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《植物生物技术与农业：展望21世纪（导读版）》首先向读者介绍了植物生物技术的背景知识和*进展，当今遗传学、基因组学以及其他各种组学的研究状况，以及目前对于遗传工程的*理解。其后的章节将介绍种质资源的改良和保存、植物育种、种子改良，以及孤雌生殖等方面的科技进展，这些内容都与农业和农业生物技术的短期和长期的成功密切相关，同时为读者深入理解后面关于新科技应用前景的章节提供背景知识。后讨论了如何解决知识产权和社会学及食品安全等问题。

《植物生物技术与农业：展望21世纪（导读版）》内容由相关领域专家精心撰写，包括对取得成果的评述，新的植物生物技术方法、产品在促进经典植物科学和农业科学的发展和在作物及其产品改良上的应用前景，植物生物技术和实用农业技术之间彼此配合、相互促进、共同发展。

《植物生物技术与农业：展望21世纪（导读版）》可以作为植物生物学、农业科技、植物分子遗传学、植物育种、食品科学、生物材料科学等领域的研究者的参考用书，以及用作农业、植物、食品和生物技术领域研究生的教学辅助用书。

撰稿人

前言

序

植物生物技术简介2011:概况和在农业上的应用

部分 植物生物技术简介

1 作物驯化的遗传学和基因组学

1.1 植物和驯化

1.1.1 涉及领域

1.1.2 驯化过的作物

1.1.3 杂草

1.1.4 外来入侵物种

1.1.5 模式品种和作物科学

1.2 对驯化过程的了解

1.2.1 早期驯化过程的相关证据

1.2.2 驯化过程的相关基因

1.2.3 驯化和遗传变异

1.2.4 与物种的形成和遗传多样性相关的遗传控制

1.2.5 玉米的驯化过程

1.2.6 豆类作物的驯化过程

1.2.7 产量性状

1.3 驯化过程中产生的杂交种和新多倍体

1.4 驯化后的选择

1.4.1 作物性状的改良

1.5 新的驯化

1.5.1 驯化产生的品种

1.5.2 消亡的作物

1.5.3 树木和生物燃料

1.5.4 适应新需求的遗传学和育种学:生态系统服务

1.6 驯化作物基因组的特性

1.7 超级驯化过程

1.8 致谢

2 鸟瞰:生物技术的新天地

2.1 前言

2.2 新一代DNA测序带动的发展

2.2.1 复合定位,全基因组,特定处理转录图

2.2.2 当前的新一代DNA测序

2.2.3 重视第三代DNA测序

2.3 实验室中的大象:数据处理

2.4 从序列到比较基因组学

2.4.1 转录子图谱

2.5 扩大基因组学工具箱:蛋白质和代谢产物

2.5.1 蛋白质组学进展

2.5.2 代谢组学集锦

2.6 基因组学前景无量:远远超越单纯的基因

2.7 展望未来:基于基因组学的生物技术和农业

2.7.1 从模式植物到农作物,从实验室到大田

2.7.2 从嗜物种到遗传资源

2.7.3 探索“未知的未知”

2.7.4 抗逆工程的重要性

2.8 致谢

3 蛋白质靶标:通过植物生物技术优化蛋白质产物是一项战略规划

3.1 前言:有关如何表达一个产量性状的策略性决定

3.2 途径:

3.2.1 通过内膜系统表达蛋白

3.2.2 在内质网中积累蛋白

3.2.3 在内质网衍生体中积累蛋白

3.2.4 在液泡或有液泡的蛋白体中积累蛋白

3.2.5 在非原质体中积累蛋白

3.2.6 在叶绿体中积累蛋白

3.2.7 在油体表面积累蛋白

3.3 种子介导的表达系统

3.4 叶子系统

3.4.1 稳定与瞬时的叶表达系统

3.4.2 叶子中的蛋白体

3.5 根毛培养

3.5.1 根毛培养体系的优越性

3.5.2 用根毛培养表达重组蛋白

3.5.3 利用生物反应器扩大根毛培养

3.6 小结和结论

4 蛋白质组学及其在植物生物技术中的应用

4.1 前言

4.2 基于质谱分析的蛋白质组学

4.2.1 质谱分析前的样品制备

4.2.2 质谱分析

4.2.3 多肽和蛋白鉴定所用的光谱

4.2.4 定量蛋白质组学

4.2.5 翻译后的修饰

4.3 植物生物技术中的蛋白质组学

4.3.1 作物蛋白质组学目前已取得的成果

4.3.2 进行植物蛋白质组学研究的模式植物拟南芥

4.3.3 农作物和其他相关的经济植物物种

4.3.4 未来的应用和前景展望

5 植物代谢组学:为农业生物技术提供应用和机遇

5.1 前言

5.2 代谢网络:基础知识

5.3 代谢组学:分析技术

5.3.1 分析平台

5.3.2 数据解析

5.4 代谢组学:在农业生物技术中的应用

5.4.1 检测物质平衡的代谢图

5.4.2 植物化学的多样性、表型和分类

5.4.3 园艺作物收获后的品质

5.4.4 逆境反应

5.4.5 功能基因组学

5.4.6 遗传育种和代谢产物数量性状位点

5.5 代谢组学:难题和前景展望

5.5.1 从模式生物到农作物

5.5.2 植物代谢的区化

5.5.3 高精确度的取样

5.5.4 初级和次生代谢带来不同的难题

5.5.5 代谢组的确定

5.5.6 代谢流量测量

5.6 展望

5.7 致谢

6 植物基因组测序:发展同线性图和关联作图的模型

6.1 前言

6.2 基因组测序:

