Nitrogen Use Efficiency in Durum Wheat (Triticum durum Desf.) Grown under Semiarid Conditions in Algeria

The proper and sustainable management of nitrogen fertilization is one of the most common problems of cereal cultivation in semiarid regions, which are characterized by a wide variability in climatic conditions. The current work was conducted to evaluate the effects of nitrogen fertilization on the agronomic and economic aspects of durum wheat cultivated under rainfed semiarid conditions in Algeria and to determine the most efficient nitrogen use efficiency (NUE) among four genotypes that are widespread in the country (tall and short, old and modern genotypes). The four genotypes, Bousselam, MBB, Megress, and GTAdur, were investigated under four nitrogen rates from 0 to 120 kg N ha−1 during three cropping seasons (2016 to 2018). The results indicate that the total nitrogen uptake at maturity (NM), nitrogen uptake by grain (NG), nitrogen harvest index (NHI), NUE and its components, such as nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE), were significantly affected by year, genotype, and nitrogen level. From this study, it appears that higher nitrogen rates improved NM and NG. However, no effects on either grain yield or marginal net return (MNR) were observed; conversely, increased nitrogen levels produced a 13% reduction in the economic return. In other words, in the North African environment, the response to nitrogen is more evident in quality than in yield, which in turn is dependent on the yearly weather conditions and cultivated genotypes. Moreover, nitrogen negatively affected NUE and its components (NUpE, NUtE). On average, NUE displayed low values (14.77 kg kg−1), mostly irregular and highly dependent on weather conditions; in the best year, it did not exceed 60% (19.87 kg kg−1) of the global average value of 33 kg kg−1. Moreover, the modern genotypes Megress (tall) and GTAdur (short) showed the best capacity to tolerate different nitrogen conditions and water shortages, providing relatively superior yields, as well as more effective N use from fertilizers and the soil than the other two genotypes

Iodine fortification plant screening process and accumulation in tomato fruits and potato Tubers

Iodine is an essential microelement for human health, and Recommended Daily Allowance (RDA) of such element should range from 40 to 200 \ub5g day-1. Because of the low iodine contents in vegetables, cereals, and many other foods, Iodine Deficiency Disorder (IDD) is one of the most widespread nutrient deficiency diseases in the world. Therefore, investigations of iodine uptake in plants with the aim of their fortification can help reaching the important health and social objective of IDD elimination. This study was conducted to determine the effects of the absorption of iodine from two different chemical forms - potassium iodide (I-) vs. potassium iodate (IO-3) - in a wide range of wild and cultivated plant species. Pot plants were irrigated with different concentrations of I- or IO-3, namely 0.05% and 0.1% (w/v) I-, and 0.05%, 0.1%, 0.2% and 0.5% (w/v) IO-3. Inhibiting effects on plant growth were observed after adding these amounts of iodine to the irrigation water. Plants wereable to tolerate better the higher levels of iodine as IO-3 rather than I- in the root environment. Among cultivated species, barley (Hordeum vulgare L.) showed the lowest, and maize (Zea mays L.) together with tobacco (Nicotiana tabacum L.) the highest biomass reductions due to iodine toxicity. After the screening, cultivated tomato and potato resulted good targets for a fortification rate study among the species screened. When fed with 0.05% iodine salts, potato (Solanum tuberosum L.) tubers and tomato (Solanum lycopersicum L.) fruits absorbed iodine up to 272 and 527 \ub5g/100 g FW from IO-3, and 1,875 and 3,900 \ub5g/100 g FW from I-. These uptake levels were well above the RDA of 150\ub5g day-1 for adults. Moreover, the agronomic efficiency of iodine accumulation of potato tubers and tomato fruits was calculated. Both plant organs showed greater accumulation efficiency for given unit of iodine from iodide than from iodate. This accumulation efficiency decreased in both potato tubers and tomato fruits at iodine concentrations higher than 0.05% for iodide, and at respectively 0.2% and 0.1% for iodate. On the basis of the uptake curve it was finally possible to calculate, although to be validated, the doses of supply in the irrigation water of iodine as iodate (0.028% for potato, and0.014% for tomato) as well as of iodide (0.004% for potato, and 0.002% for tomato), to reach the 150 \ub5g day-1 RDA for adults in 100 g of such vegetables, to efficiently control IDD

A genotypic and phenotypic information source for marker-assisted selection of cereals: the CEREALAB database

The CEREALAB database aims to store genotypic and phenotypic data obtained by the CEREALAB project and to integrate them with already existing data sources in order to create a tool for plant breeders and geneticists. The database can help them in unravelling the genetics of economically important phenotypic traits; in identifying and choosing molecular markers associated to key traits; and in choosing the desired parentals for breeding programs. The database is divided into three sub-schemas corresponding to the species of interest: wheat, barley and rice; each sub-schema is then divided into two sub-ontologies, regarding genotypic and phenotypic data, respectively

Patterns of genetic diversity and linkage disequilibrium in a highly structured Hordeum vulgare association-mapping population for the Mediterranean basin

