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15 pages, 2961 KiB

Open AccessEditor’s ChoiceArticle

The Effect of Salinity and Drought on the Essential Oil Yield and Quality of Various Plant Species of the Lamiaceae Family (Mentha spicata L., Origanum dictamnus L., Origanum onites L.)

by Michalis K. Stefanakis, Anastasia E. Giannakoula, Georgia Ouzounidou, Charikleia Papaioannou, Vaia Lianopoulou and Eleni Philotheou-Panou

Horticulturae 2024, 10(3), 265; https://doi.org/10.3390/horticulturae10030265 - 10 Mar 2024

Cited by 2 | Viewed by 1569

Abstract

Mentha spicata L., Origanum dictamnus L., and Origanum onites L. are aromatic plants that produce very important essential oils. They are considered model plants with beneficial health properties due to their antioxidant content. Enhancing the yield while maintaining the quality of essential oil [...] Read more.

Mentha spicata L., Origanum dictamnus L., and Origanum onites L. are aromatic plants that produce very important essential oils. They are considered model plants with beneficial health properties due to their antioxidant content. Enhancing the yield while maintaining the quality of essential oil is of significant commercial importance. Salinization and drought cause various effects on the yield and quality of the bioactive constituents in essential oil. By assessing the response of these plants and their secondary metabolites accumulation to different salt stress and irrigation levels, this study aims to gain insights into how plants adapt to and cope with salinity and drought. A pot experiment was conducted in the spring of 2020 to assess the effect of salinity and drought stress on the growth and essential oils content of the three aromatic plant species mentioned above. The soil mixture used was perlite and peat in a ratio of 1:1:6, while four salinity treatments (25, 50, 100, and 150 mΜ NaCl) and two levels of irrigation were applied (100% and 50%). Salinity significantly affects total chlorophyll concentration especially in higher concentrations (100 and 150 mM) in M. spicata plants, especially under 50% soil water irrigation. Under the same conditions, M. spicata contained the higher proline concentration, which was significantly greater than that in O. dictamnus and O. onites. Similar variations of malondialdehyde and hydrogen hyperoxide were revealed among the three species, with significantly higher values in M. spicata when subjected to both excess salinity and drought conditions. The major compounds identified in M. spicata were carvone, in O. dictamnus carvacrol, and p-cymene and in O. onites carvacrol. It is important to highlight that O. onites had the highest concentration of essential oil, and that the concentration increased with the increase of NaCl. This suggests that the presence of NaCl in the soil may have a stimulating effect on the production of essential oil in O. onites. However, it is plausible that the stress caused by NaCl triggers a physiological response in O. onites, leading to increased production of essential oil. This could be a protective mechanism to enhance the plant’s resistance to the stressor. Overall, O. onites and O. dictamnus appeared to be more resistant to these stress conditions than M. spicata, since they maintained their growth and essential oil quality indicators at higher levels. These two species possess mechanisms that prevent or minimize lipid peroxidation, thus protecting their cell membranes and maintaining their ultrastructure integrity. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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16 pages, 1773 KiB

Open AccessArticle

Performance Evaluation of New Table Grape Varieties under High Light Intensity Conditions Based on the Photosynthetic and Chlorophyll Fluorescence Characteristics

by Yawen He, Vivek Yadav, Shijian Bai, Jiuyun Wu, Xiaoming Zhou, Wen Zhang, Shouan Han, Min Wang, Bin Zeng, Xinyu Wu, Haixia Zhong and Fuchun Zhang

Horticulturae 2023, 9(9), 1035; https://doi.org/10.3390/horticulturae9091035 - 14 Sep 2023

Cited by 2 | Viewed by 1829

Abstract

The evaluation of photosynthetic characteristics of plants is important for the success rate of germplasm introduction. To select grape varieties with higher adaptability and trait performance, this experiment is aimed at evaluating and comparing the photosynthetic indices, chlorophyll fluorescence parameters, photosynthetic pigment content, [...] Read more.

