<i>CENL1</i>Expression in the Rib Meristem Affects Stem Elongation and the Transition to Dormancy in<i>Populus</i>

Ruonala, Raili; Rinne, Päivi L.H.; Kangasjärvi, Jaakko; Schoot, Christiaan van der

doi:10.1105/tpc.107.056721

Cited by 109 publications

(141 citation statements)

References 73 publications

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“…The other gene, c2588, belongs to the same gene family as INDETERMINATE1/EARLY HEADING DATE2 (ID1/Ehd2), a zinc-finger transcription factor and upstream regulator of FT homologs in monocots (Colasanti et al 1998;Matsubara et al 2008). While TFL1 homologs regulate flowering and other photoperiodic responses across diverse plants (Bradley et al 1997;Pnueli et al 1998;Nakagawa et al 2002;Foucher et al 2003;Guo et al 2006;Danilevskaya et al 2008;Ruonala et al 2008;Mimida et al 2009), the function of ID1/Ehd2 homologs in flowering may be monocot-specific. No direct ID1/Ehd2 ortholog exists in the A. thaliana genome, and phylogenetic analyses indicate the INDETERMINATE gene family independently diversified in the monocot and eudicot lineages (Colasanti et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Contributions of Flowering Time Genes to Sunflower Domestication and Improvement

et al. 2011

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Determining the identity and distribution of molecular changes leading to the evolution of modern crop species provides major insights into the timing and nature of historical forces involved in rapid phenotypic evolution. In this study, we employed an integrated candidate gene strategy to identify loci involved in the evolution of flowering time during early domestication and modern improvement of the sunflower (Helianthus annuus). Sunflower homologs of many genes with known functions in flowering time were isolated and cataloged. Then, colocalization with previously mapped quantitative trait loci (QTLs), expression, or protein sequence differences between wild and domesticated sunflower, and molecular evolutionary signatures of selective sweeps were applied as step-wise criteria for narrowing down an original pool of 30 candidates. This process led to the discovery that five paralogs in the FLOWERING LOCUS T/TERMINAL FLOWER 1 gene family experienced selective sweeps during the evolution of cultivated sunflower and may be the causal loci underlying flowering time QTLs. Our findings suggest that gene duplication fosters evolutionary innovation and that natural variation in both coding and regulatory sequences of these paralogs responded to a complex history of artificial selection on flowering time during the evolution of cultivated sunflower.

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Section: Discussionmentioning

confidence: 99%

Contributions of Flowering Time Genes to Sunflower Domestication and Improvement

et al. 2011

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“…A poplar (P. tremula ϫ tremuloides) reciprocal grafting experiment with WT and pBpCRE1::AtCKX2 line 7 was done essentially as described elsewhere (37). Details are provided in SI Materials and Methods.…”

Section: Methodsmentioning

confidence: 99%

Cytokinin signaling regulates cambial development in poplar

Nieminen

Immanen²,

Laxell³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

254

208

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Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula ؋ tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXI-DASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.cambial activity ͉ cambium ͉ secondary development ͉ Populus ͉ CYTOKININ OXIDASE

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“…For example, in tomato, where flowering is not responsive to photoperiod, FT and TFL1 homologs interact to regulate growth and determinacy across several developmental processes (Shalit et al, 2009), and in poplar (Populus spp), FT and TFL1 homologs also have a role in the induction of dormancy (Bö hlenius et al, 2006;Ruonala et al, 2008;Mohamed et al, 2010). Future isolation of FTb2 mutants will clearly be an important test of this possibility in pea and will clarify other aspects of FTb2 function, including its regulatory relationship with FTa1 and FTc and its interaction with TFL1 homologs.…”

Section: Two Distinct Mobile Flowering Signals In Peamentioning

confidence: 99%

The PeaGIGASGene Is aFLOWERING LOCUS THomolog Necessary for Graft-Transmissible Specification of Flowering but Not for Responsiveness to Photoperiod

et al. 2011

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Garden pea (Pisum sativum) was prominent in early studies investigating the genetic control of flowering and the role of mobile flowering signals. In view of recent evidence that genes in the FLOWERING LOCUS T (FT) family play an important role in generating mobile flowering signals, we isolated the FT gene family in pea and examined the regulation and function of its members. Comparison with Medicago truncatula and soybean (Glycine max) provides evidence of three ancient subclades (FTa, FTb, and FTc) likely to be common to most crop and model legumes. Pea FT genes show distinctly different expression patterns with respect to developmental timing, tissue specificity, and response to photoperiod and differ in their activity in transgenic Arabidopsis thaliana, suggesting they may have different functions. We show that the pea FTa1 gene corresponds to the GIGAS locus, which is essential for flowering under long-day conditions and promotes flowering under short-day conditions but is not required for photoperiod responsiveness. Grafting, expression, and double mutant analyses show that GIGAS/FTa1 regulates a mobile flowering stimulus but also provide clear evidence for a second mobile flowering stimulus that is correlated with expression of FTb2 in leaf tissue. These results suggest that induction of flowering by photoperiod in pea results from interactions among several members of a diversified FT family.

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CENL1Expression in the Rib Meristem Affects Stem Elongation and the Transition to Dormancy inPopulus

Cited by 109 publications

References 73 publications

Contributions of Flowering Time Genes to Sunflower Domestication and Improvement

Contributions of Flowering Time Genes to Sunflower Domestication and Improvement

Cytokinin signaling regulates cambial development in poplar

The PeaGIGASGene Is aFLOWERING LOCUS THomolog Necessary for Graft-Transmissible Specification of Flowering but Not for Responsiveness to Photoperiod

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