Sativa Populations Research Articles

A comprehensive analysis of morphological and biochemical parameters of <i>Medicago sativa</i> during biotic stress

Background: Parasitism is an abiotic stress that significantly threatens plant growth and severely impacts crop productivity. Plants have developed complicated regulatory mechanisms to cope with stressful conditions, undergoing morphological and biochemical changes. Objective: The article presents the first comprehensive analysis of the Medicago sativa response to the penetration of flowering parasites Orobanche lutea and Cuscuta alba. The outcome of this study aim to enhance crop quality comprehend their bioactive properties and pinpoint optimal strategies for their utilization in preventing and treating human and animal health issues. Methods: Medicago sativa, Orobanche lutea and Cuscuta alba were collected in the Ararat province, located in southeastern Armenia. The plants’ morphological structures and leaf parameters were observed. The prooxidant activity was determined by the potentiometric method. The content of total phenols, flavonoids and catechins were determined by a spectrophotometric method. Pigments were separated and identified using thin layer chromatography and a spectrophotometric method. Results: The in-situ observations of M. sativa plant and ex-situ measurements of its leaves infected by O. lutea and C. alba reveal a significant negative impact on both the reproductive success and the vegetative aspects. Infected plants exhibited minimal inflorescence development, also, substantial reductions in leaf dimensions were observed. The analysis of prooxidant activity revealed that M. sativa exhibits inherent prooxidant properties, which are amplified in the presence of parasites. The influence of dodder on prooxidant activity is much more significant (14-38%) than that of broomrape (8-42%). The percentage changes in total phenolic content were more pronounced in the presence of C. alba, but flavonoid decline was more pronounced in the presence of O. lutea, suggesting a differential impact of the two parasites. Although catechin content was not affected, photosynthetic pigments of the host plant were significantly (28-57%) reduced by the parasites. Conclusion: Findings indicate a clear morphological alteration induced by parasitic infestation. The parasites, particularly O. lutea can cause temporal isolation and allochronic speciation in M. sativa populations. Biochemical analysis highlighted a complex interplay between the host and the parasite. The biochemical impact of the parasite is reflected on the host’s primary and secondary metabolism. The observed morphological and biochemical changes highlight the need for further research to explore potential mitigation strategies, selective herbicide development, and biocontrol measures against parasitic plant infestations in agricultural ecosystems. Keywords: alfalfa; Orobanche lutea; Cuscuta alba; parasites plants; morphophysiological observations; bioactivity.

Herbicidal and Nitrogen Efficacy on Weed Management in Wheat Fields of Eastern Uttar Pradesh, India

Weeds can significantly affect crop yield and nutrient uptake, making effective management crucial in wheat fields. This study, conducted during the winter (Rabi) season of 2018-19 at the Agricultural Research Farm of Banaras Hindu University in Varanasi, aimed to assess the combined impact of different nitrogen levels and herbicide treatments on weed control and wheat production. The objective was to determine the best practices for reducing weed competition and improving crop performance. The experiment was set up using a split plot design with three replications. The treatments comprised of 3 nitrogen levels and 5 weed control methods. The study identified nine prevalent weed species in wheat fields, including Phalaris minor, Anagallis arvensis, Cynodon dactylon, Chenopodium album, Melilotus indicus, Vicia sativa, Medicago denticulata, Solanum nigrum, and Cyperus rotundus, with Anagallis arvensis, Chenopodium album and Vicia sativa being the most dominant. The application of Sulfosulfuron (25 g ha-1) combined with 2, 4-D (750 ml ha-1) resulted in the lowest weed density and biomass and the highest weed control efficiency. Additionally, performing hand weeding twice (30 and 60 days after sowing) in conjunction with 180 kg N ha-1, followed by the application of Sulfosulfuron (25 g ha-1) + 2, 4-D (750 ml ha-1), significantly reduced Anagallis arvensis, Chenopodium album and Vicia sativa population and biomass and improved weed control effectiveness. Higher weed dry weight and population results in lower plant nutrient uptake and lower dry matter of crop plant and yield.

Genome-wide association analysis identifies natural allelic variants associated with panicle architecture variation in African rice, Oryza glaberrima Steud.

