treatment were sown and placed in the same growth chamber. Three days later the final two lots, which were to be subject to no seed cold treatment, were sown and placed directly in incubators, together with the four lots from the 4°C growth chamber. The long seed cold treatment treatment thus consisted of 27 d in 4°C and the short seed cold treatment of 3 d in 4°C.
The plants were grown in Percival incubators (Percival Scientific Inc., Boone, Iowa 50036) with a 12-h photoperiod and 20°/16°C (day/night) temperature. The incubators had been modified to have incandescent as well as fluorescent light, resulting in a photosynthetically active radiation of 
100 µmol·m;ms2·s;ms1. The pots contained Pro Mix BX (Premier Horticulture Inc., Red Hill, Pennsylvania 18076).
After 52 d of growth, the three lots that were to be subjected to rosette cold treatment were put in the 4°C growth chamber for 38 d, after which they were returned to the incubators.
Data collection
Germination was scored daily by counting emerging cotyledons. Bolting was scored approximately every 2 d and noted as the date when the inflorescence appeared in the center of the rosette. The experiment was terminated after 9 mo, at which point almost all plants had flowered (Table 1). The remaining plants were moved to a greenhouse with more light to induce flowering (which usually succeeded) and enable seed collection.
Analysis
Total germination percentages for each ecotype for each treatment combination were calculated and compared using G tests with Williams' correction (Sokal and Rohlf, 1981
). The number of days to bolting from germination was calculated for each plant ignoring any days spent in rosette cold treatment.
Some ecotype/seed treatment combinations had already started to bolt before the rosette cold treatment was scheduled to start, and others did so shortly thereafter. Since the purpose of this treatment was to investigate the effect of rosette cold treatment in promoting flowering, the bolting time data with rosette cold treatment for any plants that bolted less than 1 wk after the start of rosette cold treatment were discarded.
Mean bolting times were compared using permutation tests. The few plants that had not flowered by the end of the experiment were given a bolting date corresponding to the termination of the experiment. Means and standard deviations in these cases are therefore underestimates, and comparisons with "normal" means are conservative (Table 1).
All reported significance levels are two-tailed and have not been corrected for multiple comparisons.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Ecotypes whose probability of germination was very strongly promoted (at least doubling the germination percentage) by the long seed cold treatment were KZ-9, KZ-13, OY-0, Lisse, DEM-2, and MS-0. The four Swedish ecotypes all responded negatively (basically eliminating germination for Vimmerby and Västervik) to long seed cold treatment.
The effect of cold treatment on the speed of germination, measured as the number days until 95% of the seeds that were eventually to germinate had germinated, was much simpler. In all but one case, germination was faster with long cold treatment than with short or no cold treatment, and in these cases germination was usually also faster with short than with no cold treatment. One ecotype, OY-0, showed precisely the opposite response.
Bolting
Twenty-six ecotypes germinated sufficiently well for meaningful estimates of bolting time to be made. Mean bolting times and standard deviations of the means are given in Table 1, which also shows the comparisons between the means for the different treatments.
Mean bolting time varied widely between treatments and ecotypes, ranging from 1 mo with long seed cold treatment for an ecotype from Kazakhstan to 9 mo (with some plants still not flowering) without seed cold treatment for some ecotypes from Sweden and Finland. Several generalizations can be made. First, the long seed cold treatment decreased bolting time compared to no and/or short cold treatment in all but one ecotype, TSU-0 (Fig. 1). In contrast, short seed cold treatment had a less consistent and usually minor effect; bolting time was increased for seven ecotypes (significantly so for GOT-32 and Köln) and decreased for 15 (significantly so for Vimmerby and Algutsrum). Second, significant rosette cold treatment effects always entailed a decrease in bolting time, however there was often no significant effect (Fig. 2). It is harder to generalize about the interaction between seed and rosette cold treatment, except to say that rosette cold treatment less often had a significant effect on plants that had been subjected to long seed cold treatment than on plants that had not (
2 test, P < 0.01).
