Hybrid Populations Research Articles

Gene Action for Kernel Weight Per Plant in Spring Barley

The breeding and genetic peculiarities for kernel weight per plant in spring barley varieties of different origin (Ukraine, Western European countries, and Canada), purposes of usage (forage, malting, food) and botanical varieties (covered and naked, awned and awnless) under conditions of Ukrainian Forest-Steppe were revealed. In the diallel crossing scheme with only elite malting barley varieties accordance with the additive-dominant system and overdominance in loci were found. The manifestation of kernel weight per plant was reliably increased by the dominant effects. Accordingly to the indicator of the degree of phenotypic dominance, parameters of genetic variation, graphical regression analysis, effects of GCA and constants of SCA in the hybrid populations will be effective final selection for high kernel weight per plant in later generations, when dominant alleles become homozygous. When different botanical varieties were involved in crosses much more complex gene action for the trait manifestation with strong epistasis and multidirectional dominance were determined. Thus, it is theoretically possible to select plants with high productivity on recessive or dominant basis. The negative aspect is that it will require further extensive evaluation of the splitting generations. Awned spring barley varieties Datcha and MIP Myroslav, as well as awnless variety Kozyr can be used as an effective genetic source for involvement in crossings aimed to improving the kernel weight per plant. Naked spring barley varieties require more breeding improvement in plant productivity compare to covered ones.

Identification of Near Homozygous Inbred Lines for Developing Hybrid Populations to Explore the Possibility of True Seed-Based Sugarcane Cultivation

Identification of Near Homozygous Inbred Lines for Developing Hybrid Populations to Explore the Possibility of True Seed-Based Sugarcane Cultivation

Study of phytotoxicity of Lumax herbicide in grain maize crops under conditions of the South of the Far East

The phytotoxicity of the herbicide Lumax to the hybrid population of corn P 8521, consisting of three active substances: C-metolachlor, terbutylazine and mesotrion, was studied. The studies were conducted in the Primorsky Territory in 2020 and 2021 on 2 backgrounds: clogged and weed-free which was regularly weeded during the growing seasons. The herbicide was applied before germination, in phases 2-3 and 5-6 of corn leaves at consumption rates of 4 (recommended) and 8 l/ha (twice the recommended). The soil of the experimental plots is meadow-brown podzolized, medium loamy, containing 3.8% humus in the arable horizon, PH 5.0-5.9. The herbicide Lumax, applied in the phase of 5-6 leaves, during the growing season had a phytotoxic effect on plants and corn grain yields. A significant decrease in the grain harvest was noted in 2021 when during the II and III ten-day periods of June and July there were only 35 mm of precipitation, while the norm for this period was 187 mm. When applying Lumax herbicide in the phase of 5-6 leaves, the cob length, the number of grains in it, the weight of the cob and grains from it, as well as the weight of 1000 grains significantly decreased. Corn is more tolerant to Lumax herbicide when used in the 2-3 leaf phase and less tolerant when used in the 5-6 leaf phase.

Сорт масличного льна Сания

In 2020, a new variety of oil flax Saniya, bred by the Siberian Experimental Station, a branch of V.S. Pustovoit All-Russian Research Institute of Oil Crops, was submitted for the State variety trial. The variety was developed by the method of individual selection from a hybrid population of the 3rd generation from crossing the breeding lines 39122 and 39755. Hybridization was carried out in 2012. An elite plant was selected in 2015. The variety has high oil content and thousand-seed weight. According to the results of the competitive variety trial (2018–2020), the oil flax variety Saniya exceeded the standard variety August in seed yield by 0.25 t/ha, in oil yield – by 125 kg/ha, oil content of seeds is higher than the standard variety one by 0.7 %, the thousand-seed weight is higher by 0.8 g. The new variety is intended for obtaining high-quality technical oil. The recommended regions for cultivation are Volga-Vyatka (4); Central Black Earth (5); North Caucasus (6); Middle Volga (7); Lower Volga (8); Ural (9); West Siberian (10). The originator of the variety Saniya is V.S. Pustovoit All-Russian Research Institute of Oil Crops.