6.2.1 植物基因组测序的策略

6.2.2 高通量测序方法

6.2.3 单分子测序和实时测序

6.2.4 组装和排列程序

6.2.5 基因组浏览程序

6.3 建立同线图的模式

6.3.1 定义

6.3.2 品种内比较

6.3.3 细胞遗传学有助于品种间比较

6.3.4 序列比较

6.3.5 大同线性对小同线性

6.3.6 差异的性质

6.3.7 同线性图的应用

6.3.8 工具和局限性

6.4 关联图

6.4.1 定义

6.4.2 群体大小和构成

6.4.3 标记的种类和密度

6.5 含义

7 根癌农杆菌介导的植物遗传转化

7.1 前言

7.2 遗传转化过程

7.3 植物遗传转化的一种工具:根癌农杆菌

7.4 植物遗传转化的新载体和特定载体

7.5 对植物基因组进行必要的操作以改进和控制遗传转化

7.6 采用新的限制性内切酶和新的筛选方法来控制T-DNA的整合

7.7 结论和前景展望

7.8 致谢

8 基因枪技术和其他非根癌农杆菌介导技术的植物遗传转化

8.1 前言

8.2 其他非根癌农杆菌介导的遗传转化

8.2.1 电泳转染

8.2.2 电穿孔

8.2.3 生物活性颗粒介导的基因转移

8.2.4 显微注射

8.2.5 花粉管通道

8.2.6 碳化硅晶细丝介导的遗传转化

8.3 基因枪转化

8.3.1 基因枪转化的发明

8.3.2 放电粒子的加速

8.3.3 这项“发明”硬件目前的状况

8.4 基因枪转化的优越性

8.5 在农业生物技术中基因枪转化的影响

8.5.1 基因枪转化在农作物中的应用

8.5.2 番木瓜:基因枪转化的一项研究实例

9 植物组织培养和生物技术

9.1 前言

9.2 植物组织培养方法

9.2.1 组培室的基本设置

9.2.2 培养组织的准备

9.2.3 培养基

9.2.4 培养类型

9.2.5 组织培养的环境方面

9.2.6 再生方式

9.3 农业生物技术中常用的几种培养方法

9.3.1 单倍体组织培养

9.3.2 体细胞的胚胎发生

9.3.3 人工种子

9.3.4 离体开花

9.4 前景展望

9.5 致谢

第二部分 育种生物技术

10 体细胞(无性的)程序(单倍体,原生质体,细胞选择)及其应用

10.1 总的介绍

10.2 体细胞的胚胎发生

10.2.1 前言

10.2.2 体细胞胚胎发生的方式

10.2.3 影响体细胞胚胎诱导的因素

10.2.4 植株成熟

10.2.5 植株再生

10.2.6 体细胞胚胎发生过程中的基因表达

10.2.7 大量扩繁和体细胞变异

10.3 单倍体技术

10.3.1 前言

10.3.2 单倍体植株诱导的细胞学基础

10.3.3 影响小孢子胚胎诱导的因素

10.3.4 从子房和胚珠培养诱导单倍体

10.4 原生质体培养和体细胞杂交

10.4.1 前言

10.4.2 体细胞杂种的类型

10.4.3 原生质体融合方法

10.4.4 体细胞杂种挑选

10.4.5 体细胞杂种的鉴定

10.4.6 影响杂种植株再生的因素

10.5 通过试管培养选择技术筛选和培育抗逆植物

10.5.1 前言

10.5.2 通过试管培养选择技术进行筛选和育种的常用方法

10.5.3 生物胁迫的抗性

10.5.4 非生物胁迫的耐受性

10.5.5 通过试管培养选择技术进行筛选和育种的前景展望

10.6 结论和今后的发展方向

10.7 致谢

11 植物育种中的分子标记辅助选择

11.1 背景

11.1.1 分子标记辅助选择的概念

11.1.2 历史回顾

11.2 植物性状、DNA分子标记、技术和应用

11.2.1 控制重要性状的基因

11.2.2 DNA分子标记

11.2.3 现代基因型分型技术

11.2.4 控制重要经济性状基因的鉴定

11.2.5 DNA标记在育种中的应用

11.2.6 育种过程中的分子标记辅助选择

11.3 讨论

11.3.1 实施分子标记辅助选择中的困难和瓶颈

11.3.2 基因遗传变异应用于育种的前景展望

11.4 致谢

12 雄性不育和杂交种种子生产

12.1 前言

12.2 雄配子发育

12.2.1 花粉有丝分裂Ⅰ

12.2.2 花粉有丝分裂Ⅱ

12.3 雄性不育突变体花药发育探讨

12.4 激素影响植物雄性生殖

12.4.1 赤霉素

12.4.2 赤霉素调节茉莉酸生物合成

12.4.3 油菜素类固醇

12.4.4 植物生长素

12.5 农业上的细胞质雄性不育体系

12.5.1 植物线粒体突变

12.5.2 育性恢复

12.5.3 细胞质雄性不育性状的稳定性

12.6 雄性不育性:受代谢和进化的影响

12.6.1 细胞质雄性不育是一种自然造成的状况

12.6.2 细胞器的代谢影响了花粉发育

12.7 雄性不育的遗传工程

12.8 农业上雄性不育的应用

13 鉴别和开发自发遗传变异方面的进展

13.1 作物育种过程中的自发遗传变异:从史前到绿色革命

13.2 驯化获得的作物的遗传限制

13.2.1 在野生祖先中可找到相应的自发遗传变异

13.3 拟南芥中的自发遗传变异

13.4 拟南芥的QTL分析

13.4.1 通过自发变异途径从拟南芥中分离出新基因

13.5 期望:在基因结构和组成方面的种内变异

13.5.1 结构基因组的变异:高于预期值吗?

13.6 作物QTL分析和序列变异

13.6.1 玉米中的驯化基因

13.6.2 来自水稻的实例

13.6.3 来自其他禾谷类作物的实例

13.7 分子功能变异的预测:为什么选用模式生物研究这个问题?

13.7.1 来自模式生物候选基因的关键性支持

13.7.2 用模式系统作为参照来鉴定等位基因活性

13.8 简单性状之外,还有:表观遗传学,杂种优势,遗传不相容性以及交换

13.8.1 自发变异间的不相容性

13.8.2 不同有益性状间发生的交换

13.9 扩大工具箱:全基因组关联作图

13.10 通过植物生物技术有效地开发自发变异的途径

14 从表观遗传学到表观基因组学以及它们对植物育种的影响

14.1 表观遗传改变的各种机理以及它们之间的相互作用

14.1.1 前言

14.1.2 表观遗传改变的各种机理以及它们之间的相互作用

14.2 从表观遗传学到表观基因组学

14.2.1 解密表观基因组学:关于规模和复杂性的问题

14.2.2 表观基因组学方法和获得数据的归类

14.2.3 表观基因组学资源

14.2.4 出现在表观基因组学领域里的转移因子

14.2.5 表观基因组学领域数据和资源整合的一个有说服力的实例

14.3 表观遗传表型及它们对植物育种的影响

14.3.1 营养发育过程中的表观控制和环境的作用

14.3.2 开花过程中的表观控制

14.3.3 胚乳发育和亲本印记

14.4 结论和前景展望

14.5 致谢

14.6 缩写

第三部分 植物种质资源

15 从工程学角度来看微繁、真实类型和无菌植物

15.1 前言

15.2 通过茎尖培养进行苗木扩繁

15.2.1 0期:消毒并开始无菌培养

15.2.2 Ⅰ期:开始培养

15.2.3 Ⅱ期:扩繁

15.2.4 Ⅲ期:芽和根的突出和延长

15.2.5 Ⅳ期:适应和硬化

15.3 自动化操作

15.4 能源和光照

15.5 光自养培养

15.6 在液体培养基中微繁

15.7 在微繁的试管培养和试管培养之前阶段,有植物和微生物的相互作用

15.8 用有益微生物进行接种

15.9 通过离体培养技术排除病毒污染

15.10 总结评论

15.11 致谢

16 单性生殖的调控

16.1 前言

16.2 有性生殖过程中胚珠发育概述

16.3 单性生殖过程中胚珠发育概述

16.4 种系专化

16.5 无融合生殖

16.6 大配子形成

16.7 配子专化

16.8 孤雌生殖

16.9 胚乳发育

16.10 染色质修饰和表观遗传调控

16.11 农作物无融合生殖的小结和前景展望

17 种质收集,储存和保护

17.1 前言

17.1.1 保护植物生物多样性的策略

17.1.2 易地保护技术

17.2 生物技术在种质保存中的应用

17.2.1 离体收集

17.2.2 缓慢生长条件下储存

17.2.3 深低温保藏法

17.3 结论

第四部分 控制植物对环境的反应:非生物和生物胁迫

18 加速培育耐盐,耐旱作物的整合基因组学和遗传学

18.1 非生物胁迫对农作物生产的影响

18.2 缺水:一个主要的非生物胁迫因子

18.3 盐碱

18.4 植物对非生物胁迫的反应

18.5 耐盐碱和耐旱育种:“常规方法”