|
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
), but this was in no way apparent from their germination response. Whenever a strong response was observed, it was associated with poor germination overall. Furthermore, limited repetitions of the experiment indicated that these responses were not repeatable; there appears to be a large maternal environmental component to seed germination (unpublished data). Although we attempted to control these effects by growing all seed donors (except those mentioned in Materials and Methods) together in the greenhouse, this appears not to have been sufficient to remove environmental influences on the variation in germination responses. Our results indicate that it may be difficult to infer the life cycle of A. thaliana from its germination response in the manner attempted here and provide further evidence that seed dormancy and germination are strongly influenced by environmental conditions (Kugler, 1951
; Rédei, 1970
; Baskin and Baskin, 1972
, 1983
; Napp-Zinn, 1975
, 1976
; Ratcliffe, 1976
; Koorneef and Karssen, 1994
). Ultimately, field studies will probably be necessary to determine the life cycle.
Bolting
In contrast to the germination results, the bolting results show very distinct patterns that are highly repeatable (unpublished data). It is clear that seed and rosette cold treatment are not always qualitatively equivalent. While all but two of the ecotypes responded to seed cold treatment, far fewer responded to rosette cold treatment. This agrees with previous results, mostly due to Napp-Zinn (reviewed in: Napp-Zinn, 1969
; Rédei, 1970
; Martínez-Zapater et al., 1994
), that the degree of responsiveness to cold treatment often depends on the age of the plant. Nonetheless, all ecotypes that required >100 d to bolt without cold treatment responded to both seed and rosette cold treatment, and no ecotype responded to rosette cold treatment without also responding to seed cold treatment.
For many ecotypes, a combination of rosette and long seed cold treatment did not decrease bolting time relative to long seed cold treatment alone. This supports the notion that there is a point of saturation for cold treatment (Martínez-Zapater et al., 1994
; Lee and Amasino, 1995
) even if cold treatment is done in several stages. In this context, it is notable that our short seed cold treatment (3 d) was evidently not sufficient to significantly accelerate bolting.
It should be emphasized that flowering behavior depends strongly on light conditions as well as cold treatment, and that these effects are known to interact (Martínez-Zapater et al., 1994
). This presumably explains the differences between our results and those of Karlsson, Sills, and Nienhuis (1993)
, who identified several ecotypes that did not respond to cold treatment, including two, LER and EDI-0, that seemed to respond in our study. As can be seen from Table 1, all lines except TSU-0 seem to respond to cold treatment under our conditions. TSU-0 stands out as being strikingly insensitive to cold treatment (this ecotype was also found insensitive by Karlsson, Sills, and Nienhuis [1993
]).
Finally, our study confirms previous results that there exists a wide range of natural variation for response to environmental influences on flowering time (reviewed in Martínez-Zapater et al., 1994
). It seems probable that this variation is at least partially the product of adaptation to the local environment, however no clear geographic pattern is evident. All the Swedish and Finnish ecotypes tested were late flowering and responded strongly to cold treatment, but so did ecotypes from England and the Netherlands. The ecotypes from Kazakhstan, Tadjikistan, and Libya were all early flowering, but so was the ecotype from Köln, Germany. Indeed, considerable variation exists within single populations. The two ecotypes PU-2-3 and PU-2-8 were collected from the same population, but the former flowers much later than the latter without long cold treatment, whereas they are roughly synchronized with cold treatment. DEM-2 and DEM-4 were also collected from a single population, but differ widely in flowering time. This may indicate that selection does not act in a simple way on flowering behavior, which would explain the absence of clear geographic patterns.
|
|
FOOTNOTES |
|---|
2 Author for correspondence, current address: Department of Genetics, Lund University, 223 62 Lund, Sweden.
|
LITERATURE CITED |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
———, and ———. 1983 Seasonal changes in the germination responses of buried seeds of Arabidopsis thaliana and ecological interpretation. Botanical Gazette 144: 540–543.[CrossRef]
Burn, J. E., D. J. Bagnall, J. D. Metzger, E. S. Dennis, and W. J. Peacock. 1993 Genes conferring late flowering in Arabidopsis thaliana. Genetica 90: 147–155.
