Editorial

Govindjee, Ivana Štětinová, Helena Synková, Naděžda Wilhelmová, J. Zima

Photosynthetica 2017, 55(4):1-5 | DOI: 10.1007/s11099-017-0751-y

Underestimated chlorophyll a fluorescence measurements on Buxus microphylla red winter leaves

J. G. Peng, X. R. Jiang, J. Xu, L. Guo, R. F. Gao, Y. Liu

Photosynthetica 2017, 55(4):561-567 | DOI: 10.1007/s11099-016-0660-5

Leaves under stressful conditions usually show downregulated maximum quantum efficiency of photosystem II [inferred from variable to maximum chlorophyll (Chl) a fluorescence (F_v/F_m), usually lower than 0.8], indicating photoinhibition. The usual method to evaluate the degree of photoinhibition in winter red leaves is generally by measuring the F_v/F_m on the red adaxial surface. Two phenotypes of overwintering Buxus microphylla 'Wintergreen' red leaves, with different measuring site and leaf thickness, were investigated in order to elucidate how red pigments in the outer leaf layer affected the...

Comparative analysis of ultrastructure, antioxidant enzyme activities, and photosynthetic performance in rice mutant 812HS prone to photooxidation

J. Ma, C. F. Lv, B. B. Zhang, F. Wang, W. J. Shen, G. X. Chen, Z. P. Gao, C. G. Lv

Photosynthetica 2017, 55(4):568-578 | DOI: 10.1007/s11099-016-0669-9

Under optimal conditions, most of the light energy is used to drive electron transport. However, when the light energy exceeds the capacity of photosynthesis, the overall photosynthetic efficiency drops down. The present study investigated the effects of high light on rice photooxidation-prone mutant 812HS, characterized by a mutation of leaf photooxidation 1 gene, and its wild type 812S under field conditions. Our results showed no significant difference between 812HS and 812S before exposure to high sunlight. However, during exposure to high light, shoot tips of 812HS turned yellow and their chlorophyll (Chl) content decreased. Transmission electron...

Photosynthesis of soybean cultivars released in different decades after grafting onto record-yield cultivars as rootstocks

S. Y. Li, F. Teng, D. M. Rao, H. J. Zhang, H. Y. Wang, X. D. Yao, C. M. Yu, C. H. Li, M. Z. Zhao, S. K. St. Martin, F. T. Xie

Photosynthetica 2017, 55(4):579-587 | DOI: 10.1007/s11099-016-0666-z

While photosynthesis of soybean has been enhanced by breeding, it remains to be clarified whether the improvement of root function could bring a further increase of photosynthetic capacity for the development of soybean cultivars. The objective of this grafting experiment was to determine the influence of record-yield soybean cultivars, Liaodou14 (L14) and Zhonghuang35 (Z35), as rootstocks on photosynthetic traits of cultivars released in different decades. Grafting of various soybean cultivars onto L14 or Z35 rootstocks showed a higher root physiological activity, which resulted in significant increases in some photosynthetic traits at the late grain-filling...

Inhibition of root respiration induces leaf senescence in Alhagi sparsifolia

G. L. Tang, X. Y. Li, L. S. Lin, Y. Hu, F. J. Zeng

Photosynthetica 2017, 55(4):588-602 | DOI: 10.1007/s11099-016-0674-z

Leaf senescence can be induced by numerous factors. In order to explore the relationship between root respiration and leaf senescence, we utilized different types of phloem girdling to control the root respiration of Alhagi sparsifolia and its physiological response. Our results showed that both girdling and inhibition of root respiration led to a decline of stomatal conductance, photosynthesis, transpiration rate, chlorophyll (Chl) a, Chl b, carotenoid (Car) content, Chl a/b, Chl/Car, water potential, and Chl a fluorescence, as well as to an increase of abscisic acid (ABA), proline, and malondialdehyde content in...