18.5.1 耐盐碱和耐旱的种质资源

18.5.2 植物对非生物胁迫反应的遗传剖析

18.5.3 引进新技术进行抗非生物胁迫育种

18.6 农作物的抗逆工程:转基因途径

18.6.1 渗透调节的有关基因

18.6.2 脱水反应应答因子

18.6.3 NAC类蛋白

18.6.4 离子平衡相关基因

18.6.5 氧化还原作用的调节基因

18.6.6 其他转录因子

18.7 激素和非生物胁迫

18.8 挑战和前景展望

18.9 致谢

19 对温度的分子应答

19.1 前言

19.2 植物对低温的反应

19.2.1 低温感受

19.2.2 低温信号的传导

19.3 植物反应和温度之间的交流

19.3.1 膜是感受温度振荡的触点

19.3.2 温度的变化启动了信号传导

19.4 结论

19.5 致谢

20 用生物技术途径进行植物修复

20.1 前言

20.1.1 不同污染物使用生物技术途径处理结果的概述

20.1.2 有机污染物

20.2 前景展望

20.3 致谢

21 获得对真菌和细菌病原体具有持久抗性的遗传工程植物采用的生物技术策略

21.1 前言

21.2 选择用于转基因表达的靶基因

21.2.1 植物免疫受体介导的病原体识别

21.2.2 诱导植物免疫力的激发子

21.2.3 参与植物免疫力信号网络有关的植物基因

21.2.4 抗微生物基因

21.2.5 瞄准病原体致病力决定因素的基因

21.3 在一个植物体中进行有效的病害控制需要表达多少个转基因?

21.4 转基因应该在何时何地表达?

21.4.1 病原体应答和组织特异的启动子

21.4.2 病原体应答因子和人工合成启动子

21.5 结论和前景展望

21.6 致谢

22 控制植物对环境的应答反应:病毒病

22.1 前言

22.2 植物检疫和检疫隔离的规则

22.3 植物病毒的传播

22.4 通过培养来控制病毒的策略

22.4.1 土传病毒的对策

22.4.2 气传病毒的对策

22.5 昆虫传病毒的对策

22.5.1 来源于病原体的抗性

22.5.2 由RNA介导的抗性

22.6 应用PDR(来源于病原体的抗性)的概念来开发转基因抗病毒的园艺作物

22.6.1 RNA沉默在开发抗病毒植物中的应用

22.6.2 PDR的稳定性和RNA沉默的抑制

22.7 对抗病毒的转基因植物作相关的危险性评估

22.8 结论

23 昆虫、线虫和其他害虫

23.1 前言——抗虫的遗传改良作物

23.1.1 苏云金杆菌(B.thuringiensis)的历史

23.1.2 Cry类蛋白

23.2 已商品化的抗虫作物

23.2.1 Bt玉米

23.2.2 Bt棉花

23.2.3 已停止使用的Bt抗虫作物

23.3 在开发中的Bt抗虫作物

23.3.1 Bt茄子

23.3.2 Bt水稻

23.3.3 其他Bt作物

23.4 Bt的影响

23.4.1 Bt作物的长处

23.4.2 Bt作物引发的关注

23.4.3 改进中的Bt

23.5 豇豆胰蛋白酶抑制剂

23.6 新型杀虫保护作用

23.6.1 VIP基因

23.6.2 微生物来源的毒素

23.6.3 植物来源的毒素

23.6.4 次生代谢物

23.6.5 其他来源的毒素

23.6.6 RNAi

23.7 抗线虫的作物

23.8 复合的杀虫剂

23.9 结论

第五部分 利用生物技术改良农作物的产量性状和品质性状

24 根系结构的生长控制

24.1 根系结构简介

24.2 根系生长的遗传学和发育学

24.2.1 根系组织的常规结构

24.2.2 根系结构改良的可行性

24.2.3 信号

24.2.4 细胞同一性的系统生物学概念

24.3 植物与环境相互作用

24.3.1 根系对环境的感知及其渗出作用

24.3.2 根系与微生物相互作用

24.3.3 根系结构是对养分有效性的反应

24.4 作物根系

24.4.1 根系的类型

24.4.2 胚芽期的和胚芽期后的根系

24.4.3 根系进化的策略和取舍

24.5 研究根系结构的途径

24.5.1 定量分析

24.5.2 高通量的测序分析

24.5.3 表型组学

24.6 结论性摘要

25 开花的控制

25.1 前言

25.1.1 从植物的角度来看

25.1.2 从种植者的角度来看

25.2 蛋白质控制着开花的时间

25.2.1 成花激素和开花遗传控制位点T(FT)

25.2.2 调控FT的转录因子

25.2.3 FT相对应的蛋白质或FT下游的蛋白质

25.3 影响开花时间的蛋白质的加工过程

25.3.1 组蛋白的修饰

25.3.2 赤霉素

25.3.3 miRNAs(单链小分子RNA)

25.3.4 昼夜节律钟

25.3.5 调控蛋白水解

25.3.6 糖类

25.4 开花时间由发育决定

25.4.1 幼年期

25.4.2 季节性

25.4.3 生殖周期和交替结实

25.5 摘要

25.6 致谢

26 果实的发育和成熟:从分子水平来看

26.1 果实分类

26.2 果实发育

26.2.1 果实的外形、大小和群集

26.3 果实的成熟

26.3.1 成熟突变

26.3.2 营养突变

26.3.3 保存期限突变

26.4 乙烯和水果成熟?