Population structure and genome-wide linkage disequilibrium (LD) were investigated in 192 Hordeum vulgare accessions providing a comprehensive coverage of past and present barley breeding in the Mediterranean basin, using 50 nuclear microsatellite and 1,130 DArT® markers. Both clustering and principal coordinate analyses clearly sub-divided the sample into five distinct groups centred on key ancestors and regions of origin of the germplasm. For given genetic distances, large variation in LD values was observed, ranging from closely linked markers completely at equilibrium to marker pairs at 50 cM separation still showing significant LD. Mean LD values across the whole population sample decayed below r 2 of 0.15 after 3.2 cM. By assaying 1,130 genome-wide DArT® markers, we demonstrated that, after accounting for population substructure, current genome coverage of 1 marker per 1.5 cM except for chromosome 4H with 1 marker per 3.62 cM is sufficient for whole genome association scans. We show, by identifying associations with powdery mildew that map in genomic regions known to have resistance loci, that associations can be detected in strongly stratified samples provided population structure is effectively controlled in the analysis. The population we describe is, therefore, shown to be a valuable resource, which can be used in basic and applied research in barle

Iodine uptake and distribution in horticultural and fruit tree species.

Iodine is an essential microelement for humans and iodine deficiency disorder (IDD) is one of the most widespread nutrient-deficiency diseases in the world. Iodine biofortification of plants provides an attractive opportunity to increase iodine intake in humans and to prevent and control IDD. This study was conducted to investigate the iodine uptake and accumulation in edible portion of two fruit trees: plum and nectarine, and two horticultural crops: tomato and potato. Two type of iodine treatments (soil and foliar spray application), and, for fresh market tomato, two production systems (open field and greenhouse hydroponic culture) were tested. The distribution of iodine in potato stem and leaves, and in plum tree fruits, leaves, and branches was investigated. Iodine content of potato tubers after postharvest storage and processing (cooking), and iodine content of nectarine fruits after postharvest storage and processing (peeling) were also determined. Differences in iodine accumulation were observed among the four crops, between applications, and between production systems. In open field, the maximum iodine content ranged from 9.5 and 14.3 \u3bcg 100 g 121 for plum and nectarine fruit, to 89.4 and 144.0 \u3bcg 100 g 121 for potato tuber and tomato fruit, respectively. These results showed that nectarine and plum tree accumulated significantly lower amounts of iodine in their edible tissues, in comparison with potato and tomato. The experiments also indicated hydroponic culture as the most efficient system for iodine uptake in tomato, since its fresh fruits accumulated up to 2423 \u3bcg 100 g 121 of iodine. Iodine was stored mainly in the leaves, in all species investigated. Only a small portion of iodine was moved to plum tree branches and fruits, and to potato stems and tubers. No differences in iodine content after fruit peeling was observed. A significant increase in iodine content of potato was observed after baking, whereas a significant decrease was observed after boiling. We concluded that iodine biofortified fresh market tomato salad, both from field and hydroponics cultivation, and baked potatoes can be considered as potential functional foods for IDD prevention

Determinants of barley grain yield in drought-prone Mediterranean environments

The determinants of barley grain yield in drought-prone Mediterranean environments have been studied in the Nure x Tremois (NT) population. A large set of yield and other morpho-physiological data were recorded in 118 doubled haploid (DH) lines of the population, in multi-environment field trials (18 site-year combination). Agrometeorological variables have been recorded and calculated at each site too. Four main periods of barley development were considered, vegetative, reproductive early and late grain filling phases, to dissect the effect on yield traits of the growth phases. Relationships between agrometeorological variables, grain yield (GY) and its main components (GN and GW) were also investigated by correlation. Results firstly gave a clear indication of the involvement of water consumption in determining GY and GW (r2=0.616, P=0.007 and r2=0.703, P=0.005, respectively) calculated from sowing to the early grain filling period, while GN showed its highest correlation with the total photothermal quotient (PQ) calculated for the same period (r2=0.646, P=0.013). With the only exception of total PQ calculated during the vegetative period, all significant correlations with GY were associated to water-dependent agrometeorological parameters. As a second result, the NT segregating population allowed us to weight the amount of interaction due to genotypes over environments or to environments in relation to genotypes by a GGE analysis; 47.67% of G+GE sum of squares was explained by the first two principal components. Then, the introduction of genomic information at major barley genes regulating the length of growth cycle allowed us to explain patterns of adaptation of different groups of NT lines according to the variants (alleles) harbored at venalization (Vrn-H1) in combination with earliness (Eam6) genes. The superiority of the lines carrying the Nure allele at Eam6 was confirmed by factorial ANOVA testing the four possible haplotypes obtained combining alternative alleles at Eam6 and Vrn-H1. Maximum yield potential and differentials among the NT genotypes was finally explored through Finlay-Wilkinson model to interpret grain yield of NT genotypes together with yield adaptability (Ya), as the regression coefficient bi; Ya ranged from 0.71 for NT77 to 1.20 for NT19. Lines simply harboring the Nure variants at the two genes behaved as highest yielding (3.04 t ha-1), and showed the highest yield adaptability (bi=1.05). The present study constitutes a starting point towards the introduction of genomic variables in agronomic models for barley grain yield in Mediterranean environments

