Cross Compatibility Research Articles

Tetraploid Induction by Colchicine Treatment and Crossing with a Diploid Reveals Less-Seeded Fruit Production in Pointed Gourd (Trichosanthes dioica Roxb.).

Pointed gourd (Trichosanthes dioica Roxb.) (2n = 2x = 22) is a dioecious cucurbit vegetable and green fruit that is edible after cooking. Consumers prefer to consume seedless or less-seeded fruit because seeds are unpalatable due to their hard coats. Therefore, the cross compatibility between the diploid and induced tetraploid will be helpful for seedless or less-seeded fruit production. Thus, the present study was conducted using mature seeds that were immersed in 0.05%, 0.1%, and 0.5% colchicine for 24, 48, and 72 h to induce tetraploids. These tetraploids were used as parents (male or female) in the inter-ploidy and intra-ploidy crosses. A flow cytometric analysis confirmed the induction of three tetraploids at 0.5% colchicine for 48 and 72 h soaking periods. Among these, two (2) females and one (1) male were differentiated after flower initiation. Crossing between the tetraploid’s maternal and diploid paternal parent (4x × 2x), which were revealed to be compatible, resulted in a similar fruit set rate and shape as those of the diploid. In addition, a seed number of 4x × 2x produced fruits that were drastically reduced to 1.8 seeds per fruit, whereas the natural diploid fruits had 26.4 seeds per fruit. These findings suggest that colchicine-induced tetraploid females are important genetic resources for less-seeded fruit production. The genetic stability of tetraploid clones can easily and effectively be maintained by vine cutting for advanced uses.

The functional roles of 3D heterostyly and floral visitors in the reproductive biology of Turnera subulata (Turneroideae: Passifloraceae)

Heterostyly is a floral polymorphism that reduces conflicts between sexual functions (sexual interference), such as self-pollination in self-incompatible flowers and loss of pollen to incompatible stigmas. In many distylous pollination systems, there is a remarkable structural fit between the stigmas of each morph and the part of the pollinator body where compatible (disassortative) pollen is deposited. Nevertheless, inter-morph pollen transfer is often asymmetrical, with short-styled flowers (S-morph) receiving less compatible pollen than long-styled flowers (L-morph). One way to reduce the problem of sexual interference in short-styled flowers is to place stigmas outside of the flower centre, as seen in three-dimensionally (3D) heterostylous flowers. Heterostyly in Turnera has been extensively studied; however, 3D heterostyly has not been previously reported in this genus. The aims of this study were: 1) to elucidate the pollination system of T. subulata; and 2) to assess whether 3D heterostyly promotes disassortative pollination and reduces self-pollination in short-styled flowers in this taxon. The study population of Turnera subulata exhibited an isoplethic (1:1) ratio, with two well-defined morphs, and a high floral accuracy index for both morphs. Results from an experiment in which we manipulated the 3D orientation of the style showed that compatible crosses were favoured by the 3D flower morphology, consistent with a high floral accuracy. Our results also demonstrate the functional importance of 3D heterostyly in reducing intramorph pollination, as it increases the amount of cross pollen reaching the S-morph flowers. Our results provide the first observation of the presence of 3D heterostyly in this well-studied species and demonstrate the importance of this kind of morphological specialization in ensuring efficiency in an ecologically generalized pollination system.

Recent progress of intra-specific hybridization of tea (<em>Camellia sinensis,</em> (L.) O. Kuntze) in Sri Lanka

Tea germplasm accessions are the most valuable material for tea breeding. However its utilization in the past was limited due to lack of available information. Recently generated information on genetic structure and metabolite profiles of the germplasm were used in selecting parents for hybridization programmes from 2012 to 2016. The main focus of the programme was to make crosses between three taxa of tea viz. Camellia. sinensis var. assamica (Assam type), C. sinensis var. sinensis (China type) and C. sinensis spp. lasiocalyx (Cambod type). Pollinated buds were closely-monitored and the number of crosses, number of fruits, number of seeds and reproductive parameters were recorded. A total of 3978 crosses (2405 direct crosses and 1573 reciprocal crosses) were made and 974 seeds were obtained from 595 fruits. Percentages of fruit set and seed set varied significantly among different families. Irrespective of the inter-subspecies groups, the percentage of seed germination was above 50% and was not significantly-different. Cross compatibility between taxa in terms of percentage of fruit set ranged from 4.6% to 25.6% and varied significantly. Among the inter-subspecies crosses the Assam varieties were found to be the best as female parent. The generated information would be useful for selection of parents and tea improvement programmes in the future.

