Interest in wine – and its appreciation – is on the rise to the point where some even argue that “wine is the new golf”: It generates employment, pleasure and many hobby connoisseurs ready to argue the merits of colour and bouquet.
In recent years, considerable attention focussed on flowering and fruiting; few people realise, however, that the ability of the vine to spring to new life after winter is one of its most important properties and of critical interest to the wine maker.
Scientists from the University of Western Australia and the University of Leeds (UK) have teamed up to explore the process responsible for the ability of the vine to develop buds that can not only survive winter but can make the rapid transition to new life once the good weather returns.
Assistant Professor Michael Considine explains: “Many winegrowers agree that this property underpins the successful vine and its sustainability: In nature, the buds burst randomly but the winegrower requires that all the buds burst within a few days of each other, so that the shoots and fruit develop together, which is essential to quality wine production and consistency. “
The bud houses the embryonic flowers, leaves and fruiting bodies. Being able to awaken after a long winter sleep poses many challenges/problems for the embryo (that are poorly understood), including the need to handle oxygen.
“For a bud to make the transition to air can be a rude awakening, because handling oxygen metabolism is tricky for all living organisms,” says Prof Christine Foyer, Dr Considine’s UK partner, who is also a Winthrop Research Professor at UWA. “Oxygen can even be toxic and all organisms that exist in air have developed the ability to use oxygen for respiration while protecting themselves against the potentially harmful side effects of oxygen chemistry.”
Using oxygen can create very reactive molecules called free radicals that have the potential to cause damage. All living cells have not only harnessed oxygen chemistry but also use it to their advantage in defence and the ability to react to environmental change. Quite how this is done is still a mystery and one that continues to engage the interest of researchers worldwide.
“Our research investigates how the bud handles oxygen to make this transition from the dormant state to the vigorously growing vine, with the aim gain an insight in how the bud awakens rapidly and is able to breathe oxygen without harm. This is essential information that can be used to help the grower achieve synchronous bud burst,” adds Dr Considine.
Considine, Foyer and the joint team have already demonstrated that the enclosed bud is hypoxic, that is the level of oxygen is far below the outside air. Crucially, oxygen radicals accumulate within hours of warming following a winter chill. This burst of oxygen radicals quickly disappears, suggesting that the antioxidant defences are activated. More importantly, this finding suggests that the oxygen radicals might be the wake-up signal, and that the antioxidants limit the time that the signal is present.
“We are now exploring this exciting possibility with two PhD students, Mrs Karlia Meitha and Ms Yazhini Velappan (both UWA), and thanks to their contributions and expert supervision across the continents we are making rapid progress and are looking forward to deliver new knowledge that generate practical benefits to winemakers and the viticulture industry.”
