Introduction[1] Pre-cultivated plants are types of plants that, after harvesting the economic part, the plant residuals are returned to the soil to increase the organic matter and to improve the next plant’s productivity. The use of plant residues can improve biological health by reducing the chemical inputs used in agriculture. Due to the fact that in dry areas such as North Khuzestan, the role of pre-cultivated plants and the effect of their residues on growth and performance have been studied less, this research can be done in different humidity conditions before planting the main plant, and the effects of plant residues and their role on the qualitative characteristics and organic matter of the soil and the performance of plants such as corn are promising and help farmers and researchers. Material and Methods This experiment was conducted in two neighboring farms. In each year, two experiments were conducted in a randomized complete block design with four replications in two years and two locations. Before planting corn in two fields, cultivation treatments and mixing residues of four plant species, including rice, cowpea, dill, eggplant, and fallow, were used as experimental treatments. After harvesting the pre-cultivation plant, investigate the effect of plant residues on some soil characteristics over time. In order to determine the amount of moisture stored in the soil, in two stages before planting and in the middle of the corn growing season, the percentage of soil moisture by weight was calculated. To determine the organic carbon content in the soil before planting and during the mid-growth stage of the corn plant, organic carbon was oxidized using potassium dichromate in the presence of concentrated sulfuric acid, followed by titration with semi-normal ammonium ferrous sulfate in the presence of the ortho phenanthroline reagent (Walkley, 1934). Additionally, soil nitrogen was measured in the laboratory using the Kjeldahl method (Pag et al., 1982). Results and DiscussionIn both farms, the stability of the soil grains in the second year was higher than in the first year, which is due to the placement of organic materials of plant residues in the structure of the soil grains (Koocheki et al., 2020). Soil stability increased in both farms in the second year, with the difference that the soil stability increased by 64% in WET Planting and 50% in dry Planting. In the first and second years, respectively, there was a 35 and 29% increase in soil moisture compared to the control. The results of this research showed that the positive effect of plant residues in improving the organic matter of the soil after corn cultivation in wet Planting was much higher than that of dry Planting. The rice residues increased the soil organic matter by 51 and 47% in wet Planting and dry Planting. The results of the measurement data before corn cultivation showed a significant increase in the amount of nitrogen in the soil in the second year, and this increase was 55% higher in the field with the method of wet Planting cultivation. The results of the measured data after corn cultivation in the second year showed that the amount of nitrogen in the soil increased, and the intensity of the increase in the field using the wet Planting method was 44% more than the field using the dry method. Conclusion The results of this experiment showed that the apparent specific weight of the soil in the second year, influenced by the use of plant residues, decreased over time. The preservation of plant residues has caused an increase in the amount of nitrogen in the soil, and in wet planting conditions, the intensity of its increase has been 44% more than in DRY Planting conditions. Also, by using plant residues of dill and beans, the amount of phosphorus in the soil increased.
In this work, a life cycle assessment (LCA) approach was employed to evaluate the environmental impact of viscose fibers made from cotton, wood and bamboo pulp, in accordance with the ISO 14040 standard. Utilizing SimaPro 9.5.0 software, the research employed the ReCiPe 2016 (H) V1.13 and IPCC 2013 GWP100a methodologies to assess the life cycle of viscose fibers from “cradle to gate”, quantifying their environmental impacts. The findings revealed that during the pulp production stage, the cotton cultivation process contributed significantly to environmental impacts. Notably, bamboo pulp exhibited the lowest endpoint impact category. In the fiber production stage, the treatment, utility, and impregnation processes were identified as having prominent environmental impacts, with high carbon emissions primarily attributed to GWP 100-fossil in the utility and treatment processes. The production of 1 ton of viscose fiber using cotton as the raw material exhibits the highest environmental burden, with a total impact of 506.92 Pt. Wood-based production shows a moderate environmental impact of 470.74 Pt, while bamboo demonstrates the most favorable environmental profile at 453.43 Pt. Sensitivity analysis highlighted steam consumption as the most sensitive factor influencing environmental outcomes. Additionally, electricity usage and chemical reagents emerged as sensitive factors in the production of viscose fibers from different raw materials.
