Recent Progress in Physiological and Molecular Mechanisms of Crop Plants to Biotic and Abiotic Stresses

A special issue of Agronomy (ISSN 2073-4395). This special issue belongs to the section "Crop Breeding and Genetics".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 26389

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State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China
Interests: plant biology; plant stress physiology; plant resistance against different stresses; abiotic and biotic stresses; heavy metal stresses; phytohormones; plant autophagy; plant biotechnology; plant genome editing; CRISPR/Cas9; nanoparticles; plant-bacteria interaction
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Special Issue Information

Dear Colleagues,

Many biotic (bacteria, viruses, fungi, and insects) and abiotic (drought, cold, salinity, heat, heavy metals, waterlogging, and nutrient deficiency) stresses have threatened global agriculture. Biotic and abiotic stresses significantly impact crop growth and development, which ultimately reduce yield. Crop plants must adjust their physiological and molecular characteristics to cope with these stresses. Therefore, plants have developed various mechanisms to overcome these threats of biotic and abiotic stresses. All this requires a selection process and provides a great opportunity to find the appropriate combinations of genes and phenotypes tolerant to various stresses. It is crucial to examine how a wide range of biotic and abiotic stresses affect various crops and better understand how crop plants respond to these stresses. This Special Issue aims to highlight the most recent breakthroughs in plant responses to biotic and abiotic stresses and adaptation/tolerance strategies and provides the advanced toolkit and technologies used to investigate and understand plant responses to biotic and abiotic stresses. We welcome original research articles and review papers on the effects of biotic and abiotic stresses on crop plants.

Dr. Hakim Manghwar
Guest Editor

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Keywords

  • biotic stress
  • abiotic stress
  • drought
  • cold
  • waterlogging
  • salinity
  • temperature stress
  • UV and light stress
  • heavy metals
  • bacteria
  • viruses
  • fungi
  • insects
  • stress adaptation
  • tolerance mechanism
  • crop plants
  • model plants

Published Papers (14 papers)

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14 pages, 671 KiB  
Communication
The Response of Chlorophyll Content and Ionic Composition in Tomato and Pepper Seedlings to Foliar Nutrition in Growing Chambers
by Mohunnad Massimi, László Radócz and Besarta Kabashi
Agronomy 2023, 13(9), 2234; https://doi.org/10.3390/agronomy13092234 - 26 Aug 2023
Viewed by 1057
Abstract
Studies have shown that applying specific solutions to the leaves of tomato and pepper plants can boost their output by enhancing nutrient absorption. The factorial analysis of two factors was used in data collection and statistical analysis in this experiment. The first factor [...] Read more.
Studies have shown that applying specific solutions to the leaves of tomato and pepper plants can boost their output by enhancing nutrient absorption. The factorial analysis of two factors was used in data collection and statistical analysis in this experiment. The first factor was the cultivar (Mobil, Korall, and Tyking F1 for tomatoes, and while cultivars of Carma, Fokusz, and Bobita F1 for sweet pepper), and the second was the spray treatment. Sprays used were sodium bicarbonate (0.52%), 50 mg·L−1 salicylic acid, and distilled water. The parameters collected were the SPAD index of chlorophyll and the plant sap’s content of calcium, potassium, and nitrates, with five observations for each record. Salicylic acid 50 mg·L−1 caused the highest multiple contents, particularly in the tomato cultivar Korall. The lowest multiple contents were for the Mobil cultivar. Spraying Mobil with salicylic acid (50 mg·L−1) and sodium bicarbonate (0.52%) produced the lowest chlorophyll and ionic content. Salicylic acid 50 mg·L−1 also led to the highest multiple values, particularly in the Carma pepper cultivar. The results revealed the multiple lowest contents of measured parameters were for the Bobita F1 cultivar. Finally, gardeners should consider growing Korall tomato and Carma pepper with a supportive spraying application of salicylic acid 50 mg·L−1 before seedlings are transferred to an open-air garden. Gardeners should consider the additional production-improving aspects described in existing research and seed manufacturer recommendations. Full article
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14 pages, 4813 KiB  
Article
Comparative Study of Photosynthesis Performance of Herbicide-Treated Young Triticale Plants during Drought and Waterlogging Stress
by Dessislava Todorova, Vladimir Aleksandrov, Svetoslav Anev and Iskren Sergiev
Agronomy 2023, 13(8), 1992; https://doi.org/10.3390/agronomy13081992 - 27 Jul 2023
Viewed by 918
Abstract
Owing to global climate changes, periods of soil drought or waterlogging occur. Each of these factors causes negative effects on plant physiological processes and growth. Weeds are another factor that limits plant productivity. The main task of this study is to investigate the [...] Read more.
