Coleoptile Length Research Articles

Identification of QTLs associated with the anaerobic germination potential using a set of Oryza nivara introgression lines

Rice (Oryza sativa L.) is an important crop and a staple food for half of the population around the world. The recent water and labor shortages are encouraging farmers to shift from traditional transplanting to direct-seeding. However, poor germination and slow elongation of the coleoptile constrains large-scale application of direct-seeding. This study was aimed to investigate the genetic basis of the anaerobic germination (AG) potential using a set of Oryza nivara (O. nivara) introgression lines (ILs). In this study, a total of 131 ILs were developed by introducing O. nivara chromosome segments into the elite indica rice variety 93-11 through advanced backcrossing and repeated selfing. A high-density genetic map has been previously constructed with 1,070 bin-markers. The seeds of ILs were germinated and used to measure coleoptile length under normal and anaerobic conditions. QTLs associated with AG potential were determined in rice. Based on the high-density genetic map of the IL population, two QTLs, qAGP1 and qAGP3 associated with AG tolerance were characterized and located on chromosomes 1 and 3, respectively. Each QTL explained 15% of the phenotypic variance. Specifically, the O. nivara-derived chromosome segments of the two QTLs were positively tolerance to anaerobic condition by increasing coleoptile length. In a further analysis of public transcriptome data, a total of 26 and 36 genes within qAGP1 and qAGP3 were transcriptionally induced by anaerobic stress, respectively. Utilization of O. nivara-derived alleles at qAGP1 and qAGP3 can potentially enhance tolerance to anaerobic stress at the germination stage in rice, thereby accelerating breeding of rice varieties to be more adaptative for direct-seeding.

QTL mapping using GBS and SSR genotyping reveals genomic regions controlling wheat coleoptile length and seedling emergence

Seedling emergence (SE) is an essential trait in wheat (Triticum aestivum L.) that allows desirable stand establishment even when adequate seed-zone soil moisture is present at depths of 10 cm or greater. The SE trait bestows several other advantages, including lodging resistance and improved water use efficiency. The aim of this study was to understand the genetic basis of SE. It has previously been reported that the cultivar Spinkcota has a high rate of SE and Bounty 309 has a slow rate of SE. An F2 population of 190 plants from a cross between these two parents was developed and evaluated for coleoptile length (CL) and in a specialized field SE test. The population was genotyped by simple sequence repeat (SSR) and genotyping-by-sequencing (GBS) for genetic mapping and marker discovery of the two traits. The GBS analysis was performed using 128,848,348 sequence reads with an average of 671,085 per F2 plant. From a total of 2,639 raw SNPs discovered in the F2 population, 243 high-quality SNPs along with 68 SSR markers were utilized to construct a genetic linkage map of wheat spanning 5,532.9 cM on the 21 chromosomes. Using this map, eight QTLs linked to CL and SE were detected on chromosomes 1A, 1B, 2B, 3A, and 7D. Bioinformatic dissection of the intervals under these QTLs on the wheat whole-genome sequence led to the identification of ~ 60 genes. Validated markers may enhance the understanding of this critical trait and provide a basis for marker-assisted selection.

Identification and molecular characterization of novel Rht‐1 alleles in hard red spring wheat

