ABSTRACT
Despite intense research towards the understanding of abiotic stress adaptation in tomato, the physiological adjustments and transcriptome modulation induced by combined salt and low nitrate (low N) conditions remain largely unknown. Here, three traditional tomato genotypes were grown under long-term single and combined stresses throughout a complete growth cycle. Physiological, molecular, and growth measurements showed extensive morphophysiological modifications under combined stress compared to the control, and single stress conditions, resulting in the highest penalty in yield and fruit size. The mRNA sequencing performed on both roots and leaves of genotype TRPO0040 indicated that the transcriptomic signature in leaves under combined stress conditions largely overlapped that of the low N treatment, whereas root transcriptomes were highly sensitive to salt stress. Differentially expressed genes were functionally interpreted using GO and KEGG enrichment analysis, which confirmed the stress and the tissue-specific changes. We also disclosed a set of genes underlying the specific response to combined conditions, including ribosome components and nitrate transporters, in leaves, and several genes involved in transport and response to stress in roots. Altogether, our results provide a comprehensive understanding of above- and below-ground physiological and molecular responses of tomato to salt stress and low N treatment, alone or in combination.
ABSTRACT
Plant microbial biostimulants application has become a promising and eco-friendly agricultural strategy to improve crop yields, reducing chemical inputs for more sustainable cropping systems. The soil dwelling bacterium Kocuria rhizophila was previously characterized as Plant Growth Promoting Bacteria (PGPB) for its multiple PGP traits, such as indole-3-acetic acid production, phosphate solubilization capability and salt and drought stress tolerance. Here, we evaluated by a multi-omics approach, the PGP activity of K. rhizophila on tomato, revealing the molecular pathways by which it promotes plant growth. Transcriptomic analysis showed several up-regulated genes mainly related to amino acid metabolism, cell wall organization, lipid and secondary metabolism, together with a modulation in the DNA methylation profile, after PGPB inoculation. In agreement, proteins involved in photosynthesis, cell division, and plant growth were highly accumulated by K. rhizophila. Furthermore, "amino acid and peptides", "monosaccharides", and "TCA" classes of metabolites resulted the most affected by PGPB treatment, as well as dopamine, a catecholamine neurotransmitter mediating plant growth through S-adenosylmethionine decarboxylase (SAMDC), a gene enhancing the vegetative growth, up-regulated in tomato by K. rhizophila treatment. Interestingly, eight gene modules well correlated with differentially accumulated proteins (DAPs) and metabolites (DAMs), among which two modules showed the highest correlation with nine proteins, including a nucleoside diphosphate kinase, and cytosolic ascorbate peroxidase, as well as with several amino acids and metabolites involved in TCA cycle. Overall, our findings highlighted that sugars and amino acids, energy regulators, involved in tomato plant growth, were strongly modulated by the K. rhizophila-plant interaction.
Subject(s)
Micrococcaceae , Solanum lycopersicum , Solanum lycopersicum/microbiology , Solanum lycopersicum/metabolism , Solanum lycopersicum/genetics , Solanum lycopersicum/growth & development , Micrococcaceae/metabolism , Micrococcaceae/genetics , Soil Microbiology , Gene Expression Regulation, PlantABSTRACT
Identification of novel genotypes with enhanced nitrogen use efficiency (NUE) is a key challenge for a sustainable tomato production. In this respect, the performance of a panel of thirty tomato accessions were evaluated under high (HN; 5 mM N) and low (LN; 0.5 mM N) nitrogen irrigation solutions. For each treatment, when 50% of plants reached the first flower bud stage, plant growth and biomass traits, chlorophyll, flavonol and anthocyanin indexes, nitrogen balance index (NBI), C:N ratio in leaves, stems, and roots, and NUE were evaluated. Significant (p < 0.05) effects were observed for accession, N treatment, and their interaction across all the traits. Under LN, plants showed a delayed development (40 days for HN vs. 65 days for LN) and reduced growth and biomass. On average, LN condition led to 41.8% decrease in nitrogen uptake efficiency (NUpE) but also 189.0% increase in NUtE, resulting in 62.2% overall increase in NUE. A broad range of variation among accessions was observed under both HN and LN conditions. Under LN conditions, chlorophyll index and NBI decreased, while flavonol and anthocyanin indexes increased. Leaf C:N ratio was positively correlated with nitrogen utilisation efficiency (NUtE) in both N treatments. Multi-trait analyses identified top-performing accessions under each condition, allowing to identify one accession among top performers under both conditions. Correlation analysis revealed that high root biomass and leaf C:N ratio are useful markers for selecting high NUE accessions. These findings offer valuable insights for improving tomato NUE under varying nitrogen fertilization conditions and for breeding high-NUE cultivars.
