High Stomatal Conductance in the Tomato Flacca Mutant Allows for Faster Photosynthetic Induction
Kaiser, Elias ; Morales, Alejandro ; Harbinson, Jeremy ; Heuvelink, Ep ; Marcelis, Leo F.M. - \ 2020
Frontiers in Plant Science 11 (2020). - ISSN 1664-462X
abscisic acid - air humidity - CO concentration - dynamic photosynthesis - fluctuating irradiance - stomatal conductance
Due to their slow movement and closure upon shade, partially closed stomata can be a substantial limitation to photosynthesis in variable light intensities. The abscisic acid deficient flacca mutant in tomato (Solanum lycopersicum) displays very high stomatal conductance (gs). We aimed to determine to what extent this substantially increased gs affects the rate of photosynthetic induction. Steady-state and dynamic photosynthesis characteristics were measured in flacca and wildtype leaves, by the use of simultaneous gas exchange and chlorophyll fluorometry. The steady-state response of photosynthesis to CO2, maximum quantum efficiency of photosystem II photochemistry (Fv/Fm), as well as mesophyll conductance to CO2 diffusion were not significantly different between genotypes, suggesting similar photosynthetic biochemistry, photoprotective capacity, and internal CO2 permeability. When leaves adapted to shade (50 µmol m−2 s−1) at 400 µbar CO2 partial pressure and high humidity (7 mbar leaf-to-air vapour pressure deficit, VPD) were exposed to high irradiance (1500 µmol m−2 s−1), photosynthetic induction was faster in flacca compared to wildtype leaves, and this was attributable to high initial gs in flacca (~0.6 mol m−2 s−1): in flacca, the times to reach 50 (t50) and 90% (t90) of full photosynthetic induction were 91 and 46% of wildtype values, respectively. Low humidity (15 mbar VPD) reduced gs and slowed down photosynthetic induction in the wildtype, while no change was observed in flacca; under low humidity, t50 was 63% and t90 was 36% of wildtype levels in flacca. Photosynthetic induction in low CO2 partial pressure (200 µbar) increased gs in the wildtype (but not in flacca), and revealed no differences in the rate of photosynthetic induction between genotypes. Effects of higher gs in flacca were also visible in transients of photosystem II operating efficiency and non-photochemical quenching. Our results show that at ambient CO2 partial pressure, wildtype gs is a substantial limitation to the rate of photosynthetic induction, which flacca overcomes by keeping its stomata open at all times, and it does so at the cost of reduced water use efficiency.
A single locus confers tolerance to continuous light and allows substantial yield increase in tomato
Vélez Ramírez, A.I. ; Ieperen, W. van; Vreugdenhil, D. ; Poppel, P.M.J.A. van; Heuvelink, E. ; Millenaar, F.F. - \ 2014
Nature Communications 5 (2014). - ISSN 2041-1723
differential expression analysis - photosystem-ii - lycopersicon-esculentum - greenhouse tomato - dependent phosphorylation - chlorophyll fluorescence - arabidopsis-thaliana - gene-expression - air humidity - plants
An important constraint for plant biomass production is the natural day length. Artificial light allows for longer photoperiods, but tomato plants develop a detrimental leaf injury when grown under continuous light—a still poorly understood phenomenon discovered in the 1920s. Here, we report a dominant locus on chromosome 7 of wild tomato species that confers continuous light tolerance. Genetic evidence, RNAseq data, silencing experiments and sequence analysis all point to the type III light harvesting ¿chlorophyll a/b binding protein 13 (¿CAB-13) gene as a major factor responsible for the tolerance. In Arabidopsis thaliana, this protein is thought to have a regulatory role balancing light harvesting by photosystems I and II. Introgressing the tolerance into modern tomato hybrid lines, results in up to 20% yield increase, showing that limitations for crop productivity, caused by the adaptation of plants to the terrestrial 24-h day/night cycle, can be overcome.
Can prolonged exposure to low VPD disturb the ABA signalling in stomatal guard cells?
