How Do Plants Grow?

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How Do Plants Grow? Mechanisms Underlying Auxin Action 

The Food and Agriculture Organisation of the United Nations reports that 923 million people worldwide were undernourished in 2007. Just under a quarter of these people were from the Asia‐Pacific region, excluding India and China. Over a quarter of the total were in India (FAO, 2008). Figure 1 shows a world map as we normally see it, based on land area. Figures 2‐4 show the world according to current population distribution, 2050 population and biocapacity. A comparison of these maps paints a picture of the real need for science and agriculture to work together to find better ways of maximising plant growth in order to feed the world. "The world has no alternative to pursuing Sustainable Crop Production Intensification to meet the growing food and feed demand, to alleviate poverty and to protect its natural resources” (Shivaji Pandey, Director of FAO's Plant Production and Protection Division, 2009). Dr Karine David and her team at the University of Auckland are conducting research that helps to understand how plants grow and can be applied to maximising plant growth, contributing to a global solution.


So what will it take to feed the expected 9 billion people who will inhabit the Earth by 2050? This is a complex issue that requires significant scientific knowledge about how to grow food. The issue is centred on energy, and maximising plant growth is critical. All food chains start with plants that convert light energy into chemical energy via photosynthesis. No matter what humans are eating, plants are the starting point for ensuring that there is adequate food for the world’s populations. Plant growth is influenced by genetic factors, environmental factors (water, carbon dioxide, light, nutrients) and hormones within the plant. The Plant Molecular Sciences Lab at the University of Auckland has a large team of scientists who work on understanding of plant growth and collaborate with Plant and Food Research to produce healthier fruit faster with less environmental impact.

This Understanding Gene Expression Seminar includes these resources to assist your learning :

The Challenge Questions

Download the post-seminar challenge questions here


1. The scientific research team developed understanding of the role of Auxin Binding Protein 1 (ABP1) in auxin action using two key biotechnologies:
Transgenic plants
Polymerase Chain Reaction
By creating a transgenic plant where a gene could be turned on or off, the scientific team worked out what that ABP1 gene did in the cell and therefore the plant.
(a) Explain how a transgenic plant is created and what biotechnologies are required to do this.
(b) Describe what mechanism the team used to turn the gene on and off
(c) Explain how PCR technologies are used to measure whether the gene is turned on or off
(d) Why did they also need to make observations of the plant using microscopes and simple measurements of leaves and roots?. Answer Question Here


2. The scientific team found that as well as affecting shoots and leaves, inhibiting Auxin Binding Protein affected the growth of roots. As with the shoots they ran tests with and without ethylene to check that the gene was being turned off.

The photomicrographs below show what the cells looked like in the roots The white arrows show how extensive the meristematic tissue was in the roots. Meristematic tissue is the tissue in plants that can still divide—it is undifferentiated.

We know that when ABP1 was inactive the roots did not grow.
What does the information in the micrographs above tell us about the role of ABP1 in root growth?
Why did having ABP1 turned off stop the roots from growing?

Answer Question Here

The Seminar Multimedia

Watch the seminar video here.

Download the seminar video here.

About the Presenters

Jacquie Bay   |  Karine David  

Links to your school programme

This seminar links to NCEA Level 3 Achievement Standards:

  • AS 90715  Describe the role of DNA in relaton to Gene Expression
  • AS 90716 Describe animal behaviour and plant responses in relation to environmental factors
  • AS 90718 Describe applications of biotechnological techniques

A list of objectives from your Year 13 programme that link into the seminar can be found in the Questions and Disucssion Handout.


Useful Links and References to Online Papers

Food and Agriculture Organisation of the United Nations http://www.fao.org
FAO 2008 The State of Food Insecurity in the World
Plant Molecular Sciences, Auckland, New Zealand—Functional Genomics Texture Group
Plant and Growth Hormones General Tutorial

www.worldmapper.org The World as You have Never Seen it Before
The Complete Works of Charles Darwin On-line - The Movement of Plants, 1880