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Plants, Volume 6, Issue 3 (September 2017) – 17 articles

Cover Story (view full-size image): In this study, we investigated the potential for silicon soil amendment to augment the resistance of rice against multiple insect pests in a three-year field study. Ideally, management of pests should integrate multiple tactics such as host plant resistance, insecticide application and cultural practices, and it is important to understand how silicon soil amendment can contribute to a multi-component management program. Overall, the effect of soil silicon amendment was found to be weaker than the effects of both insecticidal seed treatment and variety. However, this was among the first to document effects of silicon on a root-feeding pest in the field. Despite the weak effect of silicon on insect pests, silicon could still play an important role in rice production considering the positive effects on yield and disease suppression. View the paper
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2715 KiB  
Article
The Effect of Harvesting on the Composition of Essential Oils from Five Varieties of Ocimum basilicum L. Cultivated in the Island of Kefalonia, Greece
by Gerasimia Tsasi, Theofilos Mailis, Artemis Daskalaki, Eleni Sakadani, Panagis Razis, Yiannis Samaras and Helen Skaltsa
Plants 2017, 6(3), 41; https://doi.org/10.3390/plants6030041 - 18 Sep 2017
Cited by 28 | Viewed by 5141
Abstract
Five varieties of Ocimum basilicum L. namely lettuce, cinnamon, minimum, latifolia, and violetto were separately cultivated in field and greenhouse in the island Kefalonia (Greece). The effect of successive harvesting to the essential oil content was evaluated. In total 23 samples of essential [...] Read more.
Five varieties of Ocimum basilicum L. namely lettuce, cinnamon, minimum, latifolia, and violetto were separately cultivated in field and greenhouse in the island Kefalonia (Greece). The effect of successive harvesting to the essential oil content was evaluated. In total 23 samples of essential oils (EOs) were analyzed by GC-FID and GC-MS. Ninety-six constituents, which accounted for almost 99% of the oils, were identified. Cluster analysis was performed for all of the varieties in greenhouse and field conditions, in order to investigate the possible differentiation on the chemical composition of the essential oils, obtained between harvests during growing period. Each basil variety showed a unique chemical profile, but also the essential oil composition within each variety seems to be differentiated, affected by the harvests and the cultivation site. Full article
(This article belongs to the Special Issue Medicinal Plants and Natural Product Research)
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828 KiB  
Article
Silicon and Nitrate Differentially Modulate the Symbiotic Performances of Healthy and Virus-Infected Bradyrhizobium-nodulated Cowpea (Vigna unguiculata), Yardlong Bean (V. unguiculata subsp. sesquipedalis) and Mung Bean (V. radiata)
by Maria Luisa Izaguirre-Mayoral, Miriam Brito, Bikash Baral and Mario José Garrido
Plants 2017, 6(3), 40; https://doi.org/10.3390/plants6030040 - 15 Sep 2017
Cited by 5 | Viewed by 4186
Abstract
The effects of 2 mM silicon (Si) and 10 mM KNO3 (N)—prime signals for plant resistance to pathogens—were analyzed in healthy and Cowpea chlorotic mottle virus (CCMV) or Cowpea mild mottle virus (CMMV)-infected Bradyrhizobium-nodulated cowpea, yardlong bean and mung bean plants. [...] Read more.
