Adjustment of photosynthetic activity to drought and fluctuating light in wheat

Abstract

Drought is a major cause of losses in crop yield. Under field conditions, plants exposed to drought are usually also experiencing rapid changes in light intensity. Accordingly, plants need to acclimate to both, drought and light stress. Two crucial mechanisms in plant acclimation to changes in light conditions comprise thylakoid protein phosphorylation and dissipation of light energy as heat by non-photochemical quenching (NPQ). Here, we analyzed the acclimation efficacy of two different wheat varieties, by applying fluctuating light for analysis of plants, which had been subjected to a slowly developing drought stress as it usually occurs in the field. This novel approach allowed us to distinguish four drought phases, which are critical for grain yield, and to discover acclimatory responses which are independent of photodamage. In short-term, under fluctuating light, the slowdown of NPQ relaxation adjusts the photosynthetic activity to the reduced metabolic capacity. In long-term, the photosynthetic machinery acquires a drought-specific configuration by changing the PSII-LHCII phosphorylation pattern together with protein stoichiometry. Therefore, the fine-tuning of NPQ relaxation and PSII-LHCII phosphorylation pattern represent promising traits for future crop breeding strategies.

Drought tolerance inBrassica napusis accompanied with enhanced antioxidative protection, photosynthetic and hormonal regulation at seedling stage

“…Our results suggested that drought stress significantly declined plant growth in terms of fresh and dry biomass in all B. napus cultivars. The decrease in plant biomass due to drought stress was higher in the sensitive cultivar (GY605) than in the tolerant cultivars (ZD622, ZS11), which is in line with previous studies on B. napus , B. rapa , B. campestris , and Triticum aestivum (Cha et al, 2020; Grieco et al, 2020; Khanzada et al, 2020; Shawon et al, 2020). Similarly, several previous studies suggested that, under drought stress, the reduction in plant growth attributes is accompanied with a reduction in plants turgor pressure, cell division, cell wall biosynthesis, and cell expansion (B. Li, Feng, et al, 2020; Pakdel et al, 2020; Zaid et al, 2020).…”

“…Water shortage and high temperature work synergistically in field conditions (Chen, Li, et al, 2020). Therefore, the present study was Triticum aestivum (Cha et al, 2020;Grieco et al, 2020;Khanzada et al, 2020;Shawon et al, 2020). Similarly, several previous studies suggested that, under drought stress, the reduction in plant growth attributes is accompanied with a reduction in plants turgor pressure, cell division, cell wall biosynthesis, and cell expansion (B.…”

Drought stress delays photosynthetic induction and accelerates photoinhibition of photosystem I under fluctuating light

“…g tot is the total conductance of CO 2 between the leaf surface and sites of RuBP carboxylation (calculated as 1/g tot = 1/g s + 1/g m ). The chlorophyll fluorescence parameters were calculated as follows: to Y(II) (Grieco et al 2020).…”

“…Many studies have examined the effect of drought stress on photosynthesis under stable light intensity (Oukarroum, Schansker & Strasser 2009;Galmés et al 2013;Zivcak et al 2013). However, drought stress is rarely studied under FL conditions (Grieco et al 2020;Qu et al 2020). Under FL, plants may exhibit different photosynthetic performance when also experiencing drought stress compared with sufficient water conditions.…”

Coordination of Cyclic Electron Flow and Water–Water Cycle Facilitates Photoprotection under Fluctuating Light and Temperature Stress in the Epiphytic Orchid Dendrobium officinale

“…Once PSI is damaged, the CO 2 assimilation rate significantly decreases, impairing plant growth [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Fortunately, plants have evolved several effective mechanisms to protect PSI against photo-oxidative damage under FL [ 15 , 16 , 17 ]. In angiosperms, two alternative electron flows, cyclic electron flow (CEF) around PSI and water–water cycle (WWC), have the potential to fine-tune the redox state of PSI under FL [ 6 , 18 , 19 , 20 ].…”