Ali Niaei Fard, S. ; Meeteren, U. van - \ 2013
Journal of Experimental Botany 64 (2013)12. - ISSN 0022-0957 - p. 3551 - 3566.
abscisic-acid signal - drought stress responses - heterotrimeric g-protein - oxygen species production - anion channel slac1 - in-vitro culture - vicia-faba l - s-type anion - hydrogen-peroxide - air humidity
The response of stomata to many environmental factors is well documented. Multiple signalling pathways for abscisic acid (ABA)-induced stomatal closure have been proposed over the last decades. However, it seems that exposure of a leaf for a long time (several days) to some environmental conditions generates a sort of memory in the guard cells that results in the loss of suitable responses of the stomata to closing stimuli, such as desiccation and ABA. In this review paper we discuss changes in the normal pattern of signal transduction that could account for disruption of guard cell signalling after long-term exposure to some environmental conditions, with special emphasis on long-term low vapour pressure deficit (VPD).
Temperature integration and process-based humidity control in chrysanthemum
Körner, O. ; Challa, H. - \ 2004
Computers and Electronics in Agriculture 43 (2004)1. - ISSN 0168-1699 - p. 1 - 22.
grandiflorum ramat. kitamura - dendranthema x grandiflorum - greenhouse climate - air humidity - growth - morifolium - model - microclimate - irradiance - quality
Simulations in the authors’ previous studies have shown that a modified temperature integration regime with a 6-day averaging period and increased set-point flexibility was able to reduce annual energy consumption by up to 9% as compared to a regular temperature integration regime. The commonly applied fixed set-point for relative humidity (RH) of 80–85% strongly reduced the potential for energy saving with this regime. Therefore, a more flexible humidity control regime was developed. Simulations indicated that yearly energy consumption could be reduced by 18% as compared to a fixed set-point of 80% RH. By combining the two regimes (temperature integration and humidity control), it was predicted that the energy saving would be even greater. To test this prediction, the combined regimes were applied in two experiments with cut-flower chrysanthemum crops investigating the effect on plant development and growth. Different temperature bandwidths for temperature integration (±2, ±4, ±6 and ±8 °C) were also compared within the joint regime. Crop development was only delayed with the ±8 °C temperature bandwidth. The best regime with respect to plant development, growth, quality and energy saving (±6 °C temperature bandwidth) was compared in a spring experiment with a climate regime used in commercial practice. Energy consumption was 23.5% less with the joint regime. No negative consequences of high humidity were observed, but there was a strong increase in the dry weight of all plant organs. Total plant dry weight was 39% higher than in the regular regime. It can be concluded that energy saving and crop yield increase can be achieved simultaneously, although the dynamic temperature control has to be adjusted to the chrysanthemum developmental stage. The combined dynamic climate regime forms a promising basis for future climate controllers and is easily extendable to other greenhouse crops.
Process-based humidity control regime for greenhouse crops
Korner, O. ; Challa, H. - \ 2003
Computers and Electronics in Agriculture 39 (2003)3. - ISSN 0168-1699 - p. 173 - 192.
glasshouse tomatoes - air humidity - growth - water - microclimate - quality - yield - model
Modern greenhouses in The Netherlands are designed for efficient use of energy. Climate control traditionally aims at optimal crop performance. However, energy saving is a major issue for the development of new temperature regimes. Temperature integration (TI) results in fluctuating and often high relative humidity (RH) levels in modern, highly insulated greenhouses. At high temperature, water vapour pressure deficit (VPD) is usually high and RH consequently low and vice versa. Relatively low fixed set points (80¿85% RH) for air humidity as is common practice, may strongly influence the efficiency of TI, because heating and/or ventilation actions are required to control humidity rather than temperature. This requires much energy. Fluctuating RH may affect crop performance in several ways. Too low VPD may reduce growth due to low transpiration and associated physiological disorders. Water vapour pressure above the dew point leads to condensation on the relative cooler plant tissue and this may give rise to diseases. High VPD, on the other hand, may induce high stomatal resistance and plant water stress (PWS). The aim of the present research was the design of a process-based humidity control concept for a reference cut chrysanthemum crop cultivated with TI. RH control set points were generated as function of underlying processes. Greenhouse performance with this humidity regime and different temperature regimes were simulated with respect to greenhouse climate, energy consumption and photosynthesis. Compared with a fixed 80% RH set point, annual energy consumption of a year-round cut chrysanthemum cultivation could be reduced by 18% for TI with ±2 °C temperature bandwidth as well as for regular temperature control. For separate 12 week cultivations with planting date 1 March, energy saving could increase up to 27 or 23% for TI and regular temperature control, respectively.