Subject(s)
Nitrogen , Solanum lycopersicum , Solanum lycopersicum/genetics , Anthocyanins , Plant Breeding , Genotype , Chlorophyll , Flavonols , FertilizationABSTRACT
Background: Understanding the complex regulatory network underlying plant nitrogen (N) responses associated with high Nitrogen Use Efficiency (NUE) is one of the main challenges for sustainable cropping systems. Nitrate (NO3 -), acting as both an N source and a signal molecule, provokes very fast transcriptome reprogramming, allowing plants to adapt to its availability. These changes are genotype- and tissue-specific; thus, the comparison between contrasting genotypes is crucial to uncovering high NUE mechanisms. Methods: Here, we compared, for the first time, the spatio-temporal transcriptome changes in both root and shoot of two NUE contrasting tomato genotypes, Regina Ostuni (high-NUE) and UC82 (low-NUE), in response to short-term (within 24 h) low (LN) and high (HN) NO3 - resupply. Results: Using time-series transcriptome data (0, 8, and 24 h), we identified 395 and 482 N-responsive genes differentially expressed (DEGs) between RO and UC82 in shoot and root, respectively. Protein kinase signaling plant hormone signal transduction, and phenylpropanoid biosynthesis were the main enriched metabolic pathways in shoot and root, respectively, and were upregulated in RO compared to UC82. Interestingly, several N transporters belonging to NRT and NPF families, such as NRT2.3, NRT2.4, NPF1.2, and NPF8.3, were found differentially expressed between RO and UC82 genotypes, which might explain the contrasting NUE performances. Transcription factors (TFs) belonging to several families, such as ERF, LOB, GLK, NFYB, ARF, Zinc-finger, and MYB, were differentially expressed between genotypes in response to LN. A complementary Weighted Gene Co-expression Network Analysis (WGCNA) allowed the identification of LN-responsive co-expression modules in RO shoot and root. The regulatory network analysis revealed candidate genes that might have key functions in short-term LN regulation. In particular, an asparagine synthetase (ASNS), a CBL-interacting serine/threonine-protein kinase 1 (CIPK1), a cytokinin riboside 5'-monophosphate phosphoribohydrolase (LOG8), a glycosyltransferase (UGT73C4), and an ERF2 were identified in the shoot, while an LRR receptor-like serine/threonine-protein kinase (FEI1) and two TFs NF-YB5 and LOB37 were identified in the root. Discussion: Our results revealed potential candidate genes that independently and/or concurrently may regulate short-term low-N response, suggesting a key role played by cytokinin and ROS balancing in early LN regulation mechanisms adopted by the N-use efficient genotype RO.