Стратегія селекції соняшнику на підвищення якості олійної продукції

Goal. To study the inheritance of selection genetic determinants in F1 and subsequent generations of sunflower, which determine the increased content of fatty acids, vitamin E, and its components: α-, β-, γ-, σ-isomers of tocopherol in combination with morphobiological characteristics: oil content, protein, plant height, plant productivity, the weight of 1000 seeds in conditions of different years of testing, and create new isolines based on highly effective antioxidant activity of lines-restorers of pollen fertility. Methods. Hybridization in sunflower breeding with evaluation on laboratory equipment of oil quality by the content of tocopherol isomers, basic fatty acids, and by antioxidant activity. Seeds of inbred generations were grown in the Eastern part of the Forest-Steppe of Ukraine. Results. A study has been carried out on the variability of fatty acids, isomers of tocopherols, antioxidant activity in the seeds of samples of genetic resources of sunflower, including sources created in leading research centers, as well as the working collection of domestic selection lines, F1 hybrids and hybrid populations of different levels of inbreeding with assessment in laboratory and field conditions in different years, during 2015–2020. Assessment of total tocopherols and individual isomers α, β, γ, σ, and antioxidant activity was determined by liquid chromatography on Smartline system (Knauer, Germany). The level of development of the main valuable economic traits was assessed in different periods of plant ontogenesis. The variability was established of tocopherol isomers α — with fluctuations of 1.01–56.79 mg%; β — 0.004–57.84; γ — 0.004–34.58; σ — 0.004–17.15 mg%. A classification is proposed according to the distribution used in the selection of newly created generations of sunflower and the development of quality standards for the content of tocopherols in oil. It is proved that the γ-isomer has the highest level of antioxidant activity. This promotes the use of this type of oil, which increases dozens of times the oxidation resistance. Indicators of the number of isomers important for sunflower breeding and oil quality were determined using classical selection genetic methods. The method of inbreeding of plants obtained as a result of crosses with donors of high tocopherol content and subsequent linear selection identified new isolines with altered content, which are characterized by valuable economic characteristics. Newly created lines X1716 B; X1717 B; X1719B and X1729B have a total content of tocopherols at the level of 41.29–48.26 mg% with different levels of individual isomers, which enriches the base of the National Center for Plant Genetic Resources of Ukraine. Conclusions. Existing genotypes were identified and the new lines with different content of tocopherol isomers and antioxidant activity were created. Indicators were improved of valuable economic characteristics — plant height, the weight of 1000 seeds, plant productivity, oil content in seeds, the content of certain fatty acids, disease resistance, the level of pollen fertility recovery, and combination ability.

GENEmops: Supervised feature selection from high dimensional biomedical dataset

Identification of differentially expressed genes, lying beneath the carcinogenic expression, is still very crucial for accurate detection and treatment of the disease. The challenge of a large number of attributes compared to a small number of instances and the prediction of highly discriminative genes requires an effective method. It can be regarded as a multi-objective problem that involves minimization of the number of selected genes and maximization of the classification performance. It is expected to find the optimal count of the most significant genes which are strongly associated with the classification of cancer. In this paper, we have proposed a framework entitled as GENEmops for gene selection and subsequent classification of the disease. The core of the GENEmops is inspired by multi-objective player selection strategy based hybrid population search (MOPS-HPS). The proposed system uses a multi-filtering and adaptive parameter tuning approach for gene selection. A new graded rotational blending operator is introduced to enhance the exploitation capability of the hybrid wrapper based scheme. Unlike the most current existing methods which employ some strategy to transmute the continuous search space to binary search space, it uses an adaptive way for binary conversion which is stochastically updated during the search phase. GENEmops also improves the performance of the classifier by tuning its parameters. The efficiency of the proposed GENEmops is tested on sixteen biological datasets (eight binary class and eight multi-class) and compared with state-of-the-art computationally intelligent multi-objective approaches. Experimental results demonstrate the efficiency of the proposed work.