Owing to global climate changes, periods of soil drought or waterlogging occur. Each of these factors causes negative effects on plant physiological processes and growth. Weeds are another factor that limits plant productivity. The main task of this study is to investigate the physiological reactions of triticale to herbicide treatment and subsequent drought or waterlogging. Young triticale plants were treated with Serrate® (selective herbicide produced by Syngenta) and exposed for 7 days to drought or waterlogging. Plant growth, chlorophyll and carotenoids content, the net photosynthesis rate and chlorophyll a fluorescence were measured during the stress period and after 4 days of plant recovery. Herbicide by itself did not induce considerable changes in the abovementioned parameters during the stress period. Serrate® did not affect strongly the efficiency of the photosynthetic machinery under harsh conditions. A significant reduction in fresh weight (85%), water content (93%), net photosynthesis rate, chlorophyll a fluorescence indices Fv/Fm and Fv/F0, and leaf pigments (58% for chlorophyll a, 53% for chlorophyll b, and 45% for carotenoids) was found because of drought. Waterlogging also influenced negatively these parameters but to a smaller extent. After resuming the normal irrigation, the photosynthesis and chlorophyll a fluorescence tended to increase and showed signs of recovery. The comparative analysis of growth and photosynthetic parameters demonstrated that triticale plants subjected to waterlogging could recover to a higher degree than those exposed to drought. Full article
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21 pages, 6555 KiB  
Article
Alleviatory Effects of Silicon and 24-Epibrassinolide in Modulation of Growth, Osmolytes, Metabolites, Antioxidant Defense System, and Gene Expression in Lead-Exposed Fenugreek (Trigonella foenum-graecum L.) Plants
by Dhriti Sharma, Savita Bhardwaj, Ali Raza, Rattandeep Singh, Dhriti Kapoor, Neeta Raj Sharma and P. V. Vara Prasad
Agronomy 2023, 13(7), 1884; https://doi.org/10.3390/agronomy13071884 - 17 Jul 2023
Cited by 1 | Viewed by 1085
Abstract
Amplified concentrations of lead (Pb) in cultivable soils, being a major environmental concern, bring about malicious consequences for plant and human health. Trigonella foenum-graecum (fenugreek) is a multipurpose herb used as a spice, tonic, leafy vegetable, and therapeutic agent. Earlier works have revealed [...] Read more.
Amplified concentrations of lead (Pb) in cultivable soils, being a major environmental concern, bring about malicious consequences for plant and human health. Trigonella foenum-graecum (fenugreek) is a multipurpose herb used as a spice, tonic, leafy vegetable, and therapeutic agent. Earlier works have revealed the inhibitory effects of Pb toxicity in Trigonella, affecting its growth and productivity. Therefore, the current experimental work was planned with the purpose of evaluating the effects of exogenously supplemented silicon (Si; 2 mM) and 24-epibrassinolide (24-EBL; 10−7 M) (in both individual and combined form) on growth attributes, osmolytes, metabolite measures, and antioxidant defense mechanisms of Trigonella foenum-graecum plants in response to three discrete concentrations of Pb stress (0.5, 0.7, and 0.9 mM). The results revealed that Pb stress affected morphological parameters of fenugreek plants via the genesis of reactive oxygen species (ROS), as indicated by higher measures of oxidative damage indicators like malondialdehyde (MDA) and hydrogen peroxide (H2O2). Spraying foliage with Si together with a pretreatment of 24-EBL alone as well as in a combined form yielded better outcomes in terms of growth parameters in the Pb-stressed plants. Pb toxicity decreased osmolytes, proteins, and metabolites. Components of the antioxidative defense system, i.e., enzymes [ascorbate peroxidase (APX), guaiacol peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), together with non-enzymes [ascorbic acid (AsA) and glutathione (GSH), were downregulated when subjected to Pb toxicity. Out of all, Pb III (0.9 mM) had a more adverse impact on various parameters in fenugreek compared to Pb I (0.5 mM) and Pb II (0.7 mM). However, external supplementation with Si and 24-EBL (individually and in combination) ameliorated the Pb-mediated oxidative stress in fenugreek plants by improving the content of different osmolytes and metabolites while upregulating the functioning of the antioxidative defense system. Downregulation in the expression of SOD and CAT genes was found in Pb-stressed plants, while their expression was upregulated by Si and 24-EBL both individually and in combination. The experimental study revealed that the combined application of Si and 24-EBL was significantly better at abating the Pb metal stress in fenugreek plants when compared with their individual applications. Full article
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17 pages, 689 KiB  
Article
Effects of Nitrogen on Photosynthetic Productivity and Yield Quality of Wheat (Triticum aestivum L.)
