Int. J. Plant Biol., Volume 13, Issue 2 (June 2022) – 13 articles

The discovery of bioactive compounds for non-invasive therapy has been the goal of research groups focused on pharmacotherapy. Phytonutrients have always been attractive for researchers because they are a significant source of bioactive phytochemicals. Still, it is challenging to determine which components show high biomedical activity and bioavailability after administration. However, based on the chemical structure of these phytochemicals, their physicochemical properties can be calculated to predict the probability of gastrointestinal (GI) absorption after oral administration. Indeed, different researchers have proposed several rules (e.g., Lipinski’s, Veber’s, Ghose’s, and Muegge’s rules) to attain these predictions, but only for synthetic compounds. Most phytochemicals do not fully comply with these rules even though they show high bioactivity and high GI absorption experimentally. Here, we propose a detailed methodology using scientifically validated web-based platforms to determine the physicochemical properties of five phytochemicals found in ginger, echinacea, and tobacco. Furthermore, we analyzed the calculated data and established a protocol based on the integration of these classical rules, plus other extended parameters, that we called the Phytochemical Rule, to obtain a more reliable prediction of the GI absorption of natural compounds. This methodology can help evaluate bioactive phytochemicals as potential drug candidates and predict their oral bioavailability in patients. Full article

Phytophthora capsici is an important pathogen worldwide because its spread affects pepper production globally. The “Criollo de Morelos” pepper 334 (CM-334) is resistant to P. capsici strains, regardless of the aggressiveness of the strain or the environmental conditions. However, when the nematode Nacobbus aberrans infects peppers, they lose this resistance by a process defined as “Resistance-breaking”. Breakdown of resistance results from a transcriptomic reconfiguration of the pepper that induces some defense genes, such as WRKY-a, POX, and EAS. The interest in identifying and describing the resistance process to P. capsici, and the breakdown that occurs by N. aberrans, has allowed us to establish a model in which we can analyze the modulation process in both scenarios and identify this transcriptomic modulation. The objective of the present work is to carry out a transcriptomic analysis that demonstrates the modulation of resistance and resistance-breaking processes. It would allow us to identify relevant genes in the early (12 h) and late (24 h) stages in these processes of the CM-334 pepper. Our findings demonstrate that modulation of resistance and resistance-breaking are independent processes that depend on the presence of both pathogens (P. capsici and N. aberrans) and that their timing modulation is dynamic. Full article

In the abundant literature on plant chemistry, little attention is paid to correlations among chemical elements in tissues. The goal of the research is to establish consistent correlations among elements in the xylem of four widespread Siberian conifers. X-ray fluorescent analysis has been applied to find out the elements contained in the xylem. The method allowed finding the mean count rates of Al, P, S, K, Ca, Ti, Mn, Fe, Cu, Zn, and Sr in trunks of trees. Moreover, the xylem samples were chemically treated twice, first in alcohol and then in HCl. It was found that species factor exerts a significant influence on the elemental content of a few elements, but not on all of them. The chemical treatment decreases the impact of the species factor. The treatment increases the number of significant correlations and strength of them. In some cases (especially with Al), the correlations may change the sign of the relationship. The consistent correlations may help arrange more profound chemical research revealing the forms in which the elements exist in xylem. Full article

Among the most distantly separated plant species are those that are found on the polar regions of the northern and southern hemispheres, the so-called bipolar species. Two routes of introduction have been proposed—long-distance dispersal (LDD) and mountain hopping (MH). Shorebirds have been implicated in the distribution of the bipolar species by several authors, but the most likely participants and the most probable routes of introduction have been little investigated. The Global Biodiversity Information Facility database was accessed to determine the geographic range of those angiosperm species that have been reported to have bipolar distributions. A bipolar plant species was considered most likely to have been dispersed by LDD if it has a distinct disjunct distribution between North and South America, and through MH if it is found in intermediate latitudes. The Atlas of Bird Migrations and the Cornell Birds of the World database were searched to discover which birds make long-distance migrations from Arctic North America to the tip of South America, and their mode of travel. Twenty-three plant species have been identified as bipolar. LDD appears to have been more important than MH in their dispersal, as seventeen (75%) have disjunct distributions and six (25%) are found in intermediate latitudes. The most likely players in the LDD dispersal of the bipolar plant species are the Eskimo Curlew, Hudsonian Godwit, Red Knot, Ruddy Turnstone and Whimbrel. Of these five long flyers, the Hudsonian Godwit may have delivered the most seeds as its breeding and migration ranges overlap with the most bipolar species, 12 in all. Full article

