Wild Beet Research Articles

Nutritional value and functional properties of an underexploited Tunisian wild beet (Beta macrocarpa Guss.) in relation to soil characteristics

The study centers on the valorization of Beta macrocarpa Guss., an endangered Mediterranean wild plant that grows in Tunisia. This plant is disappearing due to a reduction in marginal areas and a lack of awareness of this important crop wild relative (CWR). This prompted us to carry out work to assess the nutritional and functional value of its plant shoots in relation to physicochemical soil properties at three different Tunisian sites covering the north (Sijoumi), the center (Enfidha) and the south (Kerkennah) of the country. All soil samples showed an alkaline pH and high salinity. Sijoumi, Enfidha and Kerkennah soils were classified as loamy, silty clay loamy and sandy, respectively. Chemical analysis revealed that all soils, especially the sandy one, were low in total nitrogen, organic matter and microelements. Plant analysis showed that shoots harvested from the loamy soil presented the highest levels of carbohydrate (19.1 g/100 g FW) and fiber (6.1 g/100 g FW) and the greatest energetic value (94 kcal/100 g FW), whereas shoots collected from the sandy soil showed the highest contents of protein (4.1 g/100 g FW), ash (5.2 g/100 g FW), total polyphenols and flavonoids (39.01 mg GAE/g DW; 27.8 mg CE/g DW), and the greatest DPPH scavenging capacity (IC50 = 0.74 mg/ml). The results suggest that Beta macrocarpa, which naturally grows in poor and salt-affected soils, could play a crucial role in maintaining the biodiversity and sustainability of agro-ecosystems, particularly in marginal areas, and could also provide an alternative source of food with significant nutritional value and health benefits.Graphical abstract

Mitochondrial phylogeny and distribution of cytoplasmic male sterility-associated genes in Beta vulgaris.

Cytoplasmic male sterility (CMS) is a mitochondrial-encoded trait that confers reproductive defects in males but not in females or any vegetative function. Why CMS is so often found in plants should be investigated from the viewpoint of mitochondrial phylogeny. Beta vulgaris, including the wild subspecies maritima and cultivated subspecies vulgaris (e.g., sugar beet), is known to be mitochondrially polymorphic, from which multiple CMS mitochondria have been found, but their evolutionary relationship has been obscure. We first refined the B. vulgaris reference mitochondrial genome to conduct a more accurate phylogenetic study. We identified mitochondrial single-nucleotide polymorphic sites from 600 B. vulgaris accessions. Principal component analysis, hierarchical clustering analysis, and creation of a phylogenetic tree consistently suggested that B. vulgaris mitochondria can be classified into several groups whose geographical distribution tends to be biased toward either the Atlantic or Mediterranean coasts. We examined the distribution of CMS-associated mitochondrial genes from Owen, E- and G-type CMS mitochondria. About one-third of cultivated beets had Owen-type CMS, which reflects the prevalence of using Owen-type CMS in hybrid breeding. Occurrence frequencies for each of the three CMS genes in wild beet were less than 4%. CMS genes were tightly associated with specific mitochondrial groups that are phylogenetically distinct, suggesting their independent origin. However, homologous sequences of the Owen type CMS gene occurred in several different mitochondrial groups, for which an intricate explanation is necessary. Whereas the origin of cultivated beet had been presumed to be Greece, we found an absence of Owen-type mitochondria in Greek accessions.

Repeat turnover meets stable chromosomes: repetitive DNA sequences mark speciation and gene pool boundaries in sugar beet and wild beets.

Sugar beet and its wild relatives share a base chromosome number of nine and similar chromosome morphologies. Yet, interspecific breeding is impeded by chromosome and sequence divergence that is still not fully understood. Since repetitive DNAs are among the fastest evolving parts of the genome, we investigated, if repeatome innovations and losses are linked to chromosomal differentiation and speciation. We traced genome and chromosome-wide evolution across 13 beet species comprising all sections of the genera Beta and Patellifolia. For this, we combined short and long read sequencing, flow cytometry, and cytogenetics to build a comprehensive framework that spans the complete scale from DNA to chromosome to genome. Genome sizes and repeat profiles reflect the separation into three gene pools with contrasting evolutionary patterns. Among all repeats, satellite DNAs harbor most genomic variability, leading to fundamentally different centromere architectures, ranging from chromosomal uniformity in Beta and Patellifolia to the formation of patchwork chromosomes in Corollinae/Nanae. We show that repetitive DNAs are causal for the genome expansions and contractions across the beet genera, providing insights into the genomic underpinnings of beet speciation. Satellite DNAs in particular vary considerably between beet genomes, leading to the evolution of distinct chromosomal setups in the three gene pools, likely contributing to the barriers in beet breeding. Thus, with their isokaryotypic chromosome sets, beet genomes present an ideal system for studying the link between repeats, genomic variability, and chromosomal differentiation and provide a theoretical fundament for understanding barriers in any crop breeding effort.