The evaluation of photosynthetic characteristics of plants is important for the success rate of germplasm introduction. To select grape varieties with higher adaptability and trait performance, this experiment is aimed at evaluating and comparing the photosynthetic indices, chlorophyll fluorescence parameters, photosynthetic pigment content, and leaf characteristics of five Chinese hybrid varieties. The results showed that under high light intensity stress, the leaf growth of ‘Ruidu Cuixia’ was most affected and its specific leaf weight was the lowest, while ‘Jing Hongbao’ had the highest chlorophyll content. The maximum net photosynthetic rate (P_nmax), maximum light quantum yield (F_v/F_m), and apparent quantum efficiency (AQE) were different among varieties. It was reported that the ‘Ruidu Zaohong’ variety had the highest P_nmax. ‘Ruidu Wuheyi’ was found to have the highest F_v/F_m, while the highest AQE was recorded for ‘Ruidu Cuixia’, with intercellular CO₂ concentration (C_i) and stomatal conductance (gs) at 292.56 μmol·mol⁻¹, 766.56 mmol·m⁻²·s⁻¹, and 66.8 μmol·m⁻²·s⁻¹, respectively. The indices of ABS/CS_m, TR_o/CS_m, and DI_o/CS_m were significantly different among varieties, and these indices of ‘Ruidu Zaohong’ were the highest. P_n was positively correlated with C_i and T_r, gs were positively correlated with F_v and TR_o/CS_m. The specific leaf area was negatively correlated with F_v/F_m and Φ_DIo. The results of the principal component analysis and TOPSIS comprehensive evaluation showed that ‘Jing Hongbao’ and ‘Ruidu Cuixia’ performed best. Overall, the measurement of the photosynthetic characteristics of the plants during the growing period provided valuable data for the varietal introduction strategies. The better photosynthetic performance of ‘Jing Hongbao’ and ‘Ruidu Cuixia’ indicates more adaptability to the long day, high light intensity, and the high-temperature climate of Xinjiang. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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19 pages, 3843 KiB

Open AccessEditor’s ChoiceArticle

Morpho-Physiological Responses of Three Italian Olive Tree (Olea europaea L.) Cultivars to Drought Stress

by Sara Parri, Marco Romi, Yasutomo Hoshika, Alessio Giovannelli, Maria Celeste Dias, Francesca Cristiana Piritore, Giampiero Cai and Claudio Cantini

Horticulturae 2023, 9(7), 830; https://doi.org/10.3390/horticulturae9070830 - 20 Jul 2023

Cited by 5 | Viewed by 2348

Abstract

Water scarcity in agriculture can limit crop production and trigger the need for more effective water resource management. As a result, it is critical to identify new crop genotypes that are more drought tolerant and perform better under low irrigation or even rain-fed [...] Read more.

Water scarcity in agriculture can limit crop production and trigger the need for more effective water resource management. As a result, it is critical to identify new crop genotypes that are more drought tolerant and perform better under low irrigation or even rain-fed conditions. The olive tree is a high-value crop that is well adapted to dry Mediterranean conditions. However, different genotypes may have developed different mechanisms of tolerance to water stress. To investigate such mechanisms, we examined three Italian olive cultivars (‘Giarraffa’, ‘Leccino’, and ‘Maurino’) grown in a greenhouse under drought stress. We found that single genotypes responded differently to the drought, though not all parameters revealed significant differences. The first major difference among the cultivars was in transpiration: the lower stomatal density and stomatal conductance of ‘Giarraffa’ allow this cultivar to use water more conservatively. In parallel with the reduction in stomatal and mesophyll conductance, the drought-stressed group of ‘Giarraffa’ maintained the electron transport rate and effective efficiency levels of photosystem II similar to those of the control until the fourth week of stress. The fluorescence parameters revealed the earlier closure of reaction photosynthetic centres in ‘Leccino’. Finally, the higher rate of electrolyte leakage in ‘Maurino’ indicated a significant ions loss in this cultivar when it was subjected to the drought. Both water management under stress conditions and the effect of drought on photosynthesis make ‘Giarraffa’ interesting to researchers studying its use in breeding or water-saving programmes. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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16 pages, 4239 KiB

Open AccessArticle

Effects of 10 Dwarfing Interstocks on Cold Resistance of ‘Tianhong 2’ Apple

by Junli Jing, Mingxiao Liu, Baoying Yin, Bowen Liang, Zhongyong Li, Xueying Zhang, Jizhong Xu and Shasha Zhou

Horticulturae 2023, 9(7), 827; https://doi.org/10.3390/horticulturae9070827 - 19 Jul 2023

Cited by 3 | Viewed by 1290

Abstract

The lack of dwarf stock with good cold resistance has affected the production of apples in northern China. Annual dormant branches of ‘Tianhong 2’ apple were grafted on 10 different dwarf interstocks (the rootstocks were the seedlings of Malus hupehensis var. Pingyiensis) [...] Read more.

