Hexaploid Genotypes Research Articles

Role of Temporal Zn Fertilization along with Zn Solubilizing Bacteria in Enhancing Zinc Content, Uptake, and Zinc Use Efficiency in Wheat Genotypes and Its Implications for Agronomic Biofortification

Wheat (Triticum aestivum L.) is a vital cereal crop for food security in Pakistan. In Zn-deficient soils, its productivity and quality suffer, affecting grain yield, Zn bioavailability, and nutrition, which can lead to malnutrition. Field experiments were conducted using factorial randomized block design at the Agricultural Research Institute (ARI) Tarnab, Peshawar, Pakistan to evaluate the impact of wheat genotypes (G1-TRB-72-311 synthetic hexaploid, G2-TRB-89-348 advanced line, and G3-Pirsabak-19-approved variety), Zn application methods (AM1: no Zn application, AM2: seed priming with 0.5% Zn, AM3: soil application of 10 kg ha−1 Zn, and AM4: foliar application of 0.5% Zn), and the experiment also explored the use of ZSB (BF1: with bacteria, BF0: without bacteria) to cope with Zn deficiency. The study revealed significant impacts on wheat’s Zn content, uptake, and nutrient efficiency, arising from genotypes variance, Zn application approaches, and ZSB. TRB-72-311 synthetic hexaploid genotype with 0.5% foliar Zn and ZSB excelled, enhancing grain (17.8%) and straw Zn (23.1%), increasing total Zn uptake (55.0%), reducing grain phytic acid (11.7%), and boosting Zn-related efficiencies in wheat. These results prompt further discussion regarding the potential implications for agricultural practices. In conclusion, utilizing the TRB-72-311 genotype with 0.5% foliar Zn application and ZSB enhances wheat’s Zn content, uptake, grain quality, and addresses malnutrition.

Distinctive root system adaptation of ploidy wheats to water stress: A cue to yield enhancement

AbstractGiven the worldwide effort to improve crop drought resistance, it is crucial to understand the mechanisms of root system adaptation of ploidy wheat to water‐deficient environments. A meta‐analysis was performed to examine the changes in root system mechanisms under drought conditions. Data used in the analysis were drawn from 192 papers, taking into account wheat ploidy levels as well as pot and field studies. The results illustrated that water stress reduced grain yield and aboveground biomass to a greater extent in diploid and tetraploid compared with hexaploid genotypes. In contrast, drought reduced root biomass, root surface area and root volume more in hexaploid than in diploid and tetraploid wheat. Under water‐limited conditions, diploid and tetraploid genotypes exhibited greater root biomass and root length densities in the topsoil. Hexaploid genotypes greatly reduced root biomass and root length density in the topsoil and maintained higher root biomass and root length density in subsoil. These genotypes also showed smaller root diameter and xylem centre vessel diameter under drought conditions. The analysis revealed that grain yield was negatively correlated with topsoil root biomass and root length density, root volume, root diameter and xylem centre vessel, but positively correlated with subsoil root mass, root length density and root vigour. The study demonstrated that domestication and selection pressures of ploidy wheat have altered wheat root system traits while improving grain yield. Greater root mass and root length densities in the subsoil facilitate access to soil moisture from deep layers, contributing to high yields in drought environments.

Physio-Chemical and Agronomic-Based Characterization of Synthetic Hexaploid Wheat Germplasm under Field Imposed Conditions of Drought and Heat Stress

Abiotic stresses, such as a drought and heat, are potential constraints limiting wheat production across the globe. This current perspective study intended to characterize the performance of exotic synthetic hexaploid (SH) wheat genotypes on a physiological, biochemical, and agronomic basis under field-based drought and heat conditions. The tri-replicate experiments were conducted in two seasons using two-factorial arrangements in a randomized complete block design (RCBD) with stresses as one factor and genotypes as another factor. The recorded data were statistically analyzed using computer-based software statistix8.1 and R-studio. In this study, all the physiological parameters (total chlorophyll, stomatal conductance, photosynthesis rate, transpiration rate, and cell membrane stability percentage), biochemical stress markers (antioxidant enzymes, glycine betaine, and proline), and agronomic traits (flag leaf area, plant height, tillers per plant, spike length, grains per spike, and thousand grain weight) varied significantly under separate and combined regimes of drought and heat stresses. All traits varied in same direction, excluding glycine betaine and proline, which varied in the opposite direction because of stress, as explicated by correlation analysis. Furthermore, PCA and heatmap analysis confirmed that the expression of the traits varied more significantly because of combined regimes of drought and heat stresses as compared to controlled and isolated applications. Interestingly, synthetic hexaploid (SH) genotypes depicted similar responses to individual and integrated regimes of drought and heat stresses. The current study proved that deciphering the physiological, biochemical, and agronomic performance of wheat genotypes under stress can provide effective criteria for the future selection of wheat germplasm for breeding against drought and heat stresses.