Genomic variation in the genus Beta based on 656 sequenced beet genomes

Cultivated beets (Beta vulgaris ssp. vulgaris) constitute important crop plants, in particular sugar beet as an indispensable source of sucrose. Several species of wild beets of the genus Beta with distribution along the European Atlantic coast, Macaronesia, and throughout the Mediterranean area exist. Thorough characterization of beet genomes is required for straightforward access to genes promoting genetic resistance against biotic and abiotic stress. Analysing short-read data of 656 sequenced beet genomes, we identified 10 million variant positions in comparison to the sugar beet reference genome RefBeet-1.2. The main groups of species and subspecies were distinguishable based on shared variation, and the separation of sea beets (Beta vulgaris ssp. maritima) into a Mediterranean and an Atlantic subgroup as suggested by previous studies could be confirmed. Complementary approaches of variant-based clustering were employed based on PCA, genotype likelihoods, tree calculations, and admixture analysis. Outliers suggested the occurrence of inter(sub)specific hybridisation, independently confirmed by different analyses. Screens for regions under artificial selection in the sugar beet genome identified 15 Mbp of the genome as variation-poor, enriched for genes involved in shoot system development, stress response, and carbohydrate metabolism. The resources presented herein will be valuable for crop improvement and wild species monitoring and conservation efforts, and for studies on beet genealogy, population structure and population dynamics. Our study provides a wealth of data for in-depth analyses of further aspects of the beet genome towards a thorough understanding of the biology of this important complex of a crop species and its wild relatives.

A study on the adaptive potential of new sterile cytoplasm of Beta patula and Beta maritima L. from wild beets of the genus Beta L.: cold resistance and traits of early sugar accumulation in introduced alloplasmic lines

Purpose. Assessment of new sugar beet breeding genotypes by a set of economically valuable traits to determine their suitability for the efficiency of the process of managing the production of bioethanol with the study of the activity of photosynthesis according to the content of chlorophylls a and b, early accumulation of carbohydrates, tolerance to low temperatures, germination of apozygous seeds and using new plasma of the substituted lines of sugar beet with introduced sterile cytoplasms from wild species Beta patula and B. maritima L. and apozygous lines A9 with S vulgaris Owen's cytoplasm. Methods. Field methods were used (pollen-free regime for the reproduction of apozygotic seeds in conditions of isolation and seed monogermity of the seed plants), laboratory methods (selection of the best experimental genotypes for cold resistance, analysis of productivity and dynamics of carbohydrate accumulation). Results. Self-fertile pollen-sterile lines A9 Beta vulgaris Sxxzz rr with an apomictic method of seed reproduction of seeds (Yaltushkiv EBS) and commercial hybrids with early carbohydrate accumulation were selected for the recessive colour of the hypocotyl r-r- and gametophytic reduced parthenogenesis for hybridization according to the scheme: A9 Beta vulgaris Sxxzz rr × Beta vulgaris Mm Rr. The influence of cytoplasmic inheritance of B. maritima and B. patula on cold resistance indicators was studied and seed samples of the experimental genotypes No. 17225, 17221, 17222, 17220, 17226, 17223 were selected among substituted lines with seed germination rates at +4°C varying from 14.3 to 40.3%. Experimental genotypes of the substituted lines, grown in the conditions of pots were selected and examined by the indicators of early accumulation of sugars, which had values from 16.2 to 17.6% during four months of vegetation; photosynthetic activity with indicators of the content of chlorophyll varying from 2.06 to 1.32%, and chlorophyll b from 1.02 to 0.65%. Conclusions. Sugar beet hybrids, created with the use of cold-resistant substituted pollen-sterile lines of sugar beet, thanks to the natural evolution of the introduced cytoplasmic genome, ensure the extension of the growing season, high productivity, early accumulation of sugars and enrichment of the crop adaptation potential. The article contains the results of the study of the early carbohydrate accumulation, photosynthetic activity of selected experimental genotypes of the substituted sugar beet lines with high seed quality and 100% monogermity. Root crops of apomictic lines were selected based on R+r hypocotyl colour, generative reduced parthenogenesis, and studied for their specifics of seed set under the pollen-free regime.

