Search

We present a detailed protocol for measuring extracellular electrical signals in plants using the electrode insertion technique. Using this approach, it is possible to measure long-distance electrical signaling induced by several stimuli, including wounding, current application, irrigation, burning, and others. Additionally, we describe how to associate gas exchange measurements using an infra-red gas analyzer (IRGA, Model Li-6400, Li-Cor) and turgor pressure measurements using a patch clamp pressure probe (ZIM-probe, YARA ZIM-plant Technology) to measure extracellular electrical signals.• The method requires a complete electrical circuit that includes a measuring device (amplifier and voltmeter) and electrodes that provide a contact between the biological material and the equipment.• The infra-red gas analyzer (IRGA), needs to be grounded because it is an important source of noise for electrophysiological measurements.• The ZIM-probe did not cause any interference in electrical signal measure.• Our approach is useful for plant physiologists wishing to implement the technique of measuring electrical signals in plants, in association with other parameters of plant physiology. In addition, our text was written for agricultural and biological scientists who are not electronics specialists.

Information about water relations within crop canopies is needed to improve our understanding of canopy resource distribution and crop productivity. In this study, we examined the dehydration/rehydration kinetics of different organs of wheat plants using ZIM-probes that continuously monitor water status non-destructively. ZIM-probes were clamped to the flag leaf and penultimate leaf of the same stem to monitor changes in turgor pressure, and a novel stem probe was clamped to the peduncle (just below the spike of the same stem) to monitor changes in stem water status. All organs behaved similarly under well-watered conditions, dehydrating and recovering at the same times of day. When water was withheld, the behaviour diverged, with the leaves showing gradual dehydration and incomplete recovery in leaf turgor pressure during the night, but the stem was affected to a lesser extent. Penultimate leaves were the most severely affected, reaching turgor loss point before the flag leaf. Upon rewatering, turgor pressure recovered but the output patch-pressure of the probes (P[sub p]) oscillated at ~30 min periods in all organs of most plants (n = 4). Oscillations in P[sub p] were attributed to oscillations in stomatal opening and appear to only occur above a threshold light intensity. The mechanisms identified in this study will be beneficial for crop productivity because the flag leaf is the source of most photoassimilates in developing grains, so the plant's ability to maintain flag leaf hydration at the expense of older leaves should moderate the impact of drought on yield. Stomatal oscillations could increase water use efficiency as the plant attempts to rehydrate after drought. [ABSTRACT FROM AUTHOR]

Changing global climatic conditions and irrigation water shortages impose water stress conditions on crops. To develop genotypes tolerant to water stress necessitates reliable high-throughput methods to study plant water status and water stress tolerance mechanisms. We report the use of a non-destructive, automated, precise and rapid system for assessing real-time water status in canola plants. Leaf patch clamp pressure probes were clamped on the leaves of four different genotypes of canola grown under field conditions. The data generated diurnal curves characterizing the pattern of turgor pressure maintenance within the leaves. A novel methodology termed 'inverse hysteresis' was developed to measure relative water stress levels in plants using the probe-derived data. The inverse hysteresis data show that genotypes CT12 and CT15 had a higher ability to withstand water stress and were more tolerant to water stress than DS23 and DS35. The chlorophyll content and seed yield were also higher in CT12 and CT15. This novel analytical tool for monitoring water status in canola plants will be of great benefit in other crop species to efficiently screen genotypes for water stress tolerance. [ABSTRACT FROM AUTHOR]

The non-invasive leaf patch clamp pressure (LPCP) probe measures the attenuated pressure of a leaf patch, Pp, in response to an externally applied magnetic force. Pp is inversely coupled with leaf turgor pressure, Pc, i.e. at high Pc values the Pp values are small and at low Pc values the Pp values are high. This relationship between Pc and Pp could also be verified for 2-m tall olive trees under laboratory conditions using the cell turgor pressure probe. When the laboratory plants were subjected to severe water stress (Pc dropped below ca. 50 kPa), Pp curves show reverse diurnal changes, i.e. during the light regime (high transpiration) a minimum Pp value, and during darkness a peak Pp value is recorded. This reversal of the Pp curves was completely reversible. Upon watering, the original diurnal Pp changes were re-established within 2-3 days. Olive trees in the field showed a similar turnover of the shape of the Pp curves upon drought, despite pronounced fluctuations in microclimate. The reversal of the Pp curves is most likely due to accumulation of air in the leaves. This assumption was supported with cross-sections through leaves subjected to prolonged drought. In contrast to well-watered leaves, microscopic inspection of leaves exhibiting inverse diurnal Pp curves revealed large air-filled areas in parenchyma tissue. Significantly larger amounts of air could also be extracted from water-stressed leaves than from well-watered leaves using the cell turgor pressure probe. Furthermore, theoretical analysis of the experimental Pp curves shows that the propagation of pressure through the nearly turgorless leaf must be exclusively dictated by air. Equations are derived that provide valuable information about the water status of olive leaves close to zero Pc. [ABSTRACT FROM AUTHOR]

We present a detailed protocol for measuring extracellular electrical signals in plants using the electrode insertion technique. Using this approach, it is possible to measure long-distance electrical signaling induced by several stimuli, including wounding, current application, irrigation, burning, and others. Additionally, we describe how to associate gas exchange measurements using an infra-red gas analyzer (IRGA, Model Li-6400, Li-Cor) and turgor pressure measurements using a patch clamp pressure probe (ZIM-probe, YARA ZIM-plant Technology) to measure extracellular electrical signals. • The method requires a complete electrical circuit that includes a measuring device (amplifier and voltmeter) and electrodes that provide a contact between the biological material and the equipment. • The infra-red gas analyzer (IRGA), needs to be grounded because it is an important source of noise for electrophysiological measurements. • The ZIM-probe did not cause any interference in electrical signal measure. • Our approach is useful for plant physiologists wishing to implement the technique of measuring electrical signals in plants, in association with other parameters of plant physiology. In addition, our text was written for agricultural and biological scientists who are not electronics specialists., (© 2021 Published by Elsevier B.V.)