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BackgroundThe green alga Chlamydomonas reinhardtii is an accepted food ingredient in the United States of America (United States), the European Union, Singapore, and China. It can be consumed in unlimited quantities. As this alga is rich in nutrients, proteins, and rough polysaccharides and contains a balanced proportion of various amino acids, it is an excellent raw material for food production. Although various edible brown and green algae are available on the market, their color and strong grassy flavor have constrained their popularity among consumers, thereby limiting their application in food additives and animal feed.MethodsChlorophyll-deficient C. reinhardtii mutants were developed using atmospheric and room temperature plasma (ARTP) technology.ResultsA yellow-colored C. reinhardtii variant (A7S80) cultivated in dark conditions was isolated. This light-sensitive variant has a mutation in the chlM gene, and it can grow heterotrophically using acetate as a carbon source.ConclusionCompared to wild-type C. reinhardtii, A7S80 has significantly lower chlorophyll levels, reduced grassy flavor, and more diverse pigments, with considerable potential for commercial application in human and animal food production, as well as in pharmaceutical and cosmetic industries.

The diversity of leaf characteristics, particularly leaf color, underscores a pivotal area of inquiry within plant science. The synthesis and functionality of chlorophyll, crucial for photosynthesis, largely dictate leaf coloration, with varying concentrations imparting different shades of green. Complex gene interactions regulate the synthesis and degradation of chlorophyll, and disruptions in these pathways can result in abnormal chlorophyll production, thereby affecting leaf pigmentation. This study focuses on Bambusa multiplex f. silverstripe, a natural variant distinguished by a spectrum of leaf colors, such as green, white, and green–white, attributed to genetic variations influencing gene expression. By examining the physiological and molecular mechanisms underlying chlorophyll anomalies and genetic factors in Silverstripe, this research sheds light on the intricate gene interactions and regulatory networks that contribute to leaf color diversity. The investigation includes the measurement of photosynthetic pigments and nutrient concentrations across different leaf color types, alongside transcriptomic analyses for identifying differentially expressed genes. The role of key genes in pathways such as ALA biosynthesis, chlorophyll synthesis, photosynthesis, and sugar metabolism is explored, offering critical insights for advancing research and plant breeding practices.

Nitrogen nutrient concentration is predominant in crop field monitoring. Noticing the deficiency pattern, providing sufficient amounts of nutrients will help to recover the crop. Sometimes it may not be possible to reverse the crop in cases of deep deficiency. It will affect the quality and quantity of the crop product in yield time. Hence, timely identification is important. Therefore, detection of chlorophyll deficiency in groundnut leaves (DCDGL) system is proposed here for nutrient deficit recognition, before a notable pattern emerges. In first phase, groundnut leaf images are collected and clustered based on chlorophyll measurement. Then, different image processing techniques like image compression, resizing, and noise reduction filters are applied and analyzed on leaf images to enhance the images and secure the predominant features. The median filter is fixed because it provides high quality output with a low noise percentage. The quality of an image is measured in decibels with the help of the peak signal to noise ratio (PSNR). Then, in the next phase, colour features and grey level co-occurrence matrix texture features are extracted and given to developed intensified multinomial classification (IMC) model to detect nutrient deficiencies in groundnut leaves. The obtained average accuracy of IMC model is 97%. The DCDGL system's performance is tested with state-of-the-art techniques like K-nearest neighbour and support vector machine. The developed model performance is superior to state-of-the-art techniques regarding accuracy. The appropriate image quality analysis and pre-processing approach helped achieve less processing time to predict nutrient deficiency before tangible symptoms. [ABSTRACT FROM AUTHOR]

Rapeseed (Brassica napus L.) is mainly used for oil production and industrial purposes. A high photosynthetic efficiency is the premise of a high yield capable of meeting people's various demands. Chlorophyll-deficient mutants are ideal materials for studying chlorophyll biosynthesis and photosynthesis. In a previous study, we obtained the mutant yl1 for leaf yellowing throughout the growth period by ethyl methanesulfonate mutagenesis of B. napus. A genetic analysis showed that the yl1 chlorophyll-deficient phenotype was controlled by one incompletely dominant gene, which was mapped on chromosome A03 by a quantitative trait loci sequencing analysis and designated as BnA03.Chd in this study. We constructed an F2 population containing 5256 individuals to clone BnA03.Chd. Finally, BnA03.Chd was fine-mapped to a 304.7 kb interval of the B. napus 'ZS11' genome containing 58 annotated genes. Functional annotation, transcriptome, and sequence variation analyses confirmed that BnaA03g0054400ZS, a homolog of AT5G13630, was the most likely candidate gene. BnaA03g0054400ZS encodes the H subunit of Mg-chelatase. A sequence analysis revealed a single-nucleotide polymorphism (SNP), causing an amino-acid substitution from glutamic acid to lysine (Glu1349Lys). In addition, the molecular marker BnaYL1 was developed based on the SNP of BnA03.Chd, which perfectly cosegregated with the chlorophyll-deficient phenotype in two different F2 populations. Our results provide insight into the molecular mechanism underlying chlorophyll synthesis in B. napus. [ABSTRACT FROM AUTHOR]

Sweetpotato (Ipomoea batatas L), the herbaceous plant cultivated for its starchy storage roots, has a complex genome (2n = 6x = 90) with the estimated genome size of about 4.5 GB. Albinism, a phenomenon that occurs in plants, is defined as the total pigment loss accompanying with insufficient chloroplast membrane differentiation. For this study, an identified natural albino mutant of Xuzi-8 cultivar was subject to RNA sequencing relative to the green plants of identical cultivar. The results showed that total chlorophyll, chlorophyll a, chlorophyll b, and carotenoids were significantly lower in albino plants than in normal green plants. In addition, the CO2 assimilation rate, intercellular CO2 concentration, conductance level, and transpiration rate were significantly higher in normal green plants than in albino mutants. High-quality reads in the total number of 27,520,273-39,862,794 were obtained following the removal of the potentially contaminated or low-quality reads from the albino-mutant and normal green sweetpotato libraries. Later, sequences were matched with the available online data of Ipomoea batatas, and a very low matching degree (2.22%) was obtained, which indicated the very few available data of Ipomoea batatas genome compared with other plants. Additionally, the obtained unigenes were conducted functional annotations and classification, including GO, KOG, and KEGG analyses. The significance level and DEGs differences between albino-mutant and normal green plants were determined according to the thresholds of FDR ≤ 0.001 and log2 FC ≥ 1. A total of 3000 unigenes were upregulated in albino mutants but normally expressed in normal green plants. These genes were involved in facilitating plant nutrition sources depending on the stored carbohydrates and fats. Furthermore, these unigenes were aligned to the DDP family zinc finger protein, glycerophosphodiester phosphodiesterase, beta-galactosidase, GDE-like, and SELMODRAFT PDDEXK. On the other hand, altogether, 2418 unigenes were downregulated in albino-mutant plants compared with normal green plants, which were responsible for chloroplast differentiation and development, chlorophyll degradation, and synthesis of other pigments. Therefore, they might be related to the defect that caused this mutant. [ABSTRACT FROM AUTHOR]

