Biology subjects

Tyerman, S.

Publications and source records attributed to Tyerman, S..

3 recordsLinked to original sources

bioRxiv2023

Transpiration Responses to Potential Volatile Signals and Hydraulic Failure in Single Leaves of Vitis vinifera (cv. Shiraz) and Arabidopsis thaliana (Col 0) Utilising Sensitive Liquid Flow and Simultaneous Gas Exchange.

Volatile organic compounds (VOCs) may communicate stress between plants. However little appears to be documented on how such VOCs affect transpiration. Changes in transpiration in response to some VOCs was examined by measurement of flow (Q) at high resolution into detached leaves of Vitis vinifera (cv. Shiraz) and Arabidopsis (Col 0). Sensors recorded arrival and decay of volatiles at the leaf lamina. Moderate xylem tensions were developed in V. vinifera leaves by incorporating a hydraulic resistance in the flow pathway. Simultaneous recording of leaf gas exchange (Assimilation, A, and Transpiration, E) for both V. vinifera and Arabidopsis revealed that for Arabidopsis Q was stochastically restricted by the gas exchange cuvette but not E in the short term. Depending on the applied supply pressure cavitation could be controlled in V. vinifera evident from reduced Q, and leaf wilting. Stomatal closure occurred upon cavitation after a transitory increase in E and A, and after wilting began and was reversed by re-pressurization. VOCs were emitted from leaves corresponding to changes in flow rate, and light to dark transitions but not to cavitation. Volatile methanol but not ethanol or methyl salicylate induced a localised dose-dependent reversible stomatal closure in both V. vinifera and Arabidopsis.

plant biology↗

bioRxiv2021

Expression of a CO2-permeable aquaporin enhances mesophyll conductance in the C4 species Setaria viridis

A fundamental limitation of photosynthetic carbon fixation is the availability of CO4. In C4 plants, primary carboxylation occurs in mesophyll cytosol, and little is known about the role of CO2 diffusion in facilitating C4 photosynthesis. We have examined the expression, localization, and functional role of selected plasma membrane intrinsic aquaporins (PIPs) from Setaria italica (foxtail millet) and discovered that SiPIP2;7 is CO2-permeable. When ectopically expressed in mesophyll cells of S. viridis (green foxtail), SiPIP2;7 was localized to the plasma membrane and caused no marked changes in leaf biochemistry. Gas-exchange and C18O16O discrimination measurements revealed that targeted expression of SiPIP2;7 enhanced the conductance to CO2 diffusion from the intercellular airspace to the mesophyll cytosol. Our results demonstrate that mesophyll conductance limits C4 photosynthesis at low pCO2 and that SiPIP2;7 is a functional CO2 permeable aquaporin that can improve CO2 diffusion at the airspace/mesophyll interface and enhance C4 photosynthesis.

plant biology↗

bioRxiv2017

Hypoxia in the grape berry linked to mesocarp cell death: the role of seed respiration and lenticels on the berry pedicel

Mesocarp cell death (CD) during ripening is common in berries of seeded Vitis vinifera L wine cultivars. We examined if hypoxia within berries is linked to CD. Internal oxygen concentration ([O2]) across the mesocarp was measured in berries from Chardonnay and Shiraz, both seeded, and Ruby Seedless, using an oxygen micro-sensor. Steep [O2] gradients were observed across the skin and [O2] decreased toward the middle of the mesocarp. As ripening progressed the minimum [O2] approached zero in the seeded cultivars and correlated to CD. Seed respiration was a large proportion of total berry respiration early in ripening but did not account for O2 deficiency late in ripening. [O2] increased towards the central axis corresponding to the presence of air spaces visualised using x-ray microCT. These connect to lenticels on the pedicel that were critical for berry O2 uptake as a function of temperature, and when blocked caused anoxia in the berry, ethanol accumulation and CD. Lenticel area on Chardonnay pedicels was higher than that for Shiraz probably accounting for the lower sensitivity of Chardonnay berry CD to high temperatures. The implications of hypoxia in grape berries are discussed in terms of its role in ripening and berry water relations.\n\nHighlightGrape berry internal oxygen concentration is dependent upon lenticels on the pedicel and cultivar differences in lenticels may account for temperature sensitivity of cell death in the mesocarp.

plant biology↗