The modern pharmaceutics actively screens an immense diversity of substances occurring in plants and other natural resources in the search for new effective medicinal agents. The Global Institute for Bioexploration (GIBEX) established by joint efforts of Rutgers University and the University of Illinois (United States) represents the organizational core of international scientific community whose activity is directed towards the search and development of new medicinal preparations from natural raw materials. The basis of GIBEX activity is the transfer of modern screening technologies to countries and geographical regions characterized by remarkable biodiversity. The GIBEX goals are to encourage the search for new natural biologically active substances, to maintain biodiversity, and to monitor the natural resources conservation.
Treatment of chlorella (Chlorella sp.) cells for 2 h in darkness with tetrapyrrole-dependent photodynamic herbicides (TDPH) derived on the basis of 0.3 mM
1,10-phenanthroline (Ph) combined with 0.6 mM Glu or 0.6 mM Gln induced the accumulation of sensitizers of photodynamic processes:
magnesium protoporphyrin IX (MgPP) and MgPP monomethyl ester (MgPPE). Within the first day after chlorella cells treated with
TDPH were illuminated, photodestruction of MgPP(E) was observed, and production of the first specific precursor of chlorophyll
(Chl), 5-aminolevulinic acid (ALA), in the cells declined. Then the accumulation of ALA was stimulated, and the level of heme,
which is a retroinhibitor of ALA synthesis, simultaneously fell. During the first two days of illumination, the content of
Chl and carotenoids in the algae treated with TDPH did not differ from their levels in control culture, which suggests a high
resistance of photosynthetic pigments to photodynamic process induced by porphyrins. Subsequently, a slight but rising in
time accumulation of pheophytin (Pheo) was observed, as well as photodestruction of Chl and carotenoids. After five days of
illumination, the difference in the content of Chl between the culture treated with TDPH and control material was 10–30% depending
on the illuminance. Chlorella cells treated with TDPH remained capable of producing Chl from exogenous ALA in the dark for
at least eight days. In the experiments simultaneously conducted with a higher plant, cucumber (Cucumis sativa L.), which accumulated in the dark essentially the same content of porphyrins in response to TDPH as algae did, the residual
level of Chl after five days of illumination was only 10–20% of control plants. It was assumed that a high tolerance of the
chlorella pigment pool to photooxidative stress induced by the accumulation of MgPP(E) and Pheo depended on a highly active
state of the antioxidant protective system and the ability of ALA molecules additionally formed under the influence of TDPH
to be converted into Chl, thereby participating in its de novo synthesis.
In the roots of bread wheat (Triticum aestivum L.) seedlings, the effects of pretreatment with 28 nM wheat germ agglutinin (WGA) and successive action of 1 mM cadmium acetate
on growth, phytohormone balance, lignin deposition, and also cadmium accumulation and distribution were studied. Priority
data on cadmium-induced ABA-mediated reversible accumulation of WGA in the roots, which was accompanied by its excretion in
the medium of seedling incubation, were obtained. Pretreatment with WGA exerted a clear protective effect on seedling growth
in the presence of cadmium, which was based on a decrease in the amplitude of stress-induced shifts in the balance between
IAA and ABA and preventing the reduction in the cytokinin level. Acceleration of lignification of the cell walls in the basal
parts of roots of seedlings pretreated with WGA and subjected to stress is shown, and this limits cadmium entry into the plant.
–wheat germ agglutinin–cadmium acetate–mitotic index–phytohormones–lignification–cadmium localization
Regulatory changes in the activity of the plasma membrane H+-ATPase in salt-stressed roots were investigated using seven-day-old seedlings of two cultivars of barley (Hordeum disticum L.) with different salt tolerances: Moskovskii-121 (salt-tolerant) and Elf (salt-sensitive). During the first hour of salt stress, the rate of proton extrusion from the excised roots increased in parallel with the ATP hydrolase activity and the amount of 14-3-3 proteins bound to H+-ATPase in isolated plasma membranes. Subsequently, all these parameters decreased and dropped after 3–6 h below the initial levels. The initial stimulation of proton extrusion from the detached barley roots was caused by osmotic stress, whereas the subsequent retardation of proton extrusion was probably caused by a toxic effect of excessive Na+ content in the cytoplasm. The salt-stress responses showed similar trends in both cultivars, with the exception that Moskovskii-121 responded faster than cv. Elf. The results indicate that 14-3-3 proteins regulate the H+-ATPase activity in the plasma membranes of barley root cells during salt stress; furthermore, the response time might be a useful indicator to discriminate cultivars with different salt tolerances.