ABSTRACT
Several Triticum species spread in cultivation in Sicily and neighboring regions over the centuries, which led to the establishment of a large genetic diversity. Many ancient varieties were widely cultivated until the beginning of the last century before being replaced by modern varieties. Recently, they have been reintroduced in cultivation in Sicily. Here, the genetic diversity of 115 and 11 accessions from Sicily and Calabria, respectively, belonging to Triticum species was evaluated using a high-density SNP array. Einkorn, emmer, and spelta wheat genotypes were used as outgroups for species and subspecies; five modern varieties of durum and bread wheat were used as references. A principal coordinates analysis (PCoA) and an unweighted pair group method with arithmetic mean (UPGMA) showed four distinct groups among Triticum species and T. turgidum subspecies. The population structure analysis distinguished five gene pools, among which three appeared private to the T. aestivum, T. turgidum subsp. Turgidum, and 'Timilia' group. The principal component analysis (PCA) displayed a bio-morphological trait relationship of a subset (110) of ancient wheat varieties and their wide variability within the T. turgidum subsp. durum subgroups. A discriminant analysis of principal components (DAPC) and phylogenetic analyses applied to the four durum wheat subgroups revealed that the improved varieties harbored a different gene pool compared to the most ancient varieties. The 'Russello' and 'Russello Ibleo' groups were distinguished; both displayed higher genetic variability compared to the 'Timilia' group accessions. This research represents a comprehensive approach to fingerprinting the old wheat Sicilian germplasm, which is useful in avoiding commercial fraud and sustaining the cultivation of landraces and ancient varieties.
Subject(s)
Genetic Variation , Triticum , Triticum/genetics , Genotype , Phylogeny , Phenotype , SicilyABSTRACT
Onion (Allium cepa L.) is an important bulb crop grown worldwide. Dormancy in bulbous plants is an important physiological state mainly regulated by a complex gene network that determines a stop of vegetative growth during unfavorable seasons. Limited knowledge on the molecular mechanisms that regulate dormancy in onion were available until now. Here, a comparison between uninfected and onion yellow dwarf virus (OYDV)-infected onion bulbs highlighted an altered dormancy in the virus-infected plants, causing several symptoms, such as leaf striping, growth reduction, early bulb sprouting and rooting, as well as a lower abscisic acid (ABA) level at the start of dormancy. Furthermore, by comparing three dormancy stages, almost five thousand four hundred (5390) differentially expressed genes (DEGs) were found in uninfected bulbs, while the number of DEGs was significantly reduced (1322) in OYDV-infected bulbs. Genes involved in cell wall modification, proteolysis, and hormone signaling, such as ABA, gibberellins (GAs), indole-3-acetic acid (IAA), and brassinosteroids (BRs), that have already been reported as key dormancy-related pathways, were the most enriched ones in the healthy plants. Interestingly, several transcription factors (TFs) were up-regulated in the uninfected bulbs, among them three genes belonging to the WRKY family, for the first time characterized in onion, were identified during dormancy release. The involvement of specific WRKY genes in breaking dormancy in onion was confirmed by GO enrichment and network analysis, highlighting a correlation between AcWRKY32 and genes driving plant development, cell wall modification, and division via gibberellin and auxin homeostasis, two key processes in dormancy release. Overall, we present, for the first time, a detailed molecular analysis of the dormancy process, a description of the WRKY-TF family in onion, providing a better understanding of the role played by AcWRKY32 in the bulb dormancy release. The TF co-expressed genes may represent targets for controlling the early sprouting in onion, laying the foundations for novel breeding programs to improve shelf life and reduce postharvest.
Subject(s)
Gene Expression Regulation, Plant , Onions , Abscisic Acid/metabolism , Gene Regulatory Networks , Gibberellins/metabolism , Onions/genetics , Onions/metabolism , PotyvirusABSTRACT
The characterization of plant genetic resources is a precondition for genetic improvement and germplasm management. The increasing use of molecular markers for DNA-based genotype signature is crucial for variety identification and traceability in the food supply chain. We collected 75 Sicilian hazelnut accessions from private and public field collections, including widely grown varieties from the Nebrodi Mountains in north east Sicily (Italy). The germplasm was fingerprinted through nine standardized microsatellites (SSR) for hazelnut identification to evaluate the genetic diversity of the collected accessions, validating SSR discrimination power. We identified cases of homonymy and synonymy among acquisitions and the unique profiles. The genetic relationships illustrated by hierarchical clustering, structure, and discriminant analyses revealed a clear distinction between local and commercial varieties. The comparative genetic analysis also showed that the Nebrodi genotypes are significantly different from the Northern Italian, Iberian, and Turkish genotypes. These results highlight the need and urgency to preserve Nebrodi germplasm as a useful and valuable source for traits of interest employable for breeding. Our study demonstrates the usefulness of molecular marker analysis to select a reference germplasm collection of Sicilian hazelnut varieties and to implement certified plants' production in the supply chain.