Studies on cross compatibility in Jasminum spp.

The present investigation was carried out to study the compatibility among six Jasminum species during 2016–17. Among open, self and artificial cross pollination, the open pollination resulted in maximum degree of fruit and seed set proving the open pollination to be the best method of pollination. The best time for pollination was the time of anthesis. The species Jasminum malabaricum and Jasminum auriculatum were superior as seed parents.

Cross Compatibility Analysis to Identify Suitable Parents of Tagetes erecta and T. patula for Heterotic Hybrid Breeding

Seven interspecific crosses of Tagetes erecta × T. patula were conducted in this study. The cross compatibility index, seed setting rate, germination rate, phenotype, ploidy level, heterosis over male parent and field performance were tested. The results showed that different cross compatibility indices of Tagetes vary greatly, from 10.44~114.41, which is far less than that of the intraspecific hybridization S-121 × I-506 index. The seed setting rate of each cross ranged from 15.67% to 49.0%, and the cross S-121 × TP-512 scored the highest seed setting rate, which was higher than that of the intraspecific cross S-121 × I-506 (35.85%). Compared with the male parent, F1 has higher plant height, wider crown width, larger flower diameter and more ray florets and earlier bloom with two exceptions. The S-121 of T. erecta was diploid. All of the male parents of T. patula were tetraploids, and the combinations were triploids. The traits of plant height, plant width, flower size and number of ray florets showed positive heterosis over the male parents, and the days leading to flowering showed both positive and negative ones. Finally, S-121 × TP-379 and S-121 × TP-512 were selected as the two best combinations. This study confirmed that the two species of marigold could be crossed for better F1 varieties with improved performance.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Transcriptome Analysis Provides Insight into the Molecular Mechanisms Underlying gametophyte factor 2-Mediated Cross-Incompatibility in Maize

In maize (Zea mays L.), unilateral cross-incompatibility (UCI) is controlled by Gametophyte factors (Ga), including Ga1, Ga2, and Tcb1; however, the molecular mechanisms underpinning this process remain unexplored. Here, we report the pollination phenotype of an inbred line, 511L, which carries a near-dominant Ga2-S allele. We performed a high-throughput RNA sequencing (RNA-Seq) analysis of the compatible and incompatible crosses between 511L and B73, to identify the transcriptomic differences associated with Ga2-mediated UCI. An in vivo kinetics analysis revealed that the growth of non-self pollen tubes was blocked at the early stages after pollination in 511L, maintaining the UCI barrier in Ga2. In total, 25,759 genes were expressed, of which, 2063 differentially expressed genes (DEGs) were induced by pollination (G_GG, G_GB, B_BB, B_BG). A gene ontology (GO) enrichment analysis revealed that these genes were specifically enriched in functions involved in cell wall strength and pectic product modification. Moreover, 1839, 4382, and 5041 genes were detected to differentially express under same pollination treatments, including B_G, BG_GG, and BB_GB, respectively. A total of 1467 DEGs were constitutively expressed between the two inbred lines following pollination treatments, which were enriched in metabolic processes, flavonoid biosynthesis, cysteine biosynthesis, and vacuole functions. Furthermore, we confirmed 14 DEGs related to cell wall modification and stress by qRT-PCR, which might be involved in Ga2-S-mediated UCI. Our results provide a comprehensive foundation for the molecular mechanisms involved in silks of UCI mediated by Ga2-S.

Research Article Characterization of gametophytic self-incompatibility of superior clones of Coffea canephora

The ability to avoid self-pollination is a trait that evolved as a manner of reducing the deleterious effects of inbreeding in various allogamous plant species, including Coffea canephora. The aim of this study was to perform directed hybridizations to characterize the compatibility groups of superior C. canephora clones, since plant selection can reduce variability for this trait. For that purpose, directed hybridizations were carried out in cross arrangements using a balanced diallel without self-fertilization and without reciprocals. The genotypes evaluated were derived from open pollination and from directed hybridizations using Encapa03 as a male parent donor of pollen grains and Robusta640, Robusta 2258, and Robusta1675 as female parent receptors of pollen grains. To control the occurrence of type I and type II errors, the likelihood ratio test was used. Compatible crosses were predominant (73.7%). Compatible crosses exhibited a mean rate of fruit set of 44%, with amplitude from 26% to 77%. Of the total of 80 crosses performed, three crosses exhibited unexpected results according to the grouping proposed (P08 x P16, P09 x P15, P09 x P16). From the degree of kinship, the genealogy of the S gene and the segregation of the alleles from one generation to another was estimated. The genotypes P12, P14, and P10 exhibited the highest estimates of LOD score associated with their clustering in groups I, II, and III. These genotypes may be used as tester plants of their compatibility groups