Pea (Pisum sativum L.) root treatment with salicylic acid (SA) changed the content of some proteins and incorporation of 14C-amino acids into proteins. The analysis of changes in these indices allowed us to subdivide all proteins into the four groups:
(1) most abundant SA-independent proteins; (2) SA-dependent proteins, which content and 14C-amino acids incorporation both increased; (3) SA-dependent proteins, which content and 14C-amino acids incorporation both decreased; and (4) SA-dependent proteins, which content was not essentially changed (referred
earlier to SA-independent proteins) but 14C-amino acids incorporation into these proteins was strongly suppressed. It is very likely that proteolysis of the proteins
referred to the fourth group is very low and even a strong inhibition of their synthesis (incorporation of 14C-amino acids) does not result in the substantial decrease in their contents. Some SA-dependent proteins were identified by
means of modern methods of proteomics: phosphoglyceromutase, S-adenosylmethionine synthase 3, enolase, chalcone isomerase,
nucleoside diphosphate kinase 1, and tioredoxin h.
–salicylic acid–proteomic analysis–
14C-amino acids–salicylate-inducible proteins
All higher plants have high-specific sites for binding fusicoccin (FCBS), a metabolite of the fungus Fusicoccum amygdaliDel. These sites are localized on the plasmalemma and produced by the association of the dimers of 14-3-3 proteins with the C-terminal autoinhibitory domain of H+-ATPase. Considering the fusicoccin binding to the plasmalemma as an index characterizing the formation of this complex, we studied the influence of osmotic stress on the interaction between 14-3-3 proteins and H+-ATPase in the suspension-cultured sugar beet cells and protoplasts obtained from them. An increase in the osmolarity of the extracellular medium up to 0.3 Osm was shown to enhance proton efflux from the cells by several times. The number of FCBS in isolated plasma membranes increased in parallel, whereas 14-3-3 proteins accumulated in this membrane to a lesser degree. The amount of H+-ATPase molecules did not change, and the ATP-hydrolase activity changed insignificantly. The data obtained indicate that osmotic stress affects H+-ATPase pumping in the plasmalemma through its influence on the coupling between H+-transport and ATP hydrolysis; 14-3-3 proteins are involved in this coupling. The interaction between the plasmalemma and the cell wall is suggested to be very important in this process.
The transport of salicylic acid (SA) in heat-stressed Vitis vinifera plants was studied with 14C-salicylic acid. All leaves of young plants were cut off except the 4th, 5th, 6th, 7th, and 8th leaves. After the 6th leaves were fed with 14C-SA, the following treatments were conducted: (1) 4th, 6th, or 8th leaves were exposed to a high temperature of 38C for 2, 6, and 12 h, respectively, while other parts of plants were kept at 27C; (2) plants were kept at 27C for 2, 6, and 12 h. The results showed that 14C-SA accumulated in the leaves stressed by heat. When the 6th leaves were at 38C, less 14C-SA was exported from these leaves than from control leaves, but when the 4th or 8th leaves were kept at 38C, more 14C-SA was exported. 14C-SA accumulation in the 4th or 8th leaves resulted from the 6th leaves directly and from the other parts of plants indirectly. These data suggested that SA was transported to a long distance and might be involved in the induction of heat tolerance.
The effects of blue light (BL), green light (GL), and red light (RL) on morphogenesis photoregulation of transgenic tobacco
(Nicotiana tabacum L.) plants containing a copy of human interleukin-18 gene were studied. Wild-type and transgenic (Il1 No.87–1 and Il18 No.7–11)
lines and derived calluses were used. Photomorphogenesis of transgenic lines under GL and RL differed substantially from that
of initial line at early stages of morphogenesis; this was expressed in hypocotyl lengthening under GL and cotyledon enhanced
expansion under RL. Growth responses to light quality were related to changes in the levels of zeatin, IAA, and ABA. Thus,
hypocotyl lengthening and increased cotyledon area under GL occurred at the elevated level of IAA and reduced level of ABA.