Ion-beam irradiation serves as a powerful tool of mutagenesis for engineering novel traits in a wide range of plants. A previous study indicated that coincidental changes in multiple traits are frequently induced by ion-beam irradiation in soybean [Glycine max (L.) Merr.], a paleopolyploid plant whose genome comprises a large number of duplicated genes. Here we analyzed the levels of isoflavones, major secondary compounds in soybean seeds, in a population of mutants with various degrees of chlorophyll deficiency induced by the mutagenesis. The isoflavones daidzin, genistin, and their respective malonylglucosides were significantly reduced in 4–9 plant lines among 28 lines analyzed. The average levels of chlorophyll in the leaf tissues were correlated with the level of each isoflavone in seeds from multiple lines. In selected mutant lines, the levels of isoflavones were lower than in the wild-type plants throughout seed development. Gene expression profiles indicated that the mRNA levels of multiple genes involved in the isoflavone synthetic pathway were also reduced during seed development in these mutants, consistent with the reduced levels of the compounds. These data suggest that ion-beam irradiation caused changes in multiple pathways of metabolism directly or indirectly and can provide useful plant resources for dissecting isoflavone synthesis and/or accumulation in soybean. [ABSTRACT FROM AUTHOR]

The partial or complete loss of chlorophylls, or albinism, is a rare phenomenon in plants. In the present study, we provide the first report of the occurrence in albino Delonix regia seedlings and describe the morpho-physiological changes associated with albinism. • Wild-type (WT) and albino seedlings were characterized. Leaflets samples were processed following common procedures for analysis with light, scanning and transmission electron microscopy. The chlorophyll a fluorescence parameters and the carbohydrate, lipid and soluble protein content were also determined in leaf and cotyledon samples of both albino and WT seedlings. • Albino seedlings showed reduced growth. They also had lower chlorophyll and protein content in foliar tissues than WT seedlings, in addition to lower concentrations of lipids and carbohydrates stored in cotyledons. The chloroplasts of albino seedlings were poorly developed, with an undefined internal membrane system and the presence of plastoglobules. Wild-type seedlings had a uniseriate and hypoestomatic epidermis. The mesophyll was dorsiventral, consisting of a layer of palisade parenchyma and two to four layers of spongy parenchyma. In albino seedlings, the spongy parenchyma was compact, with few intercellular spaces, and the thickness of the mesophyll was larger, resulting in increased thickness of the leaf blade. Albino seedlings had higher stomatal density and number of pavement cells, although the stomata had smaller dimensions. • In addition to the partial loss of chlorophylls, albino D. regia showed changes at physiological and structural levels, demonstrating the crucial nature of photosynthetic pigments during the development and differentiation of plant leaf tissues/cells. [ABSTRACT FROM AUTHOR]

Chlorophyll is vital for photosynthesis to produce sugars and other useful biochemical products in green plants. However, the molecular effects of chlorophyll deficiency in Chrysanthemum are largely unknown. In this study, we identified a bud sport mutant chrysanthemum belonging to the variety ‘Nannong Binyun’, which has yellow branches. Plant physiological studies have shown that the yellow color is revealed due to chlorophyll loss. RNA extracts of yellow and green tissues were analyzed using high-throughput RNA-sequencing, and a total of 11,649 tissue enriched unigenes that respond to chlorophyll deficiency were identified, including 4803 unigenes upregulated in yellow tissues and 6846 unigenes in green tissues. GO analysis revealed that these tissue-enriched genes may involve in the physiological processes of chlorophyll accumulation and photosynthesis. In addition, many DEGs from the families of AP2-EREBP, bHLH, MYB, and FAR1 that are associated with plant development and stress response were detected. Our study found that most of the genes from the GRAS family were downregulated in yellow leaves, indicating their putative roles in stem cell maintenance and possible contribution to leaf size determination.

Zinc oxide nanoparticles (NPs) are the third highest in terms of global production among the various inorganic nanoparticles, and there are concerns because of their worldwide availability and accumulation in the environment. In contrast, zinc is an essential element in plant growth and metabolism, and ZnO NPs (nano-ZnO) may have unknown interactions with plants due to their small sizes as well as their particular chemical and physical characteristics. The present study examined the effect of nano-ZnO (25 nm) and bulk or natural form (<1000 nm, bulk-ZnO), compared with zinc in the ionic form (ZnSO4) on Nicotiana tabacum seedlings in a nutrient solution supplemented with either nano-ZnO, bulk-ZnO (0.2, 1, 5 and 25 µM) or ZnSO4 (control) for 21 days. Results showed that nano-ZnO at most of the levels and 1 µM bulk-ZnO positively affected growth (root and shoot length/dry weight), leaf surface area and its metabolites (auxin, phenolic compounds, flavonoids), leaf enzymatic activities (CAT, APX, SOD, POX, GPX, PPO and PAL) and anatomical properties (root, stem, cortex and central cylinder diameters), while bulk-ZnO caused decreases at other levels. The activities of enzymes were induced to a greater extent by intermediate nano-ZnO levels than by extreme concentrations, and were higher in nano-ZnO treated than in bulk treated tobacco. As the ZnO level increased, the vascular expansion and cell wall thickening of the collenchyma/parenchyma cells occurred, which was more pronounced when treated by NPs than by its counterpart. The Zn content of root and leaf increased in most of ZnO treatments, whereas the Fe content of leaves decreased. Our findings indicate that tobacco responded positively to 1 µM bulk-ZnO and to nearly all nano-ZnO levels (with the best levels being at 0.2 µM and 1 µM) by morphological, physiological and anatomical adjustments. Hydroponic systems could be a reliable, versatile and sensitive method to investigate the plant responses to the nanoparticle exposure. As ZnO nanoparticles (NPs) and bulk forms possess unique physicochemical characteristics, they are globally used in different industries and may influence plant growth in the environment. As an extensive investigation of the effect of both ZnO NPs and bulk form ZnO on various morphological, physiological and anatomical features of tobacco plants, the present study pinpoints the responses compatible with ZnO-induced stress. [ABSTRACT FROM AUTHOR]