The effects of 2 mM silicon (Si) and 10 mM KNO3 (N)—prime signals for plant resistance to pathogens—were analyzed in healthy and Cowpea chlorotic mottle virus (CCMV) or Cowpea mild mottle virus (CMMV)-infected Bradyrhizobium-nodulated cowpea, yardlong bean and mung bean plants. In healthy plants of the three Vigna taxa, nodulation and growth were promoted in the order of Si + N > N > Si > controls. In the case of healthy cowpea and yardlong bean, the addition of Si and N decreased ureide and α-amino acids (AA) contents in the nodules and leaves in the order of Si + N> N > Si > controls. On the other hand, the addition of N arrested the deleterious effects of CCMV or CMMV infections on growth and nodulation in the three Vigna taxa. However, the addition of Si or Si + N hindered growth and nodulation in the CCMV- or CMMV-infected cowpea and yardlong bean, causing a massive accumulation of ureides in the leaves and nodules. Nevertheless, the AA content in leaves and nodules of CCMV- or CMMV-infected cowpea and yardlong bean was promoted by Si but reduced to minimum by Si + N. These results contrasted to the counteracting effects of Si or Si + N in the CCMV- and CMMV-infected mung bean via enhanced growth, nodulation and levels of ureide and AA in the leaves and nodules. Together, these observations suggest the fertilization with Si + N exclusively in virus-free cowpea and yardlong bean crops. However, Si + N fertilization must be encouraged in virus-endangered mung bean crops to enhance growth, nodulation and N-metabolism. It is noteworthy to see the enhanced nodulation of the three Vigna taxa in the presence of 10 mM KNO3. Full article
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Article
Antibacterial Properties of Flavonoids from Kino of the Eucalypt Tree, Corymbia torelliana
by Motahareh Nobakht, Stephen J. Trueman, Helen M. Wallace, Peter R. Brooks, Klrissa J. Streeter and Mohammad Katouli
Plants 2017, 6(3), 39; https://doi.org/10.3390/plants6030039 - 14 Sep 2017
Cited by 12 | Viewed by 5817
Abstract
Traditional medicine and ecological cues can both help to reveal bioactive natural compounds. Indigenous Australians have long used kino from trunks of the eucalypt tree, Corymbia citriodora, in traditional medicine. A closely related eucalypt, C. torelliana, produces a fruit resin with [...] Read more.
Traditional medicine and ecological cues can both help to reveal bioactive natural compounds. Indigenous Australians have long used kino from trunks of the eucalypt tree, Corymbia citriodora, in traditional medicine. A closely related eucalypt, C. torelliana, produces a fruit resin with antimicrobial properties that is highly attractive to stingless bees. We tested the antimicrobial activity of extracts from kino of C. citriodora, C. torelliana × C. citriodora, and C. torelliana against three Gram-negative and two Gram-positive bacteria and the unicellular fungus, Candida albicans. All extracts were active against all microbes, with the highest activity observed against P. aeruginosa. We tested the activity of seven flavonoids from the kino of C. torelliana against P. aeruginosa and S. aureus. All flavonoids were active against P. aeruginosa, and one compound, (+)-(2S)-4′,5,7-trihydroxy-6-methylflavanone, was active against S. aureus. Another compound, 4′,5,7-trihydroxy-6,8-dimethylflavanone, greatly increased biofilm formation by both P. aeruginosa and S. aureus. The presence or absence of methyl groups at positions 6 and 8 in the flavonoid A ring determined their anti-Staphylococcus and biofilm-stimulating activity. One of the most abundant and active compounds, 3,4′,5,7-tetrahydroxyflavanone, was tested further against P. aeruginosa and was found to be bacteriostatic at its minimum inhibitory concentration of 200 µg/mL. This flavanonol reduced adhesion of P. aeruginosa cells while inducing no cytotoxic effects in Vero cells. This study demonstrated the antimicrobial properties of flavonoids in eucalypt kino and highlighted that traditional medicinal knowledge and ecological cues can reveal valuable natural compounds. Full article
(This article belongs to the Special Issue Medicinal Plants and Natural Product Research)
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256 KiB  
Communication
Variability of Secondary Metabolites of the Species Cichorium intybus L. from Different Habitats
by Nenad M. Zlatić and Milan S. Stanković
Plants 2017, 6(3), 38; https://doi.org/10.3390/plants6030038 - 11 Sep 2017
Cited by 26 | Viewed by 4114
Abstract
The principal aim of this paper is to show the influence of soil characteristics on the quantitative variability of secondary metabolites. Analysis of phenolic content, flavonoid concentrations, and the antioxidant activity was performed using the ethanol and ethyl acetate plant extracts of the [...] Read more.