Feasibility of using smart phones to estimate chlorophyll content in corn plants

F. Vesali, M. Omid, H. Mobli, A. Kaleita

Photosynthetica 2017, 55(4):603-610 | DOI: 10.1007/s11099-016-0677-9

New spectral absorption photometry methods are introduced to estimate chlorophyll (Chl) content of corn leaves by smart phones. The first method acquires light passing through a leaf by smartphone camera, compensating for differences in illumination conditions. In order to improve performance of the method, spectral absorption photometry (SAP) with background illumination has been considered as well. Data were acquired by smartphone camera in Iowa State University maize fields. Various indices were extracted and their correlation with Chl content were examined by Minolta SPAD-502. Hue index in SAP reached R ² value of 0.59....

Photosynthetic and antioxidative upregulation in drought-stressed sesame (Sesamum indicum L.) subjected to foliar-applied salicylic acid

M. Yousefzadeh Najafabadi, P. Ehsanzadeh

Photosynthetica 2017, 55(4):611-622 | DOI: 10.1007/s11099-017-0673-8

Insufficient attention has been paid to the physiological responses of sesame to drought and it is unclear if exogenous plant growth regulators are beneficial to drought-stressed sesame. Thus, a field study was conducted on seven Sesamum indicum genotypes affected by two levels of irrigation (60 and 80% depletions in available soil water) and by foliar-applied salicylic acid (SA; 0 and 0.6 mM). Water deficit led to depressions in net photosynthetic rate, stomatal conductance, leaf area index, chlorophyll a, b, and total chlorophyll contents, maximum quantum efficiency of PSII, and plant dry matter and seed yield, despite increases...

Physiological responses of a green algae (Ulva prolifera) exposed to simulated acid rain and decreased salinity

Y. H. Li, D. Wang, X. T. Xu, X. X. Gao, X. Sun, N. J. Xu

Photosynthetica 2017, 55(4):623-629 | DOI: 10.1007/s11099-017-0689-0

In order to evaluate the combined effects of simulated acid rain (SAR) and salinity on the physiological responses of macroalgae, Ulva prolifera was cultured under three salinity treatments (5, 10, 25 ‰) and at different pH, i.e., at pH 4.4 (C), pH 4.4(F), where the pH of the culture increased from 4.4 to approximately 7.8 during the cultivation period, or in absence of SAR at pH 8.2(C), at 100 μmol(photon) m^-2 s^-1 and 20°C. Compared to 25‰ salinity, Relative growth rate (RGR) of U. prolifera was enhanced by 10‰ salinity, but decreased by 5‰ salinity. No significant differences...

Overexpression of calmodulin gene fragment from Antarctic notothenioid fish improves chilling tolerance in Nicotiana benthamiana

T. J. Zhang, L. J. Pan, Q. Huang, L. H. Zhu, N. Yang, C. L. Peng, L. B. Chen

Photosynthetica 2017, 55(4):630-637 | DOI: 10.1007/s11099-016-0682-z

Calmodulin (CaM) is a highly conserved calcium sensor protein associated with chilling tolerance in living organisms. It has four EF-hand domains for binding of four Ca²⁺, two of them located in the N-terminus, and the other two in the C-terminus. A notothenioid CaM gene fragment (CaMm), which only codes for N-terminus of CaM (with two EF-hand domains), was introduced into Nicotiana benthamiana. Effects of its overexpression on chilling tolerance in plants were explored. During 4◦C or 0◦C chilling treatment, both CaMm and CaM transgenic plants showed higher PSII maximum quantum yield, actual...

Photosynthesis and biomass allocation of cotton as affected by deep-layer water and fertilizer application depth

Z. K. Chen, Y. P. Niu, H. Ma, A. Hafeez, H. H. Luo, W. F. Zhang

Photosynthetica 2017, 55(4):638-647 | DOI: 10.1007/s11099-016-0675-y

Available water stored in deep soil layers could increase the photosynthetic capacity of cotton. It was hypothesized that the photosynthesis of cotton would be enhanced by changing the fertilizer application depth under different deep-layer water conditions. We examined two deep-layer water levels, i.e., well-watered (W₈₀) and not watered (W₀), combined with surface application (F₁₀) and deep application (F₃₀) of basal fertilizer. Compared to W₀, W₈₀ resulted in increased leaf area (LA), photosynthetic pigment contents, maximal PSII efficiency (F_v/F_m), effective...