AbstractThe introduction of the semidwarfing alleles, Rht‐B1b and Rht‐D1b, into wheat (Triticum aestivum L.) varieties significantly increased wheat yields beginning in the 1960s. Despite their agronomic advantage, Rht‐B1b and Rht‐D1b are also associated with decreased grain protein content and decreased coleoptile length. Furthermore, there is limited allelic diversity available to wheat breeders beyond Rht‐B1b and Rht‐D1b. We identified 16 ethyl methanesulfonate (EMS)‐induced Rht‐1 alleles, including a nonsense mutation in each Rht‐1 gene: Rht‐A‐Q555stop, Rht‐B‐Q420stop, and Rht‐D‐W559stop. We focused our attention for this study on stop alleles since the Rht‐B1b and Rht‐D1b alleles also contain premature stop codons. We evaluated the new nonsense alleles by measuring their impact on coleoptile length, gibberellic acid (GA) sensitivity, and DELLA/GID1 interaction. Rht‐A‐Q555stop reduced coleoptile length 16% compared with Rht‐1a (wild type) and repressed coleoptile GA perception similarly to Rht‐B1b and Rht‐D1b. Rht‐B‐Q420stop and Rht‐D‐W559stop did not affect coleoptile length. However, Rht‐B‐Q420stop reduced the ability of germinating seeds to perceive GA, but not as much as Rht‐A555stop, Rht‐B1b, or Rht‐D1b. We also tested whether the novel mutations affected the interaction between DELLA/GID1 in the presence and absence of GA. We found that Rht‐A‐Q555stop, Rht‐B‐Q420stop, and Rht‐D‐W559stop inhibited DELLA/GID1 interaction in the absence of GA, but the interaction was restored in the presence of GA. The identification of Rht‐A‐Q555stop, Rht‐B‐Q420stop, and Rht‐D‐W559stop increases the allelic diversity of Rht‐1. This study also indicates that the RHT carboxyl terminus is important for DELLA/GID1 interactions.

Characterizing reduced height wheat mutants for traits affecting abiotic stress and photosynthesis during seedling growth.

Most high-yielding, semidwarf wheat (Triticum aestivum L.) grown around the world contains either Rht1 or Rht2 genes. The success of these high-yielding cultivars is greatest in the most productive farming environments but provide marginal benefits in less favorable growing conditions such as shallow soils and low-precipitation dryland farming. Further, growing evidence suggests semidwarf genes not only affect early seedling growth but limit grain yield, especially under abiotic stress conditions. There are 23 other reduced-height mutants reported in wheat, most of which have not been functionally characterized. We evaluated these mutants along with their parents for several traits affecting seedling emergence, early seedling growth, and photosynthetic efficiency. Two- to seven-fold differences in coleoptile length, first leaf length, root length, and root angle were observed among the genotypes. Most of the mutations had a positive effect on root length, while the root angle narrowed. Coleoptile and first leaf lengths were strongly correlated with emergence. A specialized deep planting experiment identified Rht5, Rht6, Rht8, and Rht13 with significantly improved seedling emergence compared to the parent. Among the mutants, Rht4, Rht19, and Rht12 ranked highest for photosynthetic traits while Rht9, Rht16, and Rht15 performed best for early seedling growth parameters. Considering all traits collectively, Rht15 showed the most promise for utilization in marginal environments followed by Rht19 and Rht16. These wheat mutants may be useful for deciphering the underlying molecular mechanisms of understudied traits and breeding programs in arid and semiarid regions where deep planting is practiced.

Assessment of the growth of floating rice lines and resistant to salinity at the seed germination and seedling growth stage

The growth of 11 floating rice lines had already been a selection when affected by salinity stress. The method demonstrates that the amount of NaCl (0, 1, 3, 5 g/l) was irrigated into lines in a plastic round box after seeds were been nurseries on 2 days, where the growth of lines was affected by salt stress during seedling growth and germination. The study illustrated that the stress caused by salinity causes a decrease in all currents development as the salinity level increases between the growth of the currents, the coleoptile length, the number of roots, root length, fresh and dry weights varied downward trends more than 50% and germination percentage created from 96.30% to 92.55%, from zero to 5 g/l NaCl at the seed germination stage. This stage, it is apparent that the CQS28 line was the best coleoptile length (4.21 cm), the number of roots (3.72 roots), root length (12.88 cm), fresh weight (0.92 g/10 seedlings), dry weight (0.13 g/10 seedlings) and germination percentage (98.50%) overall and the CQS44 line was the lowest. These did not change when the effect of saline stress on the growth of lines in both the period was good CQS28 and less CQS44.

