lecture 15 cytokinins regulators of cell division
DESCRIPTION
Lecture 15 Cytokinins Regulators of cell division. Outline. Discovery & Structure Biosynthesis & Metabolism Biological Roles of Cytokinins Mode of Action. Discovery. G. Haberlandt ( 德国植物学家, 1913) 将打碎的植物 韧皮 组织放在马铃薯块茎 的伤口上,发现伤口附近薄壁细胞分裂。. Conclusion: - PowerPoint PPT PresentationTRANSCRIPT
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Lecture 15 Cytokinins
Regulators of cell division
Discovery & Structure
Biosynthesis & Metabolism
Biological Roles of Cytokinins
Mode of Action
Outline
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Discovery
G. Haberlandt( 德国植物学家, 1913)
将打碎的植物韧皮组织放在马铃薯块茎 的伤口上,发现伤口附近薄壁细胞分裂。
Conclusion: Substance in the phloem could induce division of parenchyma cells( 薄壁细胞 ) of potato.
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Discovery
1954 年, F. Skoog ( USA )等 重复 Haberlandt 工作,结果相同。
验证:向培养基中加生长素结果:细胞体积变大,但不分裂。
结论:促进细胞分裂的物质不是生长素。
假设:某种物质 = 生长素?
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Discovery
F. Skoog 等重新假设
细胞分裂需要合成 DNA ,
那么,促进分裂的物质是 DNA
或与 DNA 代谢产物有关?
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Discovery
Fresh DNA Cell division
Aged herring sperm DNA Cell division
( 鲱鱼 ) Herring
C. Miller (Skoog’s graduate, 1955)
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Discovery
C. Miller (Skoog’s graduate, 1955)
高压灭菌 Cell DivisionFresh DNA
结论:促进细胞分裂的不是 DNA 本身,而是 DNA 的降解产物。
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Discovery
Kinetin from herring sperm DNA (1955)
1N
N
N
H
N
NHO
CH2
N6— 呋喃甲基腺嘌呤(化学名)
2 4
56
78
9
激动素( KT )
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Discovery
1964 年,首次从植物组织分离得到细胞分裂素——玉米素 Zeatin
广泛存在于植物和细菌
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Structure
Natural CKs in plant cell
共同结构
—— 嘌呤
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Structure
Synthesized CK—— 嘌呤类
66 - 苄氨基嘌呤
6 - BA
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Structure
Synthesized CK—— 苯脲类
CPPU: N- ( 2-chloro-4-pyridy)-N’-phenylurea
氯 吡啶 苯脲
应用 果实:葡萄、草莓、西瓜、猕猴桃等 块根 茎类
生物活性比腺嘌呤类的高
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膨大剂使用不当造成西瓜爆裂
CPPU 俗称: KT30 膨大剂 膨大素 大果灵
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Biosynthesis
从头合成:甲瓦龙酸→玉米素
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甲瓦龙酸→ GA12
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酵母丝氨酸 tRNA
异戊烯基腺苷
Biosynthesis
tRNA 降解
虽然 tRNA可降解释放 iP,
但这种方式似乎不能满足植物对 CK的需要。故此途径不是 CK合成的主要途径。 ——武维华(第一版)
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Biosynthesis
Sites
CK from root tip
are transported to shoots
via the xylem.
• Primarily in root tip
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CK produced in young leaves transports in phloem.
G. Haberlandt ( 德国, 1913)
F. Skoog (美国 ,1954 )等证实:韧皮细胞中有促进细胞分裂的物质
Biosynthesis
Sites
• in shoot meristem tissues
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冠瘿组织
Biosynthesis
CK is produced in crown gall.
Sites• in shoot meristem tissues
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Metabolism
CKs in plant cells
Active or Inactive?
Free CK
Bound CK
Active
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Metabolism
Free CK
•被高浓度自由态 CK所诱导•不可逆
细胞分裂素氧化酶
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Bound CKs
N3-G ,有活性
N7-G ,无活性
N9-G ,无活性
N9-Ala
• 嘌呤环上不可逆结合
羽扇豆酸 ( 无活性 )
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葡糖葡糖苷酶可催化其释放出自由态 CK
Bound CKs
• 侧链羟基与单糖结合
CK-O-glucoside ,无活性
CK-O-xyloside( 木糖基 ) ,无活性
因此, CK-O-glucoside可能是 CK 在植物细胞的储存形式。
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Metabolism
植物组织调节活性 CK 浓度途径的多样性
N3-G ,有活性
N7-G ,无活性
N9-G ,无活性
N9-Ala
•不可逆结合 • 侧链羟基与单糖结合
CK-O-G( 无 ) ≒CK +G
CK-O- 木糖 ( 无 )
Free CK: Active Bound CK
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Lecture 15 Cytokinins
Regulators of cell division
Discovery & Structure
Biosynthesis & Metabolism
Biological Roles of Cytokinins
Mode of Action
Outline
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Biological Roles of CK
- Regulation of Cell Division
- Deetiolation 去黄化 - Apical Dominance
- Leaf Senesence ( 衰老 )
- Development of fruit and seed
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•真核细胞周期 由周期素和依赖周期素的蛋白激酶共同调节。 Cyclin Cyclin-Dependent Protein Kinase
CDK-Cyclin
IAA 诱导基因表达
CK 诱导基因表达
Biological Roles of CK
Regulation of Cell Division in vivo
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GAs
调节细胞分裂的激素: IAA, GA, CK
IAA诱导 CDK表达CK诱导 Cyclin表达
•启动细胞从 G1 期进入 S 期
•缩短 G1 期,提前进入 S 期
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Biological Roles of CK
Regulation of Cell Division in vitro
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Biological Roles of CK
Deetiolation ( 去黄化 )
Etiolated seedling 黄化苗
•叶绿体未形成•子叶未打开•顶端弯钩
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• CK promotes Chloroplast development
From Chory et al. 1994
A. Etioplasts in dark
B. Thylakoid formation in dark-grown seedling treated with CK.
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T3 - Incubation for 3 days
•CK promotes cell expansion in cotyledons
光下还是黑暗 CK 都能促进子叶伸展
子叶
in water
子叶面积增大,干重不变
•不涉及质子外流•IAA 和 GA 无此作用
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促进细胞生长的激素
IAA 促进细胞壁伸展
促进新微纤丝沉积
In discussion
IAA 、 GA 、 CK
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Biological Roles of CK
Apical Dominance 顶端优势
CK 与 IAA 相互拮抗: - CK促进侧芽生长,抑制顶芽生长; - IAA促进顶芽生长,抑制侧芽生长。
IAA
CK高
低
低
高
地上部分 CK/IAA 的相对含量调控着顶端优势。
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Biological Roles of CK
Leaf Senescence ( 衰老 )
Ipt: CK 合成基因
CK 与 ABA和乙烯的拮抗作用调节叶片衰老
- CK 延缓衰老
- ABA 和乙烯促进衰老
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Cell division and growth
Accumulation of nutrients
Biological Roles of CK
Development of fruit and seed
氨基异丁酸
黄瓜幼苗黄瓜幼苗
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Lecture 15 Cytokinins
Regulators of cell division
Discovery & Structure
Biosynthesis & Metabolism
Biological Roles of CK
Mode of Action
Outline
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Mode of Action
Learn by yourself
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Pupils played on the lawn in their school.
Christchurch, New Zealand