Flower development of Lilium longiflorum - The Lilium information ...

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The potential of VIGS in functional genetics of transcription factors In monocot species, despite many cases of significant differences in floral structure, the ABCDE model appears to be applicable, but with reservations (Nagasawa et al., 2003). Monocot genes showing homologous ABCDE functions have already been identified (reviewed by Fornara et al., 2003). Rice and maize are model species for flower development in grasses and the expression pattern of ABCDE genes is helping to clarify the organ homology between flowers from grasses and other species, considering that this topic has been a matter of discussion for a long time. In bulbous species, such as hyacinth (Hyacinthus orientalis), lily (Lilium spp.), narcissus (Narcissus pseudonarcissus), and orchids (Oncidium sp. and Dendrobium sp.), MADS-box genes involved in flower development are also being isolated and functionally characterized (Li et al., 2002; Tzeng and Yang, 2001; Tzeng et al., 2002; Hsu and Yang, 2002; Yu and Goh, 2000). Liliaceae species show an interesting floral aspect with the perianth organs (sepals and petals) evolving into petal-like structures, receiving the designation of “tepals”. This feature led to the proposition of a modified ABCDE model for the Liliaceae family members, with its B function being extended to the first whorl, in order to cope with petal characteristics of this organs (van Tunen et al., 1993). Perspectives for reverse genetics of floral transcription factors based on VIGS Overexpression of genes transcribing hpRNA of several genes involved in flower developmental pathways leads to specific and heritable silencing of the endogenous genes, resulting in null phenotypes in Arabidopsis (Chuang and Meyerowitz, 2000). VIGS of a regulatory flower developmental gene was first accomplished in N. benthamiana with its LEAFY/FLORICAULA orthologue, NFL (Ratcliff et al., 2001), opening avenues for using this system for efficient characterization of floral gene functions. Homeotic transcription factors, including the MADS-box genes involved in the ABCDE model, are perfectly suitable for assessing their function via VIGS, since they can instigate clear null phenotypes. They present a sequence structure conserved throughout evolution, that may permit studies of reverse genetics in heterologous systems, especially in model species in which VIGS is easily manipulated, such as N. benthamiana and, perhaps, rice. Our hypothesis is that a VIGS vector carrying a fragment of a homeotic transcription factor would trigger transient silencing of its endogenous homologue and 110
Chapter 7 induce phenotypes with homeotic transformations, if there is enough sequence identity between the genes involved. Importantly, the sequence structure within members from a gene family can interfere with the proper specificity of silencing, since gene boxes with highly conserved sequences can provoke functional suppression not only of the target gene but also of other members of this family (Ratcliff et al., 2001), as confirmed by Immink et al. (1999) with a crossed cosuppression event between two MADS-box genes in petunia. For optimal results leading to a specific, effective and reliable gene silencing in a heterologous system, the establishment of the level of sequence homology required is pivotal information. It is generally assumed that 85% nucleotide identity would be the lowest limit for triggering the silencing mechanism, however, experimental evidence is being awaited. Although some studies are still necessary to enable the use of VIGS in the functional identification of MADS-box genes in homo- or heterologous systems, the future seems promising and possibly in the near future this field will be open for speedy and easier functional characterization of the many genes from new species that await their function to be discovered or confirmed. Acknowledgements The authors are greatly thankful to Koen Pelgrom, Martin Verbeek and Suzan Gabriels for significant contributions during the course of this work. Anne-Marie Wolters is especially acknowledged for critical reading of the manuscript. This work was supported by the CNPq, an Organ for Science and Technology Development of the Brazilian Government (200851/98-5), and by the Dutch Ministry of Agriculture, Nature Management and Fisheries (DWK 364). REFERENCES Al-Kaff NS, Covey SN, Kreike MM, Page AM, Pinder R, Dale PJ (1998) Transcriptional and post-transcriptional plant gene silencing in response to a pathogen. Science 279: 2113- 2115 Angenent GC, Linthorst HJM, van Belkum AF, Cornelissen BJC, Bol JF (1986) RNA2 of tobacco rattle virus strain TCM encodes an unexpected gene. Nucleic Acids Res 14: 4673- 4682 111
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Flower development of Lilium longif
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Flower development of Lilium longif
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"To the people from Brazil, I dedic
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CONTENTS Chapter 1 Introduction: Li
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Chapter 1 Knowing the mechanisms of
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Chapter 1 protein interactions and
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Chapter 1 functionally active (Pela
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Chapter 1 heterologous systems. Thi
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Chapter 1 Although the festiva natu
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Chapter 1 Kramer EM, Irish VF (2000
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Chapter 1 Winter K-U, Weiser C, Kau
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Chapter 2 Introduction Mechanisms o
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Chapter 2 Lily (Lilium longiflorum
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Chapter 2 7 4 4 17 20 30 13 50 26 3
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Chapter 2 inactive in the perianth
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Chapter 2 Flowers derived from plan
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Chapter 2 LMADS1 from L. longifloru
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Chapter 2 oligo-dT primer. For ampl
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Chapter 2 Clough SJ, Bent AF (1998)
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Chapter 2 Theissen G, Becker A, Ros
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Chapter 3 Introduction Transcriptio
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Chapter 3 The ABCDE model is partic
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Chapter 3 Results and Discussion Is
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Chapter 3 6 23 13 28 22 40 77 52 41
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Chapter 3 A B Figure 4. Phenotype o
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Chapter 3 Nucleic acids isolation a
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Chapter 3 kanamycin. Surviving seed
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Chapter 3 Pelaz S, Gustafson-Brown
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Ascribing genetic function from lil
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+ = aaBB AAbb AaBb (wt) if aa + Z =
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Page 67 and 68: Discussion Ascribing genetic functi
Page 69 and 70: Cloning of LLAG1 into a binary vect
Page 71 and 72: Ascribing genetic function from lil
Page 73 and 74: Ascribing genetic function from lil
Page 75 and 76: Transformation of Lilium via partic
Page 79 and 80: lue spots per explant 2.0 1.8 1.6 1
Page 87 and 88: CHAPTER SIX FLORAL HOMEOTIC MUTANTS
Page 89 and 90: A C B D Chapter 6 Figure 1. Floral
Page 91 and 92: Chapter 6 Arabidopsis, giving the e
Page 93 and 94: as visualised in double flowers. Ch
Page 95 and 96: Chapter 6 1997). Additionally, regi
Page 97 and 98: REFERENCES Chapter 6 Byzova MV, Fra
Page 99 and 100: CHAPTER SEVEN Chapter 7 The potenti
Page 101 and 102: Chapter 7 viral vector transcripts
Page 103 and 104: Chapter 7 Guo and Kemphues, in 1995
Page 105 and 106: Initiation phase Maintenance phase
Page 107 and 108: Genes involved in the plant gene si
Page 109 and 110: Chapter 7 sterility due to flower d
Page 111 and 112: Chapter 7 shows the systematic clas
Page 113 and 114: Chapter 7 In tomato, an alternative
Page 115 and 116: Chapter 7 species, in our case part
Page 117: Chapter 7 functions from monocot ge
Page 121 and 122: Chapter 7 Covey SN, Al-Kaff NS, Lan
Page 123 and 124: Chapter 7 Li QZ, Li XG, Bai SN, Lu
Page 125 and 126: Chapter 7 Tang G, Reinhart BJ, Bart
Page 127 and 128: The ABCDE model for lily EPILOGUE E
Page 129 and 130: Epilogue is an appropriate system a
Page 131 and 132: Epilogue system, such as N. bentham
Page 133 and 134: SUMMARY Summary Lily (Lilium spp.)
Page 135 and 136: Summary the bialaphos resistance ge
Page 137 and 138: SAMENVATTING Samenvatting De lelie
Page 139 and 140: Samenvatting van Arabidopsis thalia
Page 141 and 142: RESUMO Resumo O lírio (Lilium spp.
Page 143 and 144: Resumo selvagem de Arabidopsis supe
Page 145 and 146: ACKNOWLEDGEMENTS Acknowledgements W
Page 147 and 148: Acknowledgements (two great souls);
Page 149 and 150: ABOUT THE AUTHOR About the Author V
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