Bottom-up redistribution of biomass optimizes energy allocation, water use and yield formation in dryland wheat improvement.

Modern wheat cultivars have been developed having distinct advantages in many aspects under drought stress, such as plasticity in biomass allocation and root system architecture. A better understanding of the biomass allocation mechanisms that enable modern wheat to achieve higher yields and yield-based water use efficiency (WUEg ) is essential for implementing best management strategies and identifying phenotypic traits for cultivar improvement. We systematically investigated the biomass allocation, morphological and physiological characteristics of three ploidy wheat genotypes under 80% and 50% field water-holding capacity (FC) conditions. Some crucial traits were also assessed in a complementary field experiment. The diploid and tetraploid genotypes were found to allocate more biomass to the root system, especially roots in the topsoil under drought stress. Our data illustrated that lower WUEg and yield of these old genotypes were due to excessive investment in the root system, which was associated with severely restricted canopy development. Modern hexaploid genotypes were found to allocate smaller biomass to roots and larger biomass to shoots. This not only ensured the necessary water uptake, but also allowed the plant to distribute more assimilates and limited water to the shoots. Therefore, the hexaploid genotypes have evolved a stable plant canopy structure to optimize WUEg and grain yield. This study demonstrated that the biomass shift from below ground to above ground or a more balanced root:shoot ratio tended to optimize water use and yield of the modern cultivars. This discovery provides potential guidance for future dryland wheat breeding and sustainable management strategies. © 2021 Her Majesty the Queen in Right of Canada Journal of The Science of Food and Agriculture © 2021 Society of Chemical Industry. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

High-throughput sequencing-based microsatellite genotyping for polyploids to resolve allele dosage uncertainty and improve analyses of genetic diversity, structure and differentiation: A case study of the hexaploid Camellia oleifera.

Conventional microsatellite (simple sequence repeat, SSR) genotyping methods cannot accurately identify polyploid genotypes leading to allele dosage uncertainty, introducing biases in population genetic analysis. Here, a new SSR genotyping method was developed to directly infer accurate polyploid genotypes. The frequency distribution of SSR sequences was obtained based on deep-coverage high-throughput sequencing data. Corrections were performed accounting for the "stutter peak" and amplification efficiency of SSR sequences. Perl scripts and an online SSR genotyping tool "SSRSeq" were provided to process the sequencing data and output genotypes with corrected allele dosages. Hexaploid Camellia oleifera is the dominant woody oilseed crop in China. Understanding the geographical pattern of genetic variation in wild C. oleifera is essential for the conservation and utilization of genetic resources. Six wild C. oleifera populations were sampled across geographical ranges in subtropical evergreen broadleaf forests of China. Using 35 SSR markers, the high-throughput sequencing-based SSRSeq method was applied to obtain accurate hexaploid genotypes of wild C. oleifera. The results demonstrated that the new method could resolve allele dosage uncertainty and considerably improve genetic diversity, structure and differentiation analyses for polyploids. The genetic variation patterns of wild C. oleifera across geographical ranges agree with the "central-marginal hypothesis", stating that genetic diversity is high in the central population and declines from the central to the peripheral populations, and genetic differentiation increases from the centre to the periphery. This method and findings can facilitate the utilization of wild C. oleifera genetic resources for the breeding of cultivated C. oleifera.