26.4.1 乙烯的生物合成

26.4.2 乙烯的感知和信号传导

26.4.3 对乙烯生物合成的遗传干预和感知

26.5 水果质地

26.5.1 使细胞壁解聚的酶类

26.5.2 扩展蛋白

26.5.3 蛋白糖基化

26.6 前景展望

27 生物技术在新鲜农产品的储藏期间保持采收后品质和减少损耗方面的潜在应用

27.1 前言

27.2 乙烯生物合成或感知及其与新鲜农产品采收后品质的相关性

27.3 叶菜类蔬菜和花卉在采收后的衰老

27.3.1 背景

27.3.2 衰老调控基因

27.3.3 衰老相关激素的合成或感知

27.3.4 抗氧化与衰老

27.3.5 叶绿素的降解

27.4 采收后果实、花和叶的脱落

27.4.1 背景

27.4.2 特有的离区组织的发育

27.4.3 参与脱落控制或介入激素信号传导的调控基因

27.4.4 在脱落的后期实际参与执行细胞分离的基因

27.4.5 乙烯和脱落

27.4.6 脱落的调控操纵

27.5 减少采收后对低温的敏感性

27.5.1 背景

27.5.2 细胞膜结构和细胞冷敏感性

27.5.3 抗氧化和冷敏感或冷耐受

27.5.4 对低温应答反应的调控

27.5.5 在冷胁迫时具有保护功能的分子

27.6 影响收获后的质地和外观品质

27.6.1 背景

27.6.2 软化和细胞壁水解

27.6.3 软化和细胞(组织)的膨胀

27.6.4 组织木质化

27.7 相关的植物和农业生物技术

28 通过工程途径生物合成控制质量性状的低分子量代谢产物(包括必需的营养、促进健康的植物化学物质、挥发物和芳香化合物)

28.1 一般性前言

28.2 基本营养素课程

28.2.1 必需的氨基酸

28.2.2 脂肪酸

28.2.3 维生素类

28.2.4 通过代谢工程改进矿物质的生物可利用率

28.2.5 用多基因转移来改善食物品质

28.3 对具有营养价值的次生代谢物进行工程生产的常用策略

28.3.1 鉴定生物合成基因

28.3.2 转录因子的鉴定和通过整合组学技术进行代谢工程研究

28.3.3 调节细胞器的生长

28.4 改进作为功能性和药用食品的植物的品质

28.4.1 白藜芦醇

28.4.2 花青素类和类黄酮类

28.4.3 儿茶酚类和原花色素类

28.4.4 芝麻素类

28.5 受人们钟爱的代谢产物:植物挥发物

28.5.1 植物挥发性次生代谢产物的生物化学

28.5.2 果实中的芳香化合物

28.5.3 花的气味/香味

28.5.4 植物营养器官中的挥发性有机化合物

28.6 前景

28.7 结论

28.8 致谢

第六部分 用植物作为生产工业产品、药品、生物材料和生物能源的工厂

29 疫苗、抗体和药物蛋白

29.1 前言

29.2 表达技术:细胞核转化

29.3 表达技术:质体转化

29.4 表达技术:瞬时表达系统

29.4.1 “全病毒”载体

29.4.2 磁转染

29.4.3 摆脱危险的新操作法

29.5 植物制成的药物:一种独特的销售主张?

29.6 用植物生产和加工植物特有的糖类

29.7 用植物生产及相关下游议题

29.8 用植物作为表达系统:优点和局限性

29.8.1 细胞核转化

29.8.2 质体转化

29.8.3 瞬时表达

29.9 结论与展望

29.10 致谢

30 用植物作为生产生物塑料和其他新型生物材料的工厂

30.1 前言

30.2 植物生产的主要天然生物聚合物

30.2.1 淀粉

30.2.2 纤维素

30.2.3 橡胶

30.2.4 蛋白质

30.3 由转基因植物生产的新型聚合物

30.3.1 转基因作物在生产生物聚合物中的作用

30.3.2 哪些生物聚合物应该成为转基因作物生产的目标?

30.3.3 哪些种作物应该是目标作物?

30.3.4 纤维状蛋白质

30.3.5 藻青素

30.3.6 多聚-3-羟基脂肪酸酯

30.4 结论与展望

31 来自植物和植物残渣的生物能源

31.1 前言

31.2 生物化学转换

31.2.1 粉碎

31.2.2 预处理

31.2.3 糖化作用

31.2.4 燃料的合成

31.3 热化学转换

31.3.1 高温分解

31.3.2 气化

31.4 结论性摘要

31.5 致谢

第七部分 农业植物生物技术涉及的商业、法律、社会学和公共等方面的问题

32 控制和减缓转基因从农作物流向杂草,流向野生物种,流向其他农作物

32.1 前言:转基因会发生漂流吗?

32.1.1 转基因漂流:流向什么生态系统?

32.1.2 阈值问题

32.1.3 基因控制和/或减缓转基因的流动通常是必要的

32.2 控制转基因的流动的方法

32.2.1 控制目标基因流向细胞质基因组

32.2.2 雄性不育性

32.2.3 使作物成为无性繁殖的

32.2.4 遗传学上使用限制技术又叫“终结者”