by Hafeez Noor, Zhouzuo Yan, Peijie Sun, Limin Zhang, Pengcheng Ding, Linghong Li, Aixia Ren, Min Sun and Zhiqiang Gao
Agronomy 2023, 13(6), 1448; https://doi.org/10.3390/agronomy13061448 - 24 May 2023
Cited by 9 | Viewed by 2023
Abstract
This study aims to understand the influence of chlorophyll fluorescence parameters on the yield of winter wheat in some areas of China. Nitrogen (N) application is believed to improve photosynthesis in flag leaf, which ultimately increases the final yield. The experiment was conducted [...] Read more.
This study aims to understand the influence of chlorophyll fluorescence parameters on the yield of winter wheat in some areas of China. Nitrogen (N) application is believed to improve photosynthesis in flag leaf, which ultimately increases the final yield. The experiment was conducted in the wheat experimental base of Shanxi Agricultural University in Taigu, Shanxi Province, China; before sowing, four N application rates were set—N0, N120, N150, and N210 kg ha–1 of the Yunhan-20410 variety from 2019 to 2022. The results from different parameters of research showed that the organic manure partial substitution for chemical fertilizer increased post-anthesis N uptake by 16.4 and 81.4%, thus increasing the post-anthesis photosynthetic capacity and delaying leaf senescence. N150 treatment can improve dry matter (DM) accumulation, thus promoting the increase of the yield. The maximum net photosynthesis PN value of the booting stage and flowering stage indicated that nitrogen application could significantly improve the photosynthetic rate of wheat leaves, among which medium nitrogen treatment had the most significant promoting effect. The single-photon avalanche diode (SPAD) value of the leaf of wheat in each treatment increased rapidly in a small range from the jointing stage to the booting stage, respectively. The grain yield under N fertilizer partial substitution for N fertilizer treatment increased by 23%. According to the different significance test, the effects of nitrogen application rate on net photosynthesis PN of winter wheat were extremely significant at all growth stages, indicating that changing the population distribution mode and nitrogen level could effectively improve leaf photosynthetic performance and that N150 level was the best. Full article
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17 pages, 3847 KiB  
Article
An Endophytic Fungal Isolate Paecilomyces lilacinus Produces Bioactive Secondary Metabolites and Promotes Growth of Solanum lycopersicum under Heavy Metal Stress
by Muhammad Musa, Farzana Gul Jan, Muhammad Hamayun, Gul Jan, Sumera Afzal Khan, Gauhar Rehman, Sajid Ali and In-Jung Lee
Agronomy 2023, 13(3), 883; https://doi.org/10.3390/agronomy13030883 - 16 Mar 2023
Cited by 6 | Viewed by 1836
Abstract
Heavy metal (HM) contamination in the soil and accumulation in plants poses a serious threat to crops and human health. HMs such as cadmium, mercury, lead and arsenic are widely acknowledged for their adverse effects on plants such as chlorosis, necrosis, low food [...] Read more.