Growth of callus cells in transgenic lines during zero passage differed from wild-type calluses only in darkness. The data
obtained indicate that tobacco plant transformation with the human interleukin-18 gene changed functioning of the photoregulation
systems at early developmental stages. This phenomenon is evidently explained by the pleiotropic effects of the gene inserted.
The effect of hormone-like compounds at different concentrations: 2,4-D (2 × 10−6; 2 × 10−5; and 2 × 10−4M) and 1-NAA (2 × 10−7; 2 × 10−6; 2 × 10−5; 4 × 10−5, and 6 × 10−5 M) on the growth and production of phenolic compounds, including flavans and lignin, was investigated in callus culture of
tea plant (Camellia sinensis L., a highly productive strain IFR ChS-2). The growth of the culture was vigorous, and production of phenolic compounds therein
was efficient in the medium containing 2 × 10−5 M 2,4-D. Substitution of 1-NAA for 2,4-D in all the cases decelerated the growth of the culture. These changes were more
pronounced when 2 × 10−7 and 2 × 10−6 M 1-NAA was used; in this case, biomass accumulation decreased by 1.5–2.0 times as compared with control material growing
on the medium with 2 × 10−5 M 2,4-D. In the presence of 1-NAA, the content of total soluble phenolic compounds and flavans in the calli rose by 30% on
the average as compared with control material. Accumulation of lignin remained essentially the same. Therefore, the replacement
of 2,4-D with 1-NAA in the nutrient medium used for the growing of highly productive strain of tea plant callus did not induce
considerable changes in its ability to produce phenolic compounds.
Mild heat shock induces the synthesis of heat shock proteins (HSP) protecting the cell from damages during subsequent severe
heat shock. The nature of the signal inducing transcription of Hsp genes is poorly investigated. We studied the effects of
mitochondrial inhibitors, sodium azide and dinitrophenol (DNP) on the development of induced thermotolerance and induction
of Hsp101 and Hsp60 syntheses in the suspension culture of Arabidopsis thaliana. The presence of sodium azide and DNP during mild heat shock was shown to suppress heat-induced synthesis of Hsp101 and development
of induced thermotolerance in the A. thaliana cultured cells. Severe heat shock (50°C) resulted in programmed cell death as was evident from reduced cell viability and
cytochrome c release. The results obtained permit a supposition that the functional state of mitochondria determines Hsp gene expression
in A. thaliana subjected to heat shock.
Key wordsArabidopsis thaliana–sodium azide–dinitrophenol–induced thermotolerance–mitochondria–Hsp101–Hsp60
Effects of synthetic auxins (2,4-D and NAA) on growth of true ginseng (Panax ginseng C.A. Mey) suspension culture and ginsenoside synthesis were investigated. Cell suspensions were grown for 6–8 subcultures
on media supplemented with various phytohormones. In all media supplemented with 2,4-D and cytokinins (benzyladenine or kinetin),
the cell culture showed sustained growth both in the presence and absence of casein hydrolysate. The average growth index,
determined from fresh weight increment over one subculture, equaled to 5.16 ± 0.90, and the maximum mitotic index was 2%.
These cell populations having cell volume of 10–17 × 104 μm3 were composed mostly (up to 60–80%) of 5-to 10-cell aggregates with unimodal distribution of nuclear DNA. These cell suspensions
were suitable for isolation of protoplasts. The total average content of ginsenosides in the cell culture grown in the presence
of 2,4-D constituted 0.18% of dry matter. In media supplemented with NAA, the cell growth was retarded irrespective of the
cytokinin species and presence or absence of casein hydrolysate. The growth index (the ratio of final to initial fresh weights)
was on average 2.15 ± 0.37, and the mitotic index did not exceed 0.13%. These suspensions, characterized by cell volume of
22–50 × 104 μm3, were composed of large aggregates (> 50 cells). The attempts to isolate protoplasts from these suspensions were unsuccessful.
About 25% of cells cultured in the presence of NAA had doubled nuclear DNA content by the end of the subculture. The total
content of ginsenosides in cell cultures grown with NAA was on average 4.46% of cell dry matter. The results indicate that
ginsenoside synthesis depends on the extent of differentiation in the population of true ginseng cells grown in suspension
culture. A certain extent of cytodifferentiation in the cell culture was observed in the presence of NAA, whereas 2,4-D supported
only cell proliferation in vitro.