32.2.5 启动子由化学药品诱导以利于基因控制

32.2.6 可恢复的功能阻断

32.2.7 可抑制的种子致死技术

32.2.8 反式拼接以防移动

32.2.9 一种遗传学上的分子伴侣可防止转基因杂乱地从小麦流向野生小麦和有亲缘关系的杂草

32.2.10 瞬时的转基因作物

32.3 减缓转基因的漂流

32.3.1 转基因流动减缓的证据

32.3.2 转基因流动减缓的性状将给该作物的野生型近缘种带来不利的影响吗?已有模型表明减缓是不利的

32.4 可在串联的转基因流动减缓结构中使用的一些性状

32.4.1 减缓流动使用的一些形态学性状和基因

32.4.2 转基因流动的化学减缓作用

32.4.3 需要有转基因的减缓流动的一些特殊例子

32.5 结论性摘要

33 生物技术改良植物的知识产权

33.1 前言:在有知识产权保护的农业生物技术中,进行资本化运作的研究和开发

33.2 生物技术改良植物的知识产权保护

33.2.1 国际知识产权保护协定

33.2.2 在植物生物技术中知识产权保护的类型

33.3 农业生物技术的自主经营:这是生物技术改良植物产品从研究思路到商品化的必经之路

33.4 技术转移作为一种手段来促进以生物技术为基础的农业的发展

33.5 结论和未来的需要

33.6 致谢

34 生物技术改良植物的管理问题

34.1 前言

34.2 使一种农业生物技术产品商业化

34.3 监管框架

34.3.1 美国协调框架

34.4 前景

34.4.1 特产作物的管理援助:一种新的模式

34.4.2 标准化

34.5 结论

35 增加粮食生产和减轻贫困的前景:什么样的植物生物技术能够切实履行,什么样的则不能

35.1 前言

35.2 目前的进展

35.3 下一代的发展

35.4 实际运用的障碍

36 在发展中国家中的农作物生物技术

36.1 前言

36.2 发展中国家的农业和食品:需要

36.2.1 供养不断增长的世界人口

36.2.2 营养不良和贫困

36.2.3 科技

36.3 转基因作物目前的状况

36.3.1 地理分布

36.3.2 作物、性状和农民

36.3.3 未来和趋势

36.4 在发展中国家中转基因作物对经济的影响

36.4.1 目前转基因作物的主要影响

36.4.2 农场一级收益的实证研究

36.4.3 转基因作物对贫困和贫富不均的影响

36.4.4 对农民收入的综合影响

36.4.5 宏观层面的影响

36.5 对健康的影响

36.5.1 对安全性的忧虑

36.5.2 生物强化营养的价值

36.5.3 转基因作物生物强化营养的影响

36.5.4 减少与毒素、杀虫剂和抗营养素的接触

36.6 环境

36.7 消费者对转基因食品的认可

36.7.1 不同地域有差别

36.7.2 影响人们接受转基因食品的因素

36.8 监管制度

36.8.1 监管制度的重要性

36.8.2 不同地域有差别

36.8.3 监管的经济学

36.8.4 前方的路

36.9 结论

36.10 致谢

英文索引

彩图

Arie AltmanRobert H.Smith Institute of Plant Sciences and Genetics in Agriculture Hebrew University of Jerusalem Rehovot,IsraelPaul Michael HasegawaBruno C.Moser Distinguished Professor Horticulture and Landscape Architecture Department Purdue University West Lafayette,Indiana,USA

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Genetics and genomics of crop domestication

TABLE OF CONTENTS

Plants and Domestication . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Domesticated crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Invasive species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Model species and crop sciences . . . . . . . . . . . . . . . . . 5

Understanding Domestication Processes . . . . . . . . . . . . . . . 5 Evidence of relatives and processes of early domestication . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Genes of domestication . . . . . . . . . . . . . . . . . . . . . . . . . 6 Genetic variation and domestication . . . . . . . . . . . . . . . 6 Genetic control related to diversity and speciation . . . . 6 Domestication of maize . . . . . . . . . . . . . . . . . . . . . . . . . 7 Domestication of legumes . . . . . . . . . . . . . . . . . . . . . . . 7 Yield traits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Hybrid Species and New Polyploids in Domestication . . . . 8 Post-Domestication Selection . . . . . . . . . . . . . . . . . . . . . . . . 8

Modi.cations in crop characteristics . . . . . . . . . . . . . . . 8

New Domestication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Domesticated species . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Lost crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Trees and biofuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Genetics and breeding for new uses:

Ecosystem services . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Features of Domesticated Genomes . . . . . . . . . . . . . . . . . . 11 Superdomestication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Plants and Domestication

Scope

In this review of genetics and genomics related to plant bio-technology and agriculture, we consider the nature of species that are grownas crops and used by mankind, or otherwise associated with people. We will thenreview aspects of the genetics and genome changes that have beenassociated with cropplants and their domestication from their wild rela-tives before speculating about some of the new opportunities forplant biotechnology to meet the challenges faced in the twenty-.rst century.

Domesticated crops

Domesticated crops are a subset of all plants. Domesticated species, whetherplants oranimals, are considered as those grown by people for economic or otherreasons, and that dif-fer from their closest wild relatives. Domesticated species are reliant on human intervention for theirreproduction, nutri-tion, health, planting, and dispersal. They are harvested with the possibility that a different species will be planted in theirplace. Additional characteristics selected for domesticationinclude size of harvested parts, yield or yield stability, and quality for the use of the product. There are extensive genetic differences inall of these characteristics between individu-als withina species, as well as between species, and multiple characteristics are selected at the time of domestication that make the crop worth growing by farmers for millenniaand now by today’s plant breeders.

. 2012 Elsevier Inc. All rights reserved. DOI: 10.1016/B978-0-12-381466-1.00001-8

Genomic techniques allow the underlying selectionproc-esses to be understood, exploited, and re.ned for cropimprovement. Genomic scientists cannow understand and improve the ef. ciency of exploitation of genes, genetic diversity, and controls present in crop species and their wild relatives. Domestication of plants, including selection of appropriate species and genetic changes, is one of the features of agriculture, but agriculture also requires knowledge beyond suitable genotypes ( Janick, 2005 ), such as the planting, grow-ing, protection, and harvest of the plants and the accurate timing of the various farming operations.

Domesticated plants are grown by the humanpopulation to meet arange of needs that can be summarized by the six “Fs”: food, feed, fuel, . bers (and chemicals), . owers, and pharma-ceuticals. Plants within each of these classes have substan-tial economic impact. Nevertheless, out of 400,000 species of . owering plants, less than 200 have been domesticated as food and feed plants, and just 12 species provide 75% of the food eaten (FAOStat, 2010 ). Very few of the 1000 gymno-sperms, and arguably none of the 15,000 ferns and allies, have been domesticated. New knowledge of genetics and improved techniques of selection, hybridization, or gene transfer have the potential to enable more species to be domesticated.

As well as domesticated crop species, there are many spices, pharmaceutical (and medicinal), horticultural, and garden (“. owers”) plants collected over the last millenniafrom the wild and cultivated ona small-scale. These plants may be genetically similarand as diverse as their wild rela-tives, although one ora small number of genes may have beenselected. Many of the selections require human interventionto survive, often because they are grown outside theirnatu-ral climate range or have abnormalities that are regarded as attractive or useful but reduce plant . tness. However, with the exception of some hybrids, the limited changes mean they are not normally considered as domesticated.

Weeds

Weeds and invasive species are associated with human farm-ing and habitation, although they are not normally considered as domesticated species. There has been limited genomic and genetic work on most of these species with notable excep-tions, inparticularArabidopsis thaliana. Harlanand deWet (1965) de.ned a weed as “a generally unwanted organism that thrives in habitats disturbed by man”; like crops, weed species are extremely diverse, and have different strategies for sur-vival. The effect of weeds onagriculture can be devastating, such as taking nutrition from the crop, making harvest dif. -cult, orreducing the value and quality of the harvest.

Most cropplants will not establish themselves inan envi-ronment where weeds thrive and active intervention is needed to remove competition. Inan extensive study of feral oil seed rape (canola orBrassica napus), Crawley and Brown (1995) showed the very high level of turnover of site occupancy onhighway verges, with local extinction occurring within three years in the absence of new seeding and soil disturbance. Incontrast, weeds can be notably persistent, with; for exam-ple, nettles (Urtica dioica) remaining as markers of sites of

habitationafter hundreds of years innorthern Europe in the absence of further habitation or evidence of crops. There are strong selectionpressures on weeds to bene. t from the human-created habitat at the farm (rather thanplant breeder) level, working with potentially much largerand more widely distributed populations than breeders use. Weeds may mimic the growth forms or seeds of crops and are distributed orgrow along with them. The selection is not applied to yield and quality characteristics, but on survival and popula-tion distribution or expansion, with key genes such as those for seed dormancy or dehiscence (see the sectionGenes of Domestication) potentially selected in the opposite directionfrom the seeds of a crop.