Origin and thought on the philosophical ideas of acupuncture in Chinese medicine

Acupuncture in Chinese medicine has been a treasure in Chinese traditional medicine for thousands of years. It is opposite to many basic theories in modern medicine in dynasties. Different from the cross compatibility and interactions among medical medicines, acupuncture in Chinese medicine has its own consolidation and inherent philosophical ideas. In view of this, how to discuss the philosophical ideas and its development of acupuncture in Chinese medicine becomes of great importance. It is crucial to clearly answer the three theoretical propositions in the development of acupuncture in Chinese medicine. Firstly, the differences in acupuncture should be identified between the ancient time and the modern time. The issues focus on the origin of Huangdi Neijing (Yellow Emperor's Internal Medicine) and its philosophical divergence. Secondly, the origin of acupuncture should be identified, whether it is from China or India. Thirdly, the differences in acupuncture should be identified between China and the west, focusing on the explanation and rectification of the interrelationship between the acupuncture in Chinese medicine and the western acupuncture. Hence, the basic features are discussed on the reality of acupuncture in Chinese medicine as well as its diversity. Finally, the proposition is extended on how to holistically grasp the philosophical foundation of acupuncture in Chinese medicine and its future trend.

Characterization of an intergeneric hybrid of Erianthus procerus × Saccharum officinarum and its backcross progenies

Erianthus, a related genus grouped under ‘Saccharum complex’ is seriously considered as a potential genetic resource for imparting high biomass production, multi ratooning ability, resistance to major diseases and pests and tolerance to abiotic stresses to sugarcane varieties. However introgression of Erianthus had limited success in the past in view of the high genetic distance between the two genera and the consequent low compatibility of such crosses. The inherent difficulty in precisely identifying the true hybrids from the selfed progenies from such crosses also remains a difficult task. In this article we report the production of an intergeneric hybrid GU04(28) EO2 involving Erianthus and Saccharum. The hybrid was characterized using 5s rDNA markers and evaluated for agro-morphological traits. The chromosome number of the Erianthus procerus × Saccharum officinarum hybrid approximated to 2n + n transmission with elimination of few chromosomes. The hybrid showed relatively low stalk weight and thickness, but had high yield potential in view of the high stalk population. The hybrid also showed high drought tolerance and resistance to red rot disease. This hybrid was backcrossed to a commercial sugarcane variety Co 06027. Erianthus-specific 5s rDNA marker was present in five of the BC1 progenies, thus confirming their Erianthus derivation. The chromosome number of the BC1 progenies ranged from 2n = 88–94, consistent with n + n transmission. The BC1 progenies showed significant improvement in stalk weight and juice sucrose over the F1 hybrid and it may be possible to develop varieties with commercial potential with few more backcrosses. The Erianthus × Saccharum hybrid GU04(28) EO2 is thus a potential source for diversifying the genetic base of the sugarcane varieties as it combines the genomes of two distantly related genera and also in view of its yield potential, red rot resistance and drought tolerance.

Cube term blockers without finiteness

We show that an idempotent variety has a d-dimensional cube term if and only if its free algebra on two generators has no d-ary compatible cross. We employ Hall’s Marriage Theorem to show that an idempotent variety $${\mathcal{V}}$$ of finite signature whose fundamental operations have arities n 1, . . . , n k, has a d-dimensional cube term for some d if and only if it has one of dimension $${1 + \sum_{i=1}^{k} (n_{i} - 1)}$$ . This upper bound on the dimension of a minimal-dimension cube term for $${\mathcal{V}}$$ is shown to be sharp. We show that a pure cyclic term variety has a cube term if and only if it contains no 2- element semilattice. We prove that the Maltsev condition “existence of a cube term” is join prime in the lattice of idempotent Maltsev conditions.

Fruit shape and reproductive self and cross compatibility for the performance of fruit set in an andromonoecious species: Xanthoceras sorbifolium Bunge

A replicated 6 × 6 complete diallel mating among six fruit shape types of Xanthoceras sorbifolium (yellowhorn), an andromonoecious plant known for its exceedingly low fruit and seed set, was conducted to investigate the species mating system. This mating design was implemented to investigate the relationship between fruit shape type and fruit yield, finding the most productive fruit shape-type matings, and explore maternal and paternal plants spatial arrangements for yield enhancement. The study confirmed the maternal inheritance of fruit shape type, open-pollination often associated with low fruit production, the presence of high inbreeding depression, and differential yield among fruit shape-type matings and directions and identified specific matings between fruit shape types with increased yield potential for the species’ commercial production. A high fruit yield planting spatial arrangement of parents is proposed and its pro et contra under open-pollinated production mode were discussed.