Soils and water resources of our ecosystems may contain Barium (Ba), a toxic metal naturally existent in the Earth’s crust and also can be derived from recycled wastes produced of several anthropogenic activities. As a result of this fact, the accumulation of Ba in agriculture soils would increase to reach the crops and eventually end up in the human food chain. The purpose of this work was to study tolerance and accumulation abilities in Limbarda crithmoides and Helianthus annuus treated with increasing concentrations of barium (from 0 to 500 µM) for 45 days. In order to evaluate the response of these species to Ba stress, the biomass production, the water status, and the accumulation of the secondary metabolites, macronutrients, total inorganic nitrogen (TIN), and Ba in shoots and roots, as well as chlorophyll levels, and metal tolerance index of the entire plant were assessed. Results showed an increase in plant biomass production and tolerance index in the two species with increasing Ba concentration. A significant increase in polyphenols and flavonoids levels was also shown with no negative effect on the macronutrients and TIN; however, the latter were found reduced in roots of L. crithmoides. Chlorophylls also were not affected. An average of 3000 µg·g⁻¹ DW of Ba was accumulated in each organ of L. crithmoides while H. annuus accumulated up to 1350 µg·g⁻¹ DW in the shoots. Our findings proved that L. crithmoides and H. annuus were susceptible to tolerate Ba-induced stress with high levels of Ba accumulation in the aboveground parts as well as in the roots during the 45 days of the experiments. Full article

Coffee leaves contain a wide range of leaf compounds, which vary by growth stage. Recently, the importance of coffee leaf metabolites with beneficial phytochemicals has been widely identified. This research investigated Canephora coffee’s morphological and physiological development and analyzed the phytochemical composition of the main leaf stage. Canephora coffee leaves were harvested and classified into the following five growth stages: S1 (leaf age of 1–4 days), S2 (leaf age of 5–8 days), S3 (leaf age of 9–14 days), S4 (leaf age of 15–20 days), and S5 (leaf age of 21–27 days). The antioxidant activity, total phenol content, flavonoids, and tannin content of coffee leaves at different stages were observed. The results indicated that the highest values for the leaf area, dry weight, greenness, chlorophyll content, and carotenoid content were found at the last stage (S5). The specific leaf area (SLA) differences had higher values in the S3 and S1 growth stages. The youngest leaf phase (S1) was less green, more yellow, and brighter in color than the mature phase. By comparing the assays, it was found that a significant increase in the antioxidant activity and the contents of phenolic compounds, flavonoids, and tannins were observed in the S1 and S2 growth stages. Full article

Leaf analysis is essential for diagnosing nutritional status and guiding fertilizer application. The present study aimed to investigate the appropriate time for leaf sampling and the effect of genotype on olive nutrition. We determined leaf nutrient concentrations of calcium (Ca), iron (Fe), and manganese (Mn) in five Greek (‘Amfissis’, ‘Chondrolia Chalkidikis’, ‘Koroneiki’, ‘Mastoidis’, and ‘Kalamon’) and one Spanish (‘Picual’) variety from May 2019 to April 2020. The concentrations of Ca, Fe, and Mn were significantly affected by genotype and season. The highest concentrations for all nutrients were determined in April, while the lowest were in May, June, and October. Leaf Ca concentration significantly increased progressively from May to September for all the varieties. Leaves of ‘Koroneiki’ had the highest Ca concentration. Iron concentrations were within the sufficiency thresholds for all the varieties during the whole experimental period, and ‘Mastoidis’ showed the highest concentration. Leaf Mn concentration for all the varieties increased from May to September with an instant decrease in June, apart from ‘Amfissis’. The varieties ‘Kalamon’ and ‘Chondrolia Chalkidikis’ were found to be above the Mn sufficiency threshold throughout the year. Variations among season and genotype depict the complexity of nutrient transportation in leaf tissues. Full article

