Annals of Applied Biology (2013) 162, 335-346

M. Vitali, W. Chitarra, L. Galetto, D. Bosco, C. Marzachì, M.L. Gullino, F. Spanna and C. Lovisolo (2013)
Flavescence dorée phytoplasma deregulates stomatal control of photosynthesis in Vitis vinifera
Annals of Applied Biology 162 (3), 335-346
Abstract: Flavescence dorée (FD) is among the major grapevine diseases causing high management costs; curative methods against FD are unavailable. In FD-infected plants, decrease in photosynthesis is usually recorded, but deregulation in stomatal control of leaf gas exchange during FD infection and recovery is unknown. We measured the seasonal time course of gas exchange rates in two cultivars ('Barbera' and 'Nebbiolo') during the term of 1 year when grapevines experienced a water stress and another with no drought, with difference in gas exchange rates in response to FD infection and recovery as assessed by symptom observation and phytoplasma detection through PCR analysis. Chlorophyll fluorescence was also evaluated at the time of maximum symptom severity in 'Barbera', the cultivar showing the most severe stress response to FD infection, causing the highest damage in vineyards of north-western Italy. In FD-infected plants, net photosynthesis and transpiration gradually decreased during the season, more during the no drought year than during drought. During recovery, healthy (PCR negative) plants infected 2 years before, but not those infected an year before, regained the gas exchange performances to the level as measured before infection. The relationships between stomatal conductance and the residual leaf intercellular CO₂ concentration (c_i) discriminated healthy versus FD-infected and recovered plants; at the same c_i, FD-infected leaves had higher non-photochemical quenching than healthy ones. We conclude that metabolic, not stomatal, leaf gas exchange limitation in FD-infected and recovered grapevines is the basis of plant response to FD disease. In addition, we also suggest that such response is dependent upon water stress, by showing that water stress superimposes on FD infection in terms of stomatal and metabolic non-stomatal limitations to carbon assimilation.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Domenico Bosco, Walter Chitarra, Luciana Galetto, Cristina Marzachi

Research topic(s) for pests/diseases/weeds:
damage/losses/economics

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytoplasma vitis