Crops can become weeds. In the Brassicas, for example, the same genotype may be a weed with low yield and poorcharacteristics in one environment, but arobust crop with desirable properties inanother. Volunteers ― plants from aprevious crop on the same land ― are a major challenge ingrowing many . eld crops. They thrive in the crop conditions; the economic damage from these weeds includes acting as reservoirs of crop-speci. c diseases over several seasons inarotation.

Weeds have no harvest value ina crop, reducing yields, and making crop management dif.cult, so farmers have beenimproving their weed control methods since the start of agri-culture. Inadvanced commercial farms weed control is anexpensive part of the agronomy, while for smallholders and subsistence farmers, the continuous laborrequired can be one of the most tedious and demeaning operations for the people, usually womenand children, that are involved. The removal and control of weeds is environmentally costly and involves burning, herbicides, deepplowing and multiple soil cultivations, processes leading to erosion, poor soil moisture conservation, use of large amounts of energy, loss of soil struc-ture, uncontrolled .res, and smoke orpollution. Approaches to weed control have changed continuously over millennia, including use of .re, planting methods, and plowing. As well as the application of agronomic and technological approaches to limit weed spread, breeders must also consider the genetic characteristics of weeds and both the potential of a crop to become a weed and the ease of control of weeds withinanew variety. This work interacts with making models of populationbiology based on the understanding of weed characteristics such as developmental plasticity or seed dormancy.

Invasive species

Another group of plants associated with humans are the invasive species. Along with habitat destruction, invasive species are often considered to be the major threat to bio-diversity worldwide, although Gurevitch and Padilla (2004) pointed out that the cause and effect dataare generally weak. Genetics and genomic research is required to understand the biology of invasives, so that the characteristics that led to uncontrolled displacement of native species can be avoided in the breeding of crops. The requirements of crops includ-ing high partitioning of the plant’s resources to the harvestable product, non-distribution of seeds, and uniformity of growth tend to mean that few domesticated crops have invasive char-acteristics. However, anumber of horticultural plants and those introduced for theirnovelty value have caused problems both inagriculture and the wild in very diverse environments ranging from temperate and tropical, through fresh water, grasslands, and woods to uplands, with the species taking advantage of man-made or man-in. uenced habitats. Examples of invasive species causing signi. cant problems include waterhyacinth (Eichhornia species), Rhododendron, knotweed (Fallopia japonica; Bailey et al., 2007 ), kudzu ( Pueraria spp.), and some ferns (bracken, Pteridium, and Azolla spp.). This is notable since ferns have not been domesticated as crops.

Model species and crop sciences

The diversity in growth forms, reproduction, and uses between the crops means that most crop scientists have focused their work ona single species, while fundamental studies adopted a small number of convenient models. During much of the twentieth century, majorresearch or model spe-cies were crops because they could be easily obtained and grown worldwide, and laboratory protocols, resources, and background information were extensive. Spinach was used for many studies of photosynthesis (e.g., Bassham and Calvin, 1955 ), maize was used for genetics (e.g., McClintock et al., 1981 ), and carrot or tobacco was used for tissue culture. However, for genetics, a fast generation time, small plant size, and the ability to mutagenize populations were majoradvan-tages. Researchers including Kranz, Redei, and Koornneef (e.g., Koornneef et al., 1983 ) established A. thaliana as amodel species in the 1970s, and, because of its small genome size (165 Mbp), Arabidopsis was chosen to be the .rst plant to have its DNA sequenced ( Arabidopsis Genome Initiative, 2000 ). The ease of growing large numbers under controlled conditions and extensive scienti. c resources led to it becom-ing the model forplant research in many laboratories. Rice became the second plant genome to be sequenced, because of its status as one of the world’s two major crops, relatively small genome size of 435 Mbp, and contrasting taxonomic position to Arabidopsis (e.g., Sasaki et al., 2002 ). A majorjusti. cation of these sequencing projects was the suggestionthat the gene content of all plants would be similar, apredic-tion that has largely held true (e.g., Figure 3 inArgout et al., 2011 ), although sequencing led to some surprises including the low total number of genes ― typically 30,000 ― found inall organisms.

With the advent of plant biotechnologies, genomics, math-ematical modeling, and informatics, a large number of tools and results of general nature can be applied across most crops and potential crops (see review by Moose and Mumm, 2008 ). Few crop scientists are now restricted to work onone species and need to exploit approaches and results with other crops and model species. In the genetics and genom-ics . eld there are many parallels between species, making it essential to integrate information. Throughout history and prehistory, humans have been classifying plants, assessing their similarity to use as food or medicines, and avoiding orprocessing toxic plants long before the advent of agriculture.

A succession of techniques including morphological study, crossing, karyotype analysis, DNA sequence comparisons, and now whole genome sequences has established plant relation-ships. The Angiosperm Phylogeny Group (2009) presents arobust, monophyletic phylogeny showing relationships betweenall angiosperms; better understanding of the evolu-tionand phylogeny is important for crop genetics because it shows the most closely related species to use to .nd valuable characteristics.

Understanding Domestication Processes

Evidence of relatives and processes of early domestication

The early processes of domestication can be inferred from examination of wild croprelatives and comparison with exist-ing crops at the morphological, physiological, genetic, or DNA levels. Since farming and domestication is less than 10,000 years old, the archaeological record of the introduction of species into agriculture is rich (Zeder, 2006 ) and documents some aspects of the transition from hunter?gatherer societies to sedentary, farming-based communities. Indeed, the earli-est hunter?gatherer cave paintings date from 32,000 years ago ( Clottes, 2010 ) and in combination with archaeological evidence they show the pre-agricultural period. The domesti-cationprocess happened independently in Southeast Asiaand the Middle East, and soonafter it is found in Asia, Europe, Africa, and the Americas after the retreat of the Pleistocene ice around 12,000 years ago. The domestication of all of the major crops now grown started at about the same time. Pictures of domesticated plants appear in Chinese and Arabic manuscripts up to 2000 years ago ( Paris et al., 2009; Wang et al., 2008; Janick, 2005 ) and can be correlated with archae-ological evidence. With the use of genetic markers to geno-type crops and theirrelatives found in various locations, Salamini et al. (2002) reviewed how genetic markers traced the sites of domestication of cereals to wild populations of grasses in the Near East, and Gross and Olsen (2010) dis-cussed that genetic inferences about geographical origins of crops and the number of independent domestication events are compatible with archaeological data.

Domestication of particular species, and the genetic char-acteristics that make them different from their wild relatives, are also associated with technology used inagriculture socie-ties forplanting, harvesting, threshing, transport, and storage; or long-lasting infrastructure like roads, habitations, and . eld organization; and domestic arrangements including specialized storage and preparationpremises or cooking processes. All of these give additional informationabout the genetic changes from wild species since genotypes must complement the soci-etal practices. In the .rst decade of the twenty-.rst century, genetic and genomic methods enabled examination of the processes of crop domestication, including both the identi. -cation of the genetic basis and its originand the duration of domestication ( Papa et al., 2007 ).