The purpose of this research was to know the effect of blended learning strategy on learning achievement and science process skills of students in plant tissue culture course in the Universitas Negeri Medan. The research method was quasi experiment. The population of this study was all semester VIII students of biology education program. The study sample consists of two classes, namely: class A known as control class who were taught by conventional learning strategy and class C known as experiment class who were taught by blended learning strategy. They were selected using cluster random sampling technique. The results of the study showed that tcount = 3.769, P= 0.001 at the level significance of 0.05 in learning achievements score. It also showed that tcount = 5.435 > ttable = 1.661 P= 0.001 at the level significance of 0.05 in science process skills score. Based on the study result, it can be concluded the blended learning strategy found significantly more effective in enhancing students’ learning achievement and science process skills in plant tissue culture course as compared to the conventional learning strategy.
1. An Introduction to Plant Cell and Tissue Culture 2. Basic Plant Biology for Cell Culture 3. Tissue Culture in Agriculture, Horticulture and Forestry 4. Tissue Culture in Genetic Engineering and Biotechnology 5. Culture Facilities, Sterile Technique and Media Preparation 6. Callus Cultures 7. Cell Suspension Cultures 8. Protoplast Culture 9. Haploid Cultures 10. Organ and Embryo Culture 11. Regeneration of Plants and Micropropagation 12. Somaclonal Variation 13. Bacterial Culture in the Plant Cell Culture Laboratory 14. Industrial Uses of Plant Cell Culture 15. Prospects and Future Challenges
IntroductionAgarwood, the dark-brown resin produced by Aquilaria trees, has been widely used as incense, spice, perfume or traditional medicine and 2-(2-phenethyl) chromones (PECs) are the key markers responsible for agarwood formation. But the biosynthesis and regulatory mechanism of PECs were still not illuminated. The transcription factor of basic leucine zipper (bZIP) presented the pivotal regulatory roles in various secondary metabolites biosynthesis in plants, which might also contribute to regulate PECs biosynthesis. However, molecular evolution and function of bZIP are rarely reported in Malvales plants, especially in Aquilaria trees.Methods and resultsHere, 1,150 bZIPs were comprehensively identified from twelve Malvales and model species genomes and the evolutionary process were subsequently analyzed. Duplication types and collinearity indicated that bZIP is an ancient or conserved TF family and recent whole genome duplication drove its evolution. Interesting is that fewer bZIPs in A. sinensis than that species also experienced two genome duplication events in Malvales. 62 AsbZIPs were divided into 13 subfamilies and gene structures, conservative domains, motifs, cis-elements, and nearby genes of AsbZIPs were further characterized. Seven AsbZIPs in subfamily D were significantly regulated by ethylene and agarwood inducer. As the typical representation of subfamily D, AsbZIP14 and AsbZIP41 were localized in nuclear and potentially regulated PECs biosynthesis by activating or suppressing type III polyketide synthases (PKSs) genes expression via interaction with the AsPKS promoters.DiscussionOur results provide a basis for molecular evolution of bZIP gene family in Malvales and facilitate the understanding the potential functions of AsbZIP in regulating 2-(2-phenethyl) chromone biosynthesis and agarwood formation.
Mafalda Reis Pereira, Mafalda Reis Pereira, Filipe Neves dos Santos
et al.