Assessment of cadmium phytotoxicity alleviation by silicon using chlorophyll a fluorescence

A. J. Silva, C. W. A. Nascimento, A. S. Gouveia-Neto

Photosynthetica 2017, 55(4):648-654 | DOI: 10.1007/s11099-016-0680-1

The aim of this study was to investigate the effects of silicon in alleviating cadmium stress in maize plants grown in a nutrient solution and to evaluate the potential of the spectral emission parameters and the ratio of red fluorescence (Fr) to far-red fluorescence (Ffr) in assessing the beneficial effects of Si. An experiment was carried out using a nutrient solution with a toxic dose of Cd and six doses of Si; biomass, Cd, Si, and photosynthetic pigments of the plants were measured. Chlorophyll (Chl) a fluorescence analysis demonstrated that Si alleviated Cd toxicity in plants. Chl fluorescence measurements were sensitive in detecting such...

Growth, photosynthetic performance and antioxidative response of 'Hass' and 'Fuerte' avocado (Persea americana Mill.) plants grown under high soil moisture

G. Doupis, N. Kavroulakis, G. Psarras, I. E. Papadakis

Photosynthetica 2017, 55(4):655-663 | DOI: 10.1007/s11099-016-0679-7

'Hass' and 'Fuerte' avocado plants were grown under well-watered or waterlogged conditions. Results indicated significant effects on the majority of the allometric parameters in waterlogged plants, with 'Fuerte' displaying a more pronounced growth inhibition. Waterlogged conditions caused a progressive and simultaneous decline in net photosynthetic rate and stomatal conductance, earlier in 'Fuerte' than in 'Hass'. Maximal potential quantum yield of PSII was unaffected by the soil water regime and/or variety and leaf water potential values in waterlogged plants were not more negative compared with control plants. 'Fuerte' waterlogged plants exhibited...

Progesterone increases photochemical efficiency of photosystem II in wheat under heat stress by facilitating D1 protein phosphorylation

R. L. Xue, S. Q. Wang, H. L. Xu, P. J. Zhang, H. Li, H. J. Zhao

Photosynthetica 2017, 55(4):664-670 | DOI: 10.1007/s11099-016-0681-0

Experiments were conducted to investigate the effects of exogenous progesterone on photochemical efficiency of PSII and turnover of D1 protein under heat stress during the grain-filling stage. Heat stress resulted in increases of hydrogen peroxide production, malondialdehyde content, and relative electrolytic leakage in wheat leaves, but these responses were alleviated by foliar application of progesterone. Meanwhile, activities of superoxide dismutase, catalase, and peroxidase were significantly improved in progesterone-pretreated leaves. Along with the alleviation of oxidative stress, higher abundances of STN8 and phosphorylated D1 protein and lower...

Chlorophyll fluorescence imaging can reflect development of vascular connection in grafting union in some Solanaceae species

C. Penella, A. Pina, A. San Bautista, S. López-Galarza, Ángeles Calatayud

Photosynthetica 2017, 55(4):671-678 | DOI: 10.1007/s11099-017-0690-7

Graft union development in plants has been studied mainly by destructive methods such as histological studies. The aim of this work was to evaluate whether the chlorophyll fluorescence imaging (CFI) technique is sensitive enough to reflect changes at the cellular level in different Solanaceae grafted plants 30 d after grafting, when both grafted partners were well fused and strong enough in all plant combinations. The pepper cultivar 'Adige' was grafted onto different Capsicum spp. accessions typified with different compatibility degrees; eggplant was grafted on Solanum torvum and pepper homografts as compatible unions; pepper was grafted...

