Lecture 1: Plant breeding and transformation

Transcription

1 NST PMS 1B Lecture 1: Plant breeding and transformation 1 NST PMS 1B: Origins of modern agriculture Prof. Jim Haseloff (jh295): Supplementary lecture materials at L1. Plant breeding and transformation (i) Crop breeding: Zea mays as an example, hybrid maize and the rise of agribusiness (ii) "Ground Zero" for biotechnology Agrobacterium mediated plant transformation First plant transformation experiments Biotechnology in agriculture L2. Genetics and phenotype (i) Single gene traits (ii) Reporter genes, regulatory networks and multicellularity (iii) Physiology and morphogenesis (iv) Diversity and trait development L3. Plant biotechnology (i) Genome scale DNA engineering and precision breeding (ii) Synthetic Biology (iii) Global challenges (iv) Problems and technical opportunities. Following lectures: CO 2 levels, photosynthesis and carbon capture (Hibberd); Nutrient availability (Davies); Global warming: Drought and water relations (Griffiths); Temperature responses (Tanner) 2

2 Origins of world crops Nikolai Vavilov 3 Human migration and establishment of population centres 4

3 North American megafauna 5 Human migration and mass extinction of fauna 6

4 world Wheat, Barley, Peas, Grapes ~ 13,000 years ago Rice, Soybean ~ 9,000 years ago Sorghum, Millet, Coffee Banana, Coconut Maize, Pumpkin, Bean, Potato ~ 10,000 years ago Geographical origins of global crops 7 Recreation of an Aztec market as seen by first Europeans 8

5 Archaeological maize samples 9 Domestication of maize 10

6 11 12

7 Maize breeding Image from University of California Museum of Paleontology, Understanding Evolution Sculpture of Mexica Goddess Chicomecoatl with Ears of Corn Museum of Anthropology - Mexico City - Mexico 14

8 Examples of some of the 59 native Mexican maize landraces. Photo courtesy of CIMMYT Maize Germplasm Bank 15 Maize diversity spread across South and North America 16

9 Maize domestication was accompanied by modification of many plant traits related to agronomy, growth and yield 17 Major differences between maize and teosinte map to few loci Doebley et al., PNAS (USA) 87: (1990) 18

10 Maize farming in the US Midwest circa Genetic crossing to produce hybrid Maize 20

11 Roswell Garst: marketing and adoption of hybrid maize. Growth of seed companies (like Garst Seed) and increasing use of fertilisers and pesticides. Beginning of modern agriculture and integration of industrialised approaches to food production. 21 a Percent of land planted with hybrid maize Yield increases Year b = Iowa = USA Year of hybrid introduction Grain yields (tons hectare 1 ) of hybrid maize 22

12 Maize is the world s most successful crop 23 Norman Borlaug and the Green Revolution 24 24

13 25 26

14 The Green Revolution 27 Chronology of Research Leading to Modern Plant Biotechnology.Some of the major steps and publications are listed. Ian M. Sussex Plant Cell 2008;20: by American Society of Plant Biologists 28

15 D.I. Pacurar et al. / Physiological and Molecular Plant Pathology 76 (2011) 76e81 Crown gall disease Fig. 1. Crown gall tumor on an oak tree

16 Agrobacteriun tumefaciens is the causal agent of crown gall disease 31 Agrobacterium transfers genes for tumour growth and opine biosynthesis to plant cells 32

17 Agrobacterium tumefaciens exploits a modified bacterial conjugation system in order to transform susceptible plant cells. a Conjugation T4SS Conjugative plasmid or transposon T4SS = Type IV secretion system 33 Fig. 1. Schematic of octopine-type Ti plasmid ptia6 showing locations of genes coding for plasmid maintenance (rep), infection of plant cells (vir region, T-DNA), cell survival in the tumor environment (opine catabolism), and conjugative transfer of the Ti plasmid to recipient agrobacteria (tra and trb). The various contributions of the vir gene products to T- 34