Early diagnosis of plant diseases is needed to promote sustainable plant protection strategies. Applied predictive modeling over hyperspectral spectroscopy (HS) data can be an effective, fast, cost-effective approach for improving plant disease diagnosis. This study aimed to investigate the potential of HS point-of-measurement (POM) data for in-situ, non-destructive diagnosis of tomato bacterial speck caused by Pseudomonas syringae pv. tomato (Pst), and bacterial spot, caused by Xanthomonas euvesicatoria (Xeu), on leaves (cv. cherry). Bacterial artificial infection was performed on tomato plants at the same phenological stage. A sensing system composed by a hyperspectral spectrometer, a transmission optical fiber bundle with a slitted probe and a white light source were used for spectral data acquisition, allowing the assessment of 3478 spectral points. An applied predictive classification model was developed, consisting of a normalizing pre-processing strategy allied with a Linear Discriminant Analysis (LDA) for reducing data dimensionality and a supervised machine learning algorithm (Support Vector Machine – SVM) for the classification task. The predicted model achieved classification accuracies of 100% and 74% for Pst and Xeu test set assessments, respectively, before symptom appearance. Model predictions were coherent with host-pathogen interactions mentioned in the literature (e.g., changes in photosynthetic pigment levels, production of bacterial-specific molecules, and activation of plants’ defense mechanisms). Furthermore, these results were coherent with visual phenotyping inspection and PCR results. The reported outcomes support the application of spectral point measurements acquired in-vivo for plant disease diagnosis, aiming for more precise and eco-friendly phytosanitary approaches.
Plants have been used as the main source of phytochemicals with nutritional, medicinal, cultural and cosmetic applications since times immemorial. Nowadays, achieving sustainable development, global climate change, restricted access to fresh water, limited food supply and growing energy demands are among the critical global challenges faced by humanity. Plant cell culture technology has the potential to address some of these challenges by providing effective tools for sustainable supply of phyto‐ingredients with reduced energy, carbon and water footprints. The main aim of this review is to discuss the recent trends in the development of plant cell culture technologies for production of plant‐derived substances with application in food products and cosmetic formulations. The specific technological steps and requirements for the final products are discussed in the light of the advances in cultivation technologies used for growing differentiated and undifferentiated plant in vitro systems. Future prospects and existing challenges of the commercialization of plant cell culture‐derived products have been outlined through the prism of the authors’ point of view. We expect this review will encourage scientists, policymakers and business enterprises to join efforts for speeding‐up the mass commercialization and popularization of plant cell culture technology as an eco‐friendly alternative method for sustainable production of plant‐derived additives with application in food and cosmetic products.
The in vitro tissue cultures are, beyond all difficulties, an essential tool in basic research as well as in commercial applications. Numerous works devoted to plant tissue cultures proved how important this part of the plant science is. Despite half a century of research on the issue of obtaining plants in in vitro cultures, many aspects remain unknown. The path associated with the reprogramming of explants in the fully functioning regenerants includes a series of processes that may result in the appearance of morphological, physiological, biochemical or, finally, genetic and epigenetic changes. All these changes occurring at the tissue culture stage and appearing in regenerants as tissue culture-induced variation and then inherited by generative progeny as somaclonal variation may be the result of oxidative stress, which works at the step of explant preparation, and in tissue culture as a result of nutrient components and environmental factors. In this review, we describe the current status of understanding the genetic and epigenetic changes that occur during tissue culture. Variation appeared in regenerated plants as well as variation inherited by generative progeny of regenerants can may many, positive or negative impact, of gained plant materials. This review focused on factors that triggered this phenomenon with underlying oxidative stress.