McMullen polynomials and Lipschitz flows for free-by-cyclic groups

Consider a group G and an epimorphism u_0\colon G\to \mathbb Z inducing a splitting of G as a semidirect product ker (u_0)\rtimes_\varphi \mathbb Z with ker (u_0) a finitely generated free group and \varphi\in Out (ker (u_0) ) representable by an expanding irreducible train track map. Building on our earlier work [DKL], in which we realized G as \pi_1(X) for an Eilenberg–Maclane 2-complex X equipped with a semiflow \psi , and inspired by McMullen's Teichmüller polynomial for fibered hyperbolic 3-manifolds, we construct a polynomial invariant \mathfrak m \in \mathbb Z[H_1(G;\mathbb Z)/ torsion] for (X,\psi) and investigate its properties. Specifically, \mathfrak m determines a convex polyhedral cone \mathcal C_X\subset H^1(G;\mathbb R) , a convex, real-analytic function \mathfrak H\colon \mathcal C_X\to \mathbb R , and specializes to give an integral Laurent polynomial \mathfrak m_u(\zeta) for each integral u\in \mathcal C_X . We show that \mathcal C_X is equal to the "cone of sections" of (X,\psi) (the convex hull of all cohomology classes dual to sections of of \psi ), and that for each (compatible) cross section \Theta_u\subset X with first return map f_u\colon \Theta_u\to \Theta_u , the specialization \mathfrak m_u(\zeta) encodes the characteristic polynomial of the transition matrix of f_u . More generally, for every class u\in \mathcal C_X there exists a geodesic metric d_u and a codimension-1 foliation \Omega_u of X defined by a "closed 1-form" representing u transverse to \psi so that after reparametrizing the flow \psi^u_{s} maps leaves of \Omega_u to leaves via a local e^{s\mathfrak H(u)} -homothety. Among other things, we additionally prove that \mathcal C_X is equal to (the cone over) the component of the BNS-invariant \Sigma(G) containing u_0 and, consequently, that each primitive integral u\in \mathcal C_X induces a splitting of G as an ascending HNN-extension G = Q_u\ast_{\phi_u} with Q_u a finite-rank free group and \phi_u\colon Q_u\to Q_u injective. For any such splitting, we show that the stretch factor of \phi_u is exactly given by e^{\mathfrak H(u)} . In particular, we see that \mathcal C_X and \mathfrak H depend only on the group G and epimorphism u_0 .

The assessment of incompatibility and cross-compatibility in three populations of European globeflower (Trollius europaeus L.) by observing the pollen tubes growth

<span>The European globeflower was shown to be highly self‐incompatible by flower bagging experiments, however, a very small degree of selfing was observed in natural populations. The present study is an attempt to evaluate the level of self-incompatibility (SI) in three <em>Trollius europaeus</em> populations from different sites of Poland and to assess a degree of cross-compatibility (CC) between these populations. The SI and CC of the globeflower populations were evaluated based on the pollen germination index (PGI). The observations of pollen grains germination and pollen tubes penetration were made in pistils after self- and diallel cross-pollination of globeflower plants. The pollination combinations which had the PGI equal or higher than 2 were regarded as compatible. Generally, the PGI after self-pollination of all globeflower population was over 2, indicating that they are self-compatible. Also, in two globeflower populations after cross-pollination the PGI was higher than 2 showing that there was cross-compatibility between plants of these two populations. However, the third population, from Biedrusko, was fully cross-incompatible.</span>

Field-based artificial crossings indicate partial compatibility of reciprocal crosses between Pinus sylvestris and Pinus mugo and unexpected chloroplast DNA inheritance

Crossability relationships between Scots pine (Pinus sylvestris L.) and mountain dwarf pine (Pinus mugo Turra) was studied, using artificial pollination approach. Partial compatibility of the reciprocal crossings of these species was proved experimentally, validating the idea of a spontaneous formation of their hybrid swarms under natural conditions. The hybrids were validated using organellar DNA markers and nuclear DNA microsatellites. Based on the percentage of filled seeds, the interspecific crossