Artifleck: The Study of Artifactual Responses to Light Flecks with Inappropriate Leaves

Abstract

Methods in sunfleck research commonly employ the use of experimental leaves which were constructed in homogeneous light. These experimental organs may behave unnaturally when they are challenged with fluctuating light. Photosynthetic responses to heterogeneous light and leaf macronutrient relations were determined for Cycas micronesica, Glycine max, and Zea mays leaves that were grown in homogeneous shade, heterogeneous shade, or full sun. The speed of priming where one light fleck increased the photosynthesis during a subsequent light fleck was greatest for the leaves grown in heterogeneous shade. The rate of induction and the ultimate steady-state photosynthesis were greater for the leaves that were grown in heterogeneous shade versus the leaves grown in homogeneous shade. The leaf mass per area, macronutrient concentration, and macronutrient stoichiometry were also influenced by the shade treatments. The amplitude and direction in which the three developmental light treatments influenced the response variables were not universal among the three model species. The results indicate that the historical practice of using experimental leaves which were constructed under homogeneous light to study leaf responses to fluctuating light may produce artifacts that generate dubious interpretations.

Does Fluctuating Light Affect Crop Yield? A Focus on the Dynamic Photosynthesis of Two Soybean Varieties

“… Kromdijk et al (2016) have also shown that the bioengineered acceleration of the recovery from photo-inhibition increases the overall C uptake under fluctuating light in tobacco plants. On the contrary to our second working hypothesis, our experimental data support the idea that dynamic photosynthesis is not really detrimental in green varieties continuously grown under fluctuating light ( Vialet-Chabrand et al, 2017a ; Marler, 2020 ), either in LL or HL ( Figure 1B ), because of possible plants’ dynamic and developmental acclimations to ensure optimum resource use changes in their environment ( Gjindali et al, 2021 ). Li et al (2021) have also shown that photosynthetic different acclimation strategies in wheat can maximizes C assimilation under intermittent high light conditions, and this might also be the case for soybean.…”

“…Contrarily to our initial hypothesis, dynamic photosynthesis seems to be detrimental to overall C uptake at canopy scale only for the chlorophyll deficient variety (MinnGold) in high light conditions, while the green variety (Eiko) seems to be well-adapted to light fluctuations in both low and high light. The fact that fluctuating light has been often reported to decrease C uptake in plants might be due to artifacts in the adopted protocols, which were not able to properly isolate the effects of dynamic light ( Marler, 2020 ). Our experiment did consider these last only and support the idea of new and more promising opportunities for the selection of greater crop photosynthetic efficiency by focusing on the variation in non-steady-state efficiency ( Acevedo-Siaca et al, 2020 ).…”

“…On the contrary, Garcia-Molina and Leister (2020) found a decrease in biomass accumulation after applying the same approach in Arabidopsis. However, most of the abovementioned studies have been performed at the leaf level and/or on plants grown under homogeneous light conditions and then suddenly exposed to fluctuating light ( Marler, 2020 ). Thus, even though they have been fundamental to unravel the molecular mechanisms of photosynthesis and possible strategies to improve it under fluctuating light, they can be hardly scaled up to the entire canopy ( Matsubara, 2018 ).…”