The lack of dwarf stock with good cold resistance has affected the production of apples in northern China. Annual dormant branches of ‘Tianhong 2’ apple were grafted on 10 different dwarf interstocks (the rootstocks were the seedlings of Malus hupehensis var. Pingyiensis) as test materials. Among these 10 interstocks, Huang 6, 244, NO.1, 53, 24-5, ZC9-3, Jizhen 1 were newly developed by us (Apple Research Group of Hebei Agricultural University), and three interstocks with different degrees of cold resistance (GM256–with strongest cold resistance, SH40–with stronger cold resistance, M9–with poor cold resistance) were used as controls. The semi-lethal temperature (LT50) and related physiological indexes of the branches in the overwintering process were studied. Based on the comprehensive physiological indexes, the effects of 10 interstocks on cold resistance of the ‘Tianhong 2’ apple were analyzed. The results showed that the effects of 10 kinds of interstocks on the cold resistance of ‘Tianhong 2’ apple were quite different. The order of effects on cold resistance from strong to weak was as follow: GM256 > Huang 6 > 244 >NO.1> 53 > 24-5 > ZC9-3 >Jizhen 1 > SH40 > M9. The purpose of this study was to screen out the interstocks with strong cold resistance, in order to provide some basis for the selection and utilization of interstocks with strong cold resistance in apple cultivation to further promote the development of the apple industry in China. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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21 pages, 11749 KiB

Open AccessArticle

Optimization of In Vitro Regeneration Protocol of Tomato cv. MT1 for Genetic Transformation

by Shiuli Ahmed, Wan Aina Sakeenah Wan Azizan, Md. Abdullah Yousuf Akhond, Abdul Shukor Juraimi, Siti Izera Ismail, Razu Ahmed and Muhammad Asyraf Md Hatta

Horticulturae 2023, 9(7), 800; https://doi.org/10.3390/horticulturae9070800 - 13 Jul 2023

Viewed by 2712

Abstract

The tomato (Solanum lycopersicum L.) is a major crop of global economic significance. The characterization of genes associated with agriculturally important traits is often performed using genetic transformation. To achieve an efficient transformation protocol, three components are required, namely, a regenerable target [...] Read more.

The tomato (Solanum lycopersicum L.) is a major crop of global economic significance. The characterization of genes associated with agriculturally important traits is often performed using genetic transformation. To achieve an efficient transformation protocol, three components are required, namely, a regenerable target tissue, a DNA delivery method, and a robust transformant selection system. The present study was conducted to optimize the in vitro regeneration protocol for the tomato cv. MT1. The regeneration capacity of hypocotyl and cotyledon explants was evaluated using a total of 20 concentration combinations of two plant growth regulators (PGRs) added into the basal MSB5 medium, namely, 6-benzylaminopurine (BAP) (0, 1, 2, 3, and 4 mg/L) and indole-3-acetic acid (IAA) (0, 0.05, 0.1, and 0.5 mg/L). The optimal PGRs combinations for the cotyledons and hypocotyls were MSB5 supplemented with 2 mg/L BAP and 0.5 mg/L IAA and MSB5 supplemented with 2 mg/L BAP and 0.1 mg/L IAA, respectively. To determine the minimum inhibitory concentration (MIC) of kanamycin, eight different concentrations (0, 50, 75, 100, 125, 150, 175, and 200 mg/L) were added to the MSB5 supplemented with 2 mg/L BAP and 0.5 mg/L IAA. The MIC for the cotyledons and hypocotyls were determined to be 50 mg/L and 100 mg/L, respectively. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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17 pages, 5835 KiB

Open AccessArticle

The Impact of High Temperatures in the Field on Leaf Tissue Structure in Different Grape Cultivars

by Jiuyun Wu, Riziwangguli Abudureheman, Haixia Zhong, Vivek Yadav, Chuan Zhang, Yaning Ma, Xueyan Liu, Fuchun Zhang, Qian Zha and Xiping Wang

Horticulturae 2023, 9(7), 731; https://doi.org/10.3390/horticulturae9070731 - 21 Jun 2023

Cited by 5 | Viewed by 1672

Abstract

Global warming will significantly affect grapevine growth and development. To analyze the effects of high temperature on the leaf tissue structure of grapevines in the field, 19 representative cultivars were selected from the grapevine germplasm resources garden in Turpan Research Institute of Agricultural [...] Read more.