Two barley cultivars (Hordeum vulgare L., cvs. Elo and Belogorskii) differing in salt tolerance were used to study 22Na+ uptake, expression of three isoforms of the Na+/H+ antiporter HvNHX1-3, and the cellular localization of these isoforms in the elongation zone of seedling roots. During short
(1 h) incubation, seedling roots of both cultivars accumulated approximately equal quantities of 22Na+. However, after 24-h incubation the content of 22Na+ in roots of a salt-tolerant variety Elo was 40% lower than in roots of the susceptible variety Belogorskii. The content of
22Na+ accumulated in shoots of cv. Elo after 24-h incubation was 6.5 times lower than in shoots of cv. Belogorskii and it was 4
times lower after the salt stress treatment. The cytochemical examination revealed that three proteins HvNHX1-3 are co-localized
in the same cells of almost all root tissues; these proteins were present in the tonoplast and prevacuolar vesicles. Western
blot analysis of HvNHX1-3 has shown that the content of isoforms in vacuolar membranes increased in response to salt stress
in seedling roots and shoots of both cultivars, although the increase was more pronounced in the tolerant cultivar. The content
of HvNHX1 in the seedlings increased in parallel with the enhanced expression of HvNHX1, whereas the increase in HvNHX2 and HvNHX3 protein content was accompanied by only slight changes in expression of respective
genes. The results provide evidence that salt tolerance of barley depends on plant ability to restrict Na+ transport from the root to the shoot and relies on regulatory pathways of HvNHX1-3 expression in roots and shoots during
22Na+ accumulation–tonoplast–isoforms of Na+/H+ antiporter–immunolocalization–salt stress
The effects of GA3, 24-epibrassinolide (EBL), and their combination on morphogenesis of Arabidopsis thaliana (L.) Heynh seven-day-old seedlings were studied. Four plant lines were analyzed: wild type Ler and ga4-1 mutant, belonging to the Landsberg erecta ecotype and wild type Col and det2 mutant, both of the Columbia ecotype. In ga4-1 and det2, GA4/1-and brassinosteroid-deficient mutants, the highest hypocotyl growth response to the lack of hormones was noted. The cotyledon
shape and size were dependent on EBL, and the root length was both GA3-and EBL-regulated, indicating organ specificities in the responses to these hormones. Simultaneous treatment of dark-grown
plants with GA3 and EBL exerted an additive stimulatory effect on the root growth of det2, reduced the inhibitory effect of EBL on hypocotyl elongation of ga4-1, and enhanced the effect of EBL on hypocotyl and cotyledon elongation of det2.
The effects of 24-epibrassinolide (EB) on the growth of four-day-old seedlings of Triticum aestivum L. roots, the accumulation of wheat germ agglutinin (WGA) in them, and its gene expression were studied. EB stimulated growth with two optimum concentrations, 0.4 nM and 0.4 M. Both concentrations enhanced WGA accumulation in roots, which resulted from the stimulation of its gene expression. The latter was shown by dot-blot hybridization of transcripts with a DNA probe corresponding to WGA. Since EB did not affect the level of endogenous ABA, its direct effect on WGA-gene transcription in wheat roots is suggested.
The structure of the cloned fragment of wheat (Triticum aestivum L.) TADHN gene encoding dehydrin-like protein was examined. A comparative analysis of nucleotide and deduced amino acid sequences revealed
a high homology of this fragment with sequences of the barley dhn8 gene and wheat wcor gene family. In deduced amino acid sequence of the TADHN fragment, a 15-residue region EKKGFLEKIKEKLPG was found, which corresponded to a highly conserved K-segment of dehydrins.
Wheat seedling treatment with 3.7 μM ABA and 0.4 μM 24-epibrassinolide exerted similar stimulatory effects on expression of
the TADHN gene, which indicates the involvement of dehydrins in the protective action of these phytohormones in wheat plants.
The effects of 24-epibrassinolide on growth, photosynthesis, chlorophyll content, carbohydrate fractions, and essential oil
content of rose scented geranium (Pelargonium graveolens (L.) Herit) were investigated. Foliar application of 24-epibrassinolide at 0.5, 1, and 3 μM concentrations substantially
increased the growth. 24-epibrassinolide at all concentrations improved herbage yield as reflected in the increase of foliar
biomass. Exogenous application of 24-epibrassinolide increased the rate of photosynthesis. Growth promotion was also associated
with increased chlorophyll content and resulted in the accumulation of carbohydrate fractions. At 3-μM concentration, 24-epibrassinolide
increased the total content of essential oils. The quantitative analysis of geranium oil from the geranium plant treated with
3-μM concentration revealed an increase in geraniol content and decrease in citronellol content. The present study demonstrates
a positive impact of the new group of phytohormones on the performance of geranium plant, a highly valued aromatic plant.