African rice (Oryza glaberrima Steud), a short-day cereal crop closely related to Asian rice (Oryza sativa L.), has been cultivated in Sub-Saharan Africa for ∼ 3,000 years. Although less cultivated globally, it is a valuable genetic resource in creating high-yielding cultivars that are better adapted to diverse biotic and abiotic stresses. While inflorescence architecture, a key trait for rice grain yield improvement, has been extensively studied in Asian rice, the morphological and genetic determinants of this complex trait are less understood in African rice. In this study, using a previously developed association panel of 162 O. glaberrima accessions and new SNP variants characterized through mapping to a new version of the O. glaberrima reference genome, we conducted a genome-wide association study of four major morphological panicle traits. We have found a total of 41 stable genomic regions that are significantly associated with these traits, of which 13 co-localized with previously identified QTLs in O. sativa populations and 28 were unique for this association panel. Additionally, we found a genomic region of interest on chromosome 3 that was associated with the number of spikelets and primary and secondary branches. Within this region was localized the O. sativa ortholog of the PHYTOCHROME B gene (Oglab_006903/OgPHYB). Haplotype analysis revealed the occurrence of natural sequence variants at the OgPHYB locus associated with panicle architecture variation through modulation of the flowering time phenotype, whereas no equivalent alleles were found in O. sativa. The identification in this study of genomic regions specific to O. glaberrima indicates panicle-related intra-specific genetic variation in this species, increasing our understanding of the underlying molecular processes governing panicle architecture. Identified candidate genes and major haplotypes may facilitate the breeding of new African rice cultivars with preferred panicle traits.

Assessing Intraspecific Genetic Variability in Cannabis sativa Populations of Punjab Pakistan Using RAPD and DNA Barcode Markers

Cannabis sativa possess substantial amount of omega-3 fatty acids and several medicinal benefits with potential secondary metabolites. This study employed rbcL, matK, and trnH-psbA barcode markers and RAPD marker to explore genetic diversity in C. sativa populations in Punjab, Pakistan. In population genetic study using DNA barcode markers, cladogram showed investigated samples were genetically similar; however, demonstrated significant genetic diversity with the available DNA sequences of this plant from other regions and countries. The nucleotide sequence variation (% divergence) indicated high intraspecific variation in plants of different geographical zones. However, the RAPD marker analysis displayed genetic diversity among collected Cannabis sativa samples. The principal component analysis reinforced these findings by providing a spatial representation of genetic distances among the samples that revealed a considerable genetic diversity among the collected material and significant intraspecific variation was observed, indicating diverse genetic profiles across geographical regions. This research highlights the potential of molecular markers in germplasm selection for breeding programs.

Hybridization rate and fitness of hybrids produced between the tetraploid Camelina rumelica and hexaploid Camelina sativa

Pre-release risk assessment of genetically modified (GM) Camelina sativa (L.) Crantz requires a careful evaluation of the reproductive compatibility with its closely-related Camelina species. Camelina rumelica Velen. is a naturalized weed occurring in C. sativa production region in the northwestern China. In this study, a large number of reciprocal crosses was conducted between the tetraploid C. rumelica and hexaploid C. sativa. The F1 hybrids were produced by the tetraploid C. rumelica (♀) × hexaploid C. sativa (♂) at the rate of one hybrid for 217 ovules pollinated, and one hybrid for 220 ovules pollinated in the reciprocal direction. All F1 hybrids required vernalization treatment to induce timely flowering and showed the significant lower pollen viability (< 2%) compared to the parental lines. Despite that the F1 failed to backcross with the parental lines, selfed seeds (F2) were obtained from F1 hybrids plants. The F2 hybrids showed some degree of restored pollen viability (about 20%) and successfully produced seeds by both backcrossing and self-pollination. A similar pattern was observed in the field, with F1 hybrids showing self-compatibility and reduced seed production potential. It is worthwhile to mention that all F1 and F2 plants grew well both in the greenhouse and field conditions, but with the significant lower seed production ability. A portion of selfed F2 seeds from naturally shattering persisted in the soil seedbank during summer period and subsequently germinated in late fall. By contrast, other F2 seeds may have been dormant in the soil seedbank and germinated the following spring. These altered life-cycle related traits in hybrids generates the novel ecological concerns on the persistence and population dynamics of transient hybrids in the seedbank. In summary, this study provided the evidence that the tetraploid C. rumelica and hexaploid C. sativa, which have the sympatric distributions and overlapped flowering periods, gene flow between them probably could occur. Although the rate was relatively low (about 0.5%), the introgression of life-cycle related traits into C. sativa population could alter its key life-cycle traits and raise the concerns on the soil seedbank persistence and invasiveness of transient hybrid in C. sativa production region in the northwestern China.