Heavy metal (HM) contamination in the soil and accumulation in plants poses a serious threat to crops and human health. HMs such as cadmium, mercury, lead and arsenic are widely acknowledged for their adverse effects on plants such as chlorosis, necrosis, low food quality and crop yields. Endophytic fungi secrete secondary metabolites and enhance the plant’s ability to tolerate stressful conditions. However, the role of most fungal endophytes in their host plant growth or production of metabolites under HM stress conditions needs further understanding. In the present study, we studied the HM stress alleviation capability of the endophytic fungus, Paecilomyces lilacinus (MRF), isolated from the roots of Justicia adathoda. We studied two heavy metals, namely lead and cobalt. The culture filtrate (CF) of P. lilacinus revealed IAA (68.17 µg/mL), phenols (43.31 µg/mL), flavonoids (40.59 µg/mL), sugar content (97.83 µg/mL) and proline (17 µg/mL). Additionally, DPPH-free radical scavenging activity and the antibacterial potential against Salmonella typhi and Shigella sonnei of the CF demonstrated positive results. The gas chromatography mass spectrometry analysis of the CF manifested different constituents, including (1) Trichloromethane, (2) 3,7,11,15-Tetramethyl-2-hexadecen-1-ol, (3) phytol, (4) 1,2-Benzenedicarboxylic acid, (5) bis(2-ethylhexyl) ester, (6) squalene and (7) Cyclotrisiloxane Hexamethyl. Moreover, the plant growth-promoting activity of the P. lilacinus (MRF) strain revealed a robust increase in root and shoot growth, and the fresh and dry weight of S. lycoprsicum. Further, the IAA, phenols, flavonoids, sugar, proline, relative water content and protein contents also increased in the S. lycoprsicum inoculated with P. lilacinus as compared to the control plants. The present study revealed that the inoculation of P. lilacinus alleviates the damages of HM stress and improves the physicochemical characteristics of S. lycoprsicum. Full article
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18 pages, 4169 KiB  
Article
Plant Growth Promoting Rhizobacteria (PGPR) and Arbuscular Mycorrhizal Fungi Combined Application Reveals Enhanced Soil Fertility and Rice Production
by Delai Chen, Munawar Saeed, Mian Noor Hussain Asghar Ali, Muhammad Raheel, Waqas Ashraf, Zeshan Hassan, Muhammad Zeeshan Hassan, Umar Farooq, Muhammad Fahad Hakim, Muhammad Junaid Rao, Syed Atif Hasan Naqvi, Mahmoud Moustafa, Mohammed Al-Shehri and Sally Negm
Agronomy 2023, 13(2), 550; https://doi.org/10.3390/agronomy13020550 - 14 Feb 2023
Cited by 7 | Viewed by 3200
Abstract
Rice (Oryza sativa L.) is an important crop that is grown worldwide to supply the world’s expanding food demand. In the current study, the effects of plant growth-promoting rhizobacteria (PGPR) and Arbuscular mycorrhizal fungi (AMF) on soil fertility and rice growth were [...] Read more.
Rice (Oryza sativa L.) is an important crop that is grown worldwide to supply the world’s expanding food demand. In the current study, the effects of plant growth-promoting rhizobacteria (PGPR) and Arbuscular mycorrhizal fungi (AMF) on soil fertility and rice growth were explored. Rice plants were inoculated to evaluate how AMF fungi and PGPR affect various aspects of soil and plants, implicating abiotic stress tolerances. The experiment was carried out in a completely randomized design with three replicates under the controlled conditions. Results depicted that the plants that were inoculated with a mixture of AMF and PGPR had better yields and nutritional concentrations, while both AMF and PGPR lowered soil pH and organic matter differently. Similarly, AMF and PGPR treatments significantly increased the amount of N, P, K, and B in the post-harvest soil. The PGPR-inoculated plants had a 10–40% higher buildup of N in their tissues. Similarly, when they were compared with non-infected plants, AMF-inoculated treatments demonstrated a greater N accumulation in the rice tissue. The maximum P content in plant tissues was 0.149% in PGPR5-infected plants, either alone or in combination with AMF. In T12, AMF + PGPR5 inoculated rice plants, the maximum K uptake was 1.98%, which was 54% higher than the control treatment. The sole application of AMF raised K buildup in rice tissues by 38% compared with the control treatment. The improved productivity of plants with AMF and PGPR (especially with PGPR5) was attributed to the increased availability of nutrients in the soil. As a result, rice plant growth, yield, and essential element uptakes were boosted significantly. The present study’s results suggested using the combined application of AMF + PGPR5 for improving the rice yield and for sustaining the soil health. Full article
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14 pages, 2888 KiB  
Article
Comparative Analyses of Grain Quality in Response to High Temperature during the Grain-Filling Stage between Wxa and Wxb under Indica and Japonica Backgrounds
by Xiaolei Fan, Xiaosong Sun, Rui Yang, Si Chen, Rumeng Li, Xinyue Bian, Lexiong Xia and Changquan Zhang
Agronomy 2023, 13(1), 17; https://doi.org/10.3390/agronomy13010017 - 21 Dec 2022
Cited by 3 | Viewed by 1480
Abstract
Amylose content controlled by Wx determines rice grain quality, which is easily affected by high temperature. Wxa and Wxb are the two typical Wx alleles in rice, however, their effects on quality formation in response to high temperature under the backgrounds [...] Read more.