Distribution of Biodiversity of Wild Beet Species (Genus Beta L.) in Armenia under Ongoing Climate Change Conditions.

The reported annual temperature increase and significant precipitation drop in Armenia impact the country’s ecosystems and biodiversity. The present study surveyed the geographical distribution of the local wild beet species under the ongoing climate change conditions. We showed that B. lomatogona, B. corolliflora and B. macrorhiza are sensitive to climate change and were affected to various degrees, depending on their location. The most affected species was B. lomatogona, which is at the verge of extinction. Migration for ca. 90 and 200–300 m up the mountain belt was recorded for B. lomatogona and B. macrorhiza, respectively. B. corolliflora was found at 100–150 m lower altitudes than in the 1980s. A general reduction in the beet’s population size in the native habitats was observed, with an increased number of plants within the populations, recorded for B. corolliflora and B. macrorhiza. A new natural hybrid Beta x intermedium Aloyan between B. corolliflora and B. macrorhiza was described and confirmed using chloroplast DNA trnL-trnF intergenic spacer (LF) and partially sequenced alcohol dehydrogenase (adh) of nuclear DNA. An overview of the wild beets reported in Armenia with the taxonomic background, morphological features, and distribution is provided. Conservation measures for preservation of these genetic resources are presented.

Genomic distances reveal relationships of wild and cultivated beets

Cultivated beets (Beta vulgaris ssp. vulgaris), including sugar beet, rank among the most important crops. The wild ancestor of beet crops is the sea beet Beta vulgaris ssp. maritima. Species and subspecies of wild beets are readily crossable with cultivated beets and are thus available for crop improvement. To study genomic relationships in the genus Beta, we sequence and analyse 606 beet genomes, encompassing sugar beet, sea beet, B. v. adanensis, B. macrocarpa, and B. patula. We observe two genetically distinct groups of sea beets, one from the Atlantic coast and the other from the Mediterranean area. Genomic comparisons based on k-mers identify sea beets from Greece as the closest wild relatives of sugar beet, suggesting that domestication of the ancestors of sugar beet may be traced to this area. Our work provides comprehensive insight into the phylogeny of wild and cultivated beets and establishes a framework for classification of further accessions of unknown (sub-)species assignment.

Complete pan-plastome sequences enable high resolution phylogenetic classification of sugar beet and closely related crop wild relatives

BackgroundAs the major source of sugar in moderate climates, sugar-producing beets (Beta vulgaris subsp. vulgaris) have a high economic value. However, the low genetic diversity within cultivated beets requires introduction of new traits, for example to increase their tolerance and resistance attributes – traits that often reside in the crop wild relatives. For this, genetic information of wild beet relatives and their phylogenetic placements to each other are crucial. To answer this need, we sequenced and assembled the complete plastome sequences from a broad species spectrum across the beet genera Beta and Patellifolia, both embedded in the Betoideae (order Caryophyllales). This pan-plastome dataset was then used to determine the wild beet phylogeny in high-resolution.ResultsWe sequenced the plastomes of 18 closely related accessions representing 11 species of the Betoideae subfamily and provided high-quality plastome assemblies which represent an important resource for further studies of beet wild relatives and the diverse plant order Caryophyllales. Their assembly sizes range from 149,723 bp (Beta vulgaris subsp. vulgaris) to 152,816 bp (Beta nana), with most variability in the intergenic sequences. Combining plastome-derived phylogenies with read-based treatments based on mitochondrial information, we were able to suggest a unified and highly confident phylogenetic placement of the investigated Betoideae species.Our results show that the genus Beta can be divided into the two clearly separated sections Beta and Corollinae. Our analysis confirms the affiliation of B. nana with the other Corollinae species, and we argue against a separate placement in the Nanae section. Within the Patellifolia genus, the two diploid species Patellifolia procumbens and Patellifolia webbiana are, regarding the plastome sequences, genetically more similar to each other than to the tetraploid Patellifolia patellaris. Nevertheless, all three Patellifolia species are clearly separated.ConclusionIn conclusion, our wild beet plastome assemblies represent a new resource to understand the molecular base of the beet germplasm. Despite large differences on the phenotypic level, our pan-plastome dataset is highly conserved. For the first time in beets, our whole plastome sequences overcome the low sequence variation in individual genes and provide the molecular backbone for highly resolved beet phylogenomics. Hence, our plastome sequencing strategy can also guide genomic approaches to unravel other closely related taxa.