The effects CaO nanoparticles applications on Onobrycis sativa seedlings growth under mannitol stress

In our study, two onobrycis sativa population (Uzuntekne, and Barış) were used as the material for the response to CaO NPs nanoparticulate. More DNSA and proline were collected in these two onobrycis sativa genotypes than in control seedlings while two genotypes were exposed to mannitol. Proline content highest at 150 mM mannitol and 1.5 ppm CaO while the minimum and maximum content was observed at 50–150 mM mannitol dosages. The collected of DNSA was greatly correlated with higher mannitol concentrations. Proline activities demonstrated an increasing trend against the increasing concentration of mannitol. In conclusion, the growth characteristics and physiological responses of onobrycis sativa increased, depending on genotype, mannitol and CaO dosage in the media and their interactions.

Phenotypic polymorphism of leaves among the populations of Moroccan chestnut (Castanea sativa Mill.)

Moroccan chestnut populations cover a small area in northern Morocco. They occupy great environmental and socio-economic interests. Nonetheless, such interests remained unvalued and little studied. This study aims to characterize and assess phenotypic similarities (or disparities) among the Moroccan populations of C. sativa via univariate and multivariate analyses of leaves traits. The experiments involved 6200 leaves from 31 populations, 10 trees per population, and 20 leaves per tree. Six morphometric parameters [blade area (S), perimeter (P), lamina length (LL), lamina width (LW), distance between the base and largest width (DBW), petiole length (PL)] and four ratios [LL/LW, LL/LP, LL/DBW, DBW/LP] were analyzed. Analysis of descriptive statistics within and between populations showed large variations among the studied parameters. This trend was supported as well by the analysis of variance (ANOVA) which revealed a highly significant differences (P &lt;0.0001). Furthermore, the statistical analysis revealed a high phenotypic plasticity. The correlation analysis showed a significant relationship between most of the studied parameters. The principal component analysis (PCA) assigned the studied populations into two groups. We conclude that the studied parameters have great potential to determine the phenotypic polymorphism of C. sativa populations

Genomic Analysis Provides Insights Into the Plant Architecture Variations in in situ Conserved Chinese Wild Rice (Oryza rufipogon Griff.).

In situ conserved wild rice (Oryza rufipogon Griff.) is a promising source of alleles for improving rice production worldwide. In this study, we conducted a genomic analysis of an in situ conserved wild rice population (Guiping wild rice) growing at the center of wild rice genetic diversity in South China. Differences in the plant architecture in this population were investigated. An analysis using molecular markers revealed the substantial genetic diversity in this population, which was divided into subgroups according to the plant architecture. After resequencing representative individuals, the Guiping wild rice population was compared with other O. rufipogon and Oryza sativa populations. The results indicated that this in situ conserved wild rice population has a unique genetic structure, with genes that were introgressed from aromatic and O. sativa ssp. indica and japonica populations. The QTLs associated with plant architecture in this population were detected via a pair-wise comparison analysis of the sequencing data for multiple DNA pools. The results suggested that a heading date-related gene (DHD1) might be associated with variations in plant architecture and may have originated in cultivated rice. Our findings provide researchers with useful insights for future genomic analyses of in situ conserved wild rice populations.

Intraspecific Variation for Leaf Physiological and Root Morphological Adaptation to Drought Stress in Alfalfa (Medicago sativa L.).