Cetl, I., J. Dobrovolna, and E. Effmertova. 1965 Distribution of spring and winter types in the local populations of Arabidopsis thaliana (L.) Heynh. from various localities in Western Moravia. Arabidopsis Information Service 2.
Clarke, J. H., and C. Dean. 1994 Mapping FRI, a locus controlling flowering time and vernalization response in Arabidopsis thaliana. Molecular and General Genetics 242: 81–89.
———, R. Mithen, J. K. M. Brown, and C. Dean. 1995 QTL analysis of flowering time in Arabidopsis thaliana. Molecular and General Genetics 248: 278–286.
Coupland, G. 1995 Genetic and environmental control of flowering time in Arabidopsis. Trends in Genetics 11: 393–397.
Effmertova, E. 1967 The behaviour of "summer annual", "mixed", and "winter annual" natural populations as compared with early and late races in field conditions. Arabidopsis Information Service 4.
Grime, J. P., J. G. Hodgson, and R. Hunt. 1988 Comparative plant ecology: a functional approach to common British species. Unwin&Hyman, London.
Karlsson, B. H., G. R. Sills, and J. Nienhuis. 1993 Effects of photoperiod and vernalization on the number of leaves at flowering in 32 Arabidopsis thaliana (Brassicaceae) ecotypes. American Journal of Botany 80: 646–648.[CrossRef][Web of Science]
Koorneef, M., and C. M. Karssen. 1994 Seed dormancy and germination. In C. R. Somerville and E. M. Meyerowitz [eds.], Arabidopsis, 313–334. Cold Spring Harbor Laboratory Press, Plainview, NY.
Kugler, I. 1951 Untersuchungen über das Keimverhalten einiger Rassen von Arabidopsis thaliana (L.) Heynh. Ein Beitrag zum Problem der Lichtkeimung. Beiträge zur Biologie der Pflanzen 28: 211–243.
Laibach, F. 1951 Über sommer- und winterannuelle Rassen von Arabidopsis thaliana (L.) Heynh. Ein Beitrag zur Ätiologie der Blütenbildung. Beiträge zur Biologie der Pflanzen 28: 173–210.
Lee, I., and R. Amasino. 1995 Effect of vernalization, photoperiod, and light quality on the flowering phenotype of Arabidopsis plants containing the FRIGIDA gene. Plant Physiology 108: 157–162.[Abstract]
———, A. Bleecker, and R. Amasino. 1993 Analysis of naturally occurring late flowering in Arabidopsis thaliana. Molecular and General Genetics 237: 171–176.
Martínez-Zapater, J. M., G. Coupland, C. Dean, and M. Koorneef. 1994 The transition to flowering in Arabidopsis. In C. R. Somerville and E. M. Meyerowitz [eds.], Arabidopsis, 403–434. Cold Spring Harbor Laboratory Press, Plainv iew, NY.
Napp-Zinn, K. 1969 Arabidopsis thaliana (L.) Heynh. In L. T. Evans [ed.], The induction of flowering, 291–304. Cornell University Press, Ithaca, NY.
———. 1975 On the genetical basis of light requirement in seed germination of Arabidopsis. Arabidopsis Information Service 12: 10.
———. 1976 Population genetical and gene geographical aspects of germination and flowering in Arabidopsis thaliana. Arabidopsis Information Service 13.
Ratcliffe, D. 1961 Adaptation to habitat in a group of annual plants. Journal of Ecology 49: 187–203.[CrossRef]
———. 1965 The geographical and ecological distribution of Arabidopsis and comments on physiological variation. Arabidopsis Information Service 1S.
———. 1976 Germination characteristics and their inter- and intra-population variability in Arabidopsis. Arabidopsis Information Service 13.
Rédei, G. P. 1970 Arabidopsis thaliana (L.) Heynh., a review of the genetics and biology. Bibliographia Genetica 20: 1–151.
Sanda, S. L., M. John, and R. M. Amasino. 1997 Analysis of flowering time in ecotypes of Arabidopsis thaliana. Journal of Heredity 88: 69–72.
Sokal, R. R., and F. J. Rohlf. 1981 Biometry, 2d ed. W. H. Freeman, New York, NY.