ABSTRACT
Nitrogen (N) fertilization is one of the main inputs to increase crop yield and food production. However, crops utilize only 30-40% of N applied; the remainder is leached into the soil, causing environmental and health damage. In this scenario, the improvement of nitrogen-use efficiency (NUE) will be an essential strategy for sustainable agriculture. Here, we compared two pairs of NUE-contrasting eggplant (Solanum melongena L.) genotypes, employing GC-MS and UPLC-qTOF-MS-based technologies to determine the differential profiles of primary and secondary metabolites in root and shoot tissues, under N starvation as well as at short- and long-term N-limiting resupply. Firstly, differences in the primary metabolism pathways of shoots related to alanine, aspartate and glutamate; starch, sucrose and glycine; serine and threonine; and in secondary metabolites biosynthesis were detected. An integrated analysis between differentially accumulated metabolites and expressed transcripts highlighted a key role of glycine accumulation and the related glyA transcript in the N-use-efficient genotypes to cope with N-limiting stress. Interestingly, a correlation between both sucrose synthase (SUS)- and fructokinase (scrK)-transcript abundances, as well as D-glucose and D-fructose accumulation, appeared useful to distinguish the N-use-efficient genotypes. Furthermore, increased levels of L-aspartate and L-asparagine in the N-use-efficient genotypes at short-term low-N exposure were detected. Granule-bound starch synthase (WAXY) and endoglucanase (E3.2.1.4) downregulation at long-term N stress was observed. Therefore, genes and metabolites related to these pathways could be exploited to improve NUE in eggplant.
ABSTRACT
The domestication and spreading of grapevine as well as the gene flow history had been described in many studies. We used a high-quality 7k SNP dataset of 1,038 Eurasian grape varieties with unique profiles to assess the population genetic diversity, structure, and relatedness, and to infer the most likely migration events. Comparisons of putative scenarios of gene flow throughout Europe from Caucasus helped to fit the more reliable migration routes around the Mediterranean Basin. Approximate Bayesian computation (ABC) approach made possible to provide a response to several questions so far remaining unsolved. Firstly, the assessment of genetic diversity and population structure within a well-covered dataset of ancient Italian varieties suggested the different histories between the Northern and Southern Italian grapevines. Moreover, Italian genotypes were shown to be distinguishable from all the other Eurasian populations for the first time. The entire Eurasian panel confirmed the east-to-west gene flow, highlighting the Greek role as a "bridge" between the Western and Eastern Eurasia. Portuguese germplasm showed a greater proximity to French varieties than the Spanish ones, thus being the main route for gene flow from Iberian Peninsula to Central Europe. Our findings reconciled genetic and archaeological data for one of the most cultivated and fascinating crops in the world.
ABSTRACT
The olive tree (Olea europaea L.) is a typical Mediterranean crop, important for olive and oil production. The high tendency to bear fruits in an uneven manner, defined as irregular or alternate bearing, results in a significant economic impact for the high losses in olives and oil production. Buds from heavy loaded ('ON') and unloaded ('OFF') branches of a unique olive tree were collected in July and the next March to compare the transcriptomic profiles and get deep insight into the molecular mechanisms regulating floral induction and differentiation. A wide set of DEGs related to ethylene TFs and to hormonal, sugar, and phenylpropanoid pathways was identified in buds collected from 'OFF' branches. These genes could directly and indirectly modulate different pathways, suggesting their key role during the lateral bud transition to flowering stage. Interestingly, several genes related to the flowering process appeared as over-expressed in buds from March 'OFF' branches and they could address the buds towards flower differentiation. By this approach, interesting candidate genes related to the switch from vegetative to reproductive stages were detected and analyzed. The functional analysis of these genes will provide tools for developing breeding programs to obtain olive trees characterized by more constant productivity over the years.