Dynamic genome-wide association analysis and identification of candidate genes involved in anaerobic germination tolerance in rice

BackgroundIn Asian rice production, an increasing number of countries now choose the direct seeding mode because of rising costs, labour shortages and water shortages. The ability of rice seeds to undergo anaerobic germination (AG) plays an important role in the success of direct seeding.ResultsIn this study, we used 2,123,725 single nucleotide polymorphism (SNP) markers based on resequencing to conduct a dynamic genome-wide association study (GWAS) of coleoptile length (CL) and coleoptile diameter (CD) in 209 natural rice populations. A total of 26 SNP loci were detected in these two phenotypes, of which 5 overlapped with previously reported loci (S1_ 39674301, S6_ 20797781, S7_ 18722403, S8_ 9946213, S11_ 19165397), and two sites were detected repeatedly at different time points (S3_ 24689629 and S5_ 27918754). We suggest that these 7 loci (−log10 (P) value > 7.3271) are the key sites that affect AG tolerance. To screen the candidate genes more effectively, we sequenced the transcriptome of the flooding-tolerant variety R151 in six key stages, including anaerobic (AN) and the oxygen conversion point (AN-A), and obtained high-quality differential expression profiles. Four reliable candidate genes were identified: Os01g0911700 (OsVP1), Os05g0560900 (OsGA2ox8), Os05g0562200 (OsDi19–1) and Os06g0548200. Then qRT-PCR and LC-MS/ MS targeting metabolite detection technology were used to further verify that the up-regulated expression of these four candidate genes was closely related to AG.ConclusionThe four novel candidate genes were associated with gibberellin (GA) and abscisic acid (ABA) regulation and cell wall metabolism under oxygen-deficiency conditions and promoted coleoptile elongation while avoiding adverse effects, allowing the coleoptile to obtain oxygen, escape the low-oxygen environment and germinate rapidly. The results of this study improve our understanding of the genetic basis of AG in rice seeds, which is conducive to the selection of flooding-tolerant varieties suitable for direct seeding.

Challenges of breeding for longer coleoptile in bread wheat (Triticum aestivum L.)

Bread wheat cultivars with longer coleoptile are desired for cultivation in drought prone environments where moisture is available in the deeper layers of the soil. Although there exist several studies about coleoptile length, its relations with important agronomic traits are not clear. In the present research, a diallel mating was generated of seven Iranian and overseas wheat cultivars to evaluate coleoptile length, yield and yield related traits during 2 years, and assess relationships between coleoptile length and important agronomic traits. Roshan, Iranian landrace containing Rht8, had the longest coleoptile length (8.81 cm). High narrow sense heritability (0.53 and 0.66 in 2016 and 2017, respectively) of coleoptile length indicated strong additive genetic control of this trait. Selection for longer coleoptile indirectly increased plant height (r = 0.75**), biological yield (r = 0.56**), fertile tiller numbers (r = 0.37*), days to flowering (r = 0.57**) and awn length (r = − 0.64**). Except for days to flowering and awn length, these indirect responses are appropriate in drought stress condition. Coleoptile length of gibberellic acid sensitive cultivars possessing Rht8 and Rht13 were 42% longer than gibberellic acid insensitive cultivars containing Rht1 and Rht2.

