Diurnal changes in the stomatal, mesophyll, and biochemical limitations of photosynthesis in well-watered greenhouse-grown strawberries

G. YOKOYAMA, S. ONO, D. YASUTAKE, K. HIDAKA, T. HIROTA

Photosynthetica 2023, 61(1):1-12 | DOI: 10.32615/ps.2023.001  

The diurnal variations in the factors of photosynthesis reduction under well-watered greenhouse conditions remain poorly understood. We conducted diurnal measurements of gas exchange and chlorophyll fluorescence in strawberries (Fragaria × ananassa Duch.) for three sunny days. Quantitative limitation analysis was also conducted to investigate the diurnal variations of photosynthetic limitations [stomatal (S_L), mesophyll (MC_L), and biochemical limitation (B_L)]. Under well-watered greenhouse conditions, a photosynthesis reduction was observed, and the respective limitations exhibited...

Photosynthetic performance of walnut leaves during the occurrence of leaf scorch

S.W. WANG, C.J. XING, C.F. ZHANG, T. GUO, H.L. HAO, Z.Y. ZHANG, S. WANG, J.M. SHU

Photosynthetica 2023, 61(1):13-24 | DOI: 10.32615/ps.2023.003  

To clarify the effect of leaf scorch on walnut leaf photosynthesis, photosynthetic parameters were measured in Juglans regia 'Wen185' and 'Xinxin2' symptom trees (WS, XS) and symptomless trees (WH, XH). At the early stage of infection and under the low-grade leaf scorch, WS showed significantly lower net photosynthetic rate (P_N), stomatal limitation (L_s), and higher intercellular CO₂ concentration (C_i) than those of WH. However, at the mid to late stage of infection and under the high-grade leaf scorch, WS showed significantly lower P_N, C_i, the maximal...

Improving salt tolerance of bean (Phaseolus vulgaris L.) with hydrogen sulfide

M. EKINCI, M. TURAN, S. ORS, A. DURSUN, E. YILDIRIM

Photosynthetica 2023, 61(1):25-36 | DOI: 10.32615/ps.2023.005  

The current study examined the H₂S applications on growth, biochemical and physiological parameters of bean seedlings under saline conditions. The findings of the study indicated that salt stress decreased plant growth and development, photosynthetic activity, and mineral and hormone content [excluding abscisic acid (ABA)] in bean seedlings. Plant and root fresh mass and dry mass with H₂S applications increased as compared to the control treatment at the same salinity level. Both salinity and H₂S treatments significantly affected the net assimilation rate, stomatal conductance, transpiration rate, and intercellular...

On the evolution of the concept of two light reactions and two photosystems for oxygenic photosynthesis: A personal perspective

G. GOVINDJEE

Photosynthetica 2023, 61(1):37-47 | DOI: 10.32615/ps.2023.006  

I present here a personal perspective of the evolution of the two-light reaction two-pigment scheme for the electron transport in oxygenic photosynthesis - as I have lived through it - first as a graduate student of Robert Emerson, from September 1956-January 1959, and then of Eugene Rabinowitch from February 1959-September 1960. I have provided here some of the key published work in my way and have also provided a few photographs. It is essential to remind ourselves upfront that different individuals may have different recollections of the same event (see e.g., the Japanese movie 'Rashomon' https://en.wikipedia.org/wiki/Rashomon). Thus,...

The photosynthetic function analysis for leaf photooxidation in rice

H. XU, X. CHU, K.J. GOU, D.X. JIANG, Q.Q. LI, C.G. LV, Z.P. GAO, G.X. CHEN

Photosynthetica 2023, 61(1):48-57 | DOI: 10.32615/ps.2023.004  

Photooxidative damage causes early leaf senescence and plant cell death. In this study, a light-sensitive rice cultivar, 812HS, and a non-light-sensitive cultivar, 812S, were used to investigate early leaf photooxidation. Leaf tips of 812HS exhibited yellowing under a light intensity of 720 µmol(photon) m^-2 s^-1, accompanied by a decrease in chlorophyll and carotenoids, but 812S was unaffected. The photosynthetic performance of 812HS was also poorer than that of 812S. The H₂O₂, O₂^*-, and malondialdehyde content increased sharply in 812HS, and associated antioxidant enzymes were...

Protection of nitrogenase from photosynthetic O₂ evolution in Trichodesmium: methodological pitfalls and advances over 30 years of research

A. HANIA, R. LÓPEZ-ADAMS, O. PRÁŠIL, M. EICHNER

Photosynthetica 2023, 61(1):58-72 | DOI: 10.32615/ps.2023.007  

The Trichodesmium genus comprises some of the most abundant N₂-fixing organisms in oligotrophic marine ecosystems. Since nitrogenase, the key enzyme for N₂ fixation, is irreversibly inhibited upon O₂ exposure, these organisms have to coordinate their N₂-fixing ability with simultaneous photosynthetic O₂ production. Although being the principal object of many laboratory and field studies, the overall process of how Trichodesmium reconciles these two mutually exclusive processes remains unresolved. This is in part due to contradictory results that fuel the Trichodesmium enigma....