Subject(s)
Ethylenes/pharmacology , Flowers/growth & development , Gene Regulatory Networks , Olea/growth & development , Plant Proteins/metabolism , Transcription Factors/metabolism , Transcriptome/drug effects , Cell Differentiation , Flowers/drug effects , Gene Expression Regulation, Plant , Olea/drug effects , Olea/genetics , Plant Breeding , Plant Proteins/genetics , Transcription Factors/geneticsABSTRACT
Nitrogen-use efficiency (NUE) is a complex trait of great interest in breeding programs because through its improvement, high crop yields can be maintained whilst N supply is reduced. In this study, we report a transcriptomic analysis of four NUE-contrasting eggplant (Solanum melongena) genotypes following short- and long-term exposure to low N, to identify key genes related to NUE in the roots and shoots. The differentially expressed genes in the high-NUE genotypes are involved in the light-harvesting complex and receptor, a ferredoxin-NADP reductase, a catalase and WRKY33. These genes were then used as bait for a co-expression gene network analysis in order to identify genes with the same trends in expression. This showed that up-regulation of WRKY33 triggered higher expression of a cluster of 21 genes and also of other genes, many of which were related to N-metabolism, that were able to improve both nitrogen uptake efficiency and nitrogen utilization efficiency, the two components of NUE. We also conducted an independent de novo experiment to validate the significantly higher expression of WRKY33 and its gene cluster in the high-NUE genotypes. Finally, examination of an Arabidopsis transgenic 35S::AtWRKY33 overexpression line showed that it had a bigger root system and was more efficient at taking up N from the soil, confirming the pivotal role of WRKY33 for NUE improvement.
Subject(s)
Nitrogen , Solanum melongena , Gene Expression Regulation, Plant , Nitrogen/metabolism , Plant Breeding , Solanum melongena/genetics , TranscriptomeABSTRACT
Eggplant is the second most important solanaceous berry-producing crop after tomato. Despite mapping studies based on bi-parental progenies and GWAS approaches having been performed, an eggplant intraspecific high-resolution map is still lacking. We developed a RIL population from the intraspecific cross '305E40', (androgenetic introgressed line carrying the locus Rfo-Sa1 conferring Fusarium resistance) x '67/3' (breeding line whose genome sequence was recently released). One hundred and sixty-three RILs were genotyped by a genotype-by-sequencing (GBS) approach, which allowed us to identify 10,361 polymorphic sites. Overall, 267 Gb of sequencing data were generated and ~773 M Illumina paired end (PE) reads were mapped against the reference sequence. A new linkage map was developed, including 7249 SNPs assigned to the 12 chromosomes and spanning 2169.23 cM, with iaci@liberoan average distance of 0.4 cM between adjacent markers. This was used to elucidate the genetic bases of seven traits related to anthocyanin content in different organs recorded in three locations as well as seed vigor. Overall, from 7 to 17 QTLs (at least one major QTL) were identified for each trait. These results demonstrate that our newly developed map supplies valuable information for QTL fine mapping, candidate gene identification, and the development of molecular markers for marker assisted selection (MAS) of favorable alleles.
Subject(s)
Anthocyanins/biosynthesis , Chromosomes, Plant/genetics , Genetic Linkage , Quantitative Trait Loci , Seeds/genetics , Solanum melongena/genetics , Anthocyanins/genetics , Disease Resistance , Fusarium/pathogenicity , Pigmentation , Seeds/growth & development , Seeds/metabolism , Solanum melongena/microbiology , Solanum melongena/physiologyABSTRACT
An amendment to this paper has been published and can be accessed via the original article.