An Insight into the Abiotic Stress Responses of Cultivated Beets (Beta vulgaris L.).

Cultivated beets (sugar beets, fodder beets, leaf beets, and garden beets) belonging to the species Beta vulgaris L. are important sources for many products such as sugar, bioethanol, animal feed, human nutrition, pulp residue, pectin extract, and molasses. Beta maritima L. (sea beet or wild beet) is a halophytic wild ancestor of all cultivated beets. With a requirement of less water and having shorter growth period than sugarcane, cultivated beets are preferentially spreading from temperate regions to subtropical countries. The beet cultivars display tolerance to several abiotic stresses such as salt, drought, cold, heat, and heavy metals. However, many environmental factors adversely influence growth, yield, and quality of beets. Hence, selection of stress-tolerant beet varieties and knowledge on the response mechanisms of beet cultivars to different abiotic stress factors are most required. The present review discusses morpho-physiological, biochemical, and molecular responses of cultivated beets (B. vulgaris L.) to different abiotic stresses including alkaline, cold, heat, heavy metals, and UV radiation. Additionally, we describe the beet genes reported for their involvement in response to these stress conditions.

Salt and Drought Stress Responses in Cultivated Beets (Beta vulgaris L.) and Wild Beet (Beta maritima L.).

Cultivated beets, including leaf beets, garden beets, fodder beets, and sugar beets, which belong to the species Beta vulgaris L., are economically important edible crops that have been originated from a halophytic wild ancestor, Beta maritima L. (sea beet or wild beet). Salt and drought are major abiotic stresses, which limit crop growth and production and have been most studied in beets compared to other environmental stresses. Characteristically, beets are salt- and drought-tolerant crops; however, prolonged and persistent exposure to salt and drought stress results in a significant drop in beet productivity and yield. Hence, to harness the best benefits of beet cultivation, knowledge of stress-coping strategies, and stress-tolerant beet varieties, are prerequisites. In the current review, we have summarized morpho-physiological, biochemical, and molecular responses of sugar beet, fodder beet, red beet, chard (B. vulgaris L.), and their ancestor, wild beet (B. maritima L.) under salt and drought stresses. We have also described the beet genes and noncoding RNAs previously reported for their roles in salt and drought response/tolerance. The plant biologists and breeders can potentiate the utilization of these resources as prospective targets for developing crops with abiotic stress tolerance.

Studying of the acid chitinase SE2 gene in sugar beet genotypes

Aim of the work was specific primers (FusA1F/FusA1R) testing to study the SE2 gene controlling acid chitinase effect under stress conditions. Plants of domestic and foreign sugar beet were the material for the investigation. To confirm relationship between the SE2 gene (localized to the chromosome 3) controlling steady effect of acid chitinase and sugar beet resistance to root rot, 10 sugar beet samples were genotyped using the FusA1 molecular marker. DNA-fragments of 600 and 400 b.p.in length were revealed in each of the investigated genotypes except plants of wild beet ( Beta corolliflora Zoss .). As a result of molecular-genetic studies of the SE2 gene, eight single nucleotide polymorphism (3 T/C, 2 C/G, A/G, G/A, C/T) and 3 single nucleotide inserts (nucleotide A) were identified in plants of the breeding sample No. 9 (Sh.1). Plants of this genotype showed symptoms of fusariose infection under field conditions as well. It can be concluded that the SNPs data lead to overcoming of resistance (by changing an amino-acid unit in a polypeptide), and, as consequence, to decrease of plant adaptability.