N is an essential nutrient for sugarcane (Saccharum spp. Hybribds) growth. Excess chemical nitrogen fertilizer applied still a serious problem of China sugarcane plant. Biochar has shown promise in improving crop yield and N use efficiency (NEU).However its impact on sugarcane is not well-studied. To investigate how biochar impacts on sugarcane growth and nitrogen N use efficiency (NUE), a glasshouse pot experiment was conducted using the 15N tracer method. Two cultivars, GT11 and B8, were chosen as test objects and were planted under low N(120 kg N hm-2) and high N(600 kg N hm-2)condition, respectively. The effects of low and high biochar application rates (10 t hm-2 and 20 t hm-2) on growth, nitrogen uptake, accumulation and distribution as well as NUE in GT11 and B8 were studied. Results showed that sugarcane biomass was not significantly affected by biochar application. N uptake by GT11 was significantly increased 23.91% - 45.42% by C20 and N120 condition at tillering stage and elongation stage. While N uptake by B8 showed a significant response to B10 and B20 with an increase of 27.27% and 30.40% at tillering stage,respectively. Biochar application led to 0.28% - 23.75% and 1.08% - 30.07% increase in NUE of GT11 and B8,respectively. The effect of biochar application of N from fertilizer(FF) was significant,however only C20 treatment shown remarkable response when under low N treatment. Our study suggest that the effects of biochar on sugarcane depend on varieties and the applied rate of biochar and N fertilizer.Biochar application with inorganic N could improve N uptake and N use of sugarcane.
Golden buckwheat (Fagopyrum cymosum) is used in Traditional Chinese Medicine. It has received attention because of the high value of its various medicinal and nutritional metabolites, especially flavonoids (catechin and epicatechin). However, the metabolites and their encoding genes in golden buckwheat have not yet been identified in the global landscape. This study performed transcriptomics and widely targeted metabolomics analyses for the first time on rhizomes of golden buckwheat. As a result, 10,191 differentially expressed genes (DEGs) and 297 differentially regulated metabolites (DRMs) were identified, among which the flavonoid biosynthesis pathway was enriched in both transcriptome and metabolome. The integration analyses of the transcriptome and the metabolome revealed a network related to catechin, in which four metabolites and 14 genes interacted with each other. Subsequently, an SG5 R2R3-MYB transcription factor, named FcMYB1, was identified as a transcriptional activator in catechin biosynthesis, as it was positively correlated to eight flavonoid biosynthesis genes in their expression patterns and was directly bound to the promoters of FcLAR2 and FcF3'H1 by yeast one hybrid analysis. Finally, a flavonoid biosynthesis pathway was proposed in the rhizomes of golden buckwheat, including 13 metabolites, 11 genes encoding 9 enzymes, and 1 MYB transcription factor. The expression of 12 DEGs were validated by qRT-PCR, resulting in a good agreement with the Pearson R ranging from 0.83 to 1. The study provided a comprehensive flavonoid biosynthesis and regulatory network of golden buckwheat.
Crispus M. Mbaluto, Crispus M. Mbaluto, Esraa M. Ahmad
et al.
Plants mediate interactions between different herbivores that attack simultaneously or sequentially aboveground (AG) and belowground (BG) organs. The local and systemic activation of hormonal signaling pathways and the concomitant accumulation of defense metabolites underlie such AG-BG interactions. The main plant-mediated mechanisms regulating these reciprocal interactions via local and systemic induced responses remain poorly understood. We investigated the impact of root infection by the root-knot nematode (RKN) Meloidogyne incognita at different stages of its infection cycle, on tomato leaf defense responses triggered by the potato aphid Macrosiphum euphorbiae. In addition, we analyzed the reverse impact of aphid leaf feeding on the root responses triggered by the RKN. We focused specifically on the signaling pathways regulated by the phytohormones jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), and indole-3-acetic acid (IAA) as well as steroidal glycoalkaloids as induced defense compounds. We found that aphid feeding did not induce AG hormonal signaling, but it repressed steroidal glycoalkaloids related responses in leaves, specifically when feeding on plants in the vegetative stage. Root infection by the RKN impeded the aphid-triggered repression of the steroidal glycoalkaloids-related response AG. In roots, the RKN triggered the SA pathway during the entire infection cycle and the ABA pathway specifically during its reproduction stage. RKN infection also elicited the steroidal glycoalkaloids related gene expression, specifically when it was in the galling stage. Aphid feeding did not systemically alter the RKN-induced defense responses in roots. Our results point to an asymmetrical interaction between M. incognita and Ma. euphorbiae when co-occurring in tomato plants. Moreover, the RKN seems to determine the root defense response regardless of a later occurring attack by the potato aphid AG.