Extensive Sympatry and Frequent Hybridization of Ecologically Divergent Aquatic Plants on the Qinghai-Tibetan Plateau.

Hybridization has fascinated biologists in recent centuries for its evolutionary importance, especially in plants. Hybrid zones are commonly located in regions across environmental gradients due to more opportunities to contact and ecological heterogeneity. For aquatic taxa, intrazonal character makes broad overlapping regions in intermediate environments between related species. However, we have limited information on the hybridization pattern of aquatic taxa in alpines, especially submerged macrophytes. In this study, we aimed to test the hypotheses that niche overlap and hybridization might be extensive in related aquatic plants across an altitudinal gradient. We evaluated the niche overlap in three related species pairs on the Qinghai-Tibetan Plateau and assessed the spatial pattern of hybrid populations. Obvious niche overlap and common hybridization were revealed in all three pairs of related aquatic plants. The plateau edge and river basins were broad areas for the sympatry of divergent taxa, where a large proportion of hybrid populations occurred. Hybrids are also discretely distributed in diverse habitats on the plateau. Differences in the extent of niche overlap, genetic incompatibility and phylogeographic history might lead to variation differences in hybridization patterns among the three species pairs. Our results suggested that plateau areas are a hotspot for ecologically divergent aquatic species to contact and mate and implied that hybridization may be important for the freshwater biodiversity of highlands.

Floral volatile chemical diversity in Hedychium F1 hybrid population

Floral scent profiles play crucial role in the ornamental values of cut flowers, and efficient floral scent profiling acquisition is a critical premise for quality assessment and genetic improvement of fragrant cut flowers. Despite the fact that cross breeding is an effective method for improving the fragrance of cut flowers, less focus has been paid on floral scent evaluation in cross populations due to the complexity of fragrance phenotype detection. In the current study, floral scent profile of Hedychium coronarium 'ZS', H. 'Jin' and their 110F1 hybrid cultivars were evaluated. Headspace solid phase microextraction- gas chromatography-mass spectrometry (HS–SPME–GC–MS) identified 33 volatile organic compounds (VOCs), including 15 monoterpenoids, 7 sesquiterpenoids, 9 phenylpropanoids, 1 fatty acid derivative, and 1 other, while proton transfer reaction-time of flight-mass spectrometry (PTR–ToF–MS) detected 68 masses. Correlation analysis indicated that β-myrcene, α-terpinene, eucalyptol, (E)-β-ocimene, cyclopentene, 3-isopropenyl-5, 5-, allo-ocimene, indole, isoamyl benzoate, (E)-β-famesene, m/z 74.069 and m/z 118.069 played an important role in sensory concentration of Hedychium flowers fragrance. Furthermore, partial least squares (PLS) analysis of VOCs and masses revealed that 44 masses were highly sensitive to 21 VOCs (8 monoterpenoids, 6 sesquiterpenoids, 5 benzenoids/phenylpropanoids, 1 fatty acid derivative, and indole). Overall, the data showed that two mass spectrometric methodologies were highly complementary, revealing a novel and dynamic perspective on volatile complex diversity of Hedychium F1 hybrid population cut flowers.

