A comparative study of the effects of exposure to high Cd
(50 µM) and excess Zn
(600 µM) on photosynthetic performance of hydroponically-grown durum wheat seedlings was performed. At day 8, Cd and Zn ...were added to the nutrient solution. After 7-days exposure, the chosen concentrations of both metals resulted in similar relative growth rate (RGR) inhibitions of about 50% and comparable retardations of the CO₂ assimilation rates (about 30%) in the second developed leaf of wheat seedlings. Analysis of chlorophyll a fluorescence indicated that both metals disturbed photosynthetic electron transport processes which led to a 4- to 5-fold suppression of the efficiency of energy transformation in Photosystem II. Non-specific toxic effects of Cd and Zn, which prevailed, were an inactivation of part of Photosystem II reaction centres and their transformation into excitation quenching forms as well as disturbed electron transport in the oxygen-evolving complex. The specificity of the Cd and Zn modes of action was mainly expressed in the intensity of the toxicity effects: despite the similar inhibitions of the CO₂ assimilation rates, the wheat photochemistry showed much more sensitivity to Cd than to Zn exposure.
Introduction
Centranthus kellereri
is a Bulgarian endemic plant species, found only in two locations in the world: The Balkans Mountains (Stara Planina), above the town of Vratsa, and The Pirin ...Mountains, above the town of Bansko, Bulgaria. Being endemic and endangered species precluded any significant research on it. The hypothesis of this study was that the populations of
C
.
kellereri
may represent genetically, phytochemically, and morphologically distinct forms and these will differentiate from
C
.
ruber
. Furthermore,
C
.
kellereri
possibly imperfect embryology may preclude its more widespread distribution under natural conditions.
Results
This study revealed the phytochemical profile, antioxidant activity, embryology, surface microstructural morphological traits, and genetic differences between the
C
.
kellereri
plants from the only two natural populations and compares them to the ones of the related and better-known plant
C
.
ruber
. The essential oil (EO) content in aboveground plant parts and in roots was generally low and the EO composition varied significantly as a function of plant part, year of sampling, location, and species. Methylvaleric acid was a major EO constituent in the
C
.
kellereri
EO, ranging between 60.2% and 71.7% of the total EO. The EO included monoterpenes, sequiterpenes, long-chain alkanes and fatty acids. Phytochemical analyses of plant tissue revealed the occurrence of 32 compounds that were tentatively identified as 6 simple phenolics, 18 flavonoids, 1 quinone, 1 lipid, 1 alkaloid, 2 diterpenes, and 3 triterpenes. There were differences in detected compounds between the
C
.
kellereri
plants at the two locations and between the roots and shoots in both species. The total phenols and flavonoids varied between the two species but were also dissimilar between the plants from the two populations of
C
.
kelleri
. Free radical scavenging activity, measured with ABTS and DPPH in aqueous and methanol extracts, had similar values; however, overall,
C
.
kellereri
from Vratsa showed the highest antioxidant activity while
C
.
ruber
had the lowest activity. Genetic analyses showed a clear differentiation between
C
.
kellereri
and
C
.
ruber
, and between the two populations of
C
.
kellereri
. Embryological studies revealed the peculiarities of the male and female generative spheres of the two species that were defined as being sexually reproducing. The pollen had high viability; however, the low viability of seeds demonstrated possible high sensitivity of
C
.
kellereri
to the environmental conditions, perhaps the main factor modifying and restricting the population sizes. The SEM analyses exposed differences in surface microstructural traits between the species (C.
kellereri
and
C
.
ruber
) but also between the two populations of
C
.
kellereri
. The observed dissimilarities in genetic makeup, micromorphological characteristics, and phytochemical composition strongly indicate that the two populations can be classified as distinct subspecies or varieties of
C
.
kellereri
; var.
pirinensis
and var.
balkanensis
. Further research is needed to introduce
C
.
kellereri
into culture and develop it as a high-value specialty crop or ornamental in order to conserve
C
.
kellereri
natural populations.
C
.
kellereri
may be utilized as a source for phytochemicals of interest and as an ornamental plant like
C
.
ruber
; however, it may have a greater environmental plasticity and adaptation as evidenced by its current locations.