Ion beams are powerful mutagens that can induce novel mutants in plants. We previously established a system for producing a mutant population of soybean via ion-beam irradiation, isolated plants that had chlorophyll deficiency, and maintained their progeny via self-fertilization. Here we report the characterization of the progeny plants in terms of chlorophyll content, flowering time and isoflavone content in seeds. Chlorophyll deficiency in the leaf tissues was linked with reduced levels of isoflavones, the major flavonoid compounds accumulated in soybean seeds, which suggested the involvement of metabolic changes associated with the chlorophyll deficiency. Intriguingly, flowering time was frequently altered in plants that had a reduced level of chlorophyll in the leaf tissues. Plant lines that flowered either earlier or later than the wild-type plants were detected. The observed coincidental changes were presumed to be attributable to the following origins: structural changes of DNA segments leading to the loss of multiple gene functions, or indirect effects of mutations that affect one of these traits, which were manifested as phenotypic changes in the background of the duplicated composition of the soybean genome. [ABSTRACT FROM AUTHOR]

Sweetpotato (Ipomoea batatas L), the herbaceous plant cultivated for its starchy storage roots, has a complex genome (2n = 6x = 90) with the estimated genome size of about 4.5 GB. Albinism, a phenomenon that occurs in plants, is defined as the total pigment loss accompanying with insufficient chloroplast membrane differentiation. For this study, an identified natural albino mutant of Xuzi-8 cultivar was subject to RNA sequencing relative to the green plants of identical cultivar. The results showed that total chlorophyll, chlorophyll a, chlorophyll b, and carotenoids were significantly lower in albino plants than in normal green plants. In addition, the CO2 assimilation rate, intercellular CO2 concentration, conductance level, and transpiration rate were significantly higher in normal green plants than in albino mutants. High-quality reads in the total number of 27,520,273-39,862,794 were obtained following the removal of the potentially contaminated or low-quality reads from the albino-mutant and normal green sweetpotato libraries. Later, sequences were matched with the available online data of Ipomoea batatas, and a very low matching degree (2.22%) was obtained, which indicated the very few available data of Ipomoea batatas genome compared with other plants. Additionally, the obtained unigenes were conducted functional annotations and classification, including GO, KOG, and KEGG analyses. The significance level and DEGs differences between albino-mutant and normal green plants were determined according to the thresholds of FDR ≤ 0.001 and log2 FC ≥ 1. A total of 3000 unigenes were upregulated in albino mutants but normally expressed in normal green plants. These genes were involved in facilitating plant nutrition sources depending on the stored carbohydrates and fats. Furthermore, these unigenes were aligned to the DDP family zinc finger protein, glycerophosphodiester phosphodiesterase, beta-galactosidase, GDE-like, and SELMODRAFT PDDEXK. On the other hand, altogether, 2418 unigenes were downregulated in albino-mutant plants compared with normal green plants, which were responsible for chloroplast differentiation and development, chlorophyll degradation, and synthesis of other pigments. Therefore, they might be related to the defect that caused this mutant. [ABSTRACT FROM AUTHOR]

To uncover the mechanisms that underlie the chlorina phenotype of the tea plant, this study employs morphological, biochemical, transcriptomic, and iTRAQ-based proteomic analyses to compare the green tea cultivar LJ43 and the yellow-leaf tea cultivar ZH1. ZH1 exhibited the chlorina phenotype, with significantly decreased chlorophyll content and abnormal chloroplast development compared with LJ43. ZH1 also displayed higher theanine and free amino acid content and lower carotenoid and catechin content. Microarray and iTRAQ analyses indicated that the differentially expressed genes and proteins could be mapped to the following pathways: ‘phenylpropanoid biosynthesis,’ ‘glutathione metabolism,’ ‘phenylalanine metabolism,’ ‘photosynthesis,’ and ‘flavonoid biosynthesis.’ Altered gene and protein levels in these pathways may account for the increased amino acid content and reduced chlorophyll and flavonoid content of ZH1. Altogether, this study combines transcriptomic and proteomic approaches to better understand the mechanisms responsible for the chlorina phenotype. [ABSTRACT FROM AUTHOR]

Photosynthesis, the primary source of plant biomass, is important for plant growth and crop yield. Chlorophyll is highly abundant in plant leaves and plays essential roles in photosynthesis. We recently isolated a chlorophyll-deficient mutant ( cde1 ) from ethyl methanesulfonate (EMS) mutagenized Brassica napus . Herein, quantitative proteomics analysis using the iTRAQ approach was conducted to investigate cde1 -induced changes in the proteome. We identified 5069 proteins from B. napus leaves, of which 443 showed differential accumulations between the cde1 mutant and its corresponding wild-type. The differentially accumulated proteins were found to be involved in photosynthesis, porphyrin and chlorophyll metabolism, biosynthesis of secondary metabolites, carbon fixation, spliceosome, mRNA surveillance and RNA degradation. Our results suggest that decreased abundance of chlorophyll biosynthetic enzymes and photosynthetic proteins, impaired carbon fixation efficiency and disturbed redox homeostasis might account for the reduced chlorophyll contents, impaired photosynthetic capacity and increased lipid peroxidation in this mutant. Epigenetics was implicated in the regulation of gene expression in cde1 , as proteins involved in DNA/RNA/histone methylation and methylation-dependent chromatin silencing were up-accumulated in the mutant. Biological significance Photosynthesis produces more than 90% of plant biomass and is an important factor influencing potential crop yield. The pigment chlorophyll plays essential roles in light harvesting and energy transfer during photosynthesis. Mutants deficient in chlorophyll synthesis have been used extensively to investigate the chlorophyll metabolism, development and photosynthesis. However, limited information is available with regard to the changes of protein profiles upon chlorophyll deficiency. Here, a combined physiological, histological, proteomics and molecular analysis revealed several important pathways associated with chlorophyll deficiency. This work provides new insights into the regulation of chlorophyll biosynthesis and photosynthesis in higher plants and these findings may be applied to genetic engineering for high photosynthetic efficiency in crops. [ABSTRACT FROM AUTHOR]

Background The tea plant (Camellia sinensis (L.) O. Kuntze) is one of the most economically important woody crops. Recently, many leaf color genotypes have been developed during tea plant breeding and have become valuable materials in the processing of green tea. Although the physiological characteristics of some leaf color mutants of tea plants have been partially revealed, little is known about the molecular mechanisms leading to the chlorina phenotype in tea plants. Results The yellow-leaf tea cultivar Zhonghuang 2 (ZH2) was selected during tea plant breeding. In comparison with Longjing 43 (LJ43), a widely planted green tea cultivar, ZH2 exhibited the chlorina phenotype and displayed significantly decreased chlorophyll contents. Transmission electron microscopy analysis revealed that the ultrastructure of the chloroplasts was disrupted, and the grana were poorly stacked in ZH2. Moreover, the contents of theanine and free amino acids were significantly higher, whereas the contents of carotenoids, catechins and anthocyanin were lower in ZH2 than in LJ43. Microarray analysis showed that the expression of 259 genes related to amino acid metabolism, photosynthesis and pigment metabolism was significantly altered in ZH2 shoots compared with those of LJ43 plants. Pathway analysis of 4,902 differentially expressed genes identified 24 pathways as being significantly regulated, including 'cysteine and methionine metabolism', 'glycine, serine and threonine metabolism', 'flavonoid biosynthesis', 'porphyrin and chlorophyll metabolism' and 'carotenoid biosynthesis'. Furthermore, a number of differentially expressed genes could be mapped to the 'theanine biosynthesis', 'chlorophyll biosynthesis' and 'flavonoid biosynthesis' pathways. Changes in the expression of genes involved in these pathways might be responsible for the different phenotype of ZH2. Conclusion A novel chlorophyll-deficient chlorina tea plant cultivar was identified. Biochemical characteristics were analyzed and gene expression profiling was performed using a custom oligonucleotide-based microarray. This study provides further insights into the molecular mechanisms underlying the phenotype of the chlorina cultivar of Camellia sinensis. [ABSTRACT FROM AUTHOR]

Summary: A major gene controlling chlorophyll deficiency (phenotyped by yellow leaf color, yl) in sunflower was identified and mapped in an F2 population derived from a cross between two breeding lines. Greenness degree was scored by a hand-held chlorophyll meter in the F2 population. Leaf tissue from the parents, F1 hybrids, and some F2 progenies were also sampled to determine the chlorophyll content. All F1 plants had normal green leaf color and the segregation of the plants in the F2 population fits the monogenic ratio (χ (3:1) 2=0.03, p>0.9), indicating that leaf color is a monogenic trait with normal green dominant over yellow leaf color in this population. The contents of chlorophyll a, chlorophyll b, and total chlorophyll in the yellow-leafed lines were reduced by 41.6%, 53.5%, and 44.3%, respectively, in comparison with those in the green-leafed lines. Genetic mapping with molecular markers positioned the gene, yl, to linkage group 10 of sunflower. An SSR marker, ORS 595, cosegregated with yl, and a TRAP marker, B26P17ga5-300, was linked to yl with a genetic distance of 4.2cM. The molecular marker tightly linked to the chlorophyll deficiency gene will provide insight into the process of chlorophyll metabolism in sunflower. [Copyright &y& Elsevier]

Chlorophyll is vital for photosynthesis to produce sugars and other useful biochemical products in green plants. However, the molecular effects of chlorophyll deficiency in Chrysanthemum are largely unknown. In this study, we identified a bud sport mutant chrysanthemum belonging to the variety 'Nannong Binyun', which has yellow branches. Plant physiological studies have shown that the yellow color is revealed due to chlorophyll loss. RNA extracts of yellow and green tissues were analyzed using high-throughput RNA-sequencing, and a total of 11,649 tissue enriched unigenes that respond to chlorophyll deficiency were identified, including 4803 unigenes upregulated in yellow tissues and 6846 unigenes in green tissues. GO analysis revealed that these tissue-enriched genes may involve in the physiological processes of chlorophyll accumulation and photosynthesis. In addition, many DEGs from the families of AP2-EREBP, bHLH, MYB, and FAR1 that are associated with plant development and stress response were detected. Our study found that most of the genes from the GRAS family were downregulated in yellow leaves, indicating their putative roles in stem cell maintenance and possible contribution to leaf size determination. [ABSTRACT FROM AUTHOR]

A series of strains of the homozygous species Oenothera grandiflora (characterized by the genome BB and plastome III) were combined with plastome IV from O. parviflora (BC-IV) by means of appropriate crosses. An incompatibility between genome B and plastome IV is expressed in the haplo- and diplophase: (1) B-IV pollen, though normally developed, is largely inactive. The extent of the inactivation varies between different strains and shows a seasonal fluctuation as determined by seed set in outcrossing and selfing experiments. (2) In most of the strains lethality of BB-IV embryos is the rule, leading to empty seeds. This can be ameliorated by including another plastome in the zygotes and developing embryos on account of the biparental plastid transmission in Oenothera. It can best be demonstrated in crosses with a seed parent having normal green plastids of plastome IV and mutated chlorophyll deficient plastids from a different plastome in the pollen parent, leading to variegated progeny as well as a remainder of empty seeds. (3) In about one-half of the strains the BB-IV plants exhibit a temporary bleaching of the virescens type. The incompatibily between genome B and plastome IV does not support the earlier assumption that plastome IV is the ancestor of plastomes II, III, and V. Instead, a precursor plastome is postulated from which plastomes II, III, and IV are descended. While plastome I can be derived from II, only plastome V can be descended from plastome IV. [ABSTRACT FROM AUTHOR]

The enzymes involved in the biosynthesis of chlorophyll (Chl) in pigment-deficient variegated leaves of Euonymus japonicus were investigated. Each variegated leaf was composed of clearly delineated green and white sectors. The white sectors contained almost no Chls. The rate of synthesis of 5-aminolevulinic acid (ALA) in the white sectors in vivo was twice that in the green sectors. The level of glutamate 1-semialdehyde aminotransferase in the white sectors was much higher than that in the green sectors. Plastidic tRNAGlu was also present at substantial levels in the white sectors, indicating that the system for synthesis of ALA was very active in the white sectors.The activity of porphobilinogen (PBG) synthase in the white sectors in vitro was twice that in the green sectors. In the white sectors the rate of porphyrin synthesis from PBG was 4- to 6-fold higher than in the green sectors. We measured Mg-chelatase activity indirectly in both sectors by monitoring the accumulation of Mg-protoporphyrin IX in the presence of 2,2′-dipyridyl, which inhibits isocyclic ring formation with the resultant accumulation of Mg-protoporphyrin IX. When sectors were incubated in darkness with 2,2′-dipyridyl, large amounts of protoporphyrin IX accumulated in the white sectors, whereas Mg-protoporphyrin IX mainly accumulated in the green sectors. These results suggest that the enzymes for the synthesis of porphyrin that catalyze conversion of ALA to protoporphyrin IX were very active and that the Mg-insertion step might be blocked in the white sectors, with the resultant failure to synthesize Chl. The deficiency is discussed in a comparison with that in other Chl-deficient plants. [ABSTRACT FROM AUTHOR]