Insights Into the Genetics of the Zhonghua 11 Resistance to Meloidogyne graminicola and Its Molecular Determinism in Rice

Meloidogyne graminicola is a widely spread nematode pest of rice that reduces crop yield up to 20% on average in Asia, with devastating consequences for local and global rice production. Due to the ban on many chemical nematicides and the recent changes in water management practices in rice agriculture, an even greater impact of M. graminicola can be expected in the future, stressing the demand for the development of new sustainable nematode management solutions. Recently, a source of resistance to M. graminicola was identified in the Oryza sativa japonica rice variety Zhonghua 11 (Zh11). In the present study, we examine the genetics of the Zh11 resistance to M. graminicola and provide new insights into its cellular and molecular mechanisms. The segregation of the resistance in F2 hybrid populations indicated that two dominant genes may be contributing to the resistance. The incompatible interaction of M. graminicola in Zh11 was distinguished by a lack of swelling of the root tips normally observed in compatible interactions. At the cellular level, the incompatible interaction was characterised by a rapid accumulation of reactive oxygen species in the vicinity of the nematodes, accompanied by extensive necrosis of neighbouring cells. The expression profiles of several genes involved in plant immunity were analysed at the early stages of infection during compatible (susceptible plant) and incompatible (resistant plant) interactions. Notably, the expression of OsAtg4 and OsAtg7, significantly increased in roots of resistant plants in parallel with the cell death response, suggesting that autophagy is activated and may contribute to the resistance-mediated hypersensitive response. Similarly, transcriptional regulation of genes involved in hormonal pathways in Zh11 indicated that salicylate signalling may be important in the resistance response towards M. graminicola. Finally, the nature of the resistance to M. graminicola and the potential exploitation of the Zh11 resistance for breeding are discussed.

Dissection of the Genetic Basis of Yield Traits in Line per se and Testcross Populations and Identification of Candidate Genes for Hybrid Performance in Maize.

Dissecting the genetic basis of yield traits in hybrid populations and identifying the candidate genes are important for molecular crop breeding. In this study, a BC1F3:4 population, the line per se (LPS) population, was constructed by using elite inbred lines Zheng58 and PH4CV as the parental lines. The population was genotyped with 55,000 SNPs and testcrossed to Chang7-2 and PH6WC (two testers) to construct two testcross (TC) populations. The three populations were evaluated for hundred kernel weight (HKW) and yield per plant (YPP) in multiple environments. Marker–trait association analysis (MTA) identified 24 to 151 significant SNPs in the three populations. Comparison of the significant SNPs identified common and specific quantitative trait locus/loci (QTL) in the LPS and TC populations. Genetic feature analysis of these significant SNPs proved that these SNPs were associated with the tested traits and could be used to predict trait performance of both LPS and TC populations. RNA-seq analysis was performed using maize hybrid varieties and their parental lines, and differentially expressed genes (DEGs) between hybrid varieties and parental lines were identified. Comparison of the chromosome positions of DEGs with those of significant SNPs detected in the TC population identified potential candidate genes that might be related to hybrid performance. Combining RNA-seq analysis and MTA results identified candidate genes for hybrid performance, providing information that could be useful for maize hybrid breeding.

Heterosis and Responses to Selection in Orange-Fleshed Sweetpotato (Ipomoea batatas L.) Improved Using Reciprocal Recurrent Selection.

Sweetpotato is a highly heterozygous hybrid, and populations of orange-fleshed sweetpotato (OFSP) have a considerable importance for food security and health. The objectives were to estimate heterosis increments and response to selection in three OFSP hybrid populations (H1) developed in Peru for different product profiles after one reciprocal recurrent selection cycle, namely, H1 for wide adaptation and earliness (O-WAE), H1 for no sweetness after cooking (O-NSSP), and H1 for high iron (O-HIFE). The H1 populations were evaluated at two contrasting locations together with parents, foundation (parents in H0), and two widely adapted checks. Additionally, O-WAE was tested under two environmental conditions of 90-day and a normal 120-day harvest. In each H1, the yield and selected quality traits were recorded. The data were analyzed using linear mixed models. The storage root yield traits exhibited population average heterosis increments of up to 43.5%. The quality traits examined have exhibited no heterosis increments that are worth exploiting. The storage root yield genetic gain relative to the foundation was remarkable: 118.8% for H1-O-WAE for early harvest time, 81.5% for H1-O-WAE for normal harvest time, 132.4% for H1-O-NSSP, and 97.1% for H1-O-HIFE. Population hybrid breeding is a tool to achieve large genetic gains in sweetpotato yield via more efficient population improvement and allows a rapid dissemination of globally true seed that is generated from reproducible elite crosses, thus, avoiding costly and time-consuming virus cleaning of elite clones typically transferred as vegetative plantlets. The population hybrid breeding approach is probably applicable to other clonally propagated crops, where potential for true seed production exists.

Mapping QTLs for spring green-up, plant vigor, and plant biomass in two lowland switchgrass populations.

The online version contains supplementary material available at 10.1007/s11032-022-01296-7.

Genetic mapping and prediction of flowering time and plant height in a maize Stiff Stalk MAGIC population.

The Stiff Stalk heterotic pool is a foundation of US maize seed parent germplasm and has been heavily utilized by both public and private maize breeders since its inception in the 1930s. Flowering time and plant height are critical characteristics for both inbred parents and their test crossed hybrid progeny. To study these traits, a 6-parent multiparent advanced generation intercross population was developed including maize inbred lines B73, B84, PHB47 (B37 type), LH145 (B14 type), PHJ40 (novel early Stiff Stalk), and NKH8431 (B73/B14 type). A set of 779 doubled haploid lines were evaluated for flowering time and plant height in 2 field replicates in 2016 and 2017, and a subset of 689 and 561 doubled haploid lines were crossed to 2 testers, respectively, and evaluated as hybrids in 2 locations in 2018 and 2019 using an incomplete block design. Markers were derived from a practical haplotype graph built from the founder whole genome assemblies and genotype-by-sequencing and exome capture-based sequencing of the population. Genetic mapping utilizing an update to R/qtl2 revealed differing profiles of significant loci for both traits between 635 of the DH lines and 2 sets of 570 and 471 derived hybrids. Genomic prediction was used to test the feasibility of predicting hybrid phenotypes based on the per se data. Predictive abilities were highest on direct models trained using the data they would predict (0.55-0.63), and indirect models trained using per se data to predict hybrid traits had slightly lower predictive abilities (0.49-0.55). Overall, this finding is consistent with the overlapping and nonoverlapping significant quantitative trait loci found within the per se and hybrid populations and suggests that selections for phenology traits can be made effectively on doubled haploid lines before hybrid data is available.

Precise paternal ancestry of hybrid unisexual ZW lizards (genus Darevskia: Lacertidae: Squamata) revealed by Z-linked genomic markers

Abstract We genotyped multiple populations of all seven parthenogenetic species of rock lizards, genus Darevskia, as well as their putative sexual parental populations, using double digest RAD-sequencing genomic markers. Taking advantage of the conserved homology of the ZW/ZZ sex chromosomes among lacertid lizards, we aligned our short sequence reads to a reference Z chromosome assembly of the common wall lizard Podarcis muralis. This provided unique insight into the origin of all-female hybrid populations, which inherited their single Z chromosome exclusively from a paternal ancestor. The mapped Z-linked loci were used to construct a robust time-calibrated phylogeny. In each parent–offspring species pair, the geographically nearest population of the paternal species was identified as the most likely ancestor of the respective parthenogen, mirroring the trend observed previously on the maternal side in mitochondrial DNA. The estimated splits between the sampled paternal sexual ancestors and their daughter species occurred much earlier than suggested previously and during two narrow time periods: (1) the parthenogenetic Darevskia armeniaca, D. dahli, D. uzzelli and D. rostombekowi dated back to ~0.5 or ~0.9 Mya, depending on the calibration point used, while (2) D. bendimahiensis, D. sapphirina and D. unisexualis appear to have diverged ~1 or ~2 Mya.

Drastic shift in flowering phenology of F1 hybrids causing rapid reproductive isolation in Imperata cylindrica in Japan

Abstract Hybridization is a major source of phenotypic variation and a driving force for evolution. Although novel hybrid traits can often disrupt adaptive relationships between the parental phenotypes and their environments, how new hybrid traits disrupt local adaptation remains unclear. Here, we report how a new phenotype of hybrids between two Imperata cylindrica ecotypes contributes to rapid reproductive isolation from their parents and affects hybrid fitness. We analysed 350 accessions of I. cylindrica collected from the 1980s to the 2010s throughout Japan to explore the genetic population structure of the hybrids. We surveyed the flowering periods, seed set, and germination of two ecotypes and their hybrids in both natural habitats and common gardens. Genetic analyses of population structure revealed that the hybrid populations consisted of only F1 individuals, without advanced generation hybrids. The flowering phenology of the F1 plants was delayed until autumn, 5–6 months later than the parental ecotypes. The drastic shift in flowering phenology prevents F1s from backcrossing. In addition, it changes their seed dispersal time to winter. Germination is inhibited by low temperatures, and the seeds likely decay before the next spring, resulting in the absence of an F2 generation. We identified the environmental mismatch of the F1 population as a specific mechanism for the maintenance of an only F1 population. Synthesis. We have demonstrated that this flowering phenology mismatch promotes reproductive isolation between the parents and F1s and affects various temporal components of the hybrids, resulting in a unique hybrid population consisting only of F1s. This system sheds light on the importance of hybrid traits in driving rapid reproductive isolation.

High-quality variety of soft spring wheat Omskaya 44 for the conditions of Western Siberia and Omsk region

In 2015-2018 in the conditions of the Omsk region, a comprehensive assessment of the promising breeding material of soft spring wheat was carried out. A mid-ripening variety of soft spring wheat Omskaya 44 with a complex of adaptivevaluable properties and traits for cultivation in the forest-steppe zone of the Omsk region has been prepared for the state variety testing. Variety Omskaya 44 created by the method of intraspecific hybridization and directional individual selection from the hybrid population Lutescens 248/97-11 x Omskaya 38 (k-65566, Russia) was sent for the State Variety Testing carried out in 9, 10 and 11 regions of the Russian Federation in 2019. The purpose of the research was to evaluate the results of various types of tests of a new variety of soft spring wheat Omskaya 44 in the conditions of the Omsk region. The variety is high-yielding, of mid-season type, the growing season is 88 days, the average yield over the years of research in competitive variety testing is 4.47 t/ha, which exceeds the standard variety Duet by 1.51 t/ha (LSD05 = 0.33 t/ha), the maximum yield is 5.69 t/ha. The results of the production test showed that when sowing fallow, in 2018-2021 the yield was 4.65 t/ha on the average, for the standard variety Duet - 3.02 t/ha (LSD05 = 0.29 t/ha), after cereals − 3.43 t/ha, for the standard variety − 2.67 t/ha (LSD05 = 0.27 t/ha). The new variety Omskaya 44 significantly exceeded the Duet standard and the best variety in the forest-steppe zone Omskaya 38 in terms of yield. The parameters of ecological plasticity of the new variety have been studied: linearity regression coefficient bi = 1.13, stability factor sd2 = 0.25. The basic components of commercial value of the new variety Omskaya 44 are high and stable yield, resistance to leaf diseases and the formation of high-quality grain at the level of strong wheat. In 2021 the variety Omskaya 44 was included in the State Register of Breeding Achievements approved for use in the forest-steppe zone of the Omsk region.

The Phylogeography of Rhizophora in Peninsular Malaysia: High Genetic Variation between West and East

Geographic history of Rhizophora species and hybrid is effect on their genetic structure. In addition, determining population genetic variation is essential for phylogeography research. For this phylogeography investigation, Four natural population of Rhizophora were collected from five different regions in peninsular Malaysia for this phylogeography study. This study aims to evaluate the genetic diversity of Rhizophora species namely Rhizophora apiculata , Rhizophora mucronata , Rhizophora stylosa and hybrid R. × lamarcki and clarify their genetic structure of its populations using Nucleotide polymorphism in chloroplast intergenic spacer between trnL and trnF genes was studied.The populations of Rhizophora species and hybrids were divided into two groups: the east coast populations, which were represented by samples collected from Mersing, Tanjang Piai, and Sedili; and the west coast populations, which were represented by samples collected from Mersing, Tanjang Piai, and Sedili. The population of the west coast was the second cluster. This result was supported by UPGMA analysis using MEGA5 software.

The Phylogeography of Rhizophora in Peninsular Malaysia: High Genetic Variation between West and East

Geographic history of Rhizophora species and hybrid is effect on their genetic structure. In addition, determining population genetic variation is essential for phylogeography research. For this phylogeography investigation, Four natural population of Rhizophora were collected from five different regions in peninsular Malaysia for this phylogeography study. This study aims to evaluate the genetic diversity of Rhizophora species namely Rhizophora apiculata , Rhizophora mucronata , Rhizophora stylosa and hybrid R. × lamarcki and clarify their genetic structure of its populations using Nucleotide polymorphism in chloroplast intergenic spacer between trnL and trnF genes was studied.The populations of Rhizophora species and hybrids were divided into two groups: the east coast populations, which were represented by samples collected from Mersing, Tanjang Piai, and Sedili; and the west coast populations, which were represented by samples collected from Mersing, Tanjang Piai, and Sedili. The population of the west coast was the second cluster. This result was supported by UPGMA analysis using MEGA5 software.

Conjunctive Analyses of Bulk Segregant Analysis Sequencing and Bulk Segregant RNA Sequencing to Identify Candidate Genes Controlling Spikelet Sterility of Foxtail Millet.

Foxtail millet has gradually become a model gramineous C4 crop owing to its short growth period and small genome. Research on the development of its spikelets is not only directly related to the yield and economic value of foxtail millet but also can provide a reference for studying the fertility of other C4 crops. In this study, a hybrid population containing 200 offspring was constructed from the Xinong8852 and An15 parental lines, and two extreme trait populations were constructed from the F2 generation for analysis of the spikelet sterility. The F2 population conformed to a 3:1 Mendelian segregation ratio, and it was thus concluded that this trait is likely controlled by a single recessive gene. Bulk segregant analysis sequencing (BSA-Seq) was used to determine the candidate regions and candidate genes related to the development of foxtail millet spikelets. Additionally, the functional analysis of differentially expressed genes in populations with different traits was conducted by bulk segregant RNA sequencing (BSR-Seq). Finally, conjunctive analysis of BSA-Seq and BSR-Seq results, combined with biological information analysis, revealed six genes on chromosome VII that were ultimately identified as candidate genes controlling foxtail millet spikelet development. This study provides a new reference for research on foxtail millet sterility and lays a solid foundation for the examination of fertility in other gramineous crops.

A Novel Strategy to Reveal the Landscape of Crossovers in an F1 Hybrid Population of Populus deltoides and Populus simonii.

Although the crossover (CO) patterns of different species have been extensively investigated, little is known about the landscape of CO patterns in Populus because of its high heterozygosity and long-time generation. A novel strategy was proposed to reveal the difference of CO rate and interference between Populus deltoides and Populus simonii using their F1 hybrid population. We chose restriction site-associated DNA (RAD) tags that contained two SNPs, one only receiving the CO information from the female P. deltoides and the other from the male P. simonii. These RAD tags allowed us to investigate the CO patterns between the two outbred species, instead of using the traditional backcross populations in inbred lines. We found that the CO rate in P. deltoides was generally greater than that in P. simonii, and that the CO interference was a common phenomenon across the two genomes. The COs landscape of the different Populus species facilitates not only to understand the evolutionary mechanism for adaptability but also to rebuild the statistical model for precisely constructing genetic linkage maps that are critical in genome assembly in Populus. Additionally, the novel strategy could be applied in other outbred species for investigating the CO patterns.