The botanical and mycological collections at the Royal Botanic Gardens, Kew (Kew), are the world's largest and most diverse. The researchers based at Kew are driven by a scientific mission to further develop the knowledge systems and potential uses of plants and fungi.
Kew’s Dr. Caspar Chater (Senior Research Leader) and his colleagues have recently been involved in a research project that uses Delta-T Devices’ AP4 Porometer to investigate the stomatal responses of two drought-tolerant Soybean lines.
Stomata are the pores on a leaf’s surface that play a key role in gas exchange and water regulation. Stomatal conductance (Gs), which refers to the rate at which stomata open and close, can be leveraged to measure how a plant regulates water and carbon dioxide.
Experiment Overview
Explaining the experiment, Dr Chater states, “We are interested in two novel soybean lines which exhibit a reduced stomatal density phenotype. Studies have shown that plants with reduced stomatal density have increased water use efficiency and drought tolerance.”
“In the context of both climate change and the need to decrease agricultural inputs, research into drought-tolerant crops is essential. Comparing stomatal conductance between low-stomatal density lines and a wildtype control is essential in understanding the physiological consequences of these changes.”
He continues, “We have been using the AP4 Porometer in an important preliminary stage of our soybean research – the aim of which is to answer two questions which will inform future physiological and yield experiments on these plants. Those questions are: Do we see a difference in stomatal conductance between leaves of different maturity? and how many biological replicates (number of plants, and number of leaves) should we grow?”
Image Credit: Delta-T Devices Ltd
Kew’s Use of the AP4 Porometer
Dr Chater explains their method and how they approached their readings, “In our labs at Kew it is standard practice to sample the central trifoliate at the 3rd node when carrying out stomatal conductance measurements. This approach allows for consistent and longitudinal analysis of a specific leaf’s response. The 3rd leaf node can be considered representative of the plant’s physiological state and can provide a snapshot of the overall plant physiology. Older leaves may be undergoing senescence, and younger leaves may be affected by apical dominance.”
Measurement Regime
During the initial experimental stages, Dr Chater’s team took 10 readings, five from a young soybean leaf and five from a mature leaf (Figure 1 below), and sampled three plants from each genotype. The results from the experiment are displayed in Figure 2 below.
Image Credit: Delta-T Devices Ltd
Image Credit: Delta-T Devices Ltd
The Team’s Findings
Mature leaves demonstrate considerably greater stomatal conductance when compared to young leaves. Dr Chater explains, “For all 3 genotypes, we observed that mature leaves exhibit significantly higher stomatal conductance when compared to young leaves. This indicates either an increased stomatal density, or an increased rate of gas exchange and photosynthesis in mature leaves. To answer this question in future experimentation, we will produce stomatal impressions at each timepoint.”
Mature leaves demonstrate considerably greater stomatal conductance when compared to young leaves.
Dr Chater explains, “For all 3 genotypes, we observed that mature leaves exhibit significantly higher stomatal conductance when compared to young leaves. This indicates either an increased stomatal density, or an increased rate of gas exchange and photosynthesis in mature leaves. To answer this question in future experimentation, we will produce stomatal impressions at each timepoint.”
Line 1 demonstrates far greater stomatal conductance when compared to the wild type in younger leaves.
Chater further explains, “In young leaves, Line 1 displayed significantly higher stomatal conductance compared with wildtype plants, suggesting a potentially higher stomatal density. This observation, which indicates increased water loss through transpiration, challenges our expectation for Line 1 to be a candidate as a drought-tolerant soybean. This is inconsistent with the reduced stomatal density phenotype previously observed in Line 1 and Line 2, and thus suggests the phenotype is displayed at a later stage of leaf development. Consequently, we have adjusted our sampling strategy to include leaves at every other node throughout the full experiment.”
Image Credit: Delta-T Devices Ltd
Working with the AP4
In conclusion, Dr Chater concluded that the consistent data that the AP4 Porometer has produced through this preliminary stage of the research has been essential to the success of the project.
Dr Chater said, “The instrument’s effective in-field calibration system has given us high confidence in the readings it has given.”
Image Credit: Delta-T Devices Ltd
This information has been sourced, reviewed and adapted from materials provided by Delta-T Devices Ltd.
For more information on this source, please visit Delta-T Devices Ltd.