Red mangrove (Rhizophora mangle) possesses two traits that make it an ideal species for the measurement of per generation mutation rates in natural populations: vivipary and self-pollination. Vivipary allows the scoring of offspring phenotypes when they are attached to the maternal parent and self-pollination results in the attainment of near mutation/selection equilibria in relatively few generations. Mutation rates for the multigenic mutant phenotype chlorophyll-deficiency are presented for mangroves and the rates are compared to other plant taxa. Patterns are evident for marginal vs., central populations and for variations in life-form. [ABSTRACT FROM AUTHOR]

In gamma-ray treated populations of tomato, one of the plants showed stickiness of chromosomes at meiosis. At diakinesis, some of the bivalents tended to fall apart as univalents, and at about the same time or a little later, the bivalents and/or univalents congregated into groups. At metaphase I, the number of such groups varied from 1 to 14 and the groups were of various sizes; the masses of chromatin in which the individuality of chromosomes seemed to be completely lost were spherical, oval or irregular in outline and freely dispersed in the cytoplasm. Some of the masses were so small that they might possibly represent fragments of chromosomes. As the stage passed to anaphase I, the masses dissolved into individual chromosomes, even though stickiness was still persistent but less intense. Laggards in varying numbers were also found. At completion of meiosis, in some proportion of telophase II cells, persistent laggards were found. Pollen fertility and seed set were low. The selfed M progeny of the sticky plant contained a few yellow seedlings which died at the cotyledon stage. Cytological examination of meiosis of some of the individuals of this progeny revealed stickiness again in a majority of plants. Sticky as well as normal plants in M were selfed and the M generation raised. In progenies of both kinds, yellow lethals were found in proportions that gave a good fit with three green to one yellow seedlings in many cases. The occurrence of a sticky plant in M and many such plants in M was assumed to be due to a dominant mutation induced by gamma irradiation. This, besides causing sticky meiosis, also produced recessive yellow lethal mutations. [ABSTRACT FROM AUTHOR]

High frequency of albino plant formation in isolated microspore or anther cultures is a great problem limiting the possibility of their exploitation on a wider scale. It is highly inconvenient as androgenesis-based doubled haploid (DH) technology provides the simplest and shortest way to total homozygosity, highly valued by plant geneticists, biotechnologists and especially, plant breeders, and this phenomenon constitutes a serious limitation of these otherwise powerful tools. The genotype-dependent tendency toward albino plant formation is typical for many monocotyledonous plants, including cereals like wheat, barley, rice, triticale, oat and rye - the most important from the economical point of view. Despite many efforts, the precise mechanism underlying chlorophyll deficiency has not yet been elucidated. In this chapter, we review the data concerning molecular and physiological control over proper/disturbed chloroplast biogenesis, old hypotheses explaining the mechanism of chlorophyll deficiency, and recent studies which shed new light on this phenomenon., (© 2021. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Low temperature affects a broad spectrum of cellular components in plants, such as chloroplasts, as well as plant metabolism. On the other hand, pseudouridine (Ψ) synthases are required for the most abundant post-transcriptional modification of RNA in Escherichia coli. However, the role of rice Ψ synthases in regulating chloroplast development at low temperature remains elusive. In this study, we identified the rice thermo-sensitive chlorophyll-deficient (tcd3) mutant, which displays an albino phenotype before the 4-leaf stage and ultimately dies when grown at 20 °C, but can grow normally at 32 °C. Genetic analysis showed that the mutant trait is controlled by a single recessive nuclear gene (tcd3). Map-based cloning, complementation and knockout tests revealed that TCD3 encodes a chloroplast-localized Ψ synthase. TCD3 is a cold-induced gene that is mainly expressed in leaves. The disruption of TCD3 severely affected the transcript levels of various chloroplast-associated genes, as well as ribosomal genes involved in chloroplast rRNA assembly at low temperature (20 °C), whereas the transcript levels of these genes were normal at high temperature (32 °C). These results provide a first glimpse into the importance of rice Ψ synthase gene in chloroplast development at low temperatures.

Cytoplasmic male. steriles of Brassica campestris ssp. oleifera var. brown sarson were obtained in BC[sub5] generation progenies following the repeated backcrossing of the synthetic alloploid B. oxyrrhina (2n = 18, OO) × B. campestris (2n = 20, AA). Alloplasmic B. campestris plants resemble B. campestris in morphology and growth pattern and do not exhibit any trait of B. oxyrrhina. However, the leaves are mildly chlorophyll deficient in the earlier stages and turn green at late stages in the development . the reproductive parts don not show any abnormalities except that the anthers are smaller and slenderer than the normal ones and are non-dehiscent, containing only sterile pollen. [ABSTRACT FROM AUTHOR]

In Australia, some trees of the mangrove, Avicennia marina, growing in a chronic oil polluted site, produce chlorophyll deficient (albino) propagules. We tested the hypothesis that albinism was due to an oil-induced mutant allele that controls photosynthesis. We determined whether there are genetic differences between normal and chlorophyll deficient propagules. Four gene regions (nuclear 18S–26S cistron; chloroplast - trn H -psb A, rsp 16 and mat K) were sequenced and analysed for normal and albino propagules. Mutations occurred in both nuclear (ITS) and coding chloroplast (mat K) genes of albino propagules. There were 10 mutational differences between normal and albino propagules in the mat K samples. Analysis of molecular variation (AMOVA) of the mat K dataset indicated highly significant genetic differentiation between normal and albino propagules. Our study suggests for the first time that PAHs from a chronic oil polluted site resulted in mutations in both nuclear and chloroplast genes, resulting in the production of albino propagules. [ABSTRACT FROM AUTHOR]