Global warming will significantly affect grapevine growth and development. To analyze the effects of high temperature on the leaf tissue structure of grapevines in the field, 19 representative cultivars were selected from the grapevine germplasm resources garden in Turpan Research Institute of Agricultural Sciences, XAAS. Twelve tissue structure indexes of grapevine leaves, including the thickness of the upper epidermis (TUE), the thickness of palisade tissue (TPT), leaf vein (LV), the thickness of spongy tissue (TST), the thickness of the lower epidermis (TLE), stoma (St), guard cell (GC), cuticle (Cu), leaf tissue compactness (CTR) and leaf tissue porosity (SR), were measured during the natural high-temperature period in Turpan. The results showed significant differences in the leaf tissue structure of the 19 grapevine cultivars under natural high temperature. Based on the comprehensive comparative analysis of the leaf phenotype in the field, we identified that the leaves of some cultivars, including ‘Zaoxia Wuhe’, ‘Centennial Seedless’ and ‘Kyoho’ showed strong heat tolerance, whereas grapevine cultivars ‘Golden Finger’, ‘Shine Muscat’, ‘Flame Seedless’, ‘Bixiang Wuhe’ and ‘Thompson Seedless’ showed sensitivity to high temperature. We further evaluated the heat tolerance of different grapevine cultivars by principal component analysis and the optimal segmentation clustering of ordered samples. These findings provide a theoretical basis for adopting appropriate cultivation management measures to reduce the effect of high temperatures and offer fundamental knowledge for future breeding strategies for heat-tolerant grapevine varieties. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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16 pages, 5955 KiB

Open AccessArticle

Combined Study of Transcriptome and Metabolome Reveals Involvement of Metabolites and Candidate Genes in Flavonoid Biosynthesis in Prunus avium L.

by Baochun Fu and Yongqiang Tian

Horticulturae 2023, 9(4), 463; https://doi.org/10.3390/horticulturae9040463 - 6 Apr 2023

Viewed by 1809

Abstract

Sweet cherry (Prunus avium L.) is a popular fruit tree grown for its juicy fruit and pleasing appearance. The fruit pf the sweet cherry contains active antioxidants and other chemical compounds essential for human health. For this study, we performed the transcriptomics [...] Read more.

Sweet cherry (Prunus avium L.) is a popular fruit tree grown for its juicy fruit and pleasing appearance. The fruit pf the sweet cherry contains active antioxidants and other chemical compounds essential for human health. For this study, we performed the transcriptomics and metabolomics analysis using young Green Peel (GP) and mature Red Peel (RP) from sweet cherries to understand the underlying genetic mechanism regulating fruit development and ripening. Using high-throughput RNA sequencing and ultra-performance liquid chromatography, with quadrupole time-of-flight tandem mass spectrometry, respectively, metabolic and transcript profiling was obtained. Relative to GP, there were equal quantities of pronouncedly varied metabolites in RP (n = 3564). Differentially expressed genes (DEGs, n = 3564), containing 45 transcription factor (TF) families, were recorded in RP. Meanwhile, 182 differentially expressed TF (DETF) members of 37 TF families, were displayed in abundance in RP compared to GP sweet cherries. The largest quantities of DETFs were members of the ERF (25) and basic helix–loop–helix (bHLH) (19) families, followed by the MYB (18), WRKY (18), and C2H2 (12) families. Interestingly, most ERF genes were down-regulated, whereas CCCH genes were mainly up-regulated in RP. Other DETFs exhibited significant variations. In addition, RT-QPCR results and metabolomics data together with transcriptomic data revealed that the abundance of catechin, epicatechin, rhoifolin, myricetin, keracyanin, and the other six glycosyltransferase genes was highly increased in RP when compared to GP sweet cherries. The relatively higher expression of DETFs, metabolite, and flavonoid biosynthesis in RP sweet cherries suggests the accumulation of distinct metabolites that cause red coloring during fruit development and ripening. Thus, the metabolomics and transcriptomic analysis of the current study are powerful tools for providing more valuable information for the metabolic engineering of flavonoids biosynthesis in sweet cherries. They are also helpful in understanding the relationship between genotype and phenotype. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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13 pages, 2158 KiB