Seedling elongation responses to gibberellin seed treatments in wheat

AbstractThe wheat (Triticum aestivum L.) Reduced height (Rht) alleles are widely used to prevent lodging through semi‐dwarfism. Seedling elongation and coleoptile length can be significantly decreased by some of these alleles, leading to reduced soil emergence after deep sowing in certain semi‐arid environments. Application of the elongation‐promoting hormone gibberellin A3 (GA3) as a seed treatment has been used as an alternative to improve seedling emergence. Seedling responses to GA3 seed treatment were investigated under controlled conditions in a collection of varieties differing for Rht dwarfing alleles and the ability to emerge from deep planting. Data between treated and untreated seed were collected on overall coleoptile length and emergence from deep planting in simulated pot studies. Gibberellin‐sensitive varieties, carrying either no dwarfing gene or the Rht8 dwarfing gene, responded to the GA3 seed treatment with increased coleoptile and subcrown internode elongation. Comparison of near‐isogenic lines carrying no dwarfing allele or the GA‐insensitive Rht‐B1b and/or Rht‐D1b semi‐dwarfing alleles showed that GA insensitivity was associated with reduced seedling response to GA3 seed treatment. However, there was variation in seedling elongation and GA3 response in a collection of GA‐insensitive varieties. Thus, it cannot be assumed that all Rht‐B1b and Rht‐D1b varieties will fail to respond to GA3 seed treatment. Interestingly, some better emerging GA‐insensitive varieties had longer coleoptiles after treatment, suggesting that selection for better emergence in semi‐arid regions of the U.S. Pacific Northwest may have led to responses in GA3 application independent of the dwarfing gene used.

Assessing the effect of antimycin A on morphophysiological parameters in Triticum aestivum L. exposed to high temperature

The present study was conducted to investigate the evaluation of antimycin A (AA) as a modulator of the alternative respiratory pathway (AP) on the intensity of growth processes and some physiological parameters of etiolated wheat seedlings, such as maximum length of root, length of first leaf and coleoptile, fresh and dry weights at the whole plant level, leaf area as well as relative water content, saturation water deficit, degree of leaf succulence and sclerophylly. Generally, exposure to heat stress (HS) alone caused a noticeable reduction in root length (59%), leaf length (30%), plant fresh mass (10%), dry mass (14%), and leaf area (25%) which was consistent with the progressive alteration in water relations. Furthermore, the degree of leaf succulence and degree of leaf sclerophylly were severely affected by HS in wheat seedlings. However, the results demonstrated that the application of AA did not induce such a significant reduction in the leaf length (23%), coleoptile length (5%), plant fresh weight (7%), plant dry weight (3%), and leaf area (21%) as well as water relations in etiolated wheat seedlings compared to heat-stressed plants. Taken together, the activation of AP promoted a mitigating of the damaging effect of HS in wheat seedlings supporting growth processes.

The Results of Mutations Made with Specific Ems Dose on Chickpea (Cicer arietinum L.) Germination Properties

The aim of creating induced mutations is to bring about genetic changes that increase the variation in the desired properties. The selection of appropriate mutagens depends on their availability and effectiveness at certain doses to achieve the necessary genetic modifications. This research was performed at the Dicle University Faculty of Agriculture Biotechnology Laboratory to determine the effects of 10 specific doses of EMS (Ethyl Methane Sulfonate) on mutation on the chickpea cv. Gökçe of germination characters. Seed was handled with an EMS of 0 (control), 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mM. In the germination cabinet, EMS applied seeds were left to germinate with 3 replications according to the completely randomized design with 25 seeds in each petri dishes. In the study, germination rate, coleoptile length, root length, coleoptile fresh weight, root fresh weight, coleoptile dry weight and root dry weight were measured. It was decided that there was a significant difference in all the germination features tested between the doses applied. Due to the rise in EMS doses, a reduction was defined for all features and the lowest values were obtained from the dosage of 100 mM. As a result of the study, it was determined that increasing the dose of EMS in chickpea reduces the germination rate, the seedling characteristics and the healthy growth rate of the seeds and that the effective mutation can be obtained from 50-60 mM doses.

Evaluación de la calidad física y fisiológica de semilla de maíz nativo

La calidad de las semillas es un elemento de importancia para que los productores y empresas semilleras tomen decisiones, como el tipo de semilla y superficie a sembrar, por esta razón las pruebas de calidad física y fisiológica son necesarias para estimar su eficacia. Adicionalmente el deterioro de la semilla de maíz (Zea mays L.) es causa de baja calidad física, fisiológica y sanitaria. En este estudio, realizado en el Laboratorio de Análisis de Semillas del Colegio de Postgraduados, Montecillo Estado de México en el año 2016, se evaluó el daño causado por impacto, envejecimiento acelerado y estrés de frio sobre la calidad física y fisiológica de semillas de maíz. Tomando en cuenta las variables; longitud de plántula, longitud de coleoptilo, longitud de raíz y peso de materia seca. Las diferentes pruebas mostraron que el genotipo tres correspondiente al ciclo 2015 fue de mejor vigor y calidad de semilla, en particular la prueba de frío indicó que la variedad nativa de la región es apta para zonas frías.

