Super veg
Find out more about the food you eat.
To help plant breeders improve the potatoes and tomatoes we eat we need to understand the background to the qualities (e.g. flavour) we are interested in. Below are some of the qualities investigated by EU-SOL and how genes can affect them.
Genes and nutrition
Many of the chemical pathways that contribute to the process of ripening, including the change of chlorophyll to lycopene in a tomato fruit are at least partly controlled by the quantity of light that the fruit receives. Without sufficient light it will not ripen properly.
Light, in part, stimulates the ripening process in tomatoes.
Photographer: alexharries Copyright: CC
Light falling on the fruit is absorbed and sensed by receptors, which, at certain levels of light, initiate a cascade of chemical pathways. In these pathways each chemical reaction will lead to others in a cascade. In this way one trigger reaction can (though not necessarily will) have significant and far reaching effects. Included in this network of chemical interactions are genes. The expression (or activity) of these genes are controlled by certain chemicals known as ‘transcription regulators’. In turn the products of these genes (enzymes) affect the rate of further chemical reactions. Unravelling the interplay of chemicals and genes in a ripening fruit is a massive challenge but every day we get nearer to a full understanding.
One gene involved in the level of lycopene in a tomato is det1. This gene produces a protein which acts like a brake on chemical pathways stimulated by light. Reducing the amount of this protein that gets made by a genetic modification process called ‘RNAi’ scientists have managed to increase the amount of lycopene in a tomato. In fact they have also managed to increase levels of flavanoids, chlorogenic acid (both antioxidants) and beta-carotene, a chemical necessary for human production of Vitamin A.
The gene det1 is what is often called a master switch that is a gene which affects many chemical pathways. It helps determine a fruit’s whole response to light.
Knowledge of the action of this gene in tomatoes will be useful to any efforts to breed more nutritious tomatoes. But it also increases our general knowledge of ripening in fruit and plants’ response to light; which will be of interest to many different scientists. In fact it was work done on the model plant Arabidopsis which first indicated that det1 is responsible for acting as a brake on a plants’ responses to light.
Arabidopsis is a model plant that has been extensively studied, knowledge learnt from this study can be applied to other plants.
Photographer: david joly Copyright: CC