Usmanov, P. D., V. I. Muzyka, I. G. Mednik, N. V. Glotov, V. A. Shjevchenko, and S. A. Famelis. 1978 Population genetics of Arabidopsis in the West Pamir Alai. Report I. Comparative characteristic of the Arabidopsis populations on the Hissar mountain ridge. Arabidopsis Information Service 15.
Wilson, A., and C. Dean. 1996 Anaysis of the molecular basis of vernalization in Arabidopsis thaliana. Seminars in Cell&Developmental Biology 7: 435–440.
CiteULike Complore Connotea Del.icio.us Digg Facebook Reddit Technorati Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  G. C. K. Chiang, D. Barua, E. M. Kramer, R. M. Amasino, and K. Donohue Major flowering time gene, FLOWERING LOCUS C, regulates seed germination in Arabidopsis thaliana PNAS, July 14, 2009; 106(28): 11661 - 11666. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Donohue Completing the cycle: maternal effects as the missing link in plant life histories Phil Trans R Soc B, April 27, 2009; 364(1520): 1059 - 1074. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Simon, O. Loudet, S. Durand, A. Berard, D. Brunel, F.-X. Sennesal, M. Durand-Tardif, G. Pelletier, and C. Camilleri Quantitative Trait Loci Mapping in Five New Large Recombinant Inbred Line Populations of Arabidopsis thaliana Genotyped With Consensus Single-Nucleotide Polymorphism Markers Genetics, April 1, 2008; 178(4): 2253 - 2264. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Wang, C. Mu, Y. Hou, and X. Li Optimum Harvest Time of Vicia cracca in Relation to High Seed Quality during Pod Development Crop Sci., March 19, 2008; 48(2): 709 - 715. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Kuittinen, A. Niittyvuopio, P. Rinne, and O. Savolainen Natural Variation in Arabidopsis lyrata Vernalization Requirement Conferred by a FRIGIDA Indel Polymorphism Mol. Biol. Evol., February 1, 2008; 25(2): 319 - 329. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Shindo, G. Bernasconi, and C. S. Hardtke Natural Genetic Variation in Arabidopsis: Tools, Traits and Prospects for Evolutionary Ecology Ann. Bot., June 1, 2007; 99(6): 1043 - 1054. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. R. Schlappi FRIGIDA LIKE 2 Is a Functional Allele in Landsberg erecta and Compensates for a Nonsense Allele of FRIGIDA LIKE 1 Plant Physiology, December 1, 2006; 142(4): 1728 - 1738. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. M. Ehrenreich and M. D. Purugganan The molecular genetic basis of plant adaptation Am. J. Botany, July 1, 2006; 93(7): 953 - 962. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Jakobsson, J. Hagenblad, S. Tavare, T. Sall, C. Hallden, C. Lind-Hallden, and M. Nordborg A Unique Recent Origin of the Allotetraploid Species Arabidopsis suecica: Evidence from Nuclear DNA Markers Mol. Biol. Evol., June 1, 2006; 23(6): 1217 - 1231. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Stinchcombe, A. L. Caicedo, R. Hopkins, C. Mays, E. W. Boyd, M. D. Purugganan, and J. Schmitt Vernalization sensitivity in Arabidopsis thaliana (Brassicaceae): the effects of latitude and FLC variation Am. J. Botany, October 1, 2005; 92(10): 1701 - 1707. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. D. Werner, J. O. Borevitz, N. H. Uhlenhaut, J. R. Ecker, J. Chory, and D. Weigel FRIGIDA-Independent Variation in Flowering Time of Natural Arabidopsis thaliana Accessions Genetics, July 1, 2005; 170(3): 1197 - 1207. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. J. Wender, C. R. Polisetty, and K. Donohue Density-dependent processes influencing the evolutionary dynamics of dispersal: a functional analysis of seed dispersal in Arabidopsis thaliana (Brassicaceae) Am. J. Botany, June 1, 2005; 92(6): 960 - 971. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Shindo, M. J. Aranzana, C. Lister, C. Baxter, C. Nicholls, M. Nordborg, and C. Dean Role of FRIGIDA and FLOWERING LOCUS C in Determining Variation in Flowering Time of Arabidopsis Plant Physiology, June 1, 2005; 138(2): 1163 - 1173. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S.-I Lin, J.-G. Wang, S.-Y. Poon, C.-l. Su, S.-S. Wang, and T.-J. Chiou Differential Regulation of FLOWERING LOCUS C Expression by Vernalization in Cabbage and Arabidopsis Plant Physiology, March 1, 2005; 137(3): 1037 - 1048. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. D. Werner, J. O. Borevitz, N. Warthmann, G. T. Trainer, J. R. Ecker, J. Chory, and D. Weigel Quantitative trait locus mapping and DNA array hybridization identify an FLM deletion as a cause for natural flowering-time variation PNAS, February 15, 2005; 102(7): 2460 - 2465. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Caicedo, J. R. Stinchcombe, K. M. Olsen, J. Schmitt, and M. D. Purugganan Epistatic interaction between Arabidopsis FRI and FLC flowering time genes generates a latitudinal cline in a life history trait PNAS, November 2, 2004; 101(44): 15670 - 15675. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Riihimaki and O. Savolainen Environmental and genetic effects on flowering differences between northern and southern populations of Arabidopsis lyrata (Brassicaceae) Am. J. Botany, July 1, 2004; 91(7): 1036 - 1045. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Griffith, E. Kim, and K. Donohue Life-history variation and adaptation in the historically mobile plant Arabidopsis thaliana (Brassicaceae) in North America Am. J. Botany, June 1, 2004; 91(6): 837 - 849. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Stinchcombe, C. Weinig, M. Ungerer, K. M. Olsen, C. Mays, S. S. Halldorsdottir, M. D. Purugganan, and J. Schmitt A latitudinal cline in flowering time in Arabidopsis thaliana modulated by the flowering time gene FRIGIDA PNAS, March 30, 2004; 101(13): 4712 - 4717. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Weinig, L. A. Dorn, N. C. Kane, Z. M. German, S. S. Halldorsdottir, M. C. Ungerer, Y. Toyonaga, T. F. C. Mackay, M. D. Purugganan, and J. Schmitt Heterogeneous Selection at Specific Loci in Natural Environments in Arabidopsis thaliana Genetics, September 1, 2003; 165(1): 321 - 329. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Gazzani, A. R. Gendall, C. Lister, and C. Dean Analysis of the Molecular Basis of Flowering Time Variation in Arabidopsis Accessions Plant Physiology, June 1, 2003; 132(2): 1107 - 1114. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Weinig, M. C. Ungerer, L. A. Dorn, N. C. Kane, Y. Toyonaga, S. S. Halldorsdottir, T. F. C. Mackay, M. D. Purugganan, and J. Schmitt Novel Loci Control Variation in Reproductive Timing in Arabidopsis thaliana in Natural Environments Genetics, December 1, 2002; 162(4): 1875 - 1884. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. K. Stenoien, C. B. Fenster, H. Kuittinen, and O. Savolainen Quantifying latitudinal clines to light responses in natural populations of Arabidopsis thaliana (Brassicaceae) Am. J. Botany, October 1, 2002; 89(10): 1604 - 1608. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Hagenblad and M. Nordborg Sequence Variation and Haplotype Structure Surrounding the Flowering Time Locus FRI in Arabidopsis thaliana Genetics, May 1, 2002; 161(1): 289 - 298. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. V. Minorsky Plant Physiology, May 1, 2002; 129(1): 5 - 6. [Full Text] [PDF]
|
|
|
|
|
|
J. Munir, L. A. Dorn, K. Donohue, and J. Schmitt The effect of maternal photoperiod on seasonal dormancy in Arabidopsis thaliana (Brassicaceae) Am. J. Botany, July 1, 2001; 88(7): 1240 - 1249. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 U. Johanson, J. West, C. Lister, S. Michaels, R. Amasino, and C. Dean Molecular Analysis of FRIGIDA, a Major Determinant of Natural Variation in Arabidopsis Flowering Time Science, October 13, 2000; 290(5490): 344 - 347. [Abstract] [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
