37 research outputs found

    Contrasting adaptation of xylem to dehydration in two Vitis vinifera L. sub-species

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    Xylem hydraulic properties of agricultural crop species can be linked to their region of origin, but because crop systems are often irrigated to reach optimum quality and yield, key differences in drought resistance are not often considered. We investigated how hydraulic conductivity and xylem vulnerability to drought-induced cavitation of two grapevine cultivars correspond to their centers of domestication with 'Merlot' (Vitis vinifera subspecies occidentalis) having been domesticated in a temperate forest region, and 'Thompson Seedless' (Vitis vinifera subspecies orientalis) domesticated in a semi-arid region. We used anatomical measurements and xylem vulnerability curves to evaluate hydraulic traits and drought resistance. Our results showed that 'Thompson Seedless' was significantly more vulnerable to drought-induced cavitation than 'Merlot'. Bench dehydration produced significantly different estimations of xylem vulnerability to cavitation in each cultivar. This result was consistent with anatomical measurement, with 'Thompson Seedless' stems having greater maximum stem-specific hydraulic conductivity, more vessels, higher vessel density and a greater lumen fraction than 'Merlot'. The relatively large amount of xylem vessels and lumen area in 'Thompson Seedless' is consistent with domestication in a semi-arid habitat where a greater number and size diversity of xylem vessels would be needed to transport water and meet evaporative demand as opposed to cultivars that were domesticated in temperate forest regions like 'Merlot'. These differences appear to expose 'Thompson Seedless' to high xylem vulnerability to cavitation

    Assessment of Pierce’s disease susceptibility inVitisviniferacultivars with different pedigrees

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    Pierce's disease (PD) of grapevine is caused by the bacterium Xylella fastidiosa. In this study, an integrated approach was applied to assess PD susceptibility among different Vitis vinifera cultivars that incorporated disease severity, bacterial pathoge

    Preclinical radiotherapy at the Australian Synchrotron's Imaging and Medical Beamline: Instrumentation, dosimetry and a small-animal feasibility study

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    Therapeutic applications of synchrotron X-rays such as microbeam (MRT) and minibeam (MBRT) radiation therapy promise significant advantages over conventional clinical techniques for some diseases if successfully transferred to clinical practice. Preclinical studies show clear evidence that a number of normal tissues in animal models display a tolerance to much higher doses from MRT compared with conventional radiotherapy. However, a wide spread in the parameters studied makes it difficult to make any conclusions about the associated tumour control or normal tissue complication probabilities. To facilitate more systematic and reproducible preclinical synchrotron radiotherapy studies, a dedicated preclinical station including small-animal irradiation stage was designed and installed at the Imaging and Medical Beamline (IMBL) at the Australian Synchrotron. The stage was characterized in terms of the accuracy and reliability of the vertical scanning speed, as this is the key variable in dose delivery. The measured speed was found to be within 1% of the nominal speed for the range of speeds measured by an interferometer. Furthermore, dose measurements confirm the expected relationship between speed and dose and show that the measured dose is independent of the scan direction. Important dosimetric parameters such as peak dose, valley dose, the collimator output factor and peak-to-valley dose ratio are presented for 5mm × 5mm, 10mm × 10mm and 20mm × 20mm field sizes. Finally, a feasibility study on three glioma-bearing rats was performed. MRT and MBRT doses were prescribed to achieve an average dose of 65Gy in the target, and magnetic resonance imaging follow-up was performed at various time points after irradiation to follow the tumour volume. Although it is impossible to draw conclusions on the different treatments with such a small number of animals, the feasibility of end-to-end preclinical synchrotron radiotherapy studie

    Monitoring translocations by M-FISH and three-color FISH painting techniques: A study of two radiotherapy patients

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    Purpose: To compare translocation rate using either M-FISH or FISH-3 in two patients treated for head and neck cancer, with a view to retrospective dosimetry. Materials and methods: Translocation analysis was performed on peripheral blood lymphocyte cultures from blood samples taken at different times during the radiotherapy (0 Gy, 12 Gy and 50 Gy) and a few months after the end of the treatment (follow-up). Results: Estimated translocation yield varied according to the FISH technique used. At 50 Gy and follow-up points, the translocation yields were higher with FISH-3 than with M-FISH. This difference can be attributed to three events. First, an increase in complex aberrations was observed for 50 Gy and follow-up points compared with 0 Gy and 12 Gy points. Second, at the end of treatment for patient A, involvement of chromosomes 2, 4, 12 in translocations was less than expected according to the Lucas formula. Third, a clone bearing a translocation involving a FISH-3 painted chromosome was detected. Conclusions: More translocations were detected with M-FISH than with FISH-3, and so M-FISH is expected to improve the accuracy of chromosome aberration analyses in some situations

    Quantifying the grapevine xylem embolism resistance spectrum to identify varieties and regions at risk in a future dry climate

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    Abstract Maintaining wine production under global warming partly relies on optimizing the choice of plant material for a given viticultural region and developing drought-resistant cultivars. However, progress in these directions is hampered by the lack of understanding of differences in drought resistance among Vitis genotypes. We investigated patterns of xylem embolism vulnerability within and among 30 Vitis species and sub-species (varieties) from different locations and climates, and assessed the risk of drought vulnerability in 329 viticultural regions worldwide. Within a variety, vulnerability to embolism decreased during summer. Among varieties, we have found wide variations in drought resistance of the vascular system in grapevines. This is particularly the case within Vitis vinifera, with varieties distributed across four clusters of embolism vulnerability. Ugni blanc and Chardonnay featured among the most vulnerable, while Pinot noir, Merlot and Cabernet Sauvignon ranked among the most resistant. Regions possibly at greater risk of being vulnerable to drought, such as Poitou–Charentes, France and Marlborough, New Zealand, do not necessarily have arid climates, but rather bear a significant proportion of vulnerable varieties. We demonstrate that grapevine varieties may not respond equally to warmer and drier conditions, and highlight that hydraulic traits are key to improve viticulture suitability under climate change

    Quantifying the grapevine xylem embolism resistance spectrum to identify varieties and regions at risk in a future dry climate

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    International audienceMaintaining wine production under global warming partly relies on optimizing the choice of plant material for a given viticultural region and developing drought-resistant cultivars. However, progress in these directions is hampered by the lack of understanding of differences in drought resistance among Vitis genotypes. We investigated patterns of xylem embolism vulnerability within and among 30 Vitis species and sub-species (varieties) from different locations and climates, and assessed the risk of drought vulnerability in 329 viticultural regions worldwide. Within a variety, vulnerability to embolism decreased during summer. Among varieties, we have found wide variations in drought resistance of the vascular system in grapevines. This is particularly the case within Vitis vinifera, with varieties distributed across four clusters of embolism vulnerability. Ugni blanc and Chardonnay featured among the most vulnerable, while Pinot noir, Merlot and Cabernet Sauvignon ranked among the most resistant. Regions possibly at greater risk of being vulnerable to drought, such as Poitou-Charentes, France and Marlborough, New Zealand, do not necessarily have arid climates, but rather bear a significant proportion of vulnerable varieties. We demonstrate that grapevine varieties may not respond equally to warmer and drier conditions, and highlight that hydraulic traits are key to improve viticulture suitability under climate change
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