Photosynthetica最新文献

Chlorophyll (Chl) a fluorescence measurements are widely used in the study of photosynthesis, and Reto Strasser is a well-known pioneer in this domain. In 2019, the current authors, together with Vineet Soni, and Neera Bhalla Sarin, celebrated his 75^th birthday. Here, we pay tribute to him on his 82^nd birthday through a brief description of the key results we had obtained with him, over the years, on the understanding and exploitation of the OJIP Chl a fluorescence transient. The topics of these studies have been quite diverse, from the oxygen clock, the bicarbonate effect in Photosystem II, the adaptability of plants to various stress factors, to mathematical modeling of the OJIP phase, but all based on the application of Chl a fluorescence for the understanding of oxygenic photosynthesis. Additionally, we have included here a list of the authors who have honored Reto Strasser in Photosynthetica in 2020, along with references of their papers.

Pitavia punctata (Ruiz & Pav.) Molina ('Pitao') is an endangered species that regenerates under the shade. We monitored the photochemical efficiency of photosystem II in four localities spanning the geographical distribution of the species in Central Chile. Technical fluorescence parameters and JIP-test-derived parameters were measured in trees (up to 15 m) and seedlings (< 50 cm). We observed significant effects of the type of plant and locality on the performance index (PI_ABS) and maximum fluorescence (F_M). PI_ABS was higher in trees from the Los Barros locality (PI_ABS = 41), whereas seedlings located in Colcura locality had PI_ABS = 26. Seedlings exhibited higher F_M compared to trees (F_M = 940 and 895 for seedlings and trees, respectively), particularly in locality Ramadillas (F_M = 1,025). Our results provide information on a topic largely understudied in native species in Chile and are useful for designing and monitoring restoration processes for P. punctata.

This study aimed to gain insights into the photosynthesis capacity and genotypic differences in response to drought imposed at an early growth stage of cassava. Leaf water potential (LWP), leaf gas exchange, and photosynthetic light-response curves were investigated in six field-grown cassava genotypes under full irrigation and drought imposed for 60 d during 3-5 months after planting. During the drought period, mean LWP at predawn (LWP_pre) was significantly lower than that in the control plants, while the mean midday LWP (LWP_mid) was similar. During the drought period, the mean stomatal conductance was reduced from 0.36 to 0.09 mol(H₂O) m^-2 s^-1, mean transpiration rate from 5.30 to 1.86 mmol(H₂O) m^-2 s^-1 with the concomitant reduction in net photosynthetic rate (P _N) from 27.45 to 16.34 μmol(CO₂) m^-2 s^-1. Analysis of the light-response curves revealed a reduction in the light-saturation point (I _sat), the light-saturated net photosynthetic rate (P _Nmax), and the apparent quantum yield (AQY). After rewatering for 30 d, the drought plants could fully recover. In conclusion, P _N at high light intensity, P _Nmax, I _sat, and AQY were useful parameters to differentiate genotypes for variability in drought tolerance.

The upland cotton strain YA-1 can be used for hybrid seed production and recurrent selection. However, the effect of YA-1 virescent phenotype on photosynthetic traits remains unclear. This study demonstrated that the chlorophyll and carotenoid contents, light-saturation point, light-compensation point, and PSII reaction center activities are lower than those of green leaves of wide type. In contrast, light-energy utilization efficiencies, net photosynthetic rate, transpiration rate, stomatal conductance, concentrations of Rubisco and phosphoenolpyruvate carboxylase, photosynthetic performance indices, and energy distribution parameters of the yellowish leaves of YA-1 are higher than those of wild type green leaves. The lower expression of GhHemL, GhSGRL, and GhCAO genes impairs chlorophyll biosynthesis, while the downregulation of GhZEP and GhNCED disrupts carotenoid biosynthesis, altering the pigment composition in yellowish leaves. The yellowish phenotype of YA-1 had significant positive effects on photosynthetic efficiency. This finding provides a valuable basis for optimizing the use of YA-1 in cotton breeding programs.

Ensuring global food security requires noninvasive techniques for optimizing resource use and monitoring crop health. Hyperspectral imaging (HSI) enables the precise analysis of plant physiology by capturing spectral data across narrow bands. This review explores HSI's role in agriculture, particularly its integration with unmanned aerial vehicles, AI-driven analytics, and machine learning. These advancements allow real-time monitoring of photosynthesis, chlorophyll fluorescence, and carbon assimilation, linking spectral data to plant health and agronomic decisions. Key indicators such as solar-induced fluorescence and vegetation indices enhance crop stress detection. This work compares HSI-derived metrics in differentiating nutrient deficiencies, drought, and disease. Despite its potential, challenges remain in data standardization and spectral interpretation. This review discusses solutions such as molecular phenotyping and predictive modeling, for AI-driven precision agriculture. Addressing these gaps, HSI is poised to revolutionize farming, improve climate resilience, and ensure food security.

The thermal stability of photosynthetic apparatus under osmotic/salt stress was examined in wheat cultivars grown under different climatic conditions. The thermostability of nonstressed plants did not differ significantly from each other and it was not improved by osmotic treatment in the absence of light. In contrast, the salt stress resulted in better thermostability. This was also manifested in the temperature dependence of maximal quantum yield of PSII photochemistry. The temperature dependence of steady-state fluorescence and other photosynthetic parameters indicated a moderate reduction in thermal sensitivity of photosynthesis in well-watered plants which was further enhanced by osmotic, but even more by salt treatment. It seems likely that the osmotic stress-induced thermal stability increase of PSII occurs only in energized thylakoids. The temperature dependence of quantum yield of regulated energy dissipation seems to suggest that the secondary effects of lumen pH might have a role in the protective mechanisms concerning these stresses, but salt stress can also affect thermal stability in other ways as well.

The adverse effects of cadmium on plants are accompanied by a limitation of photosynthesis, due to the production of reactive oxygen species, leading to oxidative damage to PSII and the disruption of key protein complexes involved in photosynthetic pathways. We investigated the effects of cadmium stress combined with high light in Arabidopsis thaliana, as dependent on the cadmium dose applied. The aim was to investigate the combined effect of the two stressors on photochemical processes with the hypothesis that Cd stress enhances the negative effect of the high light. The plants were treated with 0, 1, 10, and 50 mM Cd added as CdCl₂ solution to soil (potted plants), and a high light stress. The highest dose (50 mM) induced a significant oxidative stress, reduced chlorophyll fluorescence parameters related to PSII functioning and increased energy dissipation mechanisms. Elevated Cd contents impaired the electron transport and limited PSII efficiency. OJIP analysis revealed a Cd-induced K- and L-band appearance documenting LHC-PSII limitation. The combination of Cd and high light stress resulted in the photoinhibition effects in PSII, i.e., a decrease in potential and effective yields of PSII.