Genes of domestication

The “suite of traits” including seed dispersal, seed dormancy, gigantism in the harvested parts, determinate and synchronized growth, increased harvest index, and change in sweetness orbitterness have been called the “domestication syndrome” afterHammer (1984) . These characteristics make a crop worth growing, and without them the dif. culties of planting, cultiva-tion, and poor harvest make them unrewarding to grow. It is likely that a combination of all of the characteristics must be present together fora species to reach the .rst stage of domes-tication, since most of these traits in some form are present inall domesticated crops. Doebley (2004) and Doebley et al. (2006) reviewed data showing that the differences in cultivars mean that wild progenitors of crops are not easily recognizable. Furthermore, many of these characters are so disadvantageous innon-cultivated situations that the crop will not establish inthe wild ( Crawley and Brown, 1995 ): indehiscent plants will not distribute seeds, whereas anannual plant bearing seeds without dormancy means the species would not survive one bad season.

Further evidence, at least in the cereals, for the importance of the small number of domestication syndrome genes comes from the similarity of changes in several domesticates knownas convergent evolution. Paterson et al. (1995) showed that the same genes and gene pathways were involved in domes-tication of sorghum, rice, and maize. As with other genetic effects, many domestication characteristics are regulated by quantitative trait loci (QTLs) where several genes have effects ( Varshney et al., 2006 ), and transcriptional regulators (ratherthan enzymatic or structural) genes ( Doebley et al., 2006; Martin et al., 2010 ) are often involved.

Genetic variation and domestication

Genetically, any requirement for change of multiple char-acters simultaneously requires eitheran extremely unusual conjunction of genetic mutations orrecombination, or selec-tionand intercrossing to bring characters together over many generations. Clearly, the latter did not happen to any great extent, and genetic and genomic data collected over the last decade do suggest that the diversity of alleles present indomesticated species is lower than in their wild progenitors. This supports the domestication syndrome concept with anumber of characteristics coming togetherat one time. This selection has left a “genomic signature” inall current crops, present thousands of generations later, and the loss of diver-sity compared to the wild species is seenas a “genetic bot-tleneck” ( Doebley, 2004 ). Genetic analysis has shown that many of the gene alleles involved in the domestication syn-drome are present within the gene pool of wild progenitors of crops, although with a low frequency, whereas other traits are apparently new mutations ( Doebley et al., 2006; Huang et al., 2007 ; and see Chapter 13). One important approach to iden-tifying genetic bottlenecks has been comparison of genomic regions neighboring key domestication traits with selectively neutral regions; reduced variation in linked genes suggests that the number of domestication syndrome genes is limited.

The “selective sweep” of the genome ( Clark et al., 2004 ) with directional selection leads to reduced variationand link-age disequilibria ( Anhalt et al., 2008, 2009 ) in the selected regions.

Whereas only a few plants have carried critical traits related to domesticationand have been used for most sub-sequent breeding, the genetic bottleneck or “founder effect” will have reduced the diversity to a small number of gene alleles present in the original selected population (changing gene allele frequencies, eliminating rare alleles, and introduc-ing linkage disequilibrium). It has widely been considered, especially on theoretical grounds, that genetic drift will have furtherreduced the diversity after domestication, given that the selection of a few hundred varieties at most for use inbreeding represents a tiny population size. In many cultivated crops, the level of genetic polymorphism has beenreduced by 60 to 90% inpassing through the genetic bottleneck in culti-vars compared to wild relatives (e.g., Buckler et al., 2001 inmaize). Similarly, rice cultivars may include only 10 to 20% of the diversity present in the wild relatives (Zhu et al., 2007 ). Even with extensive data, it remains challenging to distinguish between the monophyletic and polyphyletic origin of a cropusing molecular markers. As noted by Zhang et al. (2009) , genetic marker data can indicate that the two cultivated rice subspecies, indica and japonica, either evolved independ-ently at different times and sites (Tang et al., 2006 ), or had a monophyletic origin from a common wild rice that subse-quently separated. The diversity restriction is not universal, and the polyphyletic origin of some polyploid crops has prob-ably reduced the bottleneck effect: hexaploid bread wheat (AABBDD genome constitution) has much of the genetic diversity present in its progenitors ( Dubcovsky and Dvorak, 2007 ) and originated recurrently with ancestral D-genomes ( Caldwell et al., 2004 ), even if all the D-genome variation is not represented ( Saeidi et al., 2008 ). Cifuentes et al. (2010) discussed the polyphyletic origin of canola (oilseed rape,

B. napus), which incorporates variation from both the dupli-cation of loci as apolyploid and from several ancestors of the tetraploid cultivars.

In domesticated species, arti. cial selection is the main evo-lutionary force because humans ― farmers and more recently plant breeders ― exert strong selectionpressure compared to that from the environment where a species is established ( Innanand Kim, 2008 ). These authors pointed out that arti-. cial selection may act onalleles that may have beenneutral variants before domestication, and the . xation of these may not remove DNA variation in the surrounding region, depend-ing on the initial frequency of the bene. cial alleles. The number of alleles selected during domestication, the popula-tion sizes, and the number of independent selection events will all affect the intensity of the selection bottleneck.

Genetic control related to diversity and speciation

While geographical isolation of populations stops gene . ow withina species, it is far from the only effect that leads to separation of genotypes. Rieseberg and Blackman (2010) have identi. ed no less than 41 different genes that can lead to reproductive isolation of populations. Genetics related to plant evolutionand isolation is arelatively recent research area, and it is clear that the identi. cation of genes that effect reproductive behavior ― recombinationand interact with effects on fertility, leading to isolationand speciation ( Heslop-Harrison, 2010 ) ― may well show how some of the selective sweeps ( Nielsen et al., 2005 ) have been driven during cropdomestication. Understanding the genetic effects and genes that enable these processes may show how levels of diversity can be maintained within species, whether in wild ecosystems or crops.

Domestication of maize

One of the best understood examples of genetic and genomic changes during domestication comes from maize (Zea mays or corn in the Americas), where the seminal work of Doebley and colleagues ( Doebley et al., 2006; Wright et al., 2005 ) identi. ed the relatively few genes giving rise to the majorphysiological and morphological differences between maize and its closest wild ancestor, teosinte (represented by sev-eral Zea species). Maize, with naked grains in multiple rows and 10 to 100 times more kernels per ear, has a very differ-ent appearance from the branched teosinte, which has grains with a hard seed coat on in. orescences that shatter (disarticu-late) whenripe and carried on multiple stalks. Among the .rst genes identi. ed was teosinte branched 1 (tb1), a transcrip-tional regulator that represses the branching ( Doebley, 2004 ). The gene teosinte glume architecture, tga1 ( Wang et al., 2005 ), is a key single-gene that controls development of the hard coat around the kernel in teosinte. It was identi.ed by high-resolution genetic mapping and map-based cloning. Doust (2007) more generally studied the developmental genetics of grass plant-architecture in genetic, evolutionary, and ecologi-cal contexts. He concluded that exploring the phylogenetic context of the crop grasses suggests new ways to identify and create combinations of morphological traits that will best suit future needs: knowledge of past events shows how future breeding canproceed.