Recent studies have shown that chlorophyll (Chl) b has an important role in the regulation of leaf senescence. However, there is only limited information about senescence of plants lacking Chl b and senescence-induced decrease in photosystem II (PSII) and photosystem I (PSI) function has not even been investigated in such plants. We have studied senescence-induced changes in photosynthetic pigment content and PSII and PSI activities in detached leaves of Chl b-deficient barley mutant, chlorina f2 f2 (clo). After 4 days in the dark, the senescence-induced decrease in PSI activity was smaller in clo compared to WT leaves. On the contrary, the senescence-induced impairment in PSII function (estimated from Chl fluorescence parameters) was much more pronounced in clo leaves, even though the relative decrease in Chl content was similar to wild type (WT) leaves (Hordeum vulgare L., cv. Bonus). The stronger impairment of PSII function seems to be related to more pronounced damage of reaction centers of PSII. Interestingly, exogenously applied plant hormone cytokinin 6-benzylaminopurine (BA) was able to maintain PSII function in the dark senescing clo leaves to a similar extent as in WT. Thus, considering the fact that without BA the senescence-induced decrease in PSII photochemistry in clo was more pronounced than in WT, the relative protective effect of BA was higher in Chl b-deficient mutant than in WT., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

To uncover mechanism of highly weakened carbon metabolism in chlorotic tea (Camellia sinensis) plants, iTRAQ (isobaric tags for relative and absolute quantification)-based proteomic analyses were employed to study the differences in protein expression profiles in chlorophyll-deficient and normal green leaves in the tea plant cultivar "Huangjinya". A total of 2110 proteins were identified in "Huangjinya", and 173 proteins showed differential accumulations between the chlorotic and normal green leaves. Of these, 19 proteins were correlated with RNA expression levels, based on integrated analyses of the transcriptome and proteome. Moreover, the results of our analysis of differentially expressed proteins suggested that primary carbon metabolism (i.e., carbohydrate synthesis and transport) was inhibited in chlorotic tea leaves. The differentially expressed genes and proteins combined with photosynthetic phenotypic data indicated that 4-coumarate-CoA ligase (4CL) showed a major effect on repressing flavonoid metabolism, and abnormal developmental chloroplast inhibited the accumulation of chlorophyll and flavonoids because few carbon skeletons were provided as a result of a weakened primary carbon metabolism. Additionally, a positive feedback mechanism was verified at the protein level (Mg chelatase and chlorophyll b reductase) in the chlorophyll biosynthetic pathway, which might effectively promote the accumulation of chlorophyll b in response to the demand for this pigment in the cells of chlorotic tea leaves in weakened carbon metabolism. [ABSTRACT FROM AUTHOR]

Background: Plastome mutants are ideal resources for elucidating the functions of plastid genes. Numerous studies have been conducted for the function of plastid genes in barley and tobacco; however, related information is limited in Chinese cabbage., Results: A chlorophyll-deficient mutant of Chinese cabbage that was derived by ethyl methanesulfonate treatment on isolated microspores showed uniformly pale green inner leaves and slow growth compared with that shown by the wild type "Fukuda 50' ('FT'). Genetic analysis revealed that cdm was cytoplasmically inherited. Physiological and ultrastructural analyses of cdm showed impaired photosynthesis and abnormal chloroplast development. Utilizing next generation sequencing, the complete plastomes of cdm and 'FT' were respectively re-mapped to the reference genome of Chinese cabbage, and an A-to-C base substitution with a mutation ratio higher than 99% was detected. The missense mutation of plastid ribosomal protein S4 led to valine substitution for glycine at residue 193. The expression level of rps4 was analyzed using quantitative real-time PCR and found lower in than in 'FT'. RNA gel-blot assays showed that the abundance of mature 23S rRNA, 16S rRNA, 5S rRNA, and 4.5S rRNA significantly decreased and that the processing of 23S, 16S rRNA, and 4.5S rRNA was seriously impaired, affecting the ribosomal function in cdm., Conclusions: These findings indicated that cdm was a plastome mutant and that chlorophyll deficiency might be due to an A-to-C base substitution of the plastome-encoded rps4 that impaired the rRNA processing and affected the ribosomal function.

The photosynthetic, optical, and morphological characteristics of a chlorophyll-deficient (Chl-deficient) "yellow" soybean mutant (MinnGold) were examined in comparison with 2 green varieties (MN0095 and Eiko). Despite the large difference in Chl content, similar leaf photosynthesis rates were maintained in the Chl-deficient mutant by offsetting the reduced absorption of red photons by a small increase in photochemical efficiency and lower non-photochemical quenching. When grown in the field, at full canopy cover, the mutants reflected a significantly larger proportion of incoming shortwave radiation, but the total canopy light absorption was only slightly reduced, most likely due to a deeper penetration of light into the canopy space. As a consequence, canopy-scale gross primary production and ecosystem respiration were comparable between the Chl-deficient mutant and the green variety. However, total biomass production was lower in the mutant, which indicates that processes other than steady state photosynthesis caused a reduction in biomass accumulation over time. Analysis of non-photochemical quenching relaxation and gas exchange in Chl-deficient and green leaves after transitions from high to low light conditions suggested that dynamic photosynthesis might be responsible for the reduced biomass production in the Chl-deficient mutant under field conditions., (© 2018 John Wiley & Sons Ltd.)

Ion beams are powerful mutagens that can induce novel mutants in plants. We previously established a system for producing a mutant population of soybean via ion-beam irradiation, isolated plants that had chlorophyll deficiency, and maintained their progeny via self-fertilization. Here we report the characterization of the progeny plants in terms of chlorophyll content, flowering time and isoflavone content in seeds. Chlorophyll deficiency in the leaf tissues was linked with reduced levels of isoflavones, the major flavonoid compounds accumulated in soybean seeds, which suggested the involvement of metabolic changes associated with the chlorophyll deficiency. Intriguingly, flowering time was frequently altered in plants that had a reduced level of chlorophyll in the leaf tissues. Plant lines that flowered either earlier or later than the wild-type plants were detected. The observed coincidental changes were presumed to be attributable to the following origins: structural changes of DNA segments leading to the loss of multiple gene functions, or indirect effects of mutations that affect one of these traits, which were manifested as phenotypic changes in the background of the duplicated composition of the soybean genome.

