Inorganic anions induce state changes in spinach thylakoid membranes

AbstractThe role of cations in excitation energy distribution between the two photosystems of photosynthesis is well established. This paper provides evidence, for the first time, for an important role of anions in the regulation of distribution of absorbed light energy between the two photosystems. Inorganic anions caused redistribution of energy more in favour of photosystem I, as judged from measurements of chlorophyll a fluorescence transients, rates of electron transport in low light and 77 K fluorescence emission spectra: the Fv/Fm ratio was decreased by inorganic anions even in the presence of DCMU, the PS II electron transport was decreased whereas PS I electron transport was increased and the F735 (77 K emission from PS I)/F685 (77 K emission from PS II) ratio was increased. Such changes were observed with inorganic anions having different valencies (Cl−, SO2−4, PO3−4): the higher the valency of the inorganic anion, the more the energy transferred towards PS I. Change in the valency of the inorganic anions thus regulates distribution of absorbed light energy between the two photosystems. However, organic anions like acetate, succinate, and citrate caused no significant changes in the Fv/Fm ratio, and in rates of PS I and PS II electron transport, showing their ineffectiveness in regulating light energy distribution

Evaluation of Indian Durum Wheat Genotypes for Yield and Quality Traits Using Additive Main-Effects and Multiplicative Interaction (AMMI) Biplot Analysis under Terminal Heat Stress Conditions

The abrupt increase of temperatures during and after the flowering period of wheat is defined as terminal heat stress, and it causes severe reductions in productivity. One hundred two durum wheat lines were evaluated against this stress for three consecutive cropping seasons (2014–2017) in Indore, Madya Pradesh (India). The main objectives were to assess their grain yield potential, stability, and rheological quality characteristics under these conditions, and identify other contributing traits to adaptation. Combined ANOVA across environments showed significant differences (P < 0.01) for all factors, and high broad sense heritability was recorded for hectoliter weight, 1000-grains weight, grain yield, number of grains per spike, spike length, days to maturity, total carotene and sedimentation values. Grain yield showed significant (P < 0.01) positive associated with biomass, harvest index, hectoliter weight and significant negative associations with day to heading and maturity. Genotypes showed explicit variation to environmental condition as supported by significant (P < 0.01) for genotype × environment interaction (GEI). The traits like early heading, maturing, high biomass and hectoliter weight were the most critical traits for adaptation under terminal heat stress. To determine effects of GEI data were subjected to GGE biplot analysis, which identified as the most stable and performing across seasons G-30 (GW 1240) for hectoliter weight and G-98 (Vijay) for grain yield. These entries can now be combined via breeding to develop superior heat stress tolerant varieties

Tapping Into Actinobacterial Genomes for Natural Product Discovery

The presence of secondary metabolite biosynthetic gene clusters (BGCs) makes actinobacteria well-known producers of diverse metabolites. These ubiquitous microbes are extensively exploited for their ability to synthesize diverse secondary metabolites. The extent of their ability to synthesize various molecules is yet to be evaluated. Current advancements in genome sequencing, metabolomics, and bioinformatics have provided a plethora of information about the mechanism of synthesis of these bioactive molecules. Accessing the biosynthetic gene cluster responsible for the production of metabolites has always been a challenging assignment. The genomic approach developments have opened a new gateway for examining and manipulating novel antibiotic gene clusters. These advancements have now developed a better understanding of actinobacterial physiology and their genetic regulation for the prolific production of natural products. These new approaches provide a unique opportunity to discover novel bioactive compounds that might replenish antibiotics’ exhausted stock and counter the microbes’ resistance crisis

Frequently asked questions about chlorophyll fluorescence, the sequel

[EN] Using chlorophyll (Chl) a fluorescence many aspects of the photosynthetic apparatus can be studied, both in vitro and, noninvasively, in vivo. Complementary techniques can help to interpret changes in the Chl a fluorescence kinetics. Kalaji et al. (Photosynth Res 122: 121-158, 2014a) addressed several questions about instruments, methods and applications based on Chl a fluorescence. Here, additionalChl a fluorescence-related topics are discussed again in a question and answer format. Examples are the effect of connectivity on photochemical quenching, the correction of F-V/F-M values for PSI fluorescence, the energy partitioning concept, the interpretation of the complementary area, probing the donor side of PSII, the assignment of bands of 77 K fluorescence emission spectra to fluorescence emitters, the relationship between prompt and delayed fluorescence, potential problems when sampling tree canopies, the use of fluorescence parameters in QTL studies, the use of Chl a fluorescence in biosensor applications and the application of neural network approaches for the analysis of fluorescence measurements. The answers draw on knowledge fromdifferent Chl a fluorescence analysis domains, yielding in several cases new insights.Kalaji, H.; Schansker, G.; Brestic, M.; Bussotti, F.; Calatayud, A.; Ferroni, L.; Goltsev, V.... (2017). Frequently asked questions about chlorophyll fluorescence, the sequel. 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SiO2 nanopriming protects PS I and PSII complexes in wheat under drought stress

abstract: Drought is an important abiotic stress that hampers the growth of plants by inhibiting photosynthesis resulting in major crop losses. Silicon is known for its role to alleviate impact of various abiotic stresses in plants. In the present study, drought sensitive wheat variety HI-1544 was subjected to drought stress (DS) by withholding irrigation. The aim of this study was to evaluate the impact of SiO2 nanopriming in protecting photosynthesis, particularly photosystems (PSI and PSII), under drought condition. DS significantly reduced the quantum yield of PSII (YII) and PSI (YI) in unprimed drought stressed (UP+DS) plants but non-significant reduction was observed in NP+DS wheat plants. Likewise a severe impairment in the electron transport rate of PSII and PSI (ETRII and ETRI) in UP+DS was noticed as compared to NP+DS plants. Among energy dissipation parameters, regulated and non-regulated energy dissipation [Y(NPQ) and Y(NO) respectively] showed prominent increase in UP+DS plants when compared to NP+DS wheat plants. Decrease in YI was accompanied by significant increase in donor Y(ND) and acceptor side Y(NA) limitation of PSI in UP+DS plants. These parameters were less affected in NP+DS wheat plants. A remarkable inhibition in the oxidation reduction kinetics of P700 was observed in UP+DS plants while it were less affected in NP+DS wheat plants. The data suggests that the impact of drought stress (DS) was more prominent on PSII than PSI. SiO2 nanopriming conferred more protection to PSII complex, thereby improving photosynthetic efficiency under DS

Honoring two stalwarts of photosynthesis research: Eva-Mari Aro and Govindjee

On behalf of the entire photosynthesis community, it is an honor, for us, to write about two very eminent scientists who were recently recognised with a Lifetime Achievement Award from the International Society of Photosynthesis Research (ISPR) on August 5, 2022; this prestigious Award was given during the closing ceremony of the 18th International Congress on Photosynthesis Research in Dunedin, New Zealand. The awardees were: Professor Eva-Mari Aro (Finland) and Professor Emeritus Govindjee Govindjee (USA). One of the authors, Anjana Jajoo, is especially delighted to be a part of this tribute to professors Aro and Govindjee as she was lucky enough to have worked with both of them