Amylose content controlled by Wx determines rice grain quality, which is easily affected by high temperature. Wxa and Wxb are the two typical Wx alleles in rice, however, their effects on quality formation in response to high temperature under the backgrounds of indica rice and japonica rice have not been systematically compared. In this study, the near-isogenic lines (NILs) of Wxa and Wxb with japonica rice 2661 and indica rice 3611 backgrounds were treated by high temperature during the grain-filling stages. High temperature accelerated the grain ripening process, decreased the thousand-kernel weight, and increased the chalkiness degree of all rice samples. However, these traits of Wx NILs with 3611 background were more susceptible to high temperature than those with 2661 background. Furthermore, high-temperature treatment decreased the amylose contents (AC) and starch viscosities but increased the gelatinization temperature of all the Wx NILs. The 3611-Wxa was atypical Wxa-type rice, whose AC was more sensitive to high temperature. The AC result was consistent with quantitative analysis of GBSSI by Western blot. In addition, the effects of Wx genotype and genetic background on rice physicochemical quality (such as the gel consistencies, starch crystallinity, and the morphological structure of starch grains) in response to high temperature were systematically analyzed. These results have important guiding significance for rice-quality improvement under high-temperature climate. Full article
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16 pages, 4302 KiB  
Article
Microbacterium oxydans Regulates Physio-Hormonal and Molecular Attributes of Solanum lycopersicum under Drought Stress
by Shumaila Siraj, Muhammad Aaqil Khan, Muhammad Hamayun, Sajid Ali, Sumera Afzal Khan, Anwar Hussain, Amjad Iqbal, Hamayoon Khan, Sang-Mo Kang and In-Jung Lee
Agronomy 2022, 12(12), 3224; https://doi.org/10.3390/agronomy12123224 - 19 Dec 2022
Cited by 5 | Viewed by 1779
Abstract
Among the types of abiotic stresses, drought is one of the most serious growth limiting factors for crop plants. In recent years, various strategies have been employed to alleviate the adverse effects of drought stress in crops, but the use of plant growth-promoting [...] Read more.
Among the types of abiotic stresses, drought is one of the most serious growth limiting factors for crop plants. In recent years, various strategies have been employed to alleviate the adverse effects of drought stress in crops, but the use of plant growth-promoting rhizobacteria (PGPR) is among the standout techniques. Currently, we have isolated 55 strains of bacteria from the rhizosphere of Achyranthes aspera L. and Calotropis procera (Aiton). However, AGH3, AGH5, and AGH9 produced significant (p = 0.05) amounts of plant hormones and exhibited siderophore and phosphate solubilization activities. Bioassay experiments on Waito-C rice demonstrated an enhanced growth in the presence of the isolate AGH3. Moreover, the isolate AGH3 promoted the growth of Solynum lycopersicum L. under drought stress. The results revealed that AGH3-associated S. lycopersicum plants showed significantly (p = 0.05) reduced production of abscisic acid (ABA) and jasmonic acid (JA) as compared with the AGH3-free plants under polyethylene glycol (PEG) stress. In addition, high expressions of SlmiR 159 (from 6- to 10-fold), SlHsfA1a (from 1- to 4-fold), and SlHAKT1 (from 0.26- to 1-fold) genes were noticed in AGH3-associated S. lycopersicum plants under drought stress. From the results, it is concluded that rhizobacteria (AGH3) can be used as a pragmatic biofertilizer to ensure organic farming under normal as well as drought conditions. Full article
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10 pages, 3310 KiB  
Article
Quantitation of Multipartite Banana Bunchy Top Virus Genomic Components and Their Transcripts in Infected Tissues of Banana (Musa acuminata)
by Sana Bashir, Sumaira Farrakh, Tayyaba Yasmin, Aish Muhammad, Tasmia Bashir, Hakim Manghwar, Freddy Mora-Poblete, Shehzad Iqbal, Alaa Baazeem and Muhammad Zeeshan Hyder
Agronomy 2022, 12(12), 2990; https://doi.org/10.3390/agronomy12122990 - 28 Nov 2022
Cited by 4 | Viewed by 1927
Abstract
Banana bunchy top disease (BBTD), caused by a Banana Bunchy Top Virus (BBTV), is the most devastating viral disease of bananas. The genome of multipartite BBTV is about 1 Kb in size and comprises six circular single-stranded (ss) DNA components, namely DNA-R, C, [...] Read more.