Effect of gibberellin-sensitive Rht18 and gibberellin-insensitive Rht-D1b dwarfing genes on vegetative and reproductive growth in bread wheat.

Gibberellin (GA)-insensitive dwarfing genes Rht-B1b and Rht-D1b that are responsible for the 'Green Revolution' have been remarkably successful in wheat improvement globally. However, these alleles result in shorter coleoptiles and reduced vigour, and hence poor establishment and growth in some environments. Rht18, on the other hand, is a GA-sensitive, dominant gene with potential to overcome some of the early growth limitations associated with Rht-B1b and Rht-D1b. We assessed progeny from both a biparental and a backcross population that contained tall, single dwarf, and double dwarf lines, to determine whether Rht18 differs from Rht-D1b and hence verify its value in wheat improvement. Progeny with Rht18 had an almost identical height to lines with Rht-D1b, and both were ~26% shorter than the tall lines, with the double dwarf 13% shorter again. However, coleoptile length of Rht18 was 42% longer than that of Rht-D1b. We detected no differences in time to terminal spikelet and anthesis, and few differences in stem or spike growth. Both dwarfing genes diverted more dry matter to the spike than tall lines from prior to heading. No differences were detected between Rht18 and Rht-D1b that could prevent the adoption of Rht18 in wheat breeding to overcome some of the limitations associated with the 'Green Revolution' genes.

Characterization of Quantitative Trait Loci for Germination and Coleoptile Length under Low-Temperature Condition Using Introgression Lines Derived from an Interspecific Cross in Rice.

Previously, five putative quantitative trait loci (QTLs) for low-temperature germination (LTG) have been detected using 96 BC3F8 lines derived from an interspecific cross between the Korean japonica cultivar “Hwaseong” and Oryza rufipogon. In the present study, two introgression lines, CR1517 and CR1518, were used as parents to detect additional QTLs and analyze interactions among QTLs for LTG. The F2 population (154 plants) along with parental lines, Hwaseong and O. rufipogon, were evaluated for LTG and coleoptile length under low-temperature conditions (13 °C). Among five QTLs for LTG, two major QTLs, qLTG1 and qLTG3, were consistently detected at 6 and 7 days after incubation. Three minor QTLs were detected on chromosomes 8 and 10. Two QTLs, qLTG10.1 and qLTG10.2, showing linkage on chromosome 10, exerted opposite effects with the Hwaseong allele at qLTG10.2 and the O. rufipogon allele at qLTG10.1 respectively, in turn, increasing LTG. Interactions among QTLs were not significant, implying that the QTLs act in an additive manner. Near-isogenic line plants with the combination of favorable alleles from O. rufipogon and Hwaseong exhibited higher LTG than two introgression lines. With regard to coleoptile length, three QTLs observed on chromosomes 1, 3, and 8 were colocalized with QTLs for LTG, suggesting the pleiotropy of the single gene at each locus. According to the results, the introgression of favorable O. rufipogon alleles could hasten the development of rice with high LTG and high coleoptile elongation in japonica cultivars.

Early Vigor of a Pyramiding Line Containing Two Quantitative Trait Loci, Phosphorus Uptake 1 (Pup1) and Anaerobic Germination 1 (AG1) in Rice (O. Sativa L.)

