植物发育生物学03 (花发育)

Bowman J L et al. Development 2012;139:4095-4098
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ABC genes in Arabidopsis and snapdragon
Arabidopsis A function APETALA1 APETALA2 PISTILLATA APETALA3 AGAMOUS
Organs W1-W4
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The triple mutant resembles the double mutant where B and C function genes are inactive
B C
A
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The SEPALLATA function (SEP1, SEP2 or SEP3) is needed to fulfill both the B function and the C function in Arabidospis.
Dong Z et al. Plant Physiol. 2005;137:1272-1282
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©2005 by American Society of Plant Biologists
Arabidopsis
Stamen Petal Sepal Carpel
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二、调控花器官发育的主要基因
1、同源异形基因与花发育
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EFFECT OF DAY LENGTH ON FLOWERING IN SDPs AND LDPs
Critical day langth
Critical day langth
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1、光周期的感受及传导
THE SITE OF PERCEPTION OF THE PHOTOPERIODIC STIMULUS IS THE LEAF
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PLANTS CAN USE CIRCADIAN RHYTHMS TO MEASURE
Entrained rhythm
Free running rhythm
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THE DISCOVERY OF PHOTOPERIODISM
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根据对光周期的反应，一般将植物分为三类：
1. Short Day Plants (SDPs) flower when day length is shorter than a critical day length. 2. Long day plants (LDPs) flower when the day length is longer than a critical day length. 3. Day-neutral plants (DNPs) are insensitive to day length, Flowering is under internal developmental control.
高等植物花发育及其调控
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第一节：植物花发育分子模型
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一、植物花器官的结构
(B)
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Ontogeny of Gifu flower. a, Gifu flower; bar = 1 mm. b, Dissection of Gifu flower; bar = 1 mm. c to k, SEM showing the floral ontogeny of wild-type L. japonicus.
Vegetative to reproductive transition
Embryonic development
Vegetative development
Reproductive development
© 2013 American Society of Plant Biologists
Multiple inductive pathways control the timing of flowering
Homeosis: ‘Something has been changed into the likeness of something else’ Bateson 1894 Wilhelm Johannsen William Bateson
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Homeotic mutants
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The Arabidopsis research group at Caltech in late 1988.
wt
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Meristem identity genes
• Inflorescence meristem identity genes
– TERMINAL FLOWER 1 (TFL1)/CEN
• Floral meristem identity genes
– LEAFY (LFY)/FLO – APETALA 1 (AP1)
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Phylogeny
Among the ABC MADSbox genes, phylogenetic position and genetic function correlate.
carpel anther
petal sepal
B A C
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Arabidopsis MADSbox genes AGL2, AGL4 and AGL9 group outside of the ABC genes in fylogeny.
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2、植物如何度量日长
光 敏 色 素 ： 吸 收 红 光 - 远 红 光 可 逆 转 换 的 光 受 体 （Phytochrome），PhyA/B/C/D/E。 隐花色素：是指能够感受蓝光和近紫外光区域的光的 一种受体（Cryptochrome)，Cry1/2。
Floral SAM
AP1
LEAFY
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VEGETATIVE1 is essential for development of the compound inflorescence in pea 复总状花序
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第三节：控制植物开花时间的分子机理
Embryonic to vegetative transition
Snapdragon SQUAMOSA
B function
GLOBOSA DEFICIENS PLENA
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C function
MADS domain family of transcription factors
（MICM1、AG、DEFA和SRF）
N MADS I K
C
MADS I K
56 aa, highly conserved, DNA-binding, dimerisation 27-42 aa, considerable sequence variability 70 aa, moderately conserved, keratin related, protein-protein interactions Poor or no sequence conservation A region present in AG and related MADS proteins
A B C
B
A C
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Are they sufficient?
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Conversion of Arabidopsis leaves into petals
Rosette leaves
Cotyledons
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Scanning electron microscopy is used to define organ identity
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Mutant phenotypes in Arabidopsis
B A C
B C
A
C
B A
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Double mutants in Arabidopsis
A B
C
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B C
A
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Double mutants in Arabidopsis
A B
C
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A B C
B A C
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B C
A
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2、同源异形基因的分离
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Quaternary complexes of MADS domain proteins
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The Quartet Model of flower development
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ABC and SEP MADS-box genes are necessary for development of flower organs
Floral SAM
Vegetative SAM
LEAFY
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LEAFY interacts with another floral control gene, APETALA1, to promote the transition from inflorescence to floral meristem.
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5、Unifying principles of flower development
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第二节：启动花发生的分生组织基因
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Meristems and phase transitions
Vegetative meristem
Inflorescence meristem
Flower meristem
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DEMONSTRATION OF LEAF-GENERATED FLORAL STIMULUS (FLORIGEN) IN THE SDP PERILLA
Induced graft donor leaf
Uninduced graft donor leaf
紫苏
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MULTIPLE INDUCTION BY A SINGLE INDUCED LEAF
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Inflorescence meristem identity gene
Inflorescence meristem
CEN
总状花序
Flower meristem
wild type
centroradialis mutant
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LEAFY/FLO controls floral meristem identity
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C N
MADS domain proteins bind DNA as dimers
M1 M2
M1
M2
transcription g e n e
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3、ABC model for organ identity determination in flowers
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THE ABC MODEL FOR FLORAL ORGAN IDENTITY
wt
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LEAFY/FLO controls floral meristem identity
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LEAFY marks the flower meristem
LEAFY RNA is expressed strongly in young flower primordia. LEAFY expression procedes expression of the homeotic genes AGAMOUS and APETALA3, which specify organ identify within the flower
W1 W2 W3 W4
Wild type
Triple mutant
Organs W1-W4
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AGL2, AGL4 and AGL9 were renamed to SEPALLATA1, SEPALLATA2 and SEPALLATA3
W1 W2 W3 W4
Wild type
Triple mutant
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Βιβλιοθήκη Baidu0
4、ABC MADS-box genes are necessary for development of flower organs
A B C
B
A C
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Are they sufficient?
No, expression of ABC genes in leaves does not convert leaves into flower organs.
When mutated, there is no change in flower phenotype.
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In a triple mutant for AGL2, AGL4 and AGL9, all organs in the Arabidopsis flower develop into sepals
• • • • Long-day photoperiod Gibberellins (GA) Vernalization Autonomous pathway
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Induction of flowering
Multiple cues
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一、光周期途径
光周期：一日之内昼夜长度的相对变化。 光周期现象：植物通过感受昼夜长短变化而调控 开花时间的现象。