Leaf trait plasticity in six forest tree species of central Amazonia

R. A. Marenco, M. A. B. Camargo, S. A. Antezana-Vera, M. F. Oliveira

Photosynthetica 2017, 55(4):679-688 | DOI: 10.1007/s11099-017-0703-6

Tropical rainforest trees adjust leaf traits during ontogeny to cope with changes in the physical environment and maximize their carbon uptake. The aim of this study was to determine the plasticity index (P_I) of leaf traits in understory and canopy leaves of six Amazonian tree species. In four of the six species the P_I of leaf traits varied within species, and in four of the ten leaf traits assessed, the P_I differed between species. The greatest P_I values were found for stomatal density (D_s) and CO₂-saturated photosynthesis, and the lowest ones were found for stomatal size, and leaf...

Photosynthetic response of four fern species from different habitats to drought stress: relationship between morpho-anatomical and physiological traits

K. Nishida, Y. T. Hanba

Photosynthetica 2017, 55(4):689-697 | DOI: 10.1007/s11099-017-0694-3

Ferns flourish in many habitats, from epiphytic to terrestrial and from sunny to shady, and such varied conditions require contrasting photosynthetic strategies to cope with drought. Four species of temperate ferns from different habitats were subjected to drought by withholding irrigation in order to investigate their photosynthetic responses. Lepisorus thunbergianus (epiphytic) had low stomatal density and showed high water-use efficiency (WUE) retaining photosynthetic activity with low relative frond water content under drought stress, which suggested their high adaptation to drought. On the other hand, low WUE with low light-saturated photosynthetic...

Photosynthetic apparatus activity in relation to high and low contents of cell wall-bound phenolics in triticale under drought stress

K. Hura, A. Ostrowska, K. Dziurka, T. Hura

Photosynthetica 2017, 55(4):698-704 | DOI: 10.1007/s11099-017-0687-2

Cell wall-bound phenolics (CWP) play an important role in the mechanisms of plant acclimation to soil drought. The study involved CWP analyses in 50 strains and 50 doubled haploid (DH) lines of winter triticale exposed to drought at their vegetative and generative stages. CWP in the plants experiencing drought at the generative stage positively correlated with their leaf water contents. The strains and DH lines characterized by high content of CWP showed higher leaf water content and higher activity of photosynthetic apparatus when exposed to drought at the generative stage compared to the strains and DH lines with the low CWP content. Furthermore,...

Variations in light energy dissipation in Woodfordia fruticosa leaves during expansion

S. B. Zhang, J. L. Zhang

Photosynthetica 2017, 55(4):705-715 | DOI: 10.1007/s11099-017-0692-5

Young leaves of tropical trees frequently appear red in color, with the redness disappearing as the leaves mature. During leaf expansion, plants may employ photoprotective mechanisms to cope with high light intensities; however, the variations in anthocyanin contents, nonphotochemical quenching (NPQ), and photorespiration during leaf expansion are poorly understood. Here, we investigated pigment contents, gas exchange, and chlorophyll (Chl) fluorescence in Woodfordia fruticosa leaves during their expansion. Young red leaves had significantly lower Chl content than that of expanding or mature leaves, but they accumulated significantly higher...

Expression of genes encoding key components of chlororespiration and cyclic electron transfer in soybean under different light qualities

X. Sun, X. F. Chen, J. B. Du, W. Y. Yang

Photosynthetica 2017, 55(4):716-722 | DOI: 10.1007/s11099-017-0705-4

Our present work showed that the expression of genes encoding PTOX (terminal oxidase of chlororespiration) and PGR5 (one essential component of cyclic electron transfer) were stimulated by red and blue light, but the stimulation under red light was soon reversed by subsequent far-red light. The expression levels of PTOX and PGR5 under simulated light quality conditions in line with maize-soybean relay strip intercropping (SRI) were obviously lower than those under simulated soybean monocropping (SM), since the lower red:far-red ratio under SRI. Measurements on photosynthetic and chlorophyll fluorescence parameters suggested a decline...