The principal aim of this paper is to show the influence of soil characteristics on the quantitative variability of secondary metabolites. Analysis of phenolic content, flavonoid concentrations, and the antioxidant activity was performed using the ethanol and ethyl acetate plant extracts of the species Cichorium intybus L. (Asteraceae). The samples were collected from one saline habitat and two non-saline habitats. The values of phenolic content from the samples taken from the saline habitat ranged from 119.83 to 120.83 mg GA/g and from non-saline habitats from 92.44 to 115.10 mg GA/g. The amount of flavonoids in the samples from the saline locality varied between 144.36 and 317.62 mg Ru/g and from non-saline localities between 86.03 and 273.07 mg Ru/g. The IC50 values of antioxidant activity in the samples from the saline habitat ranged from 87.64 to 117.73 μg/mL and from 101.44 to 125.76 μg/mL in the samples from non-saline habitats. The results confirmed that soil types represent a significant influence on the quantitative content of secondary metabolites. The greatest concentrations of phenols and flavonoids and the highest level of antioxidant activity were found in the samples from saline soil. This further corroborates the importance of saline soil as an ecological factor, as it is proven to give rise to increased biosynthesis of secondary metabolites and related antioxidant activity. Full article
(This article belongs to the Special Issue Medicinal Plants and Natural Product Research)
1683 KiB  
Review
Impact of Silicon in Plant Biomass Production: Focus on Bast Fibres, Hypotheses, and Perspectives
by Marie Luyckx, Jean-Francois Hausman, Stanley Lutts and Gea Guerriero
Plants 2017, 6(3), 37; https://doi.org/10.3390/plants6030037 - 09 Sep 2017
Cited by 34 | Viewed by 6338
Abstract
Silicon (Si) is an abundant element which, when supplied to plants, confers increased vigor and resistance to exogenous stresses, as well as enhanced stem mechanical strength. Plant species vary in their ability to take Si up and to accumulate it under the form [...] Read more.
Silicon (Si) is an abundant element which, when supplied to plants, confers increased vigor and resistance to exogenous stresses, as well as enhanced stem mechanical strength. Plant species vary in their ability to take Si up and to accumulate it under the form of silicon dioxide (SiO2) in their tissues: emblematic of this is the example of Poales, among which there is rice, a high Si accumulator. Monocots usually accumulate more Si than dicots; however, the impact that Si has on dicots, notably on economically important dicots, is a subject requiring further study and scientific efforts. In this review, we discuss the impact that Si has on bast fibre-producing plants, because of the potential importance that this element has in sustainable agriculture practices and in light of the great economic value of fibre crops in fostering a bio-economy. We discuss the data already available in the literature, as well as our own research on textile hemp. In particular, we demonstrate the beneficial effect of Si under heavy metal stress, by showing an increase in the leaf fresh weight under growth on Cd 20 µM. Additionally, we propose an effect of Si on bast fibre growth, by suggesting an action on the endogenous phytohormone levels and a mechanical role involved in the resistance to the turgor pressure during elongation. We conclude our survey with a description of the industrial and agricultural uses of Si-enriched plant biomass, where woody fibres are included in the survey. Full article
(This article belongs to the Special Issue Role of Silicon in Plants)
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1033 KiB  
Article
Litter Accumulation and Nutrient Content of Roadside Plant Communities in Sichuan Basin, China
by Huiqin He and Thomas Monaco
Plants 2017, 6(3), 36; https://doi.org/10.3390/plants6030036 - 30 Aug 2017
Cited by 3 | Viewed by 3745
Abstract
It is widely recognized that feedbacks exist between plant litter and plant community species composition, but this relationship is difficult to interpret over heterogeneous conditions typical of modified environments such as roadways. Given the need to expedite natural recovery of disturbed areas through [...] Read more.
It is widely recognized that feedbacks exist between plant litter and plant community species composition, but this relationship is difficult to interpret over heterogeneous conditions typical of modified environments such as roadways. Given the need to expedite natural recovery of disturbed areas through restoration interventions, we characterized litter accumulation and nutrient content (i.e., organic carbon, total N, and P) and quantified their association with key plant species. Plant species cover and litter characteristics were sampled at 18 successional forest plant communities along major roadways in Sichuan Basin, western China. Variation in litter across communities was assessed with principal component analysis (PCA) and species with the highest correlation to PCA axes were determined with Pearson’s r coefficients. Plant communities with the longest time since road construction (i.e., 70 years) were distinctly different in litter total N and organic carbon compared to plant communities with a shorter disturbance history. We encountered 59 plant species across sampling plots, but only four rare species (i.e., frequency < 5) were strongly correlated with litter characteristics (p < 0.01); none of which were the most abundant where they occurred. These results highlight the importance of site-specific factors (i.e., geographic location, disturbance age) regulating plant litter across heavily disturbed landscapes and how litter characteristics and rare plant species are correlated. Full article
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2129 KiB  
Article
Effect of Different Silicon Sources on Yield and Silicon Uptake of Rice Grown under Varying Phosphorus Rates
by Flavia B. Agostinho, Brenda S. Tubana, Murilo S. Martins and Lawrence E. Datnoff
Plants 2017, 6(3), 35; https://doi.org/10.3390/plants6030035 - 29 Aug 2017
Cited by 64 | Viewed by 10075
Abstract
A series of pot experiments were conducted to: (1) evaluate the effects of different Si sources (soil- and foliar-applied) on grain yield and Si accumulation of rice supplied with varying P rates, and (2) evaluate Si absorption of rice using foliar- and soil-applied [...] Read more.