Open AccessEditor’s ChoiceArticle

Differential Responses of Cherry Tomatoes (Solanum lycopersicum) to Long-Term Heat Stress

by Bo-Mi Park, Hyo-Bong Jeong, Eun-Young Yang, Min-Kyoung Kim, Ji-Won Kim, Wonbyoung Chae, Oak-Jin Lee, Sang Gyu Kim and Sumin Kim

Horticulturae 2023, 9(3), 343; https://doi.org/10.3390/horticulturae9030343 - 6 Mar 2023

Cited by 5 | Viewed by 3102

Abstract

As global warming increases day/night temperatures as well as frequencies of heat waves, studying physiological responses in long-term heat stress is required for sustainable yield production in the future. In this study, effects of long-term heat stress on photosynthetic, morphological, and yield parameters [...] Read more.

As global warming increases day/night temperatures as well as frequencies of heat waves, studying physiological responses in long-term heat stress is required for sustainable yield production in the future. In this study, effects of long-term heat stress on photosynthetic, morphological, and yield parameters of three cherry tomato accessions, HR17, HR22, and HR24, were evaluated. The experiment was conducted under two temperature greenhouse conditions, where temperature set-point for ventilation was 30 °C and 35 °C during the day for 57 days, respectively. Plants were harvested on the 35th days and 57th days after heat treatments, and their physiological and morphological characteristics and yield traits were measured. Under control conditions, HR17 and HR22 had 0.5–0.6 harvest index, while HR24 had 0.3 harvest index. On 35th days after heat treatment, although yield loss percentage of HR17 was high (43%), it produced the highest fruit yield among all three accessions. However, after longer heat treatment, HR24 produced the highest fruit yields among all accessions with the smallest yield loss (34%). Furthermore, yield loss was highly associated with reductions in nitrogen use efficiency and water content in plant body under heat stress. The results of this study will provide breeders with a new insight into selecting heat-tolerant genotypes in cherry tomatoes. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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17 pages, 2985 KiB

Open AccessArticle

Response of Warm Season Turf Grasses to Combined Cold and Salinity Stress under Foliar Applying Organic and Inorganic Amendments

by Dina Taher, Emam Nofal, Mahmoud Hegazi, Mohamed Abd El-Gaied, Hassan El-Ramady and Svein Ø. Solberg

Horticulturae 2023, 9(1), 49; https://doi.org/10.3390/horticulturae9010049 - 3 Jan 2023

Cited by 5 | Viewed by 2341

Abstract

Turfgrasses are considered an important part of the landscape and ecological system of golf courses, sports fields, parks, and home lawns. Turfgrass species are affected by many abiotic stresses (e.g., drought, salinity, cold, heat, waterlogging, and heavy metals) and biotic stresses (mainly diseases [...] Read more.

Turfgrasses are considered an important part of the landscape and ecological system of golf courses, sports fields, parks, and home lawns. Turfgrass species are affected by many abiotic stresses (e.g., drought, salinity, cold, heat, waterlogging, and heavy metals) and biotic stresses (mainly diseases and pests). In the current study, seashore paspalum (Paspalum vaginatum Sw.) and Tifway bermudagrass (Cynodon transvaalensis Burtt Davy × C. Dactylon) were selected because they are popular turfgrasses frequently used for outdoor lawns and sport fields. The effect of the combined stress from both soil salinity and cold on these warm season grasses was investigated. Some selected organic and inorganic amendments (i.e., humic acid, ferrous sulphate, and silicon) were applied as foliar sprays five times during the winter season from late October to March. This was repeated over two years in field trials involving salt-affected soils. The physiological and chemical parameters of the plants, including plant height; fresh and dry weight per plot; total chlorophyll content; and nitrogen, phosphorus, iron, and potassium content, were measured. The results showed that all the studied amendments improved the growth of seashore paspalum and Tifway bermudagrass during this period compared to the control, with a greater improvement observed when using ferrous sulphate and humic acid compared to silicon. For seashore paspalum, the highest chlorophyll content in April was recorded after the application of ferrous sulphate at a level of 1000 ppm. The current research indicates that when grown on salt-affected soils, these amendments can be used in warm-season grasses to maintain turf quality during cold periods of the year. Further research is needed to examine any negative long-term effects of these amendments and to explain their mechanisms. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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11 pages, 608 KiB