The unigeneric tribe Heliophileae encompassing more than 100 Heliophila species is morphologically the most diverse Brassicaceae lineage. The tribe is endemic to southern Africa, confined chiefly to the southwestern South Africa, home of two biodiversity hotspots (Cape Floristic Region and Succulent Karoo). The monospecific Chamira (C. circaeoides), the only crucifer species with persistent cotyledons, is traditionally retrieved as the closest relative of Heliophileae. Our transcriptome analysis revealed a whole-genome duplication (WGD) ∼26.15–29.20 million years ago, presumably preceding the Chamira/Heliophila split. The WGD was then followed by genome-wide diploidization, species radiations, and cladogenesis in Heliophila. The expanded phylogeny based on nuclear ribosomal DNA internal transcribed spacer (ITS) uncovered four major infrageneric clades (A–D) in Heliophila and corroborated the sister relationship between Chamira and Heliophila. Herein, we analyzed how the diploidization process impacted the evolution of repetitive sequences through low-coverage whole-genome sequencing of 15 Heliophila species, representing the four clades, and Chamira. Despite the firmly established infrageneric cladogenesis and different ecological life histories (four perennials vs. 11 annual species), repeatome analysis showed overall comparable evolution of genome sizes (288–484 Mb) and repeat content (25.04–38.90%) across Heliophila species and clades. Among Heliophila species, long terminal repeat (LTR) retrotransposons were the predominant components of the analyzed genomes (11.51–22.42%), whereas tandem repeats had lower abundances (1.03–12.10%). In Chamira, the tandem repeat content (17.92%, 16 diverse tandem repeats) equals the abundance of LTR retrotransposons (16.69%). Among the 108 tandem repeats identified in Heliophila, only 16 repeats were found to be shared among two or more species; no tandem repeats were shared by Chamira and Heliophila genomes. Six “relic” tandem repeats were shared between any two different Heliophila clades by a common descent. Four and six clade-specific repeats shared among clade A and C species, respectively, support the monophyly of these two clades. Three repeats shared by all clade A species corroborate the recent diversification of this clade revealed by plastome-based molecular dating. Phylogenetic analysis based on repeat sequence similarities separated the Heliophila species to three clades [A, C, and (B+D)], mirroring the post-polyploid cladogenesis in Heliophila inferred from rDNA ITS and plastome sequences.
Matthew Borden, Kelly Laplante, Juanita Popenoe
et al.
This series of Key Plant, Key Pests publications are designed for Florida gardeners, horticulturalists, and landscape professionals to help identify common pests associated with regional flora. This new 6-page publication of the UF/IFAS Environmental Horticulture Department helps identify the most common pests found on trees in the sycamore group, Platanus spp., and it provides information and general management recommendations for sycamore lace bug, bacterial leaf scorch, powdery mildew, anthracnose, and canker stain. Written by Matthew Borden, Kelly Laplante, Juanita Popenoe, Adam Dale, Caroline R. Warwick, and Brian Pearson.
https://edis.ifas.ufl.edu/ep601
Plants are autotrophic organisms that self-produce sugars through photosynthesis. These sugars serve as an energy source, carbon skeletons, and signaling entities throughout plants’ life. Post-transcriptional regulation of gene expression plays an important role in various sugar-related processes. In cells, it is regulated by many factors, such as RNA-binding proteins (RBPs), microRNAs, the spliceosome, etc. To date, most of the investigations into sugar-related gene expression have been focused on the transcriptional level in plants, while only a few studies have been conducted on post-transcriptional mechanisms. The present review provides an overview of the relationships between sugar and post-transcriptional regulation in plants. It addresses the relationships between sugar signaling and RBPs, microRNAs, and mRNA stability. These new items insights will help to reach a comprehensive understanding of the diversity of sugar signaling regulatory networks, and open onto new investigations into the relevance of these regulations for plant growth and development.