A series of pot experiments were conducted to: (1) evaluate the effects of different Si sources (soil- and foliar-applied) on grain yield and Si accumulation of rice supplied with varying P rates, and (2) evaluate Si absorption of rice using foliar- and soil-applied Si fertilizers. Three P rates, (0, 112, and 224 kg ha−1) combined with five Si treatments (wollastonite and slag applied at 4.5 ton ha−1 and one foliar Si solution applied at 20, 40 and 80 mg Si L−1) and a check were arranged in a randomized complete block design with four replications. The presence of P and Si in the soil created a synergistic effect on soil Al, Mn, and As (P < 0.01), but not on rice growth and P uptake. Wollastonite and slag application were most effective in raising rice Si content than foliar applied Si (P < 0.001). While there was an improvement in biomass (42%) and tiller production (25%) for rice receiving foliar Si, no supporting evidence was obtained in these experiments to verify leaf surface Si absorption. The application of Si-rich materials to soil still remains the most effective method for enhancing Si uptake by plants. Full article
(This article belongs to the Special Issue Practical Use of Si to Influence Plant Production)
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856 KiB  
Article
Selecting Lentil Accessions for Global Selenium Biofortification
by Dil Thavarajah, Alex Abare, Indika Mapa, Clarice J. Coyne, Pushparajah Thavarajah and Shiv Kumar
Plants 2017, 6(3), 34; https://doi.org/10.3390/plants6030034 - 26 Aug 2017
Cited by 21 | Viewed by 4633
Abstract
The biofortification of lentil (Lens culinaris Medikus.) has the potential to provide adequate daily selenium (Se) to human diets. The objectives of this study were to (1) determine how low-dose Se fertilizer application at germination affects seedling biomass, antioxidant activity, and Se [...] Read more.
The biofortification of lentil (Lens culinaris Medikus.) has the potential to provide adequate daily selenium (Se) to human diets. The objectives of this study were to (1) determine how low-dose Se fertilizer application at germination affects seedling biomass, antioxidant activity, and Se uptake of 26 cultivated lentil genotypes; and (2) quantify the seed Se concentration of 191 lentil wild accessions grown in Terbol, Lebanon. A germination study was conducted with two Se treatments [0 (control) and 30 kg of Se/ha] with three replicates. A separate field study was conducted in Lebanon for wild accessions without Se fertilizer. Among cultivated lentil accessions, PI533690 and PI533693 showed >100% biomass increase vs. controls. Se addition significantly increased seedling Se uptake, with the greatest uptake (6.2 µg g−1) by PI320937 and the least uptake (1.1 µg g−1) by W627780. Seed Se concentrations of wild accessions ranged from 0 to 2.5 µg g−1; accessions originating from Syria (0–2.5 µg g−1) and Turkey (0–2.4 µg g−1) had the highest seed Se. Frequency distribution analysis revealed that seed Se for 63% of accessions was between 0.25 and 0.75 µg g−1, and thus a single 50 g serving of lentil has the potential to provide adequate dietary Se (20–60% of daily recommended daily allowance). As such, Se application during plant growth for certain lentil genotypes grown in low Se soils may be a sustainable Se biofortification solution to increase seed Se concentration. Incorporating a diverse panel of lentil wild germplasm into Se biofortification programs will increase genetic diversity for effective genetic mapping for increased lentil seed Se nutrition and plant productivity. Full article
(This article belongs to the Special Issue Crop Enhancement for Global Food Security)
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1773 KiB  
Article
Integrating Soil Silicon Amendment into Management Programs for Insect Pests of Drill-Seeded Rice
by James M. Villegas, Michael O. Way, Rebecca A. Pearson and Michael J. Stout
Plants 2017, 6(3), 33; https://doi.org/10.3390/plants6030033 - 13 Aug 2017
Cited by 14 | Viewed by 5870
Abstract
Silicon soil amendment has been shown to enhance plant defenses against insect pests. Rice is a silicon-accumulating graminaceous plant. In the southern United States, the rice water weevil and stem borers are important pests of rice. Current management tactics for these pests rely [...] Read more.