Manganese (Mn) and aluminum (Al) toxicities are serious edaphic limitations to crop production in acidic soils. Excess Mn can be countered using a stress-adapted soil microbiota that establish symbiotic relationships with native plants. The arbuscular mycorrhizal fungi (AMF) associated with Lolium rigidum L. develop extraradical mycelia (ERM) that quickly colonize wheat and lead to greater shoot growth by promoting stress-evading mechanisms that are not yet completely explained. In the present study, wheat growth was assessed after 3 weeks on disturbed and undisturbed (intact ERM) acidic soil where the native non-mycotrophic Silene gallica L. or strongly mycotrophic L. rigidum were previously developed. The physiological and biochemical mechanisms responsible for increased growth were analyzed by assessing wheat leaf chlorophyll content, photosystem II quantum yield and performance index, enzymatic activity of ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), guaiacol peroxidase (GPX), superoxide dismutase (SOD) and contents and subcellular localization of Mn, Mg, Si and K. The soil from native plants had a beneficial effect on shoot weight and chlorophyll levels. The highest benefits were obtained for wheat grown in soil with intact ERM associated with L. rigidum. In this condition, where earlier mycorrhization was favored, the Mn content decreased, alongside the content of Si, while the Mg/Mn ratio increased. Mn was redirected to the apoplast, while Si was redirected to the symplast. The activity of APX, GPX and SOD increased, probably due to increased metabolic growth (higher shoot weight and chlorophyll content). Understanding the mechanisms induced by native AMF responsible for increasing wheat performance can contribute to the establishment of sustainable approaches for crop production in acidic soils with Mn toxicity. The use of native plant AMF developers can improve the sustainable use of natural resources in the scope of greener agricultural practices. Full article

Maca (Lepidium meyenii) is a biennial herbaceous plant of the family Brassicaceae, which recently gained research attention as well as consumer interest. Its underground storage organs are used both as a food and as traditional medicine. The storage organs, called fleshy-hypocotyls, are formed by swollen hypocotyl tissues fused with a taproot. The attempts to grow maca outside of its centre of origin have increased globally, although many cropping requirements are unknown. In terms of fleshy-hypocotyl formation, the impact of day length remains unclear. In this study the effects of day length (8 h, 16 h) on early plant development and hypocotyl thickening in yellow maca were investigated in a rhizobox experiment under controlled conditions (20 °C day and 18 °C night temperature, and relative air humidity 25–30%). Results of a 13-week cultivation period showed that number of leaves and leaf length significantly increased in plants grown under long-day (LD, 16 h) conditions as compared to those from the short-day (SD, 8 h) treatment. Furthermore, plants developed under LD conditions had larger hypocotyl width within 67 days after sowing. At 88 days after sowing, the width was almost two-fold higher. Moreover, the total root length of maca plants from LD treatment was significantly longer and had more fine roots (diameter < 0.4 mm) than in plants cultivated in SD treatment. The obtained results suggest that in early stages of plant development LD can stimulate root development and hypocotyl thickening in yellow maca. Full article

The species of Artemisia are well known in the Mediterranean region, especially in Morocco, for their traditional uses and health benefit. In this study, we were interested in two species of Artemisia, namely A. herba alba Asso and A. mesatlantica Maire. These species were collected from different soils of the Central Middle Atlas (loamy, stony, limestone and rocky soil) with different atmospheres. Extraction of essential oils from the leaves and flowering tops was carried out by hydrodistillation in Clevenger apparatus. Chemical composition analysis was further carried out using gas chromatography coupled with mass spectrometry (GC-MS). Principal component analysis (PCA) was performed to determine the similarities and dissimilarities in the chemical compositions of these six essential oils. The results obtained showed that the essential oil contents extracted from the flowering tops vary from one species to another according to the place of harvest, altitude, soil type and climate. The essential oil yield is between 0.84% and 2.19% (mL/100 g). Chemical analysis revealed that the chemotype of A. herba alba in limestone soil with a subhumid to humid atmosphere is trans-thujone (33.78%), while camphor (46.19%) is for limestone soil with a semi-arid atmosphere, vetivenic acid (14.91%) and davana ether (14.64%) are for limestone soil with a semi-arid and arid atmosphere and camphor (18.39%) is for loamy and stony soil with a semi-arid atmosphere. As for A. mesatlantica from a rocky soil on limestone with a subhumid to humid atmosphere, the main component is camphor (44.86%), and that of limestone soil with a subhumid to the humid atmosphere trans-thujone (41.08%). In addition, HCA affirmed the PCA and allowed us to distinguish between four groups. Our findings observed differences in the chemical compositions of the isolated essential oils most likely related to many factors such as the climates in the regions of the samples collected, altitudes and soil types. Full article