The Spo0B-associated GTP-binding (Obg) proteins are essential for the viability of nearly all bacteria. However, the detailed roles of Obg proteins in higher plants have not yet been elucidated. In this study, we identified a novel rice ( Oryza sativa L.) thermo-sensitive virescent mutant ( tsv3 ) that displayed an albino phenotype at 20° before the three-leaf stage while being a normal green at 32° or even at 20° after the four-leaf stage. The mutant phenotype was consistent with altered chlorophyll content and chloroplast structure in leaves. Map-based cloning and complementation experiments showed that TSV3 encoded a small GTP-binding protein. Subcellular localization studies revealed that TSV3 was localized to the chloroplasts. Expression of TSV3 was high in leaves and weak or undetectable in other tissues, suggesting a tissue-specific expression of TSV3 In the tsv3 mutant, expression levels of genes associated with the biogenesis of the chloroplast ribosome 50S subunit were severely decreased at the three-leaf stage under cold stress (20°), but could be recovered to normal levels at a higher temperature (32°). These observations suggest that the rice nuclear-encoded TSV3 plays important roles in chloroplast development at the early leaf stage under cold stress., (Copyright © 2018 Lin et al.)

The seeds of most heterotrophic plants, commonly referred to as dust seeds, are typically dispersed in the air like dust particles. Therefore, little attention has been paid to how seeds of heterotrophic plants are dispersed, owing to the notion that wind dispersal is the dominant strategy. However, inconspicuous but fleshy, indehiscent fruit can be observed in distantly related plants that have independently evolved full heterotrophy. Here I investigated the seed dispersal system in three unrelated fully heterotrophic plants with fleshy, indehiscent fruits (Yoania amagiensis, Monotropastrum humile and Phacellanthus tubiflorus) by direct observation, a differential exclusion experiment of fruit feeders and investigation on seed viability through the digestive tract. The present study revealed that camel crickets are the major seed disperser in three achlorophyllous plants in the study population. This represents the first evidence of seed dispersal by camel crickets in any angiosperm species. These heterotrophic plants grow in the understorey of densely vegetated forests where wind is probably an ineffective seed dispersal agent. Life-history traits of the achlorophyllous plants associated with heterotrophic lifestyles, such as colonization of dark understorey habitats and dust seeds, could facilitate independent recruitment of the novel endozoochorous seed dispersal system by camel crickets., (© 2017 The Author. New Phytologist © 2017 New Phytologist Trust.)

Melatonin is involved in the regulation of carbohydrate metabolism and induction of cold tolerance in plants. The objective of this study was to investigate the roles of melatonin in modulation of carbon assimilation of wild-type wheat and the Chl b-deficient mutant ANK32B in response to elevated CO 2 concentration ([CO 2 ]) and the transgenerational effects of application of exogenous melatonin (hereafter identified as melatonin priming) on the cold tolerance in offspring. The results showed that the melatonin priming enhanced the carbon assimilation in ANK32B under elevated [CO 2 ], via boosting the activities of ATPase and sucrose synthesis and maintaining a relatively higher level of total chlorophyll concentration in leaves. In addition, melatonin priming in maternal plants at grain filling promoted the seed germination in offspring by accelerating the starch degradation and improved the cold tolerance of seedlings through activating the antioxidant enzymes and enhancing the photosynthetic electron transport efficiency. These findings suggest the important roles of melatonin in plant response to future climate change, indicating that the melatonin priming at grain filling in maternal plants could be an effective approach to improve cold tolerance of wheat offspring at seedling stage., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The effects of high temperature on CO 2 assimilation rate, processes associated with photosynthetic electron and proton transport, as well as photoprotective responses, were studied in chlorophyll b-deficient mutant lines (ANK-32A and ANK-32B) and wild type (WT) of wheat (Triticum aestivum L.). Despite the low chlorophyll content and chlorophyll a-to-b ratio, the non-stressed mutant plants had the similar level of CO 2 assimilation and photosynthetic responses as WT. However, in ANK mutant plants exposed to prolonged high temperature episode (42 °C for ~10 h), we observed lower CO 2 assimilation compared to WT, especially when a high CO 2 supply was provided. In all heat-exposed plants, we found approximately the same level of PSII photoinhibition, but the decrease in content of photooxidizable PSI was higher in ANK mutant plants compared to WT. The PSI damage can be well explained by the level of overreduction of PSI acceptor side observed in plants exposed to high temperature, which was, in turn, the result of the insufficient transthylakoid proton gradient associated with low non-photochemical quenching and lack of ability to downregulate the linear electron transport to keep the reduction state of PSI acceptor side low enough. Compared to WT, the ANK mutant lines had lower capacity to drive the cyclic electron transport around PSI in moderate and high light; it confirms the protective role of cyclic electron transport for the protection of PSI against photoinhibition. Our results, however, also suggest that the inactivation of PSI in heat stress conditions can be the protective mechanism against photooxidative damage of chloroplast and cell structures.

Key Message: The cucumber chlorophyll-deficient golden leaf mutation is due to a single nucleotide substitution in the CsChlI gene for magnesium chelatase I subunit which plays important roles in the chlorophyll biosynthesis pathway. The Mg-chelatase catalyzes the insertion of Mg(2+) into the protoporphyrin IX in the chlorophyll biosynthesis pathway, which is a protein complex encompassing three subunits CHLI, CHLD, and CHLH. Chlorophyll-deficient mutations in genes encoding the three subunits have played important roles in understanding the structure, function and regulation of this important enzyme. In an EMS mutagenesis population, we identified a chlorophyll-deficient mutant C528 with golden leaf color throughout its development which was viable and able to set fruits and seeds. Segregation analysis in multiple populations indicated that this leaf color mutation was recessively inherited and the green color showed complete dominance over golden color. Map-based cloning identified CsChlI as the candidate gene for this mutation which encoded the CHLI subunit of cucumber Mg-chelatase. The 1757-bp CsChlI gene had three exons and a single nucleotide change (G to A) in its third exon resulted in an amino acid substitution (G269R) and the golden leaf color in C528. This mutation occurred in the highly conserved nucleotide-binding domain of the CHLI protein in which chlorophyll-deficient mutations have been frequently identified. The mutant phenotype, CsChlI expression pattern and the mutated residue in the CHLI protein suggested the mutant allele in C528 is unique among mutations identified so far in different species. This golden leaf mutant not only has its potential in cucumber breeding, but also provides a useful tool in understanding the CHLI function and its regulation in the chlorophyll biosynthesis pathway as well as chloroplast development.