Drought stress reduces crop biomass yield and the profitability of rainfed agricultural systems. Evaluation of populations or accessions adapted to diverse geographical and agro-climatic environments sheds light on beneficial plant responses to enhance and optimize yield in resource-limited environments. This study used the morphological and physiological characteristics of leaves and roots from two different alfalfa subspecies during progressive drought stress imposed on controlled and field conditions. Two different soils (Experiments 1 and 2) imposed water stress at different stress intensities and crop stages in the controlled environment. Algorithm-based image analysis of leaves and root systems revealed key morphological and physiological traits associated with biomass yield under stress. The Medicago sativa subspecies (ssp.) sativa population, PI478573, had smaller leaves and maintained higher chlorophyll content (CC), leaf water potential, and osmotic potential under water stress. In contrast, M. sativa ssp. varia, PI502521, had larger leaves, a robust root system, and more biomass yield. In the field study, an unmanned aerial vehicle survey revealed PI502521 to have a higher normalized difference vegetation index (vegetation cover and plant health characteristics) throughout the cropping season, whereas PI478573 values were low during the hot summer and yielded low biomass in both irrigated and rainfed treatments. RhizoVision Explorer image analysis of excavated roots revealed a smaller diameter and a narrow root angle as target traits to increase alfalfa biomass yield irrespective of water availability. Root architectural traits such as network area, solidity, volume, surface area, and maximum radius exhibited significant variation at the genotype level only under limited water availability. Different drought-adaptive strategies identified across subspecies populations will benefit the plant under varying levels of water limitation and facilitate the development of alfalfa cultivars suitable across a broad range of growing conditions. The alleles from both subspecies will enable the development of drought-tolerant alfalfa with enhanced productivity under limited water availability.

Chemical and genetic variation in feral Cannabis sativa populations across the Nebraska climate gradient

Cannabis sativa is a versatile crop that can be cultivated for fiber, seed, or phytochemicals. To take advantage of this versatility and the potential of Cannabis as a feedstock for the bioeconomy, genomics-enabled breeding programs must be strengthened and expanded. This work contributes to the foundation for such by investigating the phytochemistry and genomics of feral Cannabis populations collected from seventeen counties across the climate gradient of Nebraska. Flower tissue from male and female plants (28 total) was studied using (i) gas chromatography-mass spectrometry to assess cannabinoid profiles and (ii) RNA sequencing to determine transcript abundances. Both male and female flower tissues produced cannabinoids, and, though the compounds were more abundant in female flower tissue, the primary cannabinoid in both was usually cannabidiol. The expression of genes that mediate early steps on the cannabinoid biosynthetic pathway were upregulated in female relative to male flowers, suggesting that female versus male flower tissue cannabinoid abundance may be controlled at least in part at the transcriptional level. DNA sequencing was used to place feral Cannabis plants from Nebraska into a previously described genomic context, revealing that all the plants studied here are much more similar to previously characterized hemp-type Cannabis plants than to drug-type Cannabis plants, at least at the genetic level. This work provides foundational phytochemical knowledge and a large set of high-quality single nucleotide polymorphism markers for future studies of feral Nebraska Cannabis.

EVALUATION OF GENETIC DIVERSITY OF THE BLACK GLUTINOUS RICE BASED ON AGRO-MORPHOLOGICAL CHARACTERS

The study assessed the variations in nine agro-morphological characters among and within the black glutinous rice (Oryza sativa) population from Chau Thanh District, Tra Vinh Province. The nine quantitative agromorphological characters that were measured include culm length, leaf length, leaf width, number of panicles, panicle length, grain length, grain width, number of firm grain, and number of grain per panicle. The unweighted pair group method with arithmetic mean method and principal coordinate analysis by the NTSYS program were applied in this study to classify the nine agro-morphological characters. In addition, tocompare the variations in quantitative characters between O. sativa populations, one-way analysis of variance (ANOVA) was used. The results showed significant differences between the black glutinous rice populations for all quantitative agro-morphological characters. Moreover, some agro-morphological characters showed positive correlations to each other. The dendrogram generated from the analysis process of the agromorphological data divided the O. sativa populations into two groups with unfamiliar features. However, the O. sativa populations assessed exhibited a wide range of variations in morphological characteristics, both within the same population and among other populations with the same strains.

‘We live and die in chestnut’: remaining and adapting in the face of pest and disease outbreak in Turkey

ABSTRACT Concern is growing worldwide over the negative outcomes of rural abandonment. Yet, problematisation of this phenomenon remains limited by insufficient explanatory frameworks and lack of empirical evidence from the conditions which precede, underlie and succeed it. Accordingly, this paper presents a case from Turkey, where significant rural abandonment is locally attributed to the ravages of multiple introduced pathogens in European chestnut (Castanea sativa) populations, and where our previous investigation has verified that traditional livelihood practices mitigate damage severity at the levels of trees, plots and landscapes. In order to better understand individual stakeholder motivations for remaining acting members of chestnut landscapes in the face of such serious challenges, we conducted 142 extended ethnographic and narrative interviews with chestnut-utilising participants across Turkey’s highly diverse human and physical geography. Our results show how the struggle to remain as acting landscape members requires community livelihood adaptation, drawing on institutional memory, innovative learning and social connectedness.

