Rights: University of Waikato Published 18 March 2011 Download

Dr Sean Bulley, a senior scientist with Plant & Food Research, outlines some of the research focusing on identifying the genes that control vitamin C levels in different varieties of kiwifruit. Kiwifruit varieties show widely varying levels of vitamin C. By identifying the genes that control this variation, it may be possible to apply this knowledge to develop fruit varieties that give higher vitamin C levels.


We’ve managed to discover a lot about the nuts and bolts about how vitamin C is made. Now we need to identify what are the genes controlling the different levels and different varieties of plants. So we need to understand why that is the vitamin C biosynthetic pathway needs to use them in a breeding programme.

In order to try and find these controlling genes, we go to the germ plasm, and the germ plasm is basically the genetic resources that are available in one of our model plants. And we are looking at the individuals with low vitamin C and high vitamin C and asking what’s different about them and vice versa. And the aim is to identify gene candidates and then go through and validate them, make sure that they are actually involved in them.

This is where I’m at this stage is that I have a number of candidate genes, and many of them are unknown, and so I have to go through this whole process of finding out what they are. So it’s very exciting at this stage for me.

The end goal with all this research is to first understand what’s going on, then make rational decisions on how you might change that to what you want. And if we look at kiwifruit, kiwifruit is actually very high in vitamin C, and there’s probably not too much need to increase it any more, but kiwifruit is a wonderful test lab for us in that is has huge variations in the amount of ascorbate. By contrasting these, it gives us a lot of information of what is going on and what can happen and what we could possibly do.

By finding out that information, we can then apply it to other things. An example is apple. Apples are very low in vitamin C, but they are very widely consumed around the world, and it would be great to increase the vitamin C content of apples. You know, if you look at other fruit, bananas are also very low, and so there is all this potential here to try and apply this knowledge that we have learnt from kiwifruit and move it and use it in other crops.