The effect of nitrogen limitation in a medium on the composition of intracellular lipids in the alga Botryococcus braunii Kutz IPPAS H-252 in the course of culture development was investigated. Under the conditions of nitrogen limitation, the alga under investigation accumulated lipids as triacylglycerols, and this process was accompanied by substantial changes in the total fatty acid (FA) composition, which were manifested in a decrease in trienoic acids (from 52.8–57.2 to 19.5–24.7% of total FAs) and an increase in the content of oleic (from 1.1–1.2 to 17.1–24.4%) and saturated (from 23.7–26.0 to 32.9–46.1%) acids. In the control culture, the directionality of FA redistribution was less marked, and these changes were noticed at the later stages of culture development. Under nitrogen limitation, marked changes in the FA composition of polar lipids occurred by the 13th day, and they were characterized by an increase in the content of saturated acids (up to 76.8%) and a dramatic decrease in the content of all polyenoic acids (up to 6.8%). The changes in the FA composition of triacylglycerols were noticed as early as by the 7th day; these changes consisted in an increase in the content of oleic acid, and its high content (28.4–38.4%) was maintained up to the end of culturing. In the control culture, triacylglycerols with a high content of oleic acid were found by the 13th day, although, by this time, the content of total lipids and triacylglycerols did not change.
The fragrance gene plays an important role in high-quality rice varieties and has been widely used in breeding programs. Using
a random sample of 370 individuals from an F2 segregating population developed from a cross between a japonica rice variety 9407 with fragrant flavor and an indica variety IRBB60, the fgr locus was mapped on chromosome 8 between SSR markers, PSM465 and RM1109, with genetic distances of 0.3 cM and 0.1 cM to respective
markers. These mapping efforts confirmed the previous mapping results. A large F3 mapping population with 7300 individuals was then developed from F2 plants, in which a small chromosomal region defined by the SSR markers, PSM465 and RM1109, was heterozygous. The analysis
of recombinants in the fgr region anchored the gene locus to an interval of 28 kb flanked by the left marker NS9 and the right marker L06. Sequence
analysis of this fragment predicted three open reading frames encoding putative 3-methylcrotonyl-CoA carboxylase, putative
isoleucyl-tRNA synthetase, and betaine aldehyde dehydrogenase (BADH2). The latter was presumed to be the candidate gene for
fragrance. This result will be very useful in molecular cloning of the fgr gene and marker-assisted transfer of the fgr gene in rice breeding programs.
In our previous studies, a single segment substitution line (SSSL) W23-03-8-9-1 with substituted interval of PSM301-PSM306-PSM305-PSM304-RM3894-RM3372-RM569-RM231-RM545
on chromosome 3 has been found to comprise a gene for extremely early heading date. To map this gene, the SSSL W23-03-8-9-1
was crossed with the recipient Huajingxian (HJX74) to develop an F2 segregating population. The distribution of early and
late heading plants in this population fitted a segregation ratio of 3: 1, indicating that early heading was controlled by
a dominant gene. Using a random sample of 520 individuals from the F2 segregation population, the qHD3-1 locus was mapped between two SSR markers, RM3894 and RM3372, with genetic distances of 1.2 and 1.1 cM, respectively. For
fine mapping of qHD3-1, a large F2: 3 segregating population was developed, with 6000 individuals from the F2 plants heterozygous in the RM3894 and RM3372 regions. The analysis of recombinants in the qHD3-1 region put the gene locus into an interval of 29.5 kb flanked by the left marker 3HD8 and the right marker 3HD9. Sequence
analysis of this fragment predicted eight open reading frames. One of them, ORF8, with its molecular function predicted to
encode ribonuclease III activity and RNA binding, is considered the most interesting candidate gene.