Direct-seeded rice is one of the solutions against the issues of limited labor and time in the rice cropping system. Improved useful traits, such as fertilizer uptake and anaerobic germination, are needed to increase yield and efficiency in the direct seeding system in rice. Pup1 (Phosphorous uptake1) containing PSTOL1 is useful in improving the phosphate uptake under rainfed/upland conditions. OsTPP7 is the major gene of AG1 (Anaerobic Germination), which shows anaerobic germination. IR64-Pup1-AG1 (I-PA) was developed by pyramiding Pup1 and AG1. Around 20% of the chromosomal segments from the donor remained in I-PA. Phenotypic analysis revealed that I-PA showed better phenotypic performance under low and normal P conditions by enhancing the root system and tiller numbers during the early stage. Significantly better P uptake capacity of I-PA was observed upon a P-supplied soil condition. The coleoptile length and germination rate of I-PA showed tolerance under anaerobic-germinated conditions. PSTOL1 and OsTPP7 were independently expressed under different P conditions of soils, as well as anaerobic conditions. The newly developed breeding lines, I-PA, showed early vigor capacity through a high number of tillers, better P uptake, and germination in low-oxygen conditions. It will be a useful and improved breeding line for direct seeding rice breeding programs.

Comparative Responses of Algerian Tetraploid Wheat Cultivars to Salinity at the Seedling Stage

Salinity is one of the most abiotic stresses restricting wheat growth and productivity in arid and semi-arid regions. This study was carried out to examine the effect of salt stress induced by sodium chloride (NaCl) at different concentration levels (0, 50, 100 and 150 mM) on seed germination rate, root length, roots number, coleoptile length, root and shoot fresh weights of eleven durum wheat varieties. The results revealed significant differences among the genotypes for all the measured parameters. The increase in NaCl concentrations showed concomitant decrease in all morphological attributes, but varied depending on cultivars and levels of salinity. Seed germination rate and root length demonstrated a linear response to NaCl treatment, while significant linear and quadratic regression on salinity for roots number, coleoptile length, root and shoot fresh weights were observed. The cluster analysis based on Ward’s method sequestrated the studied genotypes into three clusters. Seed germination rate and root length showed the lowest difference among the groups; and the remaining traits: roots number, coleoptile length, root and shoot fresh weights were the most indicative of salt-tolerance. Waha, Megress and GTA dur were the most tolerant genotypes that could be used as donors of choice in wheat breeding programs targeting the improvement of salinity tolerance during the seedling stage.

Overgrowth mutants determine the causal role of gibberellin GA2oxidaseA13 in Rht12 dwarfism of wheat

The induced dwarf mutant Rht12 was previously shown to have agronomic potential to replace the conventional DELLA mutants Rht-B1b/Rht-D1b in wheat. The Rht12 dwarfing gene is not associated with reduced coleoptile length (unlike the DELLA mutants) and it is dominant, characteristics which are shared with the previously characterized dwarfing genes Rht18 and Rht14. Using the Rht18/Rht14 model, a gibberellin (GA) 2-oxidase gene was identified in the Rht12 region on chromosome 5A. A screen for suppressor mutants in the Rht12 background identified tall overgrowth individuals that were shown to contain loss-of-function mutations in GA2oxidaseA13, demonstrating the role of this gene in the Rht12 dwarf phenotype. It was concluded that Rht12, Rht18, and Rht14 share the same height-reducing mechanism through the increased expression of GA 2-oxidase genes. Some of the overgrowth mutants generated in this study were semi-dwarf and taller than the original Rht12 dwarf, providing breeders with new sources of agronomically useful dwarfism.

QTL analysis of deep‐sowing tolerance during seed germination in the maize IBM Syn4 RIL population

AbstractIn arid or semi‐arid regions, deep‐sowing is an effective treasure to ensure seeds absorbing water from deep soil layer at present. However, the existing maize varieties have poor tolerance to deep‐sowing, which is attributed to that few genes are explored and utilised. In this study, 243 IBM Syn4 recombinant inbred lines (RIL) constructed with B73 and Mo17 as parents and 1,339 DNA markers evenly distributed in 10 chromosomes, were used for QTL analysis of deep‐sowing tolerance during seed germination. There were significant differences in germination‐related traits between the parental lines at 12.5 cm sowing depth. Among them, 7, 7, 5, 10 and 2 QTLs for emergence rate, seedling length, plumule length, mesocotyl length and coleoptile length were detected, respectively. These QTLs explained 2.75% to 10.49% of the phenotypic variance with LOD scores ranging from 2.50 to 8.27. In addition, 12 overlapping QTLs formed five QTL clusters on chromosomes 3, 5, 7 and 9. This study provides a basis for molecular marker‐assisted breeding and functional study in deep‐sowing germination of maize.