Open AccessFeature PaperArticle

Ascophyllum nodosum and Silicon-Based Biostimulants Differentially Affect the Physiology and Growth of Watermelon Transplants under Abiotic Stress Factors: The Case of Drought

by Filippos Bantis and Athanasios Koukounaras

Horticulturae 2022, 8(12), 1177; https://doi.org/10.3390/horticulturae8121177 - 10 Dec 2022

Cited by 8 | Viewed by 1929

Abstract

Climate change is an inevitable process characterized by an abrupt increase in global temperature and a decrease in precipitations leading to drought incidents. Biostimulants could be a valuable tool for mitigating these harsh conditions. The objective of our study was to test the [...] Read more.

Climate change is an inevitable process characterized by an abrupt increase in global temperature and a decrease in precipitations leading to drought incidents. Biostimulants could be a valuable tool for mitigating these harsh conditions. The objective of our study was to test the efficiency of two biostimulants, a silicon-based seaweed and the seaweed Ascophyllum nodosum, to mitigate the drought stress endured by watermelon transplants during the first few weeks after transplanting. In order to achieve this, three water treatments (100%, 75%, and 50% of field capacity) were applied in pots. Important growth parameters (leaf number, fresh weight, and plant area) deteriorated depending on water availability. This was also the case for the root system development displayed by root dry weight, total length, and surface area. It is the first time the OJIP transient has been evaluated after the application of A. nodosum for drought-stressed plants. Chlorophyll fluorescence parameters showed that the photosynthetic apparatus was more stressed when A. nodosum was applied, especially in the harshest conditions (i.e., 50% field capacity). Overall, the silicon-based biostimulant failed to demonstrate drought-mitigating potential compared to the non-treated counterparts. On the other hand, A. nodosum alleviated the negative effects of water deficit, especially in the harshest conditions. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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27 pages, 5528 KiB

Open AccessArticle

Mitigation of Powdery Mildew Disease by Integrating Biocontrol Agents and Shikimic Acid with Modulation of Antioxidant Defense System, Anatomical Characterization, and Improvement of Squash Plant Productivity

by Nour El-Houda A. Reyad, Samah N. Azoz, Ayat M. Ali and Eman G. Sayed

Horticulturae 2022, 8(12), 1145; https://doi.org/10.3390/horticulturae8121145 - 5 Dec 2022

Cited by 2 | Viewed by 2622

Abstract

Squash (Cucurbita pepo L.) is a globally important vegetable, the production of which is severely constrained by powdery mildew caused by Podosphaera xanthii. In this study, we examined the effects of Trichoderma asperellum (MW965676), Streptomyces rochei (MN700192), and a mixture of [...] Read more.

Squash (Cucurbita pepo L.) is a globally important vegetable, the production of which is severely constrained by powdery mildew caused by Podosphaera xanthii. In this study, we examined the effects of Trichoderma asperellum (MW965676), Streptomyces rochei (MN700192), and a mixture of the two foliar sprays with or without shikimic acid seed priming treatment on powdery mildew severity, plant growth, and total yield during the 2020–2021 and 2021–2022 growing seasons. We also studied their immune eliciting properties by examining their enzymatic, phenolic, and hormonal functions. The combination of Trichoderma asperellum, Streptomyces rochei, and shikimic acid triggered plant defense responses, which elicited enzyme activities such as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), phenolic compound accumulation, and increased salicylic acid (SA) and jasmonic acid (JA) content. This approach yielded high-quality results in the control of powdery mildew during the two growing seasons under greenhouse conditions. Additionally, relatively large statistical differences in plant growth, total yield, mineral components, and physiological traits were observed. A GC–MS analysis of Trichoderma asperellum (MW965676) showed hemin cation as a major component, while Streptomyces rochei (MN700192) contained 2,4-di-tert-butyl phenol and the hexadecenoic acid methyl ester. With respect to the morphological changes induced by powdery mildew and the treatments, plants treated with a mixture of Trichoderma asperellum, Streptomyces rochei and shikimic acid showed an improvement in the thickness of the midvein, increased dimensions of the main midvein bundle, a larger number of xylem rows in the main midvein bundle, greater mean diameters of vessels and of parenchyma cells in the ground tissues, as well as increased thickness of the upper and lower epidermis, lamina, palisade tissue and spongy tissue. This extensive, new study is the first step toward a more profound understanding of the use of Trichoderma asperellum and Streptomyces rochei with shikimic acid-primed seeds as a potential alternative technique for attenuating powdery mildew infection in squash. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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11 pages, 2730 KiB