Maize ( L.) hybrids have transitioned to upright leaf angles (LAs) over the last 50 yr as maize yields and planting densities increased concurrently. Genetic mapping and a meta-analysis were conducted in the present study to dissect genetic factors controlling LA variation. We developed mapping populations using inbred lines B73 (Iowa Stiff Stalk Synthetic), PHW30 (Iodent, expired plant variety protection inbred), and Mo17 (Non-Stiff Stalk) that have distinct LA architectures and represent three important heterotic groups in the United States. These populations were genotyped using genotyping-by-sequencing (GBS), and phenotyped for LA in the F and F generation. Inclusive composite interval mapping across the two generations of the mapping populations revealed 12 quantitative trait loci (QTL), and a consistent QTL on chromosome 1 explained 10 to 17% of the phenotypic variance. To gain a comprehensive understanding of natural variations underlying LA variation, these detected QTL were compared with results from 19 previous studies. In total, 495 QTL were compiled and mapped into 143 genomic bins. A meta-analysis revealed that 58 genomic bins were associated with LA variation. Thirty-three candidate genes were identified in these genomic bins. Together, these results provide evidence of QTL controlling LA variation from inbred lines representing three important heterotic groups in the United States and a useful resource for future research into the molecular variants underlying specific regions of the genome associated with LA variation.
The significant increase in oil palm areas has resulted in more concerns to the environmental issues - as majority of farming activities were not conducted in sustainable ways. To address the environmental issues, the Roundtable Sustainable Palm Oil (RSPO) organization has formulated principles and criterias (PnC) for sustainable practices of the oil palm plantation as a guideline, whereby it has to be adhered by all parties involved, including the smallholders. The study is therefore conducted to analyze the sustainable management implementation among smallholders in North Sumatra. In total, 320 and 137 schemed and independent smallholders from four oil palm plantations centers in North Sumatra were interviewed in 2012 and 2018 to see their progress. The levels of implementation for each group were determined based on their scores for each of the criteria, and were compared with the independent sample t-test. The influencing factors for implementation levels were estimated by using multinomial logit model. The results showed that the level of implementation for both schemed and independent smallholders were still low in both 2012 and 2018. Education, experience and participation were identified as factors that significantly influenced their sustainable management implementation levels. Therefore, it is suggested that trainings should be emphasized to improve the sustainable management implemenatation among oil palm smallholders.
از آنجا که وجود گل جالیز در یک مزرعهی گوجهفرنگی، تأثیر سوء در تمام مراحل رشد رویشی و زایشی آن و بنابراین خسارت جبرانناپذیری در پی خواهد داشت؛ به منظور کنترل شیمیایی این علف هرز انگلی در زراعت گوجهفرنگی، آزمایشی به صورت فاکتوریل بر پایه طرح بلوکهای کامل تصادفی در سه تکرار و 12 تیمار در مزرعهای از توابع شهرستان مهاباد انجام شد. فاکتورهای آزمایشی عبارت بودند از: 1- علفکش سولفوسولفورون به مقدار 35 گرم در هکتار در سه سطح (سمپاشی در 40 و 60 روز بعد از نشاءکاری و شاهد بدون سمپاشی). 2- کودهای زیستی بارور-2 و نیتراژین هر کدام در دو سطح (مصرف کود زیستی و عدم مصرف کود زیستی). نتایج نشان داد که اثر اصلی سولفوسولفورون در دو نوبت 40 و 60 روز بعد از نشاءکاری باعث کاهش بترتیب 75 و 57 درصد از تراکم شاخههای گل جالیز در واحد سطح به ازای هر بوتهی گوجهفرنگی و نیز کاهش 60 درصد بیوماس گل جالیز شد. کاربرد سولفوسولفورن به همراه با کود زیستی بارور-2 و نیتراژین به غیر از تیمار دوبار سمپاشی سبب افزایش میانگین ارتفاع بوتهی گوجهفرنگی شد. این در حالی بود که صفات تعداد میوه و عملکرد اقتصادی گوجهفرنگی تنها تحت تأثیر کود زیستی بارور-2 قرار گرفت به طوری که کاربرد کود زیستی بارور-2 تعداد میوههای گوجهفرنگی و نیز عملکرد اقتصادی گوجهفرنگی در واحد سطح را کاهش داد. اما بر قطر میوهها و میزان گوشتی و آبدار بودن آنها همانند سایر تیمارها تاثیری بر جای نگذاشت.