Pan-genome analysis of 33 genetically diverse rice accessions reveals hidden genomic variations

Structural variations (SVs) and gene copy number variations (gCNVs) have contributed to crop evolution, domestication, and improvement. Here, we assembled 31 high-quality genomes of genetically diverse rice accessions. Coupling with two existing assemblies, we developed pan-genome-scale genomic resources including a graph-based genome, providing access to rice genomic variations. Specifically, we discovered 171,072 SVs and 25,549 gCNVs and used an Oryza glaberrima assembly to infer the derived states of SVs in the Oryza sativa population. Our analyses of SV formation mechanisms, impacts on gene expression, and distributions among subpopulations illustrate the utility of these resources for understanding how SVs and gCNVs shaped rice environmental adaptation and domestication. Our graph-based genome enabled genome-wide association study (GWAS)-based identification of phenotype-associated genetic variations undetectable when using only SNPs and a single reference assembly. Our work provides rich population-scale resources paired with easy-to-access tools to facilitate rice breeding as well as plant functional genomics and evolutionary biology research.

Chromosomal characteristics of salt stress heritable gene expression in the rice genome

BackgroundGene expression is potentially an important heritable quantitative trait that mediates between genetic variation and higher-level complex phenotypes through time and condition-dependent regulatory interactions. Therefore, we sought to explore both the genomic and condition-specific characteristics of gene expression heritability within the context of chromosomal structure.ResultsHeritability was estimated for biological gene expression using a diverse, 84-line, Oryza sativa (rice) population under optimal and salt-stressed conditions. Overall, 5936 genes were found to have heritable expression regardless of condition and 1377 genes were found to have heritable expression only during salt stress. These genes with salt-specific heritable expression are enriched for functional terms associated with response to stimulus and transcription factor activity. Additionally, we discovered that highly and lowly expressed genes, and genes with heritable expression are distributed differently along the chromosomes in patterns that follow previously identified high-throughput chromosomal conformation capture (Hi-C) A/B chromatin compartments. Furthermore, multiple genomic hot-spots enriched for genes with salt-specific heritability were identified on chromosomes 1, 4, 6, and 8. These hotspots were found to contain genes functionally enriched for transcriptional regulation and overlaps with a previously identified major QTL for salt-tolerance in rice.ConclusionsInvestigating the heritability of traits, and in-particular gene expression traits, is important towards developing a basic understanding of how regulatory networks behave across a population. This work provides insights into spatial patterns of heritable gene expression at the chromosomal level.

Validating a predictive model of cannabinoid inheritance with feral, clinical, and industrial Cannabis sativa.

PremiseHow genetic variation within a species affects phytochemical composition is a fundamental question in botany. The ratio of two specialized metabolites in Cannabis sativa, tetrahydrocannabinol (THC) and cannabidiol (CBD), can be grouped into three main classes (THC‐type, CBD‐type, and intermediate type). We tested a genetic model associating these three groups with functional and nonfunctional alleles of the cannabidiolic acid synthase gene (CBDAS).MethodsWe characterized cannabinoid content and assayed CBDAS genotypes of >300 feral C. sativa plants in Minnesota, United States. We performed a test cross to assess CBDAS inheritance. Twenty clinical cultivars obtained blindly from the National Institute on Drug Abuse and 12 Canadian‐certified grain cultivars were also examined.ResultsFrequencies of CBD‐type, intermediate‐type, and THC‐type feral plants were 0.88, 0.11, and 0.01, respectively. Although total cannabinoid content varied substantially, the three groupings were perfectly correlated with CBDAS genotypes. Genotype frequencies observed in the test cross were consistent with codominant Mendelian inheritance of the THC:CBD ratio. Despite significant mean differences in total cannabinoid content, CBDAS genotypes blindly predicted the THC:CBD ratio among clinical cultivars, and the same was true for industrial grain cultivars when plants exhibited >0.5% total cannabinoid content.ConclusionsOur results extend the generality of the inheritance model for THC:CBD to diverse C. sativa accessions and demonstrate that CBDAS genotyping can predict the ratio in a variety of practical applications. Cannabinoid profiles and associated CBDAS segregation patterns suggest that feral C. sativa populations are potentially valuable experimental systems and sources of germplasm.