Mapping adaptation of barley to droughted environments

Identifying barley genomic regions influencing the response of yield and its components to water deficits will aid in our understanding of the genetics of drought tolerance and the development of more drought tolerant cultivars. We assembled a population of 192 genotypes that represented landraces, old, and contemporary cultivars sampling key regions around the Mediterranean basin and the rest of Europe. The population was genotyped with a stratified set of 50 genomic and EST derived molecular markers, 49 of which were Simple Sequence Repeats (SSRs), which revealed an underlying population sub-structure that corresponded closely to the geographic regions in which the genotypes were grown. A more dense whole genome scan was generated by using Diversity Array Technology (DArT®) to generate 1130 biallelic markers for the population. The population was grown at two contrasting sites in each of seven Mediterranean countries for harvest 2004 and 2005 and grain yield data collected. Mean yield levels ranged from 0.3 to 6.2 t/ha, with highly significant genetic variation in low-yielding environments. Associations of yield with barley genomic regions were then detected by combining the DArT marker data with the yield data in mixed model analyses for the individual trials, followed by multiple regression of yield on markers to identify a multi-locus subset of significant markers/QTLs. QTLs exhibiting a pre-defined consistency across environments were detected in bins 4, 6, 6 and 7 on barley chromosomes 3H, 4H, 5H and 7H respectivel

Analysis of sequence variability and transcriptional profile of cannabinoid synthase genes in cannabis sativa l. Chemotypes with a focus on cannabichromenic acid synthase

Cannabis sativa L. has been long cultivated for its narcotic potential due to the accumulation of tetrahydrocannabinolic acid (THCA) in female inflorescences, but nowadays its production for fiber, seeds, edible oil and bioactive compounds has spread throughout the world. However, some hemp varieties still accumulate traces of residual THCA close to the 0.20% limit set by European Union, despite the functional gene encoding for THCA synthase (THCAS) is lacking. Even if some hypotheses have been produced, studies are often in disagreement especially on the role of the cannabichromenic acid synthase (CBCAS). In this work a set of European Cannabis genotypes, representative of all chemotypes, were investigated from a chemical and molecular point of view. Highly specific primer pairs were developed to allow an accurate distinction of different cannabinoid synthases genes. In addition to their use as markers to detect the presence of CBCAS at genomic level, they allowed the analysis of transcriptional profiles in hemp or marijuana plants. While the high level of transcription of THCAS and cannabidiolic acid synthase (CBDAS) clearly reflects the chemical phenotype of the plants, the low but stable transcriptional level of CBCAS in all genotypes suggests that these genes are active and might contribute to the final amount of cannabinoids

Combined effect of cadmium and lead on durum wheat

Cadmium (Cd) and lead (Pb) are two toxic heavy metals (HMs) whose presence in soil is generally low. However, industrial and agricultural activities in recent years have significantly raised their levels, causing progressive accumulations in plant edible tissues, and stimulating research in this field. Studies on toxic metals are commonly focused on a single metal, but toxic metals occur simultaneously. The understanding of the mechanisms of interaction between HMs during uptake is important to design agronomic or genetic strategies to limit contamination of crops. To study the single and combined effect of Cd and Pb on durum wheat, a hydroponic experiment was established to examine the accumulation of the two HMs. Moreover, the molecular mechanisms activated in the roots were investigated paying attention to transcription factors (bHLH family), heavy metal transporters and genes involved in the biosynthesis of metal chelators (nicotianamine and mugineic acid). Cd and Pb are accumulated following different molecular strategies by durum wheat plants, even if the two metals interact with each other influencing their respective uptake and translocation. Finally, we demonstrated that some genes (bHLH 29, YSL2, ZIF1, ZIFL1, ZIFL2, NAS2 and NAAT) were induced in the durum wheat roots only in response to Cd

Genetic mapping of loci for resistance to stem rust in a tetraploid wheat collection

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a major biotic constraint to wheat production worldwide. Disease resistant cultivars are a sustainable means for the efficient control of this disease. To identify quantitative trait loci (QTLs) conferring resistance to stem rust at the seedling stage, an association mapping panel consisting of 230 tetraploid wheat accessions were evaluated for reaction to five Pgt races under greenhouse conditions. A high level of phenotypic variation was observed in the panel in response to all of the races, allowing for genome-wide association mapping of resistance QTLs in wild, landrace, and cultivated tetraploid wheats. Twenty-two resistance QTLs were identified, which were characterized by at least two marker-trait associations. Most of the identified resistance loci were coincident with previously identified rust resistance genes/QTLs; however, six regions detected on chromosomes 1B, 5A, 5B, 6B, and 7B may be novel. Availability of the reference genome sequence of wild emmer wheat accession Zavitan facilitated the search for candidate resistance genes in the regions where QTLs were identified, and many of them were annotated as NOD (nucleotide binding oligomerization domain)-like receptor (NLR) genes or genes related to broad spectrum resistance