Silicon soil amendment has been shown to enhance plant defenses against insect pests. Rice is a silicon-accumulating graminaceous plant. In the southern United States, the rice water weevil and stem borers are important pests of rice. Current management tactics for these pests rely heavily on the use of insecticides. This study evaluated the effects of silicon amendment when combined with current management tactics for these rice insect pests in the field. Field experiments were conducted from 2013 to 2015. Rice was drill-planted in plots subjected to factorial combinations of variety (conventional and hybrid), chlorantraniliprole seed treatment (treated and untreated), and silicon amendment (treated and untreated). Silicon amendment reduced densities of weevil larvae on a single sampling date in 2014, but did not affect densities of whiteheads caused by stem borers. In contrast, insecticidal seed treatment strongly reduced densities of both weevil larvae and whiteheads. Higher densities of weevil larvae were also observed in the hybrid variety in 2014, while higher incidences of whiteheads were observed in the conventional variety in 2014 and 2015. Silicon amendment improved rice yields, as did chlorantraniliprole seed treatment and use of the hybrid variety. Full article
(This article belongs to the Special Issue Role of Silicon in Plants)
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5763 KiB  
Article
Differential Mechanisms of Photosynthetic Acclimation to Light and Low Temperature in Arabidopsis and the Extremophile Eutrema salsugineum
by Nityananda Khanal, Geoffrey E. Bray, Anna Grisnich, Barbara A. Moffatt and Gordon R. Gray
Plants 2017, 6(3), 32; https://doi.org/10.3390/plants6030032 - 09 Aug 2017
Cited by 27 | Viewed by 5751
Abstract
Photosynthetic organisms are able to sense energy imbalances brought about by the overexcitation of photosystem II (PSII) through the redox state of the photosynthetic electron transport chain, estimated as the chlorophyll fluorescence parameter 1-qL, also known as PSII excitation pressure. Plants [...] Read more.
Photosynthetic organisms are able to sense energy imbalances brought about by the overexcitation of photosystem II (PSII) through the redox state of the photosynthetic electron transport chain, estimated as the chlorophyll fluorescence parameter 1-qL, also known as PSII excitation pressure. Plants employ a wide array of photoprotective processes that modulate photosynthesis to correct these energy imbalances. Low temperature and light are well established in their ability to modulate PSII excitation pressure. The acquisition of freezing tolerance requires growth and development a low temperature (cold acclimation) which predisposes the plant to photoinhibition. Thus, photosynthetic acclimation is essential for proper energy balancing during the cold acclimation process. Eutrema salsugineum (Thellungiella salsuginea) is an extremophile, a close relative of Arabidopsis thaliana, but possessing much higher constitutive levels of tolerance to abiotic stress. This comparative study aimed to characterize the photosynthetic properties of Arabidopsis (Columbia accession) and two accessions of Eutrema (Yukon and Shandong) isolated from contrasting geographical locations at cold acclimating and non-acclimating conditions. In addition, three different growth regimes were utilized that varied in temperature, photoperiod and irradiance which resulted in different levels of PSII excitation pressure. This study has shown that these accessions interact differentially to instantaneous (measuring) and long-term (acclimation) changes in PSII excitation pressure with regard to their photosynthetic behaviour. Eutrema accessions contained a higher amount of photosynthetic pigments, showed higher oxidation of P700 and possessed more resilient photoprotective mechanisms than that of Arabidopsis, perhaps through the prevention of PSI acceptor-limitation. Upon comparison of the two Eutrema accessions, Shandong demonstrated the greatest PSII operating efficiency (ΦPSII) and P700 oxidizing capacity, while Yukon showed greater growth plasticity to irradiance. Both of these Eutrema accessions are able to photosynthetically acclimate but do so by different mechanisms. The Shandong accessions demonstrate a stable response, favouring energy partitioning to photochemistry while the Yukon accession shows a more rapid response with partitioning to other (non-photochemical) strategies. Full article
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1153 KiB  
Communication
High Constitutive Overexpression of Glycosyl Hydrolase Family 17 Delays Floral Transition by Enhancing FLC Expression in Transgenic Arabidopsis
by Shinichi Enoki, Nozomi Fujimori, Chiho Yamaguchi, Tomoki Hattori and Shunji Suzuki
Plants 2017, 6(3), 31; https://doi.org/10.3390/plants6030031 - 25 Jul 2017
Cited by 2 | Viewed by 3426
Abstract
Vitis vinifera glycosyl hydrolase family 17 (VvGHF17) is a grape apoplasmic β-1,3-glucanase, which belongs to glycosyl hydrolase family 17 in grapevines. β-1,3-glucanase is not only involved in plant defense response but also has various physiological functions in plants. Although VvGHF17 expression is negatively [...] Read more.