–heading date–single segment substitution line–physical mapping–sequence information
We studied the effects of cold-shock 310-kD protein (CSP310) isolated from winter rye seedlings on the energetic activity of plant mitochondria. CSP310 was shown to enhance nonphosphorylating respiration and uncoupled oxidative phosphorylation in isolated mitochondria. The uncoupling effect was enhanced with increasing protein concentration. An antibody against CSP310 interfered with the uncoupling effect of CSP310. Free fatty acids were not evidently involved in uncoupling. The physiological role of uncoupling between oxidation and phosphorylation during plant adaptation to low temperatures is discussed.
We studied the localization of polypeptides immunochemically related to subunits of cold-shock 310-kD protein from winter rye (Secale cerealeL.) in mitochondria and submitochondrial structures of winter wheat (Triticum aestivumL.) seedlings. Polypeptides were separated by SDS-PAGE and probed with the antibody against 310-kD protein from rye seedlings. Wheat mitochondria contained the following polypeptides cross-reacting with this antibody: 66, 60, 55, and 23 kD in the inner membrane; 60 and 58 kD in the outer membrane; and 66 and 55 kD in the matrix.
Barley (Hordeum vulgare L.) mutant chlorina 3613 is notable for a lack of chlorophyll b (Chl b), low content of chlorophyll a (Chl a) and carotenoids in the chloroplasts, as well as reduction in the majority of components of LHCI and LHCII. Incompletely
developed photosynthetic machinery of chlorina 3613 results in suppressed growth, lower biomass, and the declined rate of photosynthesis (as compared with the wild-type
cv. Donaria). The lack of Chl b and greater part of peripheral antenna suggests that this mutant will have difficulties during acclimation to long-term shading
because the light-harvesting role of Chl b-containing antenna becomes more important under the shortage of light. Earlier, our experiments with the mature chlorina 3613 plants shaded for one week at PAR photon flux density of 60 and 40% of that in full sunlight showed a stimulating effect
of shading on growth, biomass accumulation, and Chl a synthesis in chlorina 3613 when biosynthesis of Chl b did not occur . In this work, we investigated in more detail the changes in the content of carotenoids in chlorina 3613. We found that in Donaria at both investigated levels of illumination (60 and 40% of full sunlight) and in chlorina 3613 at 60% illumination, moderate reversible changes typical of shade-enduring plants occur in the content of carotenoids.
In chlorina 3613 at 40% illumination, the content of β-carotene increased considerably (by 3 times) with simultaneous accumulation of
Chl a. When full illumination was restored, the content of β-carotene decreased and remained on the level, which exceeded its initial
content in the plants without shading by 38%; this level, was maintained by the end of vegetation. The changes in the contents
of β-carotene and Chl a in chlorina 3613 were not accompanied by any accumulation of xanthophylls or changes in the relative content of active violaxanthin.
The obtained results suggest that a long-term shading of the leaves of mature chlorina 3613 plants induced the formation of certain components of photosynthetic apparatus: reactive centers and core parts of photosystems’
antennae as well as proteins CP26 and CP29 and in this way contributed to partial restoration of photosynthetic activity and
production process in the mutant lacking Chl b.
chlorina 3613–chlorophyll b
–β-carotene–carotenoids–light-harvesting complex–photosystems–CP26 and CP29 proteins
Responses of plants deficient in chlorophyll b (Chl b) to a long-term (lasting for 7 days) decrease in illumination and subsequent restoration of normal illumination were investigated
in chlorina 3613 mutant of barley (Hordeum vulgare L.). Efficiency of acclimation was estimated by productivity. Throughout the entire vegetation period, control chlorina 3613 plants growing under full natural illumination (PAR photon flux density of 2000–2200 μmol/(m2s)) were notable for a low content of chlorophyll a (Chl a), slow growth, and low productivity as compared with Donaria parent genotype (wild type). In the experiments, mature chlorina 3613 plants were shaded for 1 week, so that radiant flux density of PAR came to 60 or 40% of that in full sunlight. In experimental
chlorina 3613 plants subjected to shading for 7 days, accumulation of Chl a and the lack of Chl b were accompanied by activation of growth processes and rise in total biomass; in contrast, in Donaria 7-day-long shading negatively influenced the accumulation of biomass by the plants. After restoration of full natural illumination,
growth and productivity characteristics of chlorina 3613 plants, which for 7 days received only 40% of full natural illumination, became close to the characteristics of wild-type
plants. Thus, the lack of Chl b in chlorina 3613 plants did not affect growth and productivity after a 7-day-long shading (to 40% of full illumination).
chlorina 3613–chlorophyll b