The application of nanoparticles (NPs) has been proved as an efficient and promising technique for mitigating a wide range of stressors in plants. The present study elucidates the synergistic effect ...of iron oxide nanoparticles (IONPs) and silicon nanoparticles (SiNPs) in the attenuation of Cd toxicity in
. Seeds of
were treated with IONPs (10 mg/L) and SiNPs (20 mg/L). Seedlings of uniform size were transplanted to pots for 40 days. The results demonstrated that nanoparticles (NPs) enhanced growth, net photosynthetic rate, and gas exchange attributes in
plants grown in Cd-contaminated soil. Synergistic application of IONPs and SiNPs raised not only K
content, but also biosynthesis of polyamines (PAs), which alleviated Cd stress in
seedlings. Additionally, NPs decreased malondialdehyde (MDA) content and electrolyte leakage (EL) in
plants exposed to Cd stress. These findings suggest that stress alleviation was mainly attributed to the enhanced accumulation of K
content, improved antioxidant defense system, and higher spermidine (Spd) and putrescine (Put) levels. It is suggested that various forms of NPs can be applied synergistically to minimize heavy metal stress, thus increasing crop production under stressed conditions.
The present research aims at evaluating the effect of silicon on the photosynthetic rate and the chlorophyll fluorescence parameters of hydroponically grown young cucumber plants Cucumis sativus L), ...cv. Gergana, under salinity stress. The experiment was conducted in a climatic chamber at the Department of Plant Physiology and Biochemistry, Agricultural University - Plovdiv, Bulgaria. Four variants were examined: 1 - control, 2 - NaCI, 3 - Si, and 4 - NaCI + Si. Plants were grown in a nutrient solution and were treated with 50 mM NaCI and 1.5 mM Si in form of Na2SiO3. The results showed a decrease in the photosynthetic rate by 25% for the NaCI variant compared to the control. Silicon supply increased the photosynthetic rate of the salt-stressed plants by 17%. Salinity had also a negative effect on the chlorophyll fluorescence parameters and the content of photosynthetic pigments, which were dramatically reduced. It was established that the silicon supply has a positive influence on the photosynthetic rate, the chlorophyll fluorescence parameters and the pigment content of the treated cucumber plants. The content of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids increased.
Velen.,
Janka and
Wierzb. ex Heuff. are Balkan endemic species, and they are distributed in restricted territories, primarily found in dry grasslands, rocky slopes, and stony habitats. This study ...presents the results of the first embryological and micromorphological analyses of three
species (
,
, and
) from the Bulgarian flora. The aim of this study was to establish the features of the male and female reproductive sphere, as well as surface characteristics of leaves, stem, and calyx in order to understand the mode of reproduction, character, size and state of species populations and delimitation. For the embryological study, flowers and flower buds in different developmental stages were collected from plants of natural populations and treated with the classic paraffin method. Reproductive capacity was assessed using the following approaches: (1) acetocarmine test for pollen viability, (2) tetrazolium test (TTZ) for seed viability, and (3) germination test. The surfaces characteristics of leaves, stem, and calyx were analyzed by scanning electron microscopy (SEM). As a result, the study revealed the structures of the male (M) and female (F) generative spheres as well as the processes of gamete development, pollination, and endosperm and embryo formation. It was found that the three
species exhibited a high pollen viability but low seed viability and germination. The SEM analysis showed both common and distinct micromorphology features regarding epidermis, calyx and stem surfaces among the three
species. Notably, the
surfaces (leaves, calyx, stem) were clearly distinguishable from the other two
species. Regarding the nutlet surfaces, it was observed that the exocarp surfaces of
and
have a reticulate convex type surface and comprise two types of cells: (1) highly bulging, bubble-like cells; and (2) flat cells with numerous striations. On the other hand, the exocarp of
displayed rectangular or polygonal shapes without bubble-like cells, and it had a tabular to slightly convex type surface. Additionally, nutlets (seeds) of both
and
exhibited distinct papilla formations resembling non-glandular trichomes seen on the ends of the nutlets for
and over the entire surface for
. The characteristics of the embryological structures and processes, along with the absence of apomixis, characterized the three studied
species as sexually reproducing. The established balanced processes and stable structures contribute to their high reproductive potential and population stability. However, these traits may also decrease their adaptability to environmental changes.