Nuclear and mitochondrial DNA polymorphisms suggest introgression contributed to garden beet (Beta vulgaris L.) domestication

Garden beet is the ancestor of fodder beets and sugar beets, but the origin of garden beet’s genetic potential to evolve novel beet types is debatable. In this study, we analyzed nuclear and mitochondrial DNAs in 47 garden beet accessions using DNA markers. Multiple analytical methods revealed a unified population structure with subpopulations evident in the European and Caucasian accessions. We diagnosed mitochondrial genome types (mitotypes) based on mitochondrial minisatellite loci in 541 plants from the 47 accessions, revealing a major mitotype and 11 minor mitotypes in garden beets from Europe and the Caucasus region that were also present in endemic leaf beets and wild beets. Our data indicate that European and Caucasian garden beets include genetically differentiated subpopulations. Provided that the occurrence of minor mitotypes is a vestige from crosses with leaf beets and wild beets, the notion that introgression contributed to increasing the genetic diversity in the garden beet gene pool is substantiated at the molecular level.

Assembly and characterization of the genome of chard (Beta vulgaris ssp. vulgaris var. cicla)

Chard (Beta vulgaris ssp. vulgaris var. cicla) is a member of one of four different cultigroups of beets. While the genome of sugar beet, the most prominent beet crop, has been studied extensively, molecular data on other beet cultivars is scant. Here, we present a genome assembly of chard, a vegetable crop grown for its fleshy leaves. We report a de novo genome assembly of 604 Mbp, slightly larger than sugar beet assemblies presented so far. About 57 % of the assembly was annotated as repetitive sequence, of which LTR retrotransposons were the most abundant. Based on the presence of conserved genes, the chard assembly was estimated to be at least 96 % complete regarding its gene space. We predicted 34,521 genes of which 27,582 genes were supported by evidence from transcriptomic sequencing reads, and 5503 of the evidence-supported genes had multiple isoforms. We compared the chard gene set with gene sets from sugar beet and two wild beets (i.e. Beta vulgaris ssp. maritima and Beta patula) to find orthology relationships and identified genome-wide syntenic regions between chard and sugar beet. Lastly, we determined genomic variants that distinguish sugar beet and chard. Assessing the variation distribution along the chard chromosomes, we found extensive haplotype sharing between the two cultivars. In summary, our work provides a foundation for the molecular analysis of Beta vulgaris cultigroups as a basis for chard genomics and to unravel the domestication history of beet crops.

Assessment of interspecific hybridization between wild beet Beta vulgaris L. subsp. maritima and cultivated sugar beet under Moroccan conditions

Obtaining a viable and fertile beet hybrid resulting from wild and cultivated sugar beet crosses under Moroccan conditions is challenging. To deal with hybridization, barriers in sugar beet, such as concordance of flowering period between biannual and annual subspecies, flowering aptitude according to vernalization requirement, genotype incompatibility and hybrid sterility, should be overcome. In our study, interspecific hybrids were obtained from crosses between 17 cultivated sugar beet Beta vulgaris subsp. vulgaris and 17 Beta vulgaris subsp. maritima, collected in different regions of Morocco. Twenty-two agro-morphological traits were used for the evaluation of 208 hybrid plants, under greenhouse conditions. CH and WH hybrids were collected on cultivated and wild parents separately. Most of the hybrids behaved as annual plants, of which 83.17% were able to flower and produce seeds without any vernalization requirements. All WH hybrids and 57.06% of CH hybrids were morphologically similar to their wild parent. However, 24% of CH hybrids were phenotypically similar to their cultivated parent. The remaining CH hybrid plants were behaving as intermediate genotypes between both wild and cultivated parents. Our results showed the success of interspecific beet crosses and emphasized the high variability among hybrid genotypes. This is of great importance for sugar beet improvement and breeding programs and interspecific crosses patterns understanding.

Betacyanins and Betaxanthins in Cultivated Varieties of Beta vulgaris L. Compared to Weed Beets.