Banana bunchy top disease (BBTD), caused by a Banana Bunchy Top Virus (BBTV), is the most devastating viral disease of bananas. The genome of multipartite BBTV is about 1 Kb in size and comprises six circular single-stranded (ss) DNA components, namely DNA-R, C, S, M, U3, and N. Gene expression in multipartite DNA viruses is highly flexible due to variations in the copy number and transcript levels of individual genomic components. This enables them to adapt to changing conditions and maintain optimal fitness. In the current study, the copy number of each genetic component of BBTV and its transcript level were determined in the leaf, midrib, and root tissue of the infected banana plant. The results of the study showed that DNA copies (copies/ng) were higher in midrib (11,105 ± 10,704.42), followed by leaf (6902.91 ± 1651.14), and were lowest in root (23.49 ± 9.21) tissues. In contrast, the transcript level was highest in the root (312.45 ± 106.69) and lowest in the midrib (0.72 ± 0.16). This suggests that BBTV independently regulates the transcriptional level of each DNA component. The distribution of BBTV in different tissues assists the identification of significantly higher viral load tissues for early and sensitive disease diagnosis, which will be beneficial for better disease management. Full article
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17 pages, 2582 KiB  
Article
Insights into Cadmium-Induced Morphophysiological Disorders in Althea rosea Cavan and Its Phytoremediation through the Exogeneous Citric Acid
by Amir Abdullah Khan, Tongtong Wang, Zaib Un Nisa, Ghalia S. H. Alnusairi and Fuchen Shi
Agronomy 2022, 12(11), 2776; https://doi.org/10.3390/agronomy12112776 - 8 Nov 2022
Cited by 4 | Viewed by 1469
Abstract
Cadmium (Cd) is taken in plants from soil and then travels through the food cycle, posing a major threat to all the units of the ecosystem. A pot experiment was conducted to understand the influence of citric acid (CA) on Cadmium (Cd) phytoextraction [...] Read more.
Cadmium (Cd) is taken in plants from soil and then travels through the food cycle, posing a major threat to all the units of the ecosystem. A pot experiment was conducted to understand the influence of citric acid (CA) on Cadmium (Cd) phytoextraction ability of hollyhock (Althea rosea Cavan.). A. rosea plants were exposed to Cd concentrations (100 and 200 mg·kg−1), either in simultaneous administration or without adding CA (5 mM·kg−1 dry weight). The results revealed that exposing A. rosea to different levels of Cd stress, i.e., 100 and 200 mg·kg−1, significantly decreased (p < 0.05) plant growth and biochemical attributes, such as root length (RL), shoot length (SL), fresh biomass (FW), dry biomass (DW), relative water content (RWC), and chlorophyll and carotenoid contents. Meanwhile, a net increase in MDA and REL indicated Cd-induced oxidative stress in plants. However, the application of citric acid (CA) as an organic chelator helped the plants to alleviate the phytotoxic effects of Cd stress on A. rosea, which is shown in terms of enhancing plant growth and biomass; that is, the root length (27.3% and 21.12%), shoot length (32.11% and 23.02%), fresh weight (39.66% and 29.8%), and dry weight (29.8% and 57.33%) under 100 and 200 mg·kg−1 of Cd stress, respectively, were observed. CA application also helped to alleviate the level of chlorophyll and carotenoid contents; foster high level of antioxidants, such as SOD, POD, CAT, and APX; and lower concentration of MDA and EL. In addition to enhancing plant-growth attributes, the application of CA also managed to increase the phytoextraction potential of the plants by enhancing the concentration of Cd in roots and shoots tissues. This is also demonstrated by rising levels of bioaccumulation (BAC) and translocation factors (TFs). These findings showed that CA application could be a practical strategy to apply to ornamental plants, such as A. rosea seedlings, cultivated in Cd-contaminated locations, opening ways to cope with Cd stress and enhanced phytoextraction. Full article
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16 pages, 4099 KiB  
Article
The Streptomyces chromofuscus Strain RFS-23 Induces Systemic Resistance and Activates Plant Defense Responses against Tomato Yellow Leaf Curl Virus Infection
by Delai Chen, Mian Noor Hussain Asghar Ali, Muhammad Kamran, Manzoor Ali Magsi, Freddy Mora-Poblete, Carlos Maldonado, Muhammad Waris, Reem M. Aljowaie, Mohammad Yakoob Zehri and Mohamed S. Elshikh
Agronomy 2022, 12(10), 2419; https://doi.org/10.3390/agronomy12102419 - 6 Oct 2022
Cited by 2 | Viewed by 1741
Abstract
Insect-vectored plant viruses pose a serious threat to sustainable production of economically important crops worldwide. This demands a continuous search for environmentally-friendly, sustainable and efficient approaches based on biological agents to address the mounting challenges of viral disease management. To date, the efficacy [...] Read more.
