Distinct roles of electric and hydraulic signals on the reaction of leaf gas exchange upon re-irrigation in Zea mays L

• Published in: Plant, cell and environment cell and environment, 2007, Vol.30 (1), p.79-84
• Main Authors: GRAMS, THORSTEN E.E, KOZIOLEK, CHRISTIANE, LAUTNER, SILKE, MATYSSEK, RAINER, FROMM, JÖRG
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chlorophyll - metabolism; drought stress; Economic plant physiology; electrical signals; Fluorescence; Fundamental and applied biological sciences. Psychology; Gases - metabolism; Metabolism; photosynthesis; Photosynthesis, respiration. Anabolism, catabolism; Plant Leaves - metabolism; Plant physiology and development; root‐shoot communication; stomatal aperture; Water relations, transpiration, stomata; Zea mays; Zea mays - metabolism
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2006.01607.x

The hypothesis that electric and hydraulic long-distance signals modify photosynthesis and stomatal aperture upon re-irrigation in intact drought-stressed plants was examined. Maize plants (Zea mays L.) were exposed to drought conditions by decreasing the soil water content to 40-50% of field capacity. The decrease in water content resulted in a decline in stomatal conductance to 50-60% of the level in well-watered plants. Re-irrigation of the plants initiated both hydraulic and electric signals, followed by a two-phase response of the net CO₂ uptake rate and stomatal conductance of leaves. The transitional first phase (phase 1) is characterized by a rapid decrease in both levels. In the second phase (phase 2), both parameters gradually increase to levels above those of drought-stressed plants. Elimination of either the hydraulic signal by compensatory pressure application to the root system, or of the electric signal by cooling of the leaf blade gave evidence that the two signals (1) propagated independently from each other and (2) triggered the two-phase response in leaf gas exchange. The results provided evidence that the hydraulic signal initiated a hydropassive decrease in stomatal aperture and for the involvement of electric signals in the regulation of photosynthesis of drought-stressed plants.