Mining Favorable Alleles for Rice Coleoptile Elongation Length Sensitivity to Exogenous Gibberellin Under Submergence Condition

High sensitivity of rice coleoptile elongation length to exogenous gibberellin is a beneficial trait to utilize superior rice cultivars that could not be used originally under water direct-seeded conditions. In the present study, we mined favorable alleles for the trait by combining the phenotypic data of 358 rice accessions with their genotype data of 262 simple sequence repeat (SSR) markers via genome wide association mapping method. Totally, 17 SSR marker loci significantly associated with gibberellin sensitivity index (GSI) of coleoptile elongation length under 10 cm depth of water, were detected by general linear model and mixed linear model across two years, with percent phenotypic variation explained larger than 10%. Twenty nine favorable alleles for GSI on the 17 loci were discovered with phenotypic effect value (PEV) larger than 0.1 cm/cm and RM6869-110 bp showed the largest PEV (0.27 cm/cm). Based on PEV of marker-alleles having positive effects on GSI, seven parental combinations were predicted to improve GSI. In addition, 7 loci for GSI were co-located with loci associated with coleoptile elongation length per se, and one locus (RM1182 on chromosome 5) was co-located with that associated with coleoptile elongation length after gibberellin-soaked seed, under germination condition of 10 cm depth of water. These favorable allele(s) could be used to improve two target traits simultaneously.

First report of Fusarium equiseti causing crown rot and damping-off on durum wheat in Algeria

The isolation of Pathogens from wheat seeds sampled from fifty-nine locations in North-eastern Algeria showed the existence of the species Fusarium equiseti for the first time in the seeds of the durum wheat in Algeria. The identification was carried out on the basis of macroscopic and microscopic characteristics and confirmed by Molecular identification. The pathogenicity test was performed, on three durum wheat varieties to determine the impact of this isolate on the coleoptile and basal part of durum wheat. The results showed that Fusarium equiseti caused a significant diminution in length and emergence rate of coleoptile by 48.99 and 44% respectively, and a decrease in the length of the root and vegetative systems by 45.63 and 27.12%, consecutively. It also caused a diminution in the fresh weight of the root and vegetative systems by 45.65 and 22.52%, respectively.

Intraspecific Genetic Variation within and between Improved Cultivars and Landraces of Durum Wheat in Germination and Root Architectural Traits under Saline Conditions

Although the effect of salinity on plants is well established, yet evaluating genetic variation in yield-related traits under salinity stress remains useful. This study was conducted to investigate the genetic variation within and between two subgroups of durum wheat in Jordan, i.e., cultivars and landraces, in germination and root architectural traits at three salinity concentrations (50, 100 and 150 mM NaCl). The results indicate that salinity significantly impacted most traits investigated. A multivariate discriminant analysis (DA) revealed large variations (~85%) between genotypes, with significant ranking in maximum root length, total root length, seminal root length, coleoptile length, germination percentage, and total and seminal root number over the three salinities. Within the cultivar subgroup, salinity significantly influenced the germination percentage and most root traits of durum genotypes, with variable magnitudes depending on NaCl concentration and within-variety intraspecific genetic variation (ANOVAs; p < 0.05). However, within the landrace subgroup, only a salinity of 150 mM NaCl significantly affected the studied traits, and the effect of salinity on germination percentage was highly genotype dependent. Additionally, the durum genotypes in the landrace subgroup were more affected by salinity and showed more genetic variation than those in the cultivar subgroup.