Open AccessArticle

Identification and Comparative Analysis of the Rosaceae RCI2 Gene Family and Characterization of the Cold Stress Response in Prunus mume

by Lichen Yang, Ping Li, Like Qiu, Sagheer Ahmad, Jia Wang and Tangchun Zheng

Horticulturae 2022, 8(11), 997; https://doi.org/10.3390/horticulturae8110997 - 26 Oct 2022

Cited by 4 | Viewed by 1608

Abstract

Rare cold inducible 2 (RCI2) proteins are a group of low molecular weight proteins that widely exist in various tissues of plants and play crucial roles in plant growth and development and abiotic stress responses. Genome-wide identification and analysis of RCI2 have not [...] Read more.

Rare cold inducible 2 (RCI2) proteins are a group of low molecular weight proteins that widely exist in various tissues of plants and play crucial roles in plant growth and development and abiotic stress responses. Genome-wide identification and analysis of RCI2 have not been documented in Rosaceae plants. Therefore, we identified 23 RCI2 genes from seven Rosaceae plants, which were classified into three subfamilies. The RoRCI2 protein encodes a highly conserved domain of Pmp3. Three homologous PmRCI2s genes from Prunus mume were cloned and named PmRCI2-1, PmRCI2-2, and PmRCI2-3. The results of subcellular localization prediction showed that three PmRCI2s localized to membrane structures, and the abscisic acid response element were found to have the largest number in the promoter sequences of PmRCI2s. The results of quantitative real-time PCR (qRT-PCR) showed that PmRCI2-3 was significantly induced by low temperature and highly expressed in stems and buds during the endodormancy stage. Our study improves the understanding of the RCI2 family of Rosaceae plants regarding the cold responses and provides a theoretical basis for the cold-resistant breeding of P. mume. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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Review

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14 pages, 5394 KiB

Open AccessReview

Melatonin-Induced Detoxification of Organic Pollutants and Alleviation of Phytotoxicity in Selected Horticultural Crops

by Golam Jalal Ahammed and Xin Li

Horticulturae 2022, 8(12), 1142; https://doi.org/10.3390/horticulturae8121142 - 4 Dec 2022

Cited by 20 | Viewed by 2592

Abstract

Environmental pollution with organic pollutants has increased drastically in recent decades. Despite the importance of minimizing organic pollutant content such as pesticide residue in edible crops, our understanding of induced xenobiotic metabolism in plants is poor. Melatonin is a potent stress-relieving biomolecule, which [...] Read more.

Environmental pollution with organic pollutants has increased drastically in recent decades. Despite the importance of minimizing organic pollutant content such as pesticide residue in edible crops, our understanding of induced xenobiotic metabolism in plants is poor. Melatonin is a potent stress-relieving biomolecule, which exerts beneficial effects on xenobiotic metabolism in plants. Exogenous melatonin treatment not only improves photosynthesis, antioxidant defense, and plant growth but also reduces pollutant residue and xenobiotic uptake. The overexpression of melatonin biosynthetic genes enhances organic pollutant metabolism, while the suppression of endogenous melatonin biosynthesis increases organic pollutant residue in horticultural products. Studies have revealed that the glutathione-dependent detoxification pathway plays a critical role in the melatonin-induced enhanced detoxification of xenobiotics. Moreover, a role for RESPIRATORY BURST HOMOLOG (RBOH)-derived reactive oxygen species signaling has been revealed which potentially acts upstream of glutathione-dependent xenobiotic metabolism. Based on the literature, here, we reviewed the effects of organic pollutants on plants and how melatonin aids plants in enduring the effects of organic pollutant-induced stress. We also discussed the potential melatonin signaling mechanism in enhanced pesticide metabolism. Our assessment suggests that melatonin has positive impacts on plant tolerance to organic pollution, which can be used to improve the food safety of edible horticultural crops. Full article

(This article belongs to the Special Issue Horticulture Plants Stress Physiology)

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