Differential reaction of hexaploid and tetraploid wheat to Fusarium graminearum chemotypes in a controlled environment

Fusarium head blight (FHB) has a negative impact on cereal food safety, quality and yield. The majority of FHB resistance genes in wheat (Triticum spp.) have been identified based on reaction to Fusarium graminearum, which, in Canada, has two prevalent trichothecene chemotypes, 3-acetyl-deoxyinvalenol (ADON) and 15-ADON. Three hexaploid (Triticum aestivum L.) and four tetraploid (Triticum turgidum L. ssp. durum and Triticum turgidum L. spp. dicoccoides (Korn. ex Asch. & Graebn.) Thell.) wheat genotypes with different genes for resistance and with different reactions to F. graminearum were evaluated in replicated greenhouse trials to determine if the resistance genes currently deployed in Canadian wheat are effective against both the 3-ADON and 15-ADON chemotypes. The development of FHB was rated as disease severity. The genotypes showed differential responses, with a higher level of disease development in the hexaploid wheat genotypes inoculated with the 3-ADON than with the 15-ADON chemotype. The opposite was observed in the tetraploid wheat genotypes. Tetraploid genotype BGRC3487 and a hexaploid genotype ND2710 showed similar resistance to both 3-ADON and 15-ADON chemotypes. These would be effective sources to breed lines resistant to both 3-ADON and 15-ADON chemotypes and reduce FHB risk.

Assessment of morphological and anatomical variability in Triticum species, Aegilops species, interspecific and intergeneric hybrids

Wheat species and wild relatives offer promising resources for wheat improvement and research in the current period of the genetic narrowing of modern wheat cultivars. The present study was performed to evaluate the morphological and anatomical traits of 20 diverse genotypes including Triticum and Aegilops species with intergeneric and interspecific wheat hybrids, which were compared with modern bread and durum wheat cultivars locally adapted to rainfed and irrigated conditions. The study showed that stomata density and size ranged from 55.3 to 108.6 stomata/mm2 and 401.4 to 1296 µm2, respectively, in the selected genotypes. Moving tetraploid to hexaploid genotypes, increased chromosome numbers yielded lower densities of large stomata in wheat species and hybrids. In this regard, the stomatal patterns of two hexaploid wheat hybrids and a wheat species including ‘Agrotriticum’, ‘Aegilotriticum’, and T. compactum, were of low density and large size stomata compared to T. durum cv. ‘Kunduru 1149’ with high density and small size stomata. Interestingly, the wild progenitor of the bread wheat D genome, Ae. tauschii, had a high density of the smallest stomata among the studied genotypes. The study further indicated that morphological parameters decreased under rainfed conditions compared to those under irrigated conditions, with levels varying among the genotypes. The rainfed flag leaf area and 1000-grain weight varied from 0.9 to 23.7 cm2 and from 7.3 to 61.9 g, respectively under rainfed conditions, while they ranged from 1.2 to 35.7 cm2 and 11.5 to 69.9 g under irrigated conditions. The flag leaf area had a significant and strong association with 1000-grain weight under rainfed (r2= 0.79) and irrigated (r2 = 0.77) conditions. T. turanicum and T. polonicum were characterized by the significantly highest 1000-grain weight in both rainfed and irrigated conditions. This study suggests that these wheat species with high 1000-grain weight might have promising alleles to be transferred into durum wheat to increase grain yield.

Assessment of Heat Tolerance in Some Wheat Species and Interspecific Hybrids

Twelve accessions including two diploid, four tetraploid and six hexaploid genotypes were used in this study to assess heat tolerance in wheat. All possible crosses were made and the resulted hybrids with their parents were subsequently evaluated for heat tolerance in two sowing dates. Evaluation was based on 1000 grain weight, grain yield per plant, cell membrane thermostability and tetrazolium chloride reduction. Results revealed significant variability among wheat genotypes and hybrids in all evaluated traits under favorable and heat stress conditions. However, tetraploid genotypes showed the highest performance under heat stress followed by hexaploid and diploid genotypes, respectively. According to results of heat tolerance index, one tolerant and one susceptible parent from each ploidy level along with 6 related interspecific hybrids were chosen to be involved in molecular analysis. Target region amplification polymorphism (TRAP) markers were used based on fixed primers of heat shock protein genes. TRAP clearly confirmed the morpho-physiological findings and generated a dendrogram which was quietly like that of morpho-physiological data. TRAP was able to generate one and five specific bands for diploid and hexaploid genotypes respectively, while no specific bands were generated for tetraploid. In addition, the different genomes showed some shared bands between each other revealing their relationship. Interestingly, two specific bands for tolerant genotypes of different ploidy level were generated which were absent in all susceptible genotypes. Findings herein are of high importance and could help in successive breeding programs for wheat improvement.