Vitis vinifera glycosyl hydrolase family 17 (VvGHF17) is a grape apoplasmic β-1,3-glucanase, which belongs to glycosyl hydrolase family 17 in grapevines. β-1,3-glucanase is not only involved in plant defense response but also has various physiological functions in plants. Although VvGHF17 expression is negatively related to the length of inflorescence in grapevines, the physiological functions of VvGHF17 are still uncertain. To clarify the physiological functions of VvGHF17, we conducted a phenotypic analysis of VvGHF17-overexpressing Arabidopsis plants. VvGHF17-overexpressing Arabidopsis plants showed short inflorescence, similar to grapevines. These results suggested that VvGHF17 might negatively regulate the length of inflorescence in plants. VvGHF17 expression induced a delay of floral transition in Arabidopsis plants. The expression level of FLOWERING LOCUS C (FLC), known as a floral repressor gene, in inflorescence meristem of transgenic plants were increased by approximately 10-fold as compared with wild plants. These results suggest that VvGHF17 induces a delay of floral transition by enhancing FLC expression and concomitantly decreases the length of plant inflorescence. Full article
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2878 KiB  
Article
Sphenostylis stenocarpa (ex. A. Rich.) Harms., a Fading Genetic Resource in a Changing Climate: Prerequisite for Conservation and Sustainability
by Catherine Veronica Nnamani, Sunday Adesola Ajayi, Happiness Ogba Oselebe, Christopher John Atkinson, Anastasia Ngozi Igboabuchi and Eucharia Chizoba Ezigbo
Plants 2017, 6(3), 30; https://doi.org/10.3390/plants6030030 - 12 Jul 2017
Cited by 22 | Viewed by 9097
Abstract
The southeastern part of Nigeria is one of the major hotspots of useful plant genetic resources. These endemic species are associated with a rich indigenous knowledge and cultural diversity in relation to their use and conservation. Sphenostylis stenocarpa (ex. A. Rich.) [...] Read more.
The southeastern part of Nigeria is one of the major hotspots of useful plant genetic resources. These endemic species are associated with a rich indigenous knowledge and cultural diversity in relation to their use and conservation. Sphenostylis stenocarpa (ex. A. Rich.) Harms., (African Yam Bean (AYB)), is one such crop within the family of Fabaceae. Its nutritional and eco-friendly characteristics have value in ameliorating malnutrition, hidden hunger and environmental degradation inherent in resource-poor rural and semi-rural communities throughout Africa. However, lack of information from the custodians of this crop is limiting its sustainable development. Therefore, ethnobotanical surveys on the diversity, uses, and constraints limiting the cultivation and use of the crop in southeastern Nigeria were carried out. Five-hundred respondents were randomly selected and data collected through oral interviews and focused group discussion (FGD). Semi-structured questionnaires (SSQ) were also used to elicit information from a spectrum of AYB users comprising community leaders, farmers, market women and consumers in five States. Results showed that the majority of the respondents lacked formal education and were of the age group of 40–50 years, while the female gender dominated with limited access to land and extension officers. Seed coat colour largely determined utilization. Long cooking time, requirement for staking materials, aging of farmers and low market demand were among the major constraints limiting further cultivation and utilization of AYB. In-situ conservation was by hanging dried fruits by the fireside, beside the house, storing in earthenware, calabash gourds, cans and bottles. It is concluded that there is urgent need to scale up conservation through robust linkages between contemporary scientific domains and indigenous peoples in order to harness and incorporate the rich indigenous knowledge in local communities for enhanced scientific knowledge, biodiversity conservation and its sustainable utilization for food security. Full article
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1093 KiB  
Article
Alfalfa Responses to Gypsum Application Measured Using Undisturbed Soil Columns
by Rebecca Tirado-Corbalá, Brian K. Slater, Warren A. Dick and Dave Barker
Plants 2017, 6(3), 29; https://doi.org/10.3390/plants6030029 - 11 Jul 2017
Cited by 14 | Viewed by 3970
Abstract
Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG)] are produced from coal combustion in the United States, but only 4% is used for agricultural purposes. [...] Read more.
Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG)] are produced from coal combustion in the United States, but only 4% is used for agricultural purposes. The objective of this study was to evaluate the effects of (1) untreated, (2) short-term (4-year annual applications of gypsum totaling 6720 kg ha−1), and (3) long-term (12-year annual applications of gypsum totaling 20,200 kg ha−1) on alfalfa (Medicago sativa L.) growth and nutrient uptake, and gypsum movement through soil. The study was conducted in a greenhouse using undisturbed soil columns of two non-sodic soils (Celina silt loam and Brookston loam). Aboveground growth of alfalfa was not affected by gypsum treatments when compared with untreated (p > 0.05). Total root biomass (0–75 cm) for both soils series was significantly increased by gypsum application (p = 0.04), however, increased root growth was restricted to 0–10 cm depth. Soil and plant analyses indicated no unfavorable environmental impact from of the 4-year and 12-year annual application of FGDG. We concluded that under sufficient water supply, by-product gypsum is a viable source of Ca and S for land application that might benefit alfalfa root growth, but has less effect on aboveground alfalfa biomass production. Undisturbed soil columns were a useful adaptation of the lysimeter method that allowed detailed measurements of alfalfa nutrient uptake, root biomass, and yield and nutrient movement in soil. Full article
(This article belongs to the Special Issue Soil Fertility and Nutrient Cycling)
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2020 KiB  
Review
The Polyketide Components of Waxes and the Cer-cqu Gene Cluster Encoding a Novel Polyketide Synthase, the β-Diketone Synthase, DKS
by Penny Von Wettstein-Knowles
Plants 2017, 6(3), 28; https://doi.org/10.3390/plants6030028 - 10 Jul 2017
Cited by 12 | Viewed by 4687
Abstract
The primary function of the outermost, lipophilic layer of plant aerial surfaces, called the cuticle, is preventing non-stomatal water loss. Its exterior surface is often decorated with wax crystals, imparting a blue–grey color. Identification of the barley Cer-c, -q and -u genes [...] Read more.
The primary function of the outermost, lipophilic layer of plant aerial surfaces, called the cuticle, is preventing non-stomatal water loss. Its exterior surface is often decorated with wax crystals, imparting a blue–grey color. Identification of the barley Cer-c, -q and -u genes forming the 101 kb Cer-cqu gene cluster encoding a novel polyketide synthase—the β-diketone synthase (DKS), a lipase/carboxyl transferase, and a P450 hydroxylase, respectively, establishes a new, major pathway for the synthesis of plant waxes. The major product is a β-diketone (14,16-hentriacontane) aliphatic that forms long, thin crystalline tubes. A pathway branch leads to the formation of esterified alkan-2-ols. Full article
(This article belongs to the Special Issue The Plant Cuticle)
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2882 KiB  
Review
Cuticular Waxes of Arabidopsis thaliana Shoots: Cell-Type-Specific Composition and Biosynthesis
by Daniela Hegebarth and Reinhard Jetter
Plants 2017, 6(3), 27; https://doi.org/10.3390/plants6030027 - 07 Jul 2017
Cited by 19 | Viewed by 7331
Abstract
It is generally assumed that all plant epidermis cells are covered with cuticles, and the distinct surface geometries of pavement cells, guard cells, and trichomes imply functional differences and possibly different wax compositions. However, experiments probing cell-type-specific wax compositions and biosynthesis have been [...] Read more.