There are 11 different varieties of Beta vulgaris L. that are used in the food industry, including sugar beets, beetroots, Swiss chard, and fodder beets. The typical red coloration of their tissues is caused by the indole-derived glycosides known as betalains that were analyzed in hypocotyl extracts by UV/Vis spectrophotometry to determine the content of betacyanins (betanin) and of betaxanthins (vulgaxanthin I) as constituents of the total betalain content. Fields of beet crops use to be also infested by wild beets, hybrids related to B. vulgaris subsp. maritima or B. macrocarpa Guss., which significantly decrease the quality and quantity of sugar beet yield; additionally, these plants produce betalains at an early stage. All tested B. vulgaris varieties could be distinguished from weed beets according to betacyanins, betaxanthins or total betalain content. The highest values of betacyanins were found in beetroots ‘Monorubra’ (9.69 mg/100 mL) and ‘Libero’ (8.42 mg/100 mL). Other beet varieties contained less betacyanins: Sugar beet ‘Labonita’ 0.11 mg/100 mL; Swiss chard ‘Lucullus,’ 0.09 mg/100 mL; fodder beet ‘Monro’ 0.15 mg/100 mL. In contrast with weed beets and beetroots, these varieties have a ratio of betacyanins to betaxanthins under 1.0, but the betaxanthin content was higher in beetcrops than in wild beet and can be used as an alternative to non-red varieties. Stability tests of selected varieties showed that storage at 22 °C for 6 h, or at 7 °C for 24 h, did not significantly reduce the betalain content in the samples.

Fodder beet is a reservoir of drought tolerance alleles for sugar beet breeding

Drought leads to serious yield losses and followed by increasing food prices. Thereby, drought tolerance is one of most important, pivotal issues for plant breeding and is determined by the very complex genetic architecture, which involves a lot of genes engaged in many cell processes. Within genomes of currently cultivated sugar beet forms, the number of favourable allelic variants is limited. However, there is a potential to identify genes related to drought tolerance deposited in genomes of wild or fodder relatives. Therefore, the goal of our study, was to identify the source of allelic variants involved in drought tolerance using a large spectrum of sugar or fodder beets and their wild relatives for analyses. Based on the drought tolerance index, calculated for morphophysiological traits, it was demonstrated that some of selected fodder beets showed the highest level of drought tolerance. The most drought tolerant fodder beet genotype did not show differences in the level of expression of genes engaged in osmoprotection and the antioxidative system, between control and drought condition, compared to sugar and wild beets. The genetic distance between selected beet forms was broad and ranged from 18 to 87%, however the most drought tolerant sugar, fodder and wild beets showed high genetic similarity and formed the common clade. Based on obtained results we propose that an adequate broad source of genes related to drought tolerance occurs in fodder beets, the crossing with which is easier, less time-consuming and more cost-effective than with wild forms of beets.

Genomes of the wild beets Beta patula and Beta vulgaris ssp. maritima.

SummaryWe present draft genome assemblies of Beta patula, a critically endangered wild beet endemic to the Madeira archipelago, and of the closely related Beta vulgaris ssp. maritima (sea beet). Evidence‐based reference gene sets for B. patula and sea beet were generated, consisting of 25 127 and 27 662 genes, respectively. The genomes and gene sets of the two wild beets were compared with their cultivated sister taxon B. vulgaris ssp. vulgaris (sugar beet). Large syntenic regions were identified, and a display tool for automatic genome‐wide synteny image generation was developed. Phylogenetic analysis based on 9861 genes showing 1:1:1 orthology supported the close relationship of B. patula to sea beet and sugar beet. A comparative analysis of the Rz2 locus, responsible for rhizomania resistance, suggested that the sequenced B. patula accession was rhizomania susceptible. Reference karyotypes for the two wild beets were established, and genomic rearrangements were detected. We consider our data as highly valuable and comprehensive resources for wild beet studies, B. patula conservation management, and sugar beet breeding research.

Efficacy of Certain Tribenuron-Methyl Formulations for the Control of Broad-Leaved Weeds in Wheat under Field Conditions