ABSTRACT
In Sicily, small differences exist between wild and cultivated rosemary biotypes; VOCs and genetic profiles may be a useful tool to distinguish them. A germplasm collection of Rosmarinus officinalis L. was harvested from 15 locations in Sicily. Eleven wild and four cultivated populations were collected and, due to the surveyed area covered, they can be considered as a representative panel of Sicilian genetic background of the species. Ex situ plant collection was transferred to the field cultivation in homogeneous conditions for characterizing through a multidisciplinary approach. The study included morphological traits observations (growth habitus, flower color, number and size of leaves, length and number of internodes), VOC profiles using HS-SPME, genome size by flow cytometry analysis, and genetic characterization by means of DNA and nuclear microsatellite (nSSR) investigation. To detect any pattern within- and among-populations variability, all morphological and chemical data were submitted to ANOVA, while clustering and structure population analysis were carried out using genetic profiles. The present work allowed us to distinguish rather well between wild and cultivated genotypes and to underline the biodiversity richness among rosemary Sicilian germplasm, never highlighted, useful for future breeding programs addressed to exploit this important resource.
Subject(s)
Rosmarinus/genetics , Analysis of Variance , Flow Cytometry , Microsatellite Repeats/genetics , Plant Leaves/genetics , Plant Leaves/metabolismABSTRACT
Eggplant (Solanum melongena L.) yield is highly sensitive to N fertilization, the excessive use of which is responsible for environmental and human health damage. Lowering N input together with the selection of improved Nitrogen-Use-Efficiency (NUE) genotypes, more able to uptake, utilize, and remobilize N available in soils, can be challenging to maintain high crop yields in a sustainable agriculture. The aim of this study was to explore the natural variation among eggplant accessions from different origins, in response to Low (LN) and High (HN) Nitrate (NO3 - ) supply, to identify NUE-contrasting genotypes and their NUE-related traits, in hydroponic and greenhouse pot experiments. Two eggplants, AM222 and AM22, were identified as N-use efficient and inefficient, respectively, in hydroponic, and these results were confirmed in a pot experiment, when crop yield was also evaluated. Overall, our results indicated the key role of N-utilization component (NUtE) to confer high NUE. The remobilization of N from leaves to fruits may be a strategy to enhance NUtE, suggesting glutamate synthase as a key enzyme. Further, omics technologies will be used for focusing on C-N metabolism interacting networks. The availability of RILs from two other selected NUE-contrasting genotypes will allow us to detect major genes/quantitative trait loci related to NUE.
Subject(s)
Genetic Variation , Nitrates/metabolism , Nitrogen/metabolism , Solanum melongena/genetics , Solanum melongena/metabolism , Analysis of Variance , Biomass , Chlorophyll/metabolism , Ecotype , Flavonoids/metabolism , Fruit/metabolism , Gene Expression Regulation, Plant , Inheritance Patterns/genetics , Plant Leaves/metabolism , Plant Roots/anatomy & histology , Plant Shoots/anatomy & histology , Plant Stems/metabolism , Quantitative Trait, HeritableABSTRACT
BACKGROUND: Magna Graecia is the ancient name for the modern geopolitical region of South Italy extensively populated by Greek colonizers, shown by archeological and historical evidence to be the oldest wine growing region of Italy, crucial for the spread of specialized viticulture around Mediterranean shores. Here, the genetic diversity of Magna Graecia grape germplasm was assessed and its role in grapevine propagation around the Mediterranean basin was underlined. RESULTS: A large collection of grapevines from Magna Graecia was compared with germplasm from Georgia to the Iberian Peninsula using the 18 K SNP array. A high level of genetic diversity of the analyzed germplasm was determined; clustering, structure analysis and DAPC (Discriminant Analysis of Principal Components) highlighted the genetic relationships among genotypes from South Italy and the Eastern Mediterranean (Greece). Gene flow from east (Georgia) to west (Iberian Peninsula) was identified throughout the large number of detected admixed samples. Pedigree analysis showed a complex and well-structured network of first degree relationships, where the cultivars from Magna Graecia were mainly involved. CONCLUSIONS: This study provided evidence that Magna Graecia germplasm was shaped by historical events that occurred in the area due to the robust link between South Italian and Greek genotypes, as well as, by the availability of different thermal resources for cultivars growing in such different winegrowing areas. The uniqueness of this ampelographic platform was mainly an outcome of complex natural or human-driven crosses involving elite cultivars.