Variation in fruit traits and infestation ratios in natural sweet chestnut (Castanea sativa) populations under chestnut weevil (Curculio elephas) damage

Sweet chestnut (Castanea sativa Mill.) is one of the most important species in agro-forestry and horticulture. Turkey is an important C. sativa gene centre and fruit production region. The present study aimed to measure the variations in fruit width, length, thickness and weight in four different natural C. sativa populations in Turkey and determine the loss of fruit traits due to damage by chestnut weevil (Curculio elephas (Gyllenhal, 1836)) (Coleoptera: Curculionidae). Fruits were collected from four populations (Istanbul-Bahcekoy, Canakkale-Bayramic, Balikesir- Erdek and Bursa-Uludag) of phenotypically healthy sweet chestnut trees, measurements were taken, and the fruits were classified into those damaged by C. elephas and those not. Analysis revealed significant differences among and within the populations in all fruit traits, and between the sound and damaged fruits, with the average fruit width, length, thickness and weight being 24.8 mm, 23.1 mm, 15.3 mm and 3.4 g, respectively. Bursa-Uludag population had the highest healthy fruit ratio (70%), with some individuals in the population yielding healthy fruits at ratios > 90%. In the Balikesir-Erdek population, however, where the percentage of damaged fruits was the highest (54%), it was determined that some trees suffered more than 90% damage in contrast to the Bursa-Uludag population. In the fruits infested by C. elephas, the approximate percentages of loss in fruit width, length, thickness and weight were 6, 4, 7 and 30%, respectively. The fruit weight loss percentages varied between 25% and 32% among the populations.

Adaptive evolution of chestnut forests to the impact of ink disease in Spain

AbstractPhytophthora cinnamomi (Pc) is an extremely destructive soil‐borne pathogen of Asiatic origin responsible for “ink disease” in chestnut. This work assesses the adaptive potential to the impact of Pc of four Spanish populations of Castanea sativa undergoing different selection pressures. To explore the evolvability of C. sativa to Pc in the selected populations, parameters obtained from neutral and functional genetic diversity were compared with estimates of quantitative genetic variability. Nine expressed sequence tags‐simple sequence repeat (EST‐SSR) markers were selected and their transferability and polymorphism in 137 C. sativa individuals were evaluated. To test the potential of EST‐SSR markers for early selection of Pc tolerant plant material, the offspring of selected individuals were challenged with Pc. Expressed sequence tags‐simple sequence repeat markers and seedling life expectancy after Pc inoculation revealed significant different responses of C. sativa populations to Pc. The genetic variability observed within populations showed the potential response capacity of Spanish C. sativa populations to undergo fast adaptive evolution. The heritability value obtained for the “life expectancy” variable (h2 = 0.21 ± 0.11) indicated that selection for resistance to Pc is possible. Genetic patterns reflected two evolutionarily meaningful groupings of populations, corresponding to the different selective pressure of the oomycete between sites. The differentiation coefficient obtained through markers classified as under neutral selection (FST = 0.185) was lower than the quantitative genetic differentiation of “life expectancy” between C. sativa populations (QST = 0.682), providing evidence that selection acted spatially in a heterogeneous manner. A first link has been identified in trees between population structure and adaptive responses to pathogen‐induced selection. The study identified one marker under positive selection that could be used in marker assisted selection to predict resistance to Pc in non‐inoculated C. sativa trees.

Transcriptome responses to different herbivores reveal differences in defense strategies between populations of Eruca sativa