It is generally assumed that all plant epidermis cells are covered with cuticles, and the distinct surface geometries of pavement cells, guard cells, and trichomes imply functional differences and possibly different wax compositions. However, experiments probing cell-type-specific wax compositions and biosynthesis have been lacking until recently. This review summarizes new evidence showing that Arabidopsis trichomes have fewer wax compound classes than pavement cells, and higher amounts of especially long-chain hydrocarbons. The biosynthesis machinery generating this characteristic surface coating is discussed. Interestingly, wax compounds with similar, long hydrocarbon chains had been identified previously in some unrelated species, not all of them bearing trichomes. Full article
(This article belongs to the Special Issue The Plant Cuticle)
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665 KiB  
Article
Variation in Yield Responses to Elevated CO2 and a Brief High Temperature Treatment in Quinoa
by James A. Bunce
Plants 2017, 6(3), 26; https://doi.org/10.3390/plants6030026 - 05 Jul 2017
Cited by 23 | Viewed by 5147
Abstract
Intraspecific variation in crop responses to global climate change conditions would provide opportunities to adapt crops to future climates. These experiments explored intraspecific variation in response to elevated CO2 and to high temperature during anthesis in Chenopodium quinoa Wild. Three cultivars of [...] Read more.
Intraspecific variation in crop responses to global climate change conditions would provide opportunities to adapt crops to future climates. These experiments explored intraspecific variation in response to elevated CO2 and to high temperature during anthesis in Chenopodium quinoa Wild. Three cultivars of quinoa were grown to maturity at 400 (“ambient”) and 600 (“elevated”) μmol·mol−1 CO2 concentrations at 20/14 °C day/night (“control”) temperatures, with or without exposure to day/night temperatures of 35/29 °C (“high” temperatures) for seven days during anthesis. At control temperatures, the elevated CO2 concentration increased the total aboveground dry mass at maturity similarly in all cultivars, but by only about 10%. A large down-regulation of photosynthesis at elevated CO2 occurred during grain filling. In contrast to shoot mass, the increase in seed dry mass at elevated CO2 ranged from 12% to 44% among cultivars at the control temperature. At ambient CO2, the week-long high temperature treatment greatly decreased (0.30 × control) or increased (1.70 × control) seed yield, depending on the cultivar. At elevated CO2, the high temperature treatment increased seed yield moderately in all cultivars. These quinoa cultivars had a wide range of responses to both elevated CO2 and to high temperatures during anthesis, and much more variation in harvest index responses to elevated CO2 than other crops that have been examined. Full article
(This article belongs to the Special Issue Plant Adaptation to Climate Change)
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Review
Occurrence and Biosynthesis of Alkyl Hydroxycinnamates in Plant Lipid Barriers
by Frédéric Domergue and Dylan K. Kosma
Plants 2017, 6(3), 25; https://doi.org/10.3390/plants6030025 - 30 Jun 2017
Cited by 14 | Viewed by 6995
Abstract
The plant lipid barriers cuticle and suberin represent one of the largest biological interfaces on the planet. They are comprised of an insoluble polymeric domain with associated organic solvent-soluble waxes. Suberin-associated and plant cuticular waxes contain mixtures of aliphatic components that may include [...] Read more.
The plant lipid barriers cuticle and suberin represent one of the largest biological interfaces on the planet. They are comprised of an insoluble polymeric domain with associated organic solvent-soluble waxes. Suberin-associated and plant cuticular waxes contain mixtures of aliphatic components that may include alkyl hydroxycinnamates (AHCs). The canonical alkyl hydroxycinnamates are comprised of phenylpropanoids, typically coumaric, ferulic, or caffeic acids, esterified with long chain to very long chain fatty alcohols. However, many related structures are also present in the plant kingdom. Although their functions remain elusive, much progress has been made on understanding the distribution, biosynthesis, and deposition of AHCs. Herein a summary of the current state of knowledge on plant AHCs is provided. Full article
(This article belongs to the Special Issue The Plant Cuticle)
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