Pinus heldreichii Christ. (Bosnian pine), a Tertiary relict and Balkan sub-endemic, has not been comprehensively studied for its essential oil (EO) profile and bioactivity of its different plant ...parts. This study aimed to determine the EO yield, composition and antimicrobial activity from different parts of P. heldreichii at three different populations (mountains) in Bulgaria. Furthermore, the study assessed the antioxidant activities of plant tissue, including leaves (needles), twigs wood, male and female cones. The EOs yield from different plant parts ranged from 0.09 % (leaves) to 0.74 % (wood of twigs), with monoterpenes being the predominant class. Limonene, α-pinene, β-caryophyllene, germacrene D, β-pinene, and β-myrcene were detected in the EO extracted from all analyzed trees. However, these compounds were not found in the EO extracted from all plant parts of the same trees. Four chemical groups (chemotypes) were identified for EO from twigs, and three chemotypes were identified for EO from leaves. The chemotypes were based on the percent ratio of the main EO constituents (>5 %). Leaves tissue showed the highest values in terms of polyphenols and flavonoids, as well as higher ABTS radical scavenging activity, while the highest antimicrobial activity against Staphylococcus aureus subsp. aureus was seen in the EOs obtained from twigs. This is the first study to identify several chemotypes based on leaf and twigs EO of P. heldreichii distributed in Bulgarian flora. Furthermore, the EO of twigs tips (TT), male cones (MC), and wood of one-two-year-old twigs (WT) of the same trees were reported for the first time. The total polyphenol, flavonoid content, and radical scavenging activity of tissues of annual twigs wood and biennial twigs wood, leaf tissue, MC tissue, and the twigs tips tissue is also reported for the first time in the accessible literature. These findings highlight the potential of P. heldreichii to provide EOs with varying compositions and bioactivities, making them suitable for nutraceutical, pharmacological, and potentially food additive applications. Furthermore, the identification of chemotype accessions in this study suggests their selection for the development of new forest crop as a source for natural products with desirable composition and bioactivity.
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Boiss (Lamiaceae) is a Bulgarian endemic species. Overall, the essential oil (EO) composition of
was different from that of the other
species reported in the literature. The main EO constituents of
...were (
)-caryophyllene, germacrene D, and caryophyllene oxide. The effect of the harvest stage was significant only on α-copaene, (
)-caryophyllene, caryophyllene oxide, and τ-muurolol. The concentration of α-copaene (1.26-1.83% range of the total oil), (
)-caryophyllene (31-41%), caryophyllene oxide (6.4-11.8%), and τ-muurolol (1.3-2.8%) were the highest at 2-3 pair of leaves or before flowering and lower at flowering. The harvest stage did not significantly affect the concentrations of the other six identified EO compounds β-bourbonene (1.1%), α-humulene (2.8%), germacrene D (23.3%), bicyclogermacrene (2.85%), δ-cadinene (1.1%), and spathulenol (2.8%). In a separate experiment, grinding of the biomass prior to EO extraction had a significant effect only on the concentrations of D-limonene (0.24-3.3%) and bicyclogermacrene (3.6-9.1%). Grinding in water or without water, maceration, and addition of Tween
20 had rather small effects on the EO profile. The identified EO constituents and their mean concentrations in this experiment were (
)-caryophyllene (25.4%), germacrene D (17.6%), caryophyllene oxide (9.1%), spathulenol (6.5%), τ-muurolol (5.0%), carvacrol (3.9%), α-copaene (2.5%), β-bourbonene (2.5%), δ-cadinene (2.4%), α-humulene (1.8%), and Z-β-farnesene (1.3%). Embryological studies observed anther and the development of the male gametophyte and ovule and development of the female gametophyte of
. Furthermore, pollen and seed viability assays were conducted, and mass spectrometry-based metabolomics analysis of an extract from shoots revealed the presence of 45 natural products, identified as flavonoids, phenolic acids, and (tri)terpenoids. Overall, the phytochemistry and some of the microscopic analyses distinguished this endemic species from other species in
.
The use of herbicides is ? traditional method for weed control in crop-producing systems. Along with the high effective weed control, herbicides might cause phytotoxicity for crop plants, due to ...insufficient herbicide selectivity, combining herbicide treatment with unsuitable meteorological conditions, long-term persistence of herbicide in the soil or off-target transfer of the herbicide--drift. Imazamox is a selective herbicide of imidazolinone group, used to control annual and perennial weeds in imidazolinone-resistant (IMI-R) crops. Protein hydrolysates (PHs) are a group of plant biostimulants containing small peptides and free amino acids, reported to ameliorate plant abiotic stress tolerance, including herbicide phytotoxicity. This report evaluates the damaging effect of simulated imazamox drift on growth, photosynthetic performance and productivity of maize plants as well as the efficiency of foliar application by protein hydrolysates as therapy means. The received results demonstrated that the simulated imazamox herbicide drift has a strong inhibiting effect on maize plants. This is well illustrated by the retarded growth of maize plants, their disrupted photosynthetic activity and productivity losses. The foliar supply of PHs to imazamox damaged maize plants ameliorates their photosynthetic performance, growth and crop productivity.
In the present study, the complete chloroplast genome of Vitis davidii Foex strain 'SJTU003' was assembled and subjected to phylogenetic analysis. This chloroplast genome of 'SJTU003' was 161,335 bp ...in length, including two inverted repeat regions (IRa and IRb) that were separated by a large single-copy region (89,570 bp) and a small single-copy region (19,059 bp). The genome contained 133 genes, including 88 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis indicated that V. davidii is most closely related to Vitis flexuosa and Vitis amurensis.
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