Associate Professor Tim O'Hare joined QAAFI’s Centre for Nutrition and Food Sciences in October 2010. He is a Plant Physiologist co-located at UQ Gatton and the Coopers Plains Health and Food Science Precinct in Brisbane. His research aims to increase the nutrient density of fruit, vegetables and nuts through genetic, environmental or agronomic biofortification. His work overlaps with plant biochemistry, molecular biology, consumer science and human health.

He obtained his PhD in 1989 from the University of Queensland, before working for the Queensland Department of Agriculture and Fisheries in fruit and vegetable research in Hamilton (Brisbane), the Atherton Tableland (Tropical North Queensland) and Gatton (Lockyer Valley).

Research Interests

  • Zeaxanthin-biofortified sweetcorn for eye health
    Zeaxanthin is an orange pigment that is selectively accumulated in the human eye (specifically the macula) to protect against blue light oxidation of photoreceptors (macular degeneration). Because we are unable to synthesise zeaxanthin, it must be obtained through our diet or through supplements. Although yellow sweetcorn is a good dietary source of zeaxanthin, the amount of sweetcorn that would be required to give sufficient dosage is in the range of between 4-11 cobs a day. We have subsequently developed a zeaxanthin-biofortified sweetcorn with 10 times the concentration of zeaxanthin, reducing consumption down to less than a single cob as part of a normal meal. Research interests include changes in the zeaxanthin profile of the rest of the corn plant, bioaccessibilty/bioavailability of corn-based zeaxanthin to humans, other corn-based zeaxanthin sources such as popcorn and non-sweet maize.
  • Deep pink high-lycopene tomatoes
    Lycopene is the red pigment in tomatoes, and has been linked to a reduced incidence in prostate cancer, a leading cause of death in men. The concentration of lycopene is able to be manipulated by the combination of several key mutations that either modify the amount of lycopene that is synthesised, or increases the storage capability of this compound in the fruit cells. Unfortunately, high-lycopene tomatoes, which have about 3 times as much lycopene, look similar to standard tomatoes, unless they are cut open. However, introducing another mutation which removes a cloaking pigment in the skin allows the fruit to reveal its deep-pink colour, visually differentiating it from standard tomatoes.
  • Development of super-sweet purple sweetcorn
    Purple sweetcorn currently does not exist, partly because the pathway for the pigment producing purple colouration (anthocyanin) is extremely closely linked to a gene preventing sugar accumulation. We have recently broken this linkage, enabling the development of purple sweetcorn. Initially developed from non-sweet Peruvian purple maize, the development of a purple sweetcorn requires further extensive study in this totally novel crop. Anthocyanins have also been links to a range of health benefits, particularly in relation to cardiovascular disease. Areas of further interest include molecular biology of the anthocyanin pigment pathway, kernel physiology, postharvest pigment development and storage, and bioaccessibility of the anthocyanin pigment in the human body.
  • Understanding the fatty acid profile of macadamia nuts
    Three quarters of the weight of a macadamia kernel consists of oil. This oil largely consists of the mono-unsaturated oils, oleic acid (as in olive oil) and the relatively unique omega-7 oil, palmitoleic acid. Macadamias also contain a small but significant proportion of saturated fat, considered to be detrimental to cardiovascular health. Further reduction of the saturated fat content of macadamia, by increasing their conversion to beneficial mono-unsaturated fats is currently under investigation. Factors including genetics of the wide Australian native germplasm collection, the unique fatty acid pathway, and effect of pollinators are current areas of research interest.
  • High-zeaxanthin orange capsicums for eye health
    Zeaxanthin is an orange pigment that is actively accumulated in the human macula from dietary sources to protect against blue light oxidation of human photoreceptors. Destruction of photoreceptors leads to macular degeneration, the leading form of blindness in Australia. Increasing dietary intake of zeaxanthin is associated with an increase in our macular pigment optical density, which is further linked to slowing the later stages of macular degeneration. Although zeaxanthin is relatively rare in the Western diet, orange capsicums (unlike red or green capsicums) appear to be a particularly good source, with concentrations approaching that of artificial supplement tablets. Research interests include the zeaxanthin pigment diversity across orange capsicums and chillies, the genetic control of zeaxanthin accumulation, and the potential further increase in zeaxanthin concentration.
  • Zinc-biofortification of sweetcorn by foliar sprays
    Zinc is an essential mineral vital to human health. Vegetarian sources of zinc are normally limited to legume crops, such as beans. However, zinc concentrations in other vegetables such as sweetcorn can be increased through foliar zinc sprays, especially during kernel development. Although it may be possible to increase the genetic potential to increase zinc uptake, this can be further augmented, as much as 70%, by direct foliar application. How this occurs is not fully understood, but it appears to bypass the bottlenecks that are present via normal soil uptake.
  • Colour variation in strawberries - the purple strawberry
    Strawberries are generally red in colour, due to a specific anthocyanin pigment called pelargonidin. Colour can vary however across the genetic germplasm, resulting in deeper reds, or even burgundies, that are almost purple. Although anthocyanins have generally been linked to cardiovascular health benefits, different types of anthocyanins may potentially vary not just in colour, but also in their efficacy. Research interest includes the relationship between anthocyanin profile and colour, it distribution between different fruiting and vegetative tissues, and genetic means of how this colour is controlled.