Plants are in intimate association with a great diversity of pathogenic and mutualistic microbes that use host plants for proliferation. Plants, in turn, have evolved mechanisms that are contingent upon their innate immune system to resist perceived biotic stresses. The objective of this work is to determine the antimicrobial properties of an allium-based antimicrobial formulation named CUSTOS on the growth of plant pathogenic microorganisms such as fungi, oomycetes, and bacteria. Two anthracnose-related species of the fungal genus Colletotrichum, Colletotrichum gloeosporioides, the oomycete Phytophthora cactorum, and the bacterium Xanthomonas fragariae associated with strawberry plants were tested in vitro. Furthermore, two fungi Alternaria dauci and Botrytis cinerea, associated with carrot plants, were tested in planta. CUSTOS inhibited the growth of all plant pathogens tested. We found that both curative and preventive planta treatments with CUSTOS inhibited the growth of Alternaria dauci and Botrytis cinerea in carrots. Furthermore, the differential expression levels of the PR 10 genes were correlated with the magnitude of infection. We also found that the field application of CUSTOS on strawberry plants results in a reduction of fungal pathogens on strawberry fruits stored under refrigeration. In summary, CUSTOS may induce pathogen resistance in fruit and vegetable plants and can be used as both a curative and a preventive against rotting and disease. Full article

It is important to select buckwheat varieties suitable for foraging and determining their best harvest time as increasing attention was paid to the forage value of buckwheat. Here, eight tartary buckwheat varieties were identified as suitable for forage based on their potential forage value through assaying the contents of ash, crude protein, crude fiber, crude fat, acid detergent fiber, neutral detergent fiber, nitrogen free extract, calcium, phosphorus, total flavonoids, and rutin in these tartary buckwheat varieties at flowering, pustulation, and mature stages, respectively. In addition, analysis of relative feed value (RFV), relative forage quality (RFQ), and principal component analysis (PCA) based on the assayed contents was applied for comprehensive evaluation of these tartary buckwheat varieties. Results showed that all the eight tartary buckwheat varieties possessed potential high forage value as their RFV is from 121.31% to 217.39% and RFQ from 117.26% to 224.54% at all three stages. In particular, both RFV and RFQ values of PS-07 reached the highest at the flowering stage among the eight tartary buckwheat varieties, followed by CQ-3 and EWPS. Accordingly, the comprehensive scoring of principal component values of PS-07 and CQ-3 are relatively higher at the flowering stage. Our research thus revealed that the eight tartary buckwheat varieties are all suitable for forage, and also provided an experimental basis for selecting the eight tartary buckwheat varieties harvested at different growth stages for livestock forage. Full article

Grapevine “bois noir”, related to the presence of ‘Candidatus Phytoplasma solani’ (‘Ca. P. solani’), represents a serious threat in several vine-growing areas worldwide. In surveys conducted over two years, mild and/or moderate symptoms and lower pathogen titer were mainly associated with ‘Ca. P. solani’ strains harboring a secY gene sequence variant (secY52), whereas severe symptoms and higher titer were mainly observed in grapevines infected by phytoplasma strains carrying any one of another four variants. A comparison of amino acid sequences of the protein SecY of ‘Ca. P. solani’ strains revealed the presence of conservative and semi-conservative substitutions. The deduced three-dimensional (3D) protein analysis unveiled that one semi-conservative substitution identified in the sequence variant secY52 is responsible for a structural disordered region that probably confers a flexibility for binding to distinct molecular complexes. In fact, the other analyzed variants show an organized structure and the 3D in silico prediction allowed the identification of β-sheets. Thus, differences in symptom severity and pathogen concentration observed in grapevines infected by ‘Ca. P. solani’ strains carrying distinct secY gene sequence variants suggest a possible relationship between SecY protein structure and phytoplasma strain virulence. Full article