Wheat breeding highlights drought tolerance while ignores the advantages of drought avoidance: A meta-analysis

Crop tolerance and avoidance are critical adaptation mechanisms to cope with drought stress but they contribute differently to grain yield formation. Little is known about the different roles of these two mechanisms in long-term crop breeding. A meta-analysis was conducted to determine the different effects of drought tolerance and avoidance mechanisms on the drought adaptation of wheat crops. The meta-analysis summarized the results of 283 published papers in international journals, and illustrated that primitive wheat genotypes, including wild, cultivated diploids, tetraploids and old hexaploids, preferentially showed a drought avoidance strategy, as evidenced by large root biomass, small leaf area, and reduced stomatal conductance under water deficits. Modern hexaploid genotypes showed stronger drought tolerance advantages, such as high leaf water potential and osmotic adjustment, with a small root system. The meta-analysis indicated that the breeding process of dryland wheat has been continuously enhancing drought tolerance while weakening drought avoidance. Under severe water deficits, old hexaploid wheat genotypes with drought avoidance characteristics showed lower reduction of aboveground biomass and yield than modern genotypes with stronger drought tolerance features, while under mild and moderate water deficits genotypes with stronger drought tolerance features had higher yields and aboveground biomass. The meta-analysis provide information for making decisions on the direction of modern crop breeding and the implementing of managing practices to cope with drought stress, which frequency and severity is increasing with the advent of climate change.

Molecular Assisted Selection for Pollination-Constant and Non-Astringent Type without Male Flowers in Spanish Germplasm for Persimmon Breeding

Persimmon (Diospyros kaki Thunb) species is a hexaploid genotype that has a morphologically polygamous gyonodioecious sexual system. D. kaki bears unisexual flowers. The presence of male flowers resulted in the presence of seeds in the varieties. The fruits of persimmon are classified according to their astringency and the pollination events that produced seeds and modify the levels of astringency in the fruit. The presence of seeds in astringent varieties as pollination variant astringent (PVA), pollination variant non-astringent (PVNA) and pollination constant astringent (PCA) resulted in fruits not marketable. Molecular markers that allow selection of the varieties according to the type of flowers at the plantlet stage would allow selection of seedless varieties. In this study, a marker developed in D. lotus by bulk segregant analysis (BSA) and amplified fragment length polymorphism (AFLP) markers, named DlSx-AF4, has been validated in a germplasm collection of persimmon, results obtained agree with the phenotype data. A second important trait in persimmon is the presence of astringency in ripened fruits. Fruits non-astringent at the ripen stage named pollination constant non-astringent (PCNA) are the objective of many breeding programs as they do not need removal of the astringency by a postharvest treatment. Astringency in the hexaploid persimmon is a dominant trait. The presence of at least one astringent allele confers astringency to the fruit. In this paper we checked the marker developed linked to the AST gene. Our goal has been to validate both markers in germplasm from different origins and to test the usefulness in a breeding program.

Genetic variability assessment in bread wheat (Triticum aestivum) grown in Algeria using microsatellites SSR markers

Abstract. Kara K, Rached-Kanouni M, Mnasri S, Khammar H, Ben Naceur MB. 2020. Genetic variability assessment in bread wheat (Triticum aestivum) grown in Algeria using microsatellites SSR markers. Biodiversitas 21: 2638-2644. The assessment of genetic diversity is a key step in evaluating the adaptation of populations to new environmental conditions, and thus in the selection of new cultivars. The present investigation aimed to assess genetic variability of bread wheat (Triticum aestivum L.) genotypes grown in Algeria. The 17 hexaploid genotypes of bread wheat were assessed using 16 molecular microsatellites of SSR (Simple Sequence Repeat). Among the 16 microsatellite markers tested, only 11 markers were the most polymorphic and reproducible. The Polymorphism Information Content (PIC) values per locus varied from 0.14 to 0.70 with an average of 0.48 and 0.49. Genetic similarity between genotypes varied from 0.27 and 0.92 with an average of 0.60. The highest genetic distance value of 0.92 has been scored between Kauz/Pastor/Fiscal and Wbll1*2/Brambling. The lowest value of 0.27 has been scored between Cham6 and Pastor/Wbll1. Genetic similarity was calculated by molecular derived data and used to produce a dendrogram. The genotypes were grouped in two clear clusters according to their origin and pedigree. The first cluster included wheat genotypes Ain Abid (local genotypes), Attila/2 Pastor, and 5119 (introduced genotypes). The second group revealed high polymorphism and was subdivided into four sub-groups. This high level of diversity revealed among the accessions of wheat, grown in Algeria could be used in breeding programs.

