Gas exchange, biomass and non-structural carbohydrates dynamics in vines under combined drought and biotic stress

Abstract

Background Intensity of drought stress and pest attacks is forecasted to increase in the near future posing a serious threat to natural and agricultural ecosystems. Knowledge on potential effects of a combined abiotic-biotic stress on whole-plant physiology is lacking. We monitored the water status and carbon metabolism of a vine rootstock with or without scion subjected to water shortening and/or infestation with the sucking insect phylloxera (Daktulosphaira vitifoliae Fitch). We measured non-structural carbohydrates and biomass of different plant organs to assess the stress-induced responses at the root, stem, and leaf level. Effects of watering on root infestation were also addressed. Results Higher root infestation was observed in drought-stressed plants compared to well-watered. The drought had a significant impact on most of the measured functional traits. Phylloxera further influenced vines water and carbon metabolism and enforced the sink strength of the roots by stimulating photosynthates translocation. The insect induced carbon depletion, reprogramed vine development, while preventing biomass compensation. A synergic effect of biotic-abiotic stress could be detected in several physiological and morphological traits. Conclusions Our results indicate that events of water shortage favour insects’ feeding damage and increase the abundance of root nodosities. Root phylloxera infestation imposes a considerable stress to the plants which might exacerbate the negative effects of drought.

Vine mealybugs disrupt biomass allocation in grapevine

“…Similar to that study, P. ficus caused stress at the leaf-level and reduced the LMA, suggesting that infested grapevines invest less carbon per unit leaf area compared to the uninfested controls and the low-density treatment. Surprisingly, despite the reduced LMA, phylloxerated grapevines did not show a decline in leaf or stem biomass (Savi et al, 2019), while in our study the reduced LMA translated into reduced leaf biomass. Lower biomass allocation to leaves and stems might be a direct consequence of 1) the carbon export towards the P. ficus population, affecting stems at lower infestation levels than leaves, 2) a reallocation of carbohydrates from the stems to the leaves, 3) the redirection of energy to secondary metabolic pathways (defence, repair, signalling, phytohormonal networks) (Timm and Reineke, 2014), or 4) a reduced source availability due to reduced photosynthetic capacity.…”

“…The LMA of grapevine plants in the present study varied between 3.16 and 4.03 mg/cm 2 for the high-density and the control treatment respectively; this is somewhat lower than the LMA of Riesling grapevines, which showed a reduction from 6.1 to 5.6 mg/cm 2 when leaves were infested with phylloxera (Savi et al, 2019). Similar to that study, P. ficus caused stress at the leaf-level and reduced the LMA, suggesting that infested grapevines invest less carbon per unit leaf area compared to the uninfested controls and the low-density treatment.…”

“…Leafhoppers have been shown to affect vegetative growth and photosynthesis of grapevines (Candolfi et al, 1993;Lenz et al, 2009Lenz et al, , 2012. Grape phylloxera, Daktulosphaira vitifoliae Fitch, infestations have been shown to increase defoliation and impact the water and carbon metabolism of grapevines (Botton and Walker, 2009;Savi et al, 2019). Simbiken et al (2015) showed that feeding of scale insects impacts chlorophyll content, leaf drop, and other foliar parameters of grapevines.…”

Candidate genes and SNPs associated with stomatal conductance under drought stress in Vitis

“…The accumulation of these carbohydrates also improved the water stress tolerance in several plants, such as Arabidopsis thaliana [ 74 – 76 ], Medicago sativa [ 77 ], Xerophyta viscosa [ 78 ], Zea mays [ 79 ], Coffea [ 80 ] and Malus domestica [ 81 ]. Grapevines subjected to drought generally show an overall reduction of sugars [ 82 ], probably due to a decreased carbon fixation, except for galactinol and raffinose, which accumulate upon water deficit conditions [ 17 ], suggesting, therefore, that their biosynthesis is strictly related to stress. Furthermore, the concentration of osmolytes like raffinose in guard cells has a role in the regulation of stomata aperture [ 83 , 84 ].…”

Comparative Transcriptome Analysis of Two Root-Feeding Grape Phylloxera (D. vitifoliae) Lineages Feeding on a Rootstock and V. vinifera

“…host plants by imbibing the cellular content retrieved from the nutritive organoid root or histoid leaf galls [ 8 , 9 , 10 ]. Grape phylloxera root infestation manipulates the host vine physiology by modulating the water, mineral, and assimilate transport pathways [ 11 , 12 , 13 ], interfering with host plant defense mechanisms [ 14 , 15 , 16 , 17 , 18 ] and facilitating secondary root infections by phytopathogenic soil-borne microorganisms [ 19 ], altogether leading to host plant damage or even vine death depending on concomitant biotic and abiotic environmental factors [ 20 , 21 ]. Motile grape phylloxera L1 larvae move and probe Vitis spp.…”