18 Fig. 4. Genetic organization of the A. tumefaciens Ti plasmid-encoded virb and trb operons. The virb genes and some of the known functions of the encoded products are presented at the top. This T4SS is closely related in operon organization and subunit composition to a T4SS encoded by the E. coli conjugative plasmid pkm101. The Trb system is closely related in operon organization and subunit composition to a T4SS encoded by the E. coli conjugative plasmid RP4. Genes encoding protein homologs are identically color-coded

19 Side view I layer Cap Main body Cut-out C C Outer membrane VirB7 and VirB9 VirB10 N O layer N Inner membrane Tilted outer membrane side Tilted inner membrane side Figure 4 Structure of a type IV secretion core complex. The core complex 53 is composed of TraN (a VirB7 homologue), TraO (a VirB9 homologue) and TraF (a VirB10 homologue), which are encoded by the Escherichia coli conjugative plasmid pkm101. This structure was obtained using cryo-electron microscopy and is viewed from the side (upper left panel), tilted towards the outer membrane side (lower left panel) and tilted towards the inner membrane side (lower right panel). The cut-out view (upper right panel) details the proposed transmembrane regions and the localization of the VirB7, VirB9 and VirB10 homologues within the structure. C, carboxy-terminal domain; N, amino-terminal domain. 37 Fig. 1. Schematic of octopine-type Ti plasmid ptia6 showing locations of genes coding for plasmid maintenance (rep), infection of plant cells (vir region, T-DNA), cell survival in the tumor environment (opine catabolism), and conjugative transfer of the Ti plasmid to recipient agrobacteria (tra and trb). The various contributions of the vir gene products to T- 38

20 Agrobacterium transformation of plant cells is mediated by intercellular signalling, attachment, virulence protein catalysed DNA transfer to the nucleus and genome integration. 39 Fig. 1. Schematic of octopine-type Ti plasmid ptia6 showing locations of genes coding for plasmid maintenance (rep), infection of plant cells (vir region, T-DNA), cell survival in the tumor environment (opine catabolism), and conjugative transfer of the Ti plasmid to recipient agrobacteria (tra and trb). The various contributions of the vir gene products to T- 40

21 Removal of the tumour-forming genes, and separation of the virulence functions (Vir genes) on a separate helper plasmid allows simpler manipulation of the T-DNA and genes to be inserted into the plant genome. Fig. 2. Schematic representation of a Ti plasmid (A), and diagrams of a typical binary Disarmed binary plasmids 41 Artificial genes for expression in plants 42

22 Summary of Agrobacterium mediated gene transfer and plant regeneration 43 44

23 Biolistic delivery of DNA 45 46

24 Expansion of the gene pool 47 FIGURE 4 GM plant production around the world ASIA EUROPE NORTH AMERICA ATLANTIC OCEAN AFRICA SOUTH AMERICA INDIAN OCEAN AUSTRALIA % GM Country Arable land used to farm GM plants (Mha) Available arable land (Mha) % GM Myanmar Mexico Spain India Colombia Canada Sudan China Honduras < Paraguay Chile < Pakistan Portugal < South Africa Vietnam < >0.1 Uruguay Czech Republic < >0.1 Bolivia Slovakia < >0.1 Philippines Costa Rica < >0.1 Australia Bangladesh < >0.1 Burkina Faso Romania < >0.1 Country Arable land Available used to farm GM plants (Mha) arable land (Mha) USA 70.9 Brazil 44.2 Argentina Note: Core data values are rounded to one decimal place. Data compiled from James Clive Global Status of Commercialized Biotech/GM Crops: ISAAA Brief No. 51. ISAAA: Ithaca, NY 48

25 Figure 3. Important Historical Milestones in Plant Transformation. Since its beginning in 1977, the pace of crop transformation technology development has not been linear. In recent years, the genome editing revolution begs for crop transformation improvements to enable greater food security. 49 Don t forget: Prof Sir David Baulcombe & Prof Howard Griffiths Present the IB Plant and Microbial Welcome Debate FOOD SECURITY Which will be the most effective strategies for the next generation of crop improvement? Monday 10th October 2016 Refreshments from 17:00, debate starts 17:15, in the Large Lecture Theatre, Department of Plant Sciences 50