Technically, works such as those previously mentioned have focused on making experimental hybrid populations forgenetically mapping traits that can be identi. ed as domestica-tionrelated. Another group of researchers took a large-scale approach to characterizing how bottlenecks and arti. cial selection have altered genetic variation during domesticationof teosinte to form maize using an unbiased, genome-wide approach. Wang et al. (2005; see also Vigouroux et al., 2005 ) measured single nucleotide polymorphism (SNP) levels in774 genes, and found that the maize inbred lines had only 57% of the variationpresent in the teosinte sample, show-ing evidence for the genetic bottleneck. The genes could be divided into two classes based on the variation signatures at single nucleotides (SNPs): 2?5% of the genes were underselection during domesticationand have been selected with 10 times the intensity of the selectively neutral genes where limited population size alone has reduced the variation. Yamasaki et al. (2005, 2007) sequenced 1095 maize genes from various lines and identi.ed eight genes with no variationbetween inbred maize lines, but with SNP variation in teos-inte; six showed selection throughout the DNA sequence of the gene, while two had signatures of selection in the 3 por-tion of each gene. The functions of the genes, examined afterthe analysis, were “consistent with agronomic selection fornutritional quality, maturity, and productivity,” although most had not been identi. ed previously as being associated with their selection in the crop.

Domestication of legumes

Weeden (2007) examined the domestication of the pea(Pisum sativum), and identi. ed approximately 20 genes orQTLs responsible for the domestication of it. Because of the availability of arange of germplasm from the pea, a time line for the “domestication syndrome” genes could be established. Domestication syndrome characters including indehiscent pods, seed dormancy, gigantism as seed weight, and earliness were seen in the most primitive lines, while dwar.ng, harvest index, photoperiod-sensitivity and white . owering, along with additional seed weight traits, appeared much more recently. This is evidence for the model shown by Gross and Olsen(2010) that domestication is a two-stage process. First, is arapid process that makes the crop worthwhile to grow, includ-ing the domestication syndrome traits that allow a crop to be reliably sown, cultivated, and harvested such as uniform seed germinationand fruit ripening. This is then followed by astage acquiring traits overa longerperiod that improves the crop.

A second .nding of Weeden (2007) showed that, although the phenotypic characters are similar, the genes involved inpea domesticationare different from those in the commonbean, Phaseolus, contrasting with the conclusion showing con-vergent evolution inrice, maize, and sorghum ( Paterson et al., 1995 ). Weeden is optimistic that the presence of multiple genes means that there are several ways for breeders to mod-ify unwanted characters and avoid detrimental effects associ-ated with some otherwise valuable alleles.

Several studies have investigated the genetic diversity and signatures of domestication in soybean, a species with a centerof originand domestication in South China. Guo et al. (2010) proposed a single origin with a moderately severe genetic bot-tleneck during domestication, showing that wild soybeans in South China have an unexploited and valuable gene pool for future breeding. However, Hyten et al. (2006) examined otherpopulations, .nding that there were several rounds of reduction of genetic diversity, following domestication in Asiato produce numerous Asian landraces and introduction of afew genotypes to North America. Notably, they found mod-ern cultivars retained 72% of the sequence diversity present in the Asian landraces but lost 79% of rare alleles, with the major constrictions of diversity coming .rst from the domes-tication event, and secondly from the introduction of a small number of races to North America, while later breeding has had less effect.

Grasses tend to have in. orescences where all individuals . ower togetherand the seeds reach maturity at a similar time,

which is certainly anadvantage foragriculture. However, other wild plants . owerand set seed overa long part of the crop season, making growing and harvest of the ripe seed dif-. cult. In species such as soybean (Glycine max), determinacy of growth through the character of a terminal . ower is anagronomically important trait associated with the domestica-tion. Most soybean cultivars are classi.able into indeterminate and determinate growth habit, whereas G. soja, the wild pro-genitor of soybean, is indeterminate. Tian et al. (2010) took acandidate-gene approach to demonstrate that the determinate growth habit in soybean is controlled by a single gene homolo-gous to TFL1 (terminal . ower) inArabidopsis, which is area-sonable expectation. The genetics of the determinate habit has been known since the 1970s, and mapped more recently. There are, as expected from the known genetic background of soybean, four homologous copies for the determinate genes.

Yield traits

Yield, affected by gigantism and number of harvested units, is normally a quantitative trait with continuous variationand complex heritability. However, analysis and partitioning of yield components, combined with use of well-designed test crosses and large populations, is allowing key regions of the genome ― in some cases now correlated with genes ― to be identi. ed. Genes increasing harvestable yield have beenextensively studied using genetic and genomic approaches. Measurements of yield components, starting long before extensive use of genomic approaches, showed that, for exam-ple, rice yield includes traits such as grainnumberand grainweight, or durationand rate of grain-. lling, and is regulated by multiple QTLs ( Yano, 2001 ). Use of appropriate hybrid populations segregating for yield characteristics, such as bio-mass in forage grasses (ryegrass, Lolium perenne; Anhalt et al., 2009 ) or fruit yield in tomato, Solanum lycopersicoides (Lycopersicon esculentum; Cong et al., 2002 ), is showing that genetic regions on the mapare responsible fora large part of the variation in yield observed. However, oftena large number of genetic regions are identi. ed: in tomato, no less than 28 different QTLs affecting fruit weight have been iden-ti. ed ( Cong et al., 2002 ). QTL analysis is also of potential importance when identifying characters where the same gene affects different traits; this could indicate selection in oppo-site directions is unlikely to succeed (e.g., grainproteinand yield orpalatability/sweetness and insect resistance).

Hybrid Species and New Polyploids in Domestication

Most of the species previously discussed have a genetic struc-ture similar to their wild relatives, such as fertility and repro-duction through seeds. However, a group of crop species have a different genomic constitution from wild species, bringing together copies of genomes from different ancestral species that are not found normally innature. This includes species that have different chromosome numbers from theirrelatives or that are hybrids (see Molnár et al., 2010).

Among early domesticates, the banana is an interesting example. Wild, fertile, diploid bananas have small fruits and large seeds

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奥尔特曼所著的《植物生物技术与农业(展望21世纪导读版)(英文版)》希望能够向读者提供在植物生物技术本身及其成果方面权威的和**的知识、技术方法和进展，内容涵盖从基本的生物学发现到其在农业和其他生命科学中的应用。本书内容由相关领域专家精心撰写，包括对取得成果的评述，新的植物生物技术方法、产品在促进经典植物科学和农业科学的发展和在作物及其产品改良上的应用前景，植物生物技术和实用农业技术之间彼此配合、相互促进。