Miguel Ángel Sánchez-Hernández, Clemente Villanueva-Verduzco, César Sánchez-Hernández
et al.
Se realizó un estudio en la Universidad Autónoma Chapingo, Estado de México, durante 2001, con el objetivo de estimar en calabaza (Cucurbita pepo L.) la respuesta a la selección participativa in situ en caracteres de planta, calidad de fruto y rendimiento de semilla. Se evaluaron dos variedades de la Sierra Norte de Puebla seleccionadas in situ: Mazapa (ciclos de selección 1 a 3), La Libertad (ciclos de selección 1 a 3) y un testigo, a una densidad de 27,639 plantas·ha-1, en un diseño de bloques completos al azar con cuatro repeticiones. La mayor respuesta por ciclo de selección, en promedio de localidades, ocurrió en la variedad Mazapa para número de frutos por planta (0.29 frutos; 31.8 %), altura (1.0 cm; 6.1 %) y ancho de fruto (0.5 cm; 2.4 %), grosor de pulpa (0.1 cm; 5.8 %), altura (0.034; 1.6 %) y ancho de semilla (0.001 cm; 0.11 %). La va- riedad La Libertad destacó en peso de semilla por fruto (12 g·fruto-1; 21 %) y en peso de frutos por planta (0.1 kg·fruto-1; 6.6 %). El segundo ciclo de selección de la variedad Mazapa sobresalió en peso de fruto (3.77 kg), peso de semilla por planta (98 g), grosor de pulpa (2.6 cm), alto de fruto (23.6 cm), ancho de fruto (20.3 cm) y ancho de semilla (0.934 cm). El tercer ciclo de selección en Mazapa mostró los valores más altos en número de frutos por planta (1.49), peso de fruto por hectárea (123.5 t·ha-1) y rendimiento de semilla por hectárea (3.83 t·ha-1).
Nitric oxide (NO) is emerging as an important regulatory player in the Rhizobium-legume symbiosis. The occurrence of NO during several steps of the symbiotic interaction suggests an important, but yet unknown, signaling role of this molecule for root nodule formation and functioning. The identification of the molecular targets of NO is key for the assembly of the signal transduction cascade that will ultimately help to unravel NO function. We have recently shown that the key nitrogen assimilatory enzyme Glutamine Synthetase (GS) is a molecular target of NO in root nodules of Medicago truncatula, being post-translationally regulated by tyrosine nitration in relation to nitrogen fixation. In functional nodules of M. truncatula NO formation has been located in the bacteroid containing cells of the fixation zone, where the ammonium generated by bacterial nitrogenase is released to the plant cytosol and assimilated into the organic pools by plant GS. We propose that the NO-mediated GS post-translational inactivation is connected to nitrogenase inhibition induced by NO and is related to metabolite channeling to boost the nodule antioxidant defenses. Glutamate, a substrate for GS activity is also the precursor for the synthesis of glutathione (GSH), which is highly abundant in root nodules of several plant species and known to play a major role in the antioxidant defense participating in the ascorbate/GSH cycle. Existing evidence suggests that upon NO-mediated GS inhibition, glutamate could be channeled for the synthesis of GSH. According to this hypothesis, GS would be involved in the NO-signaling responses in root nodules and the NO-signaling events would meet the nodule metabolic pathways to provide an adaptive response to the inhibition of symbiotic nitrogen fixation by reactive nitrogen species (RNS).