Photosynthetic machinery under salinity stress: Trepidations and adaptive mechanisms

T.V. VINEETH, G.K. KRISHNA, P.H. PANDESHA, L. SATHEE, S. THOMAS, D. JAMES, K.T. RAVIKIRAN, S. TARIA, C. JOHN, N.M. VINAYKUMAR, B.M. LOKESHKUMAR, H.S. JAT, J. BOSE, D. CAMUS, S. RATHOR, S.L. KRISHNAMURTHY, P.C. SHARMA

Photosynthetica 2023, 61(1):73-93 | DOI: 10.32615/ps.2023.002  

Chloroplasts and photosynthesis are the physiologically fateful arenas of salinity stress. Morphological and anatomical alterations in the leaf tissue, ultrastructural changes in the chloroplast, compromise in the integrity of the three-layered chloroplast membrane system, and defects in the light and dark reactions during the osmotic, ionic, and oxidative phases of salt stress are conversed in detail to bring the salinity-mediated physiological alterations in the chloroplast on to a single platform. Chloroplasts of salt-tolerant plants have evolved highly regulated salt-responsive pathways. Thylakoid membrane remodeling, ion homeostasis, osmoprotection,...

Professor Charles Percival Whittingham (1922-2011)

C.H. FOYER, A.J. KEYS, M.A.J. PARRY, G. GOVINDJEE

Photosynthetica 2023, 61(1):94-96 | DOI: 10.32615/ps.2023.010  

Downregulated expression of TaDeg7 inhibits photosynthetic activity in bread wheat (Triticum aestivum L.)

F.F. LIU, G.P. LI, H.W. LI

Photosynthetica 2023, 61(1):97-107 | DOI: 10.32615/ps.2023.008  

Deg proteases play critical roles in photoprotection and PSII-repair circle, which remains elusive in cereal crops including wheat. Here, a Deg7-encoding gene TaDeg7 was silenced in wheat via a Barley stripe mosaic virus-induced gene-silencing system (BSMV-VIGS). When the expression level of TaDeg7 was downregulated, the photosynthetic activity including CO₂ assimilation rate, actual photochemical efficiency of PSII, and electron transport rate declined while the nonphotochemical quenching increased significantly. When grown in high light, the BSMV:TaDeg7 plants accumulated more soluble sugar, malondialdehyde,...

The life story of Albert W. Frenkel (1919-2015): a pioneer in photosynthesis research

G. GOVINDJEE, S. FRENKEL

Photosynthetica 2023, 61(1):108-114 | DOI: 10.32615/ps.2023.015  

In this historical perspective, we focus on selected discoveries that Albert Frenkel (1919-2015) made all by himself - single-handedly - which is the discovery of photophosphorylation and NAD reduction in anoxygenic photosynthetic bacteria. Then, we present various aspects of his research life through his unpublished letters with some key scientists in his research field. To give a glimpse of his personal life, we have also provided some photographs.

The physiological responses of critically endangered species Ardisia gigantifolia Stapf (Primulaceae) to different light intensities

R. LIU, X.E. NING, D.M. LI, L. CHEN, Z.L. NING

Photosynthetica 2023, 61(1):115-123 | DOI: 10.32615/ps.2023.011  

To investigate the light intensity suitable for the growth of Ardisia gigantifolia Stapf, morphology, photosynthetic parameters, and indicators of oxidative stress were analyzed under different light intensities. Compared to high-irradiance treatment, medium and low-irradiance treatments promoted plant growth and restricted transpiration. Compared to medium irradiance, plants under high and low irradiance exhibited significantly lower maximal photochemical efficiency, potential photochemical efficiency, and electron transport rate, but significantly higher malondialdehyde content. This indicated that both excessive light and severe shading inhibited...

Morphological and physiological responses of two Osmanthus fragrans cultivars to salt stress

C.Y. GUO, C.J. MENG, M. YUE

Photosynthetica 2023, 61(1):124-134 | DOI: 10.32615/ps.2023.012  

We examined the morphological and physiological responses of Osmanthus fragrans 'Yingui' (Yin) and O. fragrans 'Jingui' (Jin) to different NaCl concentrations. NaCl concentrations significantly affected plant height and leaf mass per area. Total biomass decreased by 22.8-41.8% under moderate and high NaCl which inhibited O. fragrans growth. The ratio of root to shoot biomass in Yin was 44.3% higher than that in Jin at high NaCl concentrations which suggested that Yin possesses conservative resource acquisition strategies to resist salt stress. Compared to Yin, Jin showed higher net photosynthesis, stomatal conductance, and intercellular...