Subject(s)
Genetic Variation/genetics , Polymorphism, Single Nucleotide/genetics , Vitis/genetics , Crop Production/history , DNA, Plant/genetics , Genotype , Genotyping Techniques , Georgia (Republic) , Greece , History, Ancient , Italy , Mediterranean Region , Pedigree , SpainABSTRACT
BACKGROUND: The ability of maize populations/landraces to tolerate drastically extreme environments over the past four centuries in Algeria leads to characterize these genetic resources for germplasm management as well as the identification of the best landraces useful for genetic improvement. Thus, the aim of the present work was a fingerprinting of an Algerian maize collection (47 landraces) from Saharan oasis by using 24 agro-morphological traits and18 Simple Sequence Repeats to evaluate genetic diversity and population structure. RESULTS: Phenotypic traits showed large significant variation in which earliness, plant size, ear and kernel features and crop yield appeared the most discriminant traits among landraces by using principal component analysis (PCA). One hundred ninety-seven different alleles were detected with a high mean number of allele per locus (10.9). The selected SSR were highly informative with PIC values > 0.65 as well as an overall genetic diversity (0.47) highlighting a broad genetic variability in the analyzed landraces. Genetic structure analysis revealed a high genetic differentiation among the 47 maize landraces with an overall Fst value (0.33). Cluster analysis for morphological traits as well as for SSR markers grouped the 47 Algerian populations regardless their geographic origin. CONCLUSIONS: Maize from Algerian desert harbors a wide genetic diversity offering a source of novel/unique alleles useful for maize breeding programs to face the ongoing and future major challenge, the climate changes.
Subject(s)
Zea mays/classification , Zea mays/genetics , Africa, Northern , Algeria , Genetic Variation , Microsatellite Repeats , Phenotype , Phylogeny , Plant Breeding , Population/geneticsABSTRACT
In this study, the effects (5 days) of the secondary metabolite trans-cinnamic acid on maize leaves (Zea mays L.), through a physiological and an untargeted metabolomic approach, were evaluated. A reduction in leaf growth and development accompanied by a decrease in protein content was observed in treated seedlings. Besides, trans-cinnamic acid stimulated the photosynthetic machinery with a significant increment in pigment content (chlorophyll a, b and carotenoids), a stimulation of the light adapted PSII efficiency (ɸII) as well as the chlorophyll a fluorescence (YNO), the apparent electron transport rate, and the regulated dissipation of the energy (YNPQ). By contrast, the dark adapted PSII parameter (Fv/Fm) was not affected suggesting that no physical damages to the antenna complex were caused by trans-cinnamic acid. These results suggested that maize seedlings were experiencing a stress but, at the same time, were able to cope with it. This hypothesis was confirmed by both the increment in benzoic and salicylic acids, important molecules involved in stress response, and the metabolomic results, which pointed out that the seedlings are directing their metabolism towards galactose production modulating its pathway, which is pivotal for the production of the antioxidant compound ascorbic acid (ASA). Indeed, in treated plants, a significant increment in total ASA content (28%) was observed. The results suggested that the main strategy adopted by plants to cope with trans-cinnamic-induced stress consisted in the modulation of their metabolism in order to increase the total ASA and carotenoids concentration, radical scavenging species.