Two field experiments were conducted during 2017-2018 and 2018-2019 seasons to evaluate the effect of eight tribenuron-methyl formulations (four as WG 75% and four as DF 75%) beside hand weeding (twice at 21 and 42 DAS) on broad-leaved weeds (BLWs) in wheat under field conditions. All the agricultural practices were carried out uniformly as recommended. All treatments were arranged in randomized complete block design and replicated four times each of 42 m2 (6×7 m). All formulations were applied at the rate of 8.0 gm fed.-1 in 200 L. water fed.-1 by Knapsack sprayer (CP3) at 30 days after sowing (DAS). After two months from sowing (2MAS) (one month after treatment, one MAT), weeds were collected from an area of 2m2 which was randomly selected from each plot (by using a square woody frame, 50 cm×50 cm). The removed annual BLWs were identified and counted for density as number m-2 and biomass [fresh weight gm m-2] in all treatments. In the untreated control, biomass, biomass%, density and density% for each BLW were recorded. The common prevailed annual BLWs in the experimental wheat field during both seasons were annual Sowthistle (Sonchus oleraceus L.), cheese weed, little mallow (Malva parviflora L.), chicory (Cichorium pumpilum Jacq.), dentated dock (Rumex dentatus L.), medic (Medicago intertexta (L.) Mill.), scarlet pimpernel (Anagallis arvensis L.), sea beet, wild beet (Beta vulgaris L.) and sweet clover, Indian melilot (Melilotus indica L.). The results clearly indicated that biomass and density were varied according to the dominant weed species and from season to another. The BLWs were the most dominant and also they were common in wheat fields and the biomass and density of BLWs were varied between years and weeds. The herbicidal treatments gave the minimum weed biomass and density and gave good weed control efficiency (WCE %) than hand weeding treatments. Granstar formulation completely controlled C. pumpilum weed (in the first season), A. arvensis, R. dentatus and S. oleraceus weeds (in the second season). Skylla formulation completely controlled M. parviflora and R. dentatus weeds in the first season. The tested tribenuron-methyl formulations did not cause complete control for B. vulgaris, M. intertexta and M. indica weeds in both seasons. In all cases, the herbicidal treatments increased significantly the biological yield, grain yield, straw yield, harvest index and thousand grain weight in comparison with untreated control. Also, Granstar, Skylla and Cash Cool herbicides were the most effective, while Ownostar was the least effective. We can concluded that, Granstar, Skylla and Cash Cool formulations are the most effective in controlling broad-leaved weeds in wheat field and consequently increased the grain yield.

GENOTYPIC VARIATIONS IN SALT TOLERANCE OF SOME EGYPTIAN WILD BEET ACCESSIONS

This study reports for the first time the eco-physiological responses of some Egyptian wild beet accessions (WB1013, WB1021 and WB1026) under saline irrigation. The plants were exposed to five seawater salinities (0, 20, 30, 40 and 60% sws) for 6 weeks in a sandy culture in the greenhouse. Low salinity (20% sws) slightly enhanced the plant fresh weight of both WB1013 and WB1021 genotypes by 5% and 3% respectively, but significantly reduced that of WB1026 genotype by about 10%. Higher seawater salinities, however, caused progressive growth reductions in all accessions, with maximum growth inhibition, being 59% in WB1026 at 60% sws. Tolerance threshold was lowest (being at 20% sws) for WB1026, but highest (reached 40% sws) for both genotypes WB1013 and WB1021. EC50 was at salinity level of 40 – 60% sws for WB1026 genotype, but higher than 60% sws for genotypes WB1013 and WB1021. These indicate that both accessions WB1013 and WB1021 are more salt-tolerant when compared with WB1026. The higher salt tolerance of WB1013 and WB1021 accessions is largely conferred by higher leaf K+/Na+ ratio, due to low Na+ and Cl- accumulation under saline conditions compared to WB1026. This was associated with lower dry weights and ion leakage, and with higher leaf area, chlorophyll readings, total soluble carbohydrates and Ca2+ concentrations when compared with WB1026. Both WB1013 and WB1021 accessions do not only offer the possibility of being an alternative promising cash crops under seawater irrigation, but also, through an understanding of its physiology, may provide possible routes to enhance salt tolerance in other beet crops.

Predicting genotype environmental range from genome-environment associations.

Genome-environment association methods aim to detect genetic markers associated with environmental variables. The detected associations are usually analysed separately to identify the genomic regions involved in local adaptation. However, a recent study suggests that single-locus associations can be combined and used in a predictive way to estimate environmental variables for new individuals on the basis of their genotypes. Here, we introduce an original approach to predict the environmental range (values and upper and lower limits) of species genotypes from the genetic markers significantly associated with those environmental variables in an independent set of individuals. We illustrate this approach to predict aridity in a database constituted of 950 individuals of wild beets and 299 individuals of cultivated beets genotyped at 14,409 random single nucleotide polymorphisms (SNPs). We detected 66 alleles associated with aridity and used them to calculate the fraction (I) of aridity-associated alleles in each individual. The fraction I correctly predicted the values of aridity in an independent validation set of wild individuals and was then used to predict aridity in the 299 cultivated individuals. Wild individuals had higher median values and a wider range of values of aridity than the cultivated individuals, suggesting that wild individuals have higher ability to resist to stress-aridity conditions and could be used to improve the resistance of cultivated varieties to aridity.