Leaf colour regulation is important in photosynthesis and dry material production. Most of the reported chlorophyll-deficient loci are recessive. The dominant locus is rarely reported, although it may be more important than the recessive locus in the regulation of photosynthesis efficiency. During the present study, we mapped a chlorophyll-deficient dominant locus (CDE1) from the ethyl methanesulfonate-mutagenized Brassica napus line NJ7982. Using an F2 population derived from the chlorophyll-deficient mutant (cde1) and the canola variety 'zhongshuang11', a high-density linkage map was constructed, consisting of 19 linkage groups with 2,878 bins containing 13,347 SNP markers, with a total linkage map length of 1,968.6 cM. Next, the CDE1 locus was mapped in a 0.9-cM interval of chromosome C08 of B. napus, co-segregating with nine SNP markers. In the following fine-mapping of the gene using the inherited F2:3 populations of 620 individuals, the locus was identified in an interval with a length of 311 kb. A bioinformatics analysis revealed that the mapping interval contained 22 genes. These results produced a good foundation for continued research on the dominant locus involved in chlorophyll content regulation.

The soybean [Glycine max (L.) Merr.] chlorophyll-deficient line MinnGold is a spontaneous mutant characterized by yellow foliage. Map-based cloning and transgenic complementation revealed that the mutant phenotype is caused by a nonsynonymous nucleotide substitution in the third exon of a Mg-chelatase subunit gene (ChlI1a) on chromosome 13. This gene was selected as a candidate for a different yellow foliage mutant, T219H (Y11y11), that had been previously mapped to chromosome 13. Although the phenotypes of MinnGold and T219H are clearly distinct, sequencing of ChlI1a in T219H identified a different nonsynonymous mutation in the third exon, only six base pairs from the MinnGold mutation. This information, along with previously published allelic tests, were used to identify and clone a third yellow foliage mutation, CD-5, which was previously mapped to chromosome 15. This mutation was identified in the ChlI1b gene, a paralog of ChlI1a. Sequencing of the ChlI1b allele in CD-5 identified a nonsynonymous substitution in the third exon that confers an identical amino acid change as the T219H substitution at ChlI1a. Protein sequence alignments of the two Mg-chelatase subunits indicated that the sites of amino acid modification in MinnGold, T219H, and CD-5 are highly conserved among photosynthetic species. These results suggest that amino acid alterations in this critical domain may create competitive inhibitory interactions between the mutant and wild-type ChlI1a and ChlI1b proteins., (Copyright © 2015 Campbell et al.)

Background: Etiolated seedlings initiate grana stacking and chlorophyll biosynthesis in parallel with the first exposure to light, during which phytochromes play an important role. Functional phytochromes are biosynthesized separately for two components. One phytochrome is biosynthesized for apoprotein and the other is biosynthesized for the chromophore that includes heme oxygenase (HO)., Methodology/principal Finding: We isolated a ho1 homolog by map-based cloning of a maize elongated mesocotyl2 (elm2) mutant. cDNA sequencing of the ho1 homolog in elm2 revealed a 31 bp deletion. De-etiolation responses to red and far-red light were disrupted in elm2 seedlings, with a pronounced elongation of the mesocotyl. The endogenous HO activity in the elm2 mutant decreased remarkably. Transgenic complementation further confirmed the dysfunction in the maize ho1 gene. Moreover, non-appressed thylakoids were specifically stacked at the seedling stage in the elm2 mutant., Conclusion: The 31 bp deletion in the ho1 gene resulted in a decrease in endogenous HO activity and disrupted the de-etiolation responses to red and far-red light. The specific stacking of non-appressed thylakoids suggested that the chlorophyll biosynthesis regulated by HO1 is achieved by coordinating the heme level with the regulation of grana stacking.

Residual chlorophyll in chlorophyll-deficient (albino) areas of variegated leaves of Ficus benjamina originates from guard cell chloroplasts. Photosynthetic features of green and albino sectors of F. benjamina were studied by imaging the distribution of the fluorescence decrease ratio Rfd within a leaf calculated from maximum (Fm) and steady-state leaf chlorophyll fluorescence (Fs) at 690 and 740 nm. Local areas of albino sectors demonstrated an abnormally high Rfd(740)/Rfd(690) ratio. Fluorescence transients excited in albino sectors at red (640 and 690 nm) wavelengths showed an abrupt decrease of the Rfd values (0.4 and 0.1, correspondingly) as compared with those excited at blue wavelengths (1.7-2.4). This "Red Drop" was not observed for green sectors. Normal and chlorophyll-deficient leaf sectors of F. benjamina were also tested for linear and cyclic electron transport in thylakoids. The tests have been performed studying fluorescence at a steady-state phase with CO(2)-excess impulse feeding, photoacoustic signal generated by pulse light source at wavelengths selectively exciting PSI, fluorescence kinetics under anaerobiosis and fluorescence changes observed by dual-wavelength excitation method. The data obtained for albino sectors strongly suggest the possibility of a cyclic electron transport simultaneously occurring in guard cell thylakoids around photosystems I and II under blue light, whereas linear electron transport is absent or insufficient.

Bare-root transplants of strawberry (Fragaria ananassa Duch. cv. 'Selva') were transferred to nutrient solutions with or without iron (Fe). After six weeks of growth, plants grown in solution lacking Fe were chlorotic and showed morphological changes in roots typical of Fe deficiency. Subsequently, four treatments were applied for nine days: plants grown in continued absence of Fe (Fe0); plants grown in continued presence of 10 μM Fe (Fe10); foliar application of ferrous sulphate every two days to chlorotic plants (Fe-leaves); and growth of chlorotic plants in solution with ferrous sulphate (Fe-solution). After six days, the chlorophyll (Chl) content in leaves of Fe-solution plants was similar to that in Fe10 plants. Under the Fe-leaves treatment, a slight regreening of new leaves was observed only by the end of the experiment. After nine days, ferric chelate reductase (FC-R) activity was unchanged in Fe10 but increased in Fe0 plants. The FC-R activity of Fe-solution plants was similar to the initial value for chlorotic plants, whereas it was reduced drastically under the Fe-leaves treatment. The Fe concentration in leaves of Fe0 and Fe10 was similar, whereas the Fe-solution and Fe-leaves treatments enhanced leaf Fe concentration. In contrast to the Fe-solution treatment, foliar application of Fe did not increase the Fe concentration in roots. Under our experimental conditions, FC-R activity in strawberry appeared to be deactivated rapidly by pulses of Fe applied by foliar sprays. Deactivation was slower if Fe was applied directly to roots, which suggested that the plants had greater opportunity to take Fe., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)