BackgroundIntraspecific variations among induced responses might lead to understanding of adaptive variations in defense strategies against insects. We employed RNA-Seq transcriptome screening to elucidate the molecular basis for phenotypic differences between two populations of Eruca sativa (Brassicaceae), in defense against larvae of the generalist and specialist insects, Spodoptera littoralis and Pieris brassicae, respectively. The E. sativa populations originated from desert and Mediterranean sites, where the plants grow in distinct habitats.ResultsResponses to elicitation of the plants’ defenses against wounding and insect herbivory resulted in more upregulated transcripts in plants of the Mediterranean population than in those of the desert. PCA analysis differentiated between the two populations and between the elicitation treatments. Comprehensive analysis indicated that defense responses involved induction of the salicylic acid and jasmonic acid pathways in plants of the desert and Mediterranean populations, respectively. In general, the defense response involved upregulation of the aliphatic glucosinolates pathway in plants of the Mediterranean population, whereas herbivory caused downregulation of this pathway in desert plants. Further quantitative RT-PCR analysis indicated that defense response in the desert plants involved higher expression of nitrile-specifier protein (NSP) than in the Mediterranean plants, suggesting that in the desert plants glucosinolates breakdown products are directed to simple-nitriles rather than to the more toxic isothiocyanates. In addition, the defense response in plants of the desert population involved upregulation of flavonoid synthesis and sclerophylly.ConclusionsThe results indicated that differing defense responses in plants of the two populations are governed by different signaling cascades. We suggest that adaptive ecotypic differentiation in defense strategies could result from generalist and specialist herbivore pressures in the Mediterranean and desert populations, respectively. Moreover, the defense responses in plants of the desert habitat, which include upregulation of mechanical defenses, also could be associated with their dual role in defense against both biotic and abiotic stresses.

The Eurasian steppe belt in time and space: Phylogeny and historical biogeography of the false flax (Camelina Crantz, Camelineae, Brassicaceae)

Stretching 8000 km from the Pannonian basin and the Danube delta in the West to the Manchuria region in the East and reaching up to 1000 km in width, the Eurasian steppe belt is the vastest steppe region worldwide. However, our knowledge about the temporal and spatial patterns of floral origin and evolution of the Eurasian Steppe is limited and inconclusive. Case studies on typical steppe flora may help us close such gaps. The study subject of this project was Camelina – a taxon which occupies open dry habitats in temperate zones of Eurasia. To infer the evolutionary history of this genus, maximum likelihood optimisation in RAxML and Bayesian Inference approach were carried out, based on the nuclear external transcribed spacer region. Furthermore, we performed a secondarily calibrated time estimation analysis using Bayesian optimisation in BEAST to infer potential influence of climatic shifts and paleogeographic events on the distribution patterns of Camelina and carried out an ancestral area reconstruction analysis using a Bayesian Binary Method. Our study resulted in a well-supported phylogeny that corresponds with the species morphology and uncovered several genetically distinct inter- and intraspecific lineages which appear to correlate geographically. Time divergence estimation argue for the diversification of Camelina to have taken place in the Middle East around the transition from Pliocene to Pleistocene (3-2 mya), and its historical biogeography to have been under a strong influence of several glacial periods and their palaeoclimatic and palaeoenvironmental consequences. Its young age also explains the subtle morphological character differences among species and high interspecific hybridisation potential. We further discuss the rediscovery of wild Camelina sativa populations and propose the external transcribed spacer as a ribotype identifying region for young and rapidly evolving core eudicot lineages.

Adaptive diversity and drought tolerance in Castanea sativa assessed through EST-SSR genic markers

Increasing drought conditions in Mediterranean countries are negatively impacting the survival and productivity of Castanea sativa Mill. The study aimed to select EST-SSR markers associated with drought stress developed in Quercus spp. and evaluate their transferability and polymorphism in C. sativa. Eight EST-SSR markers were selected to examine the adaptive potential of four wild populations of C. sativa in relation to drought tolerance. To validate markers, offspring of the study trees were water stressed and their drought tolerance was assessed. EST-SSR markers and leaf wilting of seedlings after drought treatment revealed a north–south gradient of C. sativa populations. The heritability value obtained for the ‘leaf wilting’ trait (h² = 0.26 ± 0.08) indicated that selection for drought tolerance is possible. The differentiation coefficient of markers showing neutral selection (FST = 0.080) was lower than the quantitative genetic differentiation of populations (QST = 0.28), indicating that selection of drought tolerant trees acted spatially in a heterogeneous manner. When assessing the genetic structure of populations, FIR080 was identified as outlier locus under positive selection. When assessing the phenotypic tolerance to drought of offspring, GOT004 and GOT045 were identified as outlier loci under balancing selection and FIR059 was identified as an outlier locus under positive selection. FIR059 showed three private alleles for drought-susceptible individuals and two private alleles for drought-tolerant individuals and could therefore be considered as a candidate marker to predict drought tolerance in unstressed C. sativa trees. Combined use of functional markers and phenotypic traits is a powerful approach to determine genetic variation at the adaptive level in C. sativa. The results illustrate the potential of EST-SSR markers for early selection of drought tolerant plant material.