Siberian gene pool of steppe cherry polyploids (Prunus fruticosa Pall.): cytomorphological estimation and prospects for breeding

The first spontaneous cherry polyploids were detected in the Altai gene pool of Russia and inside of the interspecific hybrids of Prunus fruticosa Pall. only. To date, polyploid genotypes with a complex of economically valuable traits and of various origins has preserved in the collection of FASCA. Collection includes: 1) F1 of spontaneous origin; 2) F2 obtained from hybridization of the first spontaneous hexaploid genotypes; 3) hybrids induced in vitro. These hybrids have a genetic origin from steppe cherry crossings with P. cerasus L., P. maackii Rupr., P. serrulata Lindl., P. canescens Bois., P. incisa Thumb., etc. Hexaploid amitotic clone lines were obtained by of 0.1% trifluralin treatment. The cellular mechanism of polyploids occurrence is the male and female unreduced gametes functioning. The study of microsporogenesis in 38 hybrids has revealed the 17 genetic producers of unreduced male gametes. According to the ploidy level of seedlings, the 8 sources of unreduced female gametes were selected. The morphophysiological characteristics of mature pollen were studied and the patterns for the preliminary selection of polyploids were revealed. The main strategy for the cherry breeding in the 21th century is the creation of polygenome hybrids with increased adaptation and high fruit quality.

Mode of reproduction and meiotic chromosome behavior in Acroceras macrum

AbstractAcroceras macrum Stapf is a high‐quality C3 grass species adapted to the subtropics. It is a valuable forage resource in frequently flooded environments. The objectives were to analyze the type of polyploidy, mode of reproduction, and estimate seed and pollen fertility. A living collection of 22 tetraploid and five hexaploid genotypes of A. macrum was analyzed. Type of polyploidy was analyzed from chromosomal pairing at diakinesis and prometaphase I, and meiotic irregularities were evaluated during the microsporogenesis. Pollen viability was also examined. Bivalents predominated in tetraploids and trivalents in hexaploids. Meiotic abnormalities were more frequent in hexaploids than in tetraploids, and they were mainly related to mechanisms of chromosome nondisjunction. The reproductive mode was determined by cytological analysis of megasporogenesis and megagametogenesis, seed fertility under different pollination methods, and molecular progeny tests. In both tetraploid and hexaploid races, only the development of single meiotically derived embryo sacs was observed. Greater seed production in outcrossing compared with selfing indicated a primarily allogamous matting system. Progenies from crosses between genetically different tetraploid genotypes amplified male‐specific molecular markers, indicating a hybrid origin and solid evidence of sexual reproduction. Population breeding approaches developed for sexual cross‐pollinated species are suited for improving A. macrum.

Новые генетические источники для селекции видов Prunus L. на полиплоидном уровне

This research is aimed at studying of the chromosomal number distribution within the new, in vitro cultured, amitotic
 clonal lines of Prunus species, at comparing of the fertility and size of pollen for triploid and hexaploid amitotic clones and
 at identifying of new genetic sources and their subsequent use in breeding. Methods. The standard cytological and statistical
 methods were used in this scientific work. Results. The regularities of induced polyploids output both from the initial number
 of chromosomes and from the origin and individual characteristics of the original genotypes were established. For amitotic
 hexaploid genotypes of hybrid cherry, high pollen quality was discovered at the level of 81,8–92,6 % of fertility (in triploids
 the 4,6–18,8 % of such pollen was found), therefore, the studied 4 clonal cherry genotypes (12-1-1Т2, 12-1-1Т6, 12-1-2Т3,
 12-1-2Тv) are recommended for breeding of resistant to fungal diseases varieties. No significant differences were found in the
 diameter of fertile pollen (46.3–47.8 μm) between cherry amitotic triploids and hexaploids. Therefore, in all likelihood, fertile
 pollen in triploids carries an unreduced triploid set of chromosomes. Prime scientific novelty. A completely new and original
 selection material for the genus Prunus L. – polyploid hybrids of P. fruricosa Pall. with rare East-Asiatic cherry species P. serrulata Lindl., P. canescens Bois., P. incisa. Thoub. were studied. The arguments in favor of a positive breeding prospect for the
 transfer of new cherries varieties to the hexaploid level (2n = 48), including an in vitro culture method of chromosome number
 doubling for the sterile triploid interspecific hybrids, have been obtained. The first created tetraploid (2n = 32) amitotic clonal
 lines of microcherry P. pumila L. must be tested in crosses with thorns and hybrids of thorns.

Effect of elevated carbon dioxide on plant biomass and grain protein concentration differs across bread, durum and synthetic hexaploid wheat genotypes

Atmospheric carbon dioxide conditions predicted for future climates cause increases in wheat biomass, but also decreases wheat grain protein concentration. We investigated the response of grain protein concentration of wheat to elevated carbon dioxide in nineteen wheat genotypes, including five tetraploid, eleven hexaploid and three synthetic hexaploid genotypes to test whether decreased grain protein is genotype dependent and whether it is caused by biomass dilution. These were grown in ambient and elevated carbon dioxide conditions simultaneously. Shoot biomass and grain samples were taken at maturity. The grain protein concentration, grain biomass, shoot biomass and harvest index were analysed for each genotype. Despite most genotypes increasing in total grain protein (g), the majority of genotypes decreased in grain protein concentration (%) under elevated carbon dioxide. Elevated carbon dioxide caused an increase in grain biomass for all genotypes and total shoot biomass for most genotypes, with harvest index increasing for all genotypes except the two synthetic hexaploids CPI133814 and CPI133811. Most of the differences between wheat types were not statistically significant, suggesting that the individual genotype of wheat plants determines the response to elevated carbon dioxide rather than the wheat type.

Constituents of a mixed-ploidy population of Solidago altissima differ in plasticity and predicted response to selection under simulated climate change.

Polyploids possess unique attributes that influence their environmental tolerance and geographic distribution. It is often unknown, however, whether cytotypes within mixed-ploidy populations are also uniquely adapted and differ in their responses to environmental change. Here, we examine whether diploids and hexaploids from a single mixed-ploidy population of Solidago altissima differ in plasticity and potential response to natural selection under conditions simulating climate change. Clonal replicates of diploid and hexaploid genotypes were grown in a randomized split-plot design under two temperature (+1.9°C) and two watering treatments (-13% soil moisture) implemented with open-top passive chambers placed under rainout shelters. Physiological, phenological, morphological traits, and a fitness correlate, reproductive biomass, were measured and compared among treatments. Differences in traits suggest that diploids are currently better adapted to low- water availability than hexaploids. Both ploidy levels had adaptive plastic responses to treatments and are predicted to respond to selection, but often for different traits. Water availability generally had a stronger effect than temperature, but for some traits the effect of water depended on temperature. Diploid and hexaploid S. altissima may maintain fitness in the short term through adaptive plasticity and evolution depending on which traits are important in a warmer, drier environment. Hexaploids may be at a disadvantage compared to diploids because fewer traits were heritable. Our results underscore the importance of studying combinations of climate variables that are predicted to change simultaneously.

Response of wild Avena species to fungal infection of grain

Sixty-six accessions belonging to Avena species (A. atlantica, A. canariensis, A. clauda, A. damascena, A. hirtula, A. longiglumis, A. wiestii, A. agadiriana, A. barbata, A. vaviloviana, A. insularis, A. magna, A. murphyi, A. fatua, A. ludoviciana, A. occidentalis, A. sterilis, A. sativa, and A. byzantina) obtained from the N. I. Vavilov Institute of Plant Genetic Resources (VIR) were tested for the infection of grain by Alternaria and Cladosporium at the genus level and by a group of trichothecene-producing Fusarium fungi. Real-time PCR was performed to quantify fungal abundance and ELISA was performed for mycotoxin analysis in grain. The average amounts of all tested fungi in tetraploid Avena species were higher than those in diploid and hexaploid species. Low amounts of deoxynivalenol (DON) were detected in seven hexaploid genotypes (A. sterilis, A. byzantina, A. sativa, and A. fatua) and one diploid genotype (A. wiestii). The relationship between some morphological traits (1000-grain weight, percent of husk, trichome density, and plant height) of Avena species and grain infection by fungi and mycotoxins was investigated. Alternaria and Cladosporium fungi could not penetrate the husk. A highly negative correlation of the amounts of their DNA with the proportions of husk in grain as well as with trichome density was found. In contrast, a significant positive correlation between the amount of Fusarium DNA and these traits was found. A strong negative correlation between plant height and DNA of the analyzed fungi was found. The oats least infected by Alternaria, Cladosporium, and Fusarium fungi and containing low amounts of DON were accessions of the hexaploids A. byzantina, A. fatua, A. sativa, A. sterilis, and the diploid A. wiestii.

Chitinase Activities in Wheat and Its Relative Species

Abstract Defense components such as chitinases (EC 3.2.1.14) are crucial for plants to cope diseases. Despite of that the pattern and activities of these enzymes in agronomically important Triticale is unexplored. This work is aimed to study chitinase activities in the leaves of plants of early developmental stages in two diploids (Aegilops tauschii Coss., Triticum monococcum L.), four tetraploids (Ae. cylindrical Host, Ae. triuncialis L., T. araraticum Jakubyz, T. dicoccum Schrank) and two hexaploids (T. aestivum L., T. spelta L.). The leaves were subjected to quantitative and qualitative activity assays using synthetic 4-methylumbelliferyl-β-D-N,N´,N´´-triacetylchitotrioside and glycolchitin as substrates, respectively. Our results showed that the activities of chitinases with specificity towards short oligomers were variable and genotype dependent. The enzyme activities in the tetra- and hexaploid genotypes were significantly higher than in diplod counterparts. In the gel detection assays were revealed up to four fractions (~20, 30, 42 and 95 kDa) of proteins with the chitinase activity towards long chain polymers. The isoform of ~30 kDa was identified in all analyzed genotypes. Among the seven acidic and three basic chitinase fractions identified, three acidic (ChiA, ChiB, ChiC) and two (ChiH, ChiI) fractions were present in all genotypes. None of the isoforms can be assigned as specific with respect to ploidy.

Morphological and physiological responses of different wheat genotypes to chilling stress: a cue to explain yield loss.

The eco-physiological mechanism of wheat yield loss resulting from chilling stress is a fundamental scientific issue. However, previous studies have focused on hexaploid wheats, and few studies on the morphological and physiological plasticity of wheat plants. Six different wheat genotypes were tested under chilling stress to investigate the physio-morphological parameters as well as the loss of grain yield in growth chambers. Chilling stress resulted in significant loss in grain yield in all genotypes. Under chilling stress, diploid wheats generated zero harvest, and tetraploid genotypes also suffered from a pronounced loss in grain yield, compared with the control group. In contrast, hexaploid genotypes acquired relatively high maintenance rate of grain yield among three species. Diploid and tetraploid wheat genotypes maintained relatively large leaf area and high photosynthetic rates, but they were subjected to significant declines in vascular bundle number and productive tillers as a consequence of the inhibition by sink growth under chilling stress. The hexaploid wheats were found to have relatively low leaf area and photosynthetic rates. These genotypes also stored more soluble carbohydrates and exhibited stronger sink enhancement, ensuring the translocation and redistribution of assimilates. Our findings provided a new theoretical understanding of yield stabilization in the domestication process of wheat genotypes under chilling stress. © 2017 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture © 2017 Society of Chemical Industry.

Diversity of the species of genus Avena revealed by morphological characters and resistance to Fusarium infection of grain

Sixty six genotypes belong to wild and cultivated Avena species from the VIR collection were evaluated for infection of grain by Fusarium fungi and mycotoxins in accumulation. Among genotypes 13.6, 28.8, and 57.6% were diploid, tetraploid, and hexaploid oats, respectively.
 The aim of this study was to recognize the interrelationship between the wild species of the genus Avena not subjected to formal breeding programs, and Fusarium fungi, which have been reported as predominant seed borne pathogens. The real-time PCR was used to simultaneously detect and quantify fungi in grain of Avena genotypes. Mycotoxin analysis was performed by ELISA. The average amount of Fusarium DNA and deoxynivalenol (DON) in groups of the tetraploid oats were higher than they were found in the groups of di- and hexaploid species. It was determining the strong correlation between the presence of Tri-Fusarium DNA and DON content (p 0,01). The low amounts of DON in the grain were detected in seven hexaploid genotypes (A. byzantina, A. sterilis, A. sativa, and A. fatua) and one diploid A. wiestii. The connection of morphological characters (weight of 1000 grains, husk hardness, trichomes profusion and plant height) of Avena species and the indicators of Fusarium infection were analyzed. Only biomass of Fusarium has demonstrated significant connection with weight of 1000 grains. Significant correlation between the hardness of husk and the amounts of Fusarium DNA (p 0,01) was detected. For Fusarium the strong protective effect of the husk from the penetration of pathogens into grain was evident.