Insect-vectored plant viruses pose a serious threat to sustainable production of economically important crops worldwide. This demands a continuous search for environmentally-friendly, sustainable and efficient approaches based on biological agents to address the mounting challenges of viral disease management. To date, the efficacy of actinomycetes bacteria against DNA plant viruses remains unknown. Here, through comparative analyses, we demonstrate that the RFS-23 strain of Streptomyces cellulase possesses protective activity as it positively regulated the plant growth and development. and diminished the severity, of disease symptoms, together with reduced accumulation of Tomato yellow leaf curl virus (TYLCV) DNA. The RFS-23 strain maintained relative chlorophyll contents by promoting the expression of genes (CLH1, HEMA1 and PORA) associated with chlorophyll biogenesis. As compared to another strain, CTF-20, the RSF-23 induced a significantly higher expression of plant defense-related genes (NbCIS and NbNCED) associated with biogenesis and accumulation of salicylic acid and abscisic acid. Additionally, the activity of antioxidant enzymes (SOD, CAT, POD and MDA) was significantly enhanced by RSF-23 treatment, despite the presence of viral infection. These findings suggest that RSF-23 is a novel biocontrol agent with protective activity, and it could be a potential candidate for the management of plant viral infections. Full article
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19 pages, 2384 KiB  
Article
Endophytic Candida membranifaciens from Euphorbia milii L. Alleviate Salt Stress Damages in Maize
by Farzana Gul Jan, Muhammad Hamayun, Anwar Hussain, Gul Jan, Sajid Ali, Sumera Afzal Khan and In-Jung Lee
Agronomy 2022, 12(10), 2263; https://doi.org/10.3390/agronomy12102263 - 21 Sep 2022
Cited by 9 | Viewed by 1779
Abstract
Fungal endophytes are not widely known for their role in bioactive metabolite production and salinity stress alleviation in different crop plants. Presently, we investigated the salt stress (NaCl, KCl, and H2SO4) mitigation capabilities of fungal endophyte Candida membranifaciens (FH15) [...] Read more.
Fungal endophytes are not widely known for their role in bioactive metabolite production and salinity stress alleviation in different crop plants. Presently, we investigated the salt stress (NaCl, KCl, and H2SO4) mitigation capabilities of fungal endophyte Candida membranifaciens (FH15) isolated from Euphorbia milii L. The pure culture filtrate (CF) of C. membranifaciens revealed siderophore production and solubilization of phosphate, with high levels of indoleacetic acid (IAA: 35.8µg/mL), phenolics (70 µg/mL), and flavonoids (50 µg/mL) by using a UV spectrophotometer. The LC/MS analysis of the CF showed different phenols and flavonoids that were identified as Salicylic acid, Baicalein, Aconitic acid, Feruloylquinic acid, Coniferyl aldehyde hexoside, Pentose, Chlorogenic acid, Myricetin, Propoxyphene, and Amino-flunitrazepam. Inoculation of maize seedlings with C. membranifaciens significantly (p = 0.05) enhanced the fresh and dry biomass, carotenoid, and chlorophyll contents under 100 mM salt stress conditions. Similarly, the catalase, peroxidase activity, phenols, proline flavonoids and relative water contents (RWC) of the maize plants were enhanced. More interestingly, the inoculation of C. membranifaciens on maize revealed a higher endogenous IAA level as compared to non-inoculated control plants. Endophyte C. membranifaciens inoculation on maize seedlings under salt stress revealed a 20.87% and 16.60% increase in fresh and dry biomass, as well as significantly enhanced root shoot length and allied growth attributes, in addition to an alleviation of the adverse effects of salinity stress. Conclusively, endophytic C. membranifaciens significantly enhanced the growth attributes of maize and mitigated the adverse effects of salinity stress. Such endophytic fungal strain could be used for further field trails to enhance agricultural productivity and facilitate sustainable agricultural practices. Full article
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Review

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23 pages, 3936 KiB  
Review
A Systematic Review on the Improvement of Cd Stress Tolerance in Ramie Crop, Limitations and Future Prospective
by Adnan Rasheed, Hongdong Jie, Pengliang He, Xueying Lv, Basharat Ali, Yushen Ma, Hucheng Xing, Saad Almari, Rehab O. Elnour, Muhammad Umair Hassan, Syed Faheem Anjum Gillani and Yucheng Jie
Agronomy 2023, 13(7), 1793; https://doi.org/10.3390/agronomy13071793 - 4 Jul 2023
Viewed by 1354
Abstract
Cadmium (Cd) is a non-essential, highly phytotoxic metal and damages ramie plant growth and development even at low concentrations. Ramie is one of the most significant crops in China, with excellent fiber quality and immense industrial importance. Planting Cd-tolerant ramie cultivars can prevent [...] Read more.
Cadmium (Cd) is a non-essential, highly phytotoxic metal and damages ramie plant growth and development even at low concentrations. Ramie is one of the most significant crops in China, with excellent fiber quality and immense industrial importance. Planting Cd-tolerant ramie cultivars can prevent yield loss on contaminated soil. Previously, significant efforts have been made to develop Cd tolerance in ramie. However, the Cd tolerance mechanism is still not fully understood; hence, breeding industrial crops is critical to tackling the ongoing challenges. Cd tolerance is a complex genetic mechanism requiring high-level molecular studies to clarify the genes network. Genetic studies have identified several Cd-tolerant genes in ramie, which led to the development of several ramie cultivars suitable to grow on toxic soils; however, due to the continuous rise in Cd toxicity, potent molecular tools are critical in modern-day breeding programs. Genetic engineering, and transcriptome analysis have been used to develop abiotic stress tolerance in ramie, but QTL mapping and clustered regularly interspaced short palindromic repeats (CRISPR) are rarely studied. However, studies are still limited in addressing this issue. This review critically elaborated on using QTL mapping, transcriptomes, transcription factors, CRISPR/Cas9, and genetic engineering to enhance Cd tolerance in ramie. These genes/QTL should be transferred or edited into sensitive cultivars using genetic engineering or CRISPR/Cas9. CRISPR/Cas9 is highly recommended because it provides targeted gene editing in ramie, its use is limited and can address the research gaps, and it would revolutionize the field of agriculture. Limitations, gaps, and future potential are briefly discussed. This review paper presents new clues to help future researchers comprehensively understand Cd tolerance in ramie and develop tolerant cultivars for industrial purposes. Full article
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21 pages, 6482 KiB  
Review
Breeding Drought-Tolerant Maize (Zea mays) Using Molecular Breeding Tools: Recent Advancements and Future Prospective
by Adnan Rasheed, Hongdong Jie, Basharat Ali, Pengliang He, Long Zhao, Yushen Ma, Hucheng Xing, Sameer H. Qari, Muhammad Umair Hassan, Muhammad Rizwan Hamid and Yucheng Jie
Agronomy 2023, 13(6), 1459; https://doi.org/10.3390/agronomy13061459 - 25 May 2023
Cited by 3 | Viewed by 3409
Abstract
As a most significant cereal crop, maize provides vital nutritional components to humans and livestock. Drought stress curtails maize growth and yield by impairing several morphological, physiological, and biochemical functions. The rising threats of drought stress significantly affect global food security and increase [...] Read more.
As a most significant cereal crop, maize provides vital nutritional components to humans and livestock. Drought stress curtails maize growth and yield by impairing several morphological, physiological, and biochemical functions. The rising threats of drought stress significantly affect global food security and increase the ratio of hunger and starvation. The use of molecular breeding techniques has enabled maize researchers to deeply examine the genetic control of drought tolerance and the genetic differences between genotypes to drought stress. Despite the significant progress in molecular genetics, the drought tolerance mechanism is still not fully understood. With the advancements in molecular research, researchers have identified several molecular factors associated with maize tolerance to drought stress. Quantitative trait loci (QTL) mapping and genome-wide association study (GWAS) analysis have led to identifying QTL, and genes linked to drought tolerance in maize that can be further exploited for their possible breeding applications. Transcriptome and transcription factors (TFs) analysis has revealed the documentation of potential genes and protein groups that might be linked to drought tolerance and accelerate the drought breeding program. Genetic engineering has been used to develop transgenic maize cultivars that are resistant to drought stress. Clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) is a new ray of hope to edit the gene of interest to enhance drought tolerance in maize and save both time and cost in cultivar development. In the current review article, we have tried to present an updated picture of the advancements of drought tolerance in maize and its future prospects. These organized pieces of information can assist future researchers in understanding the basis of drought tolerance to adopt a potential breeding tool for breeding drought-tolerant maize cultivars. Full article
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