This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

The Key Genes for Horticultural Markets program was established to characterise plant genes with potential to improve horticultural crops and increase Australia’s competitive position in world markets. Targeted traits included the consistency, availability, and quality of fruit and vegetables in the marketplace and enhanced novelty in terms of size, shape, colour, ‘mouth feel’ properties and antioxidant content.

The program was comprised of three interlinked approaches that generated gene-based tools for use in horticultural breeding programs.

Approach 1 focused on a gene, named ARF8, which was central to seed set and to the shape and size of both seedy and seedless fruit. This research identified critical components of reproductive physiology that limited fruit set, and provided important information for the development of new seedless varieties for a range of horticultural crops. Proof-of-concept experiments in the model crop tomato demonstrated that modified forms of the ARF8 gene could be used to enhance seedless fruit production.

In approach 2, novel genes to facilitate the action of the plant growth regulator gibberellic acid and enable the manipulation of stem, leaf, fruit and seed characters were identified. This research identified two groups of candidate genes: auxin related genes that could be used to promote stem and fruit growth and genes that regulated the action of gibberellic acid and enabled seedless fruit production.

The third approach built on the first two and identified genes that modified the important characters of colour, mouth feel and health properties. The main focus was on two related classes of plant chemicals that were involved in the determination and expression of leaf and fruit colour (anthocyanins), and in flavour and mouth feel (tannins). The research characterised a class of genes (known as the PAP genes) that were shown to induce colour formation in leaves, seeds and fruits of test plants. Related work in apple demonstrated that skin colour (green or red) was controlled by an apple PAP gene. Based on this discovery, a gene-based marker was developed that could be used in breeding programs to accurately predict skin colour in apple seedlings many years before flowering occurred.

The crucial next step was to ensure that Australian horticulture benefited from this research by using these tools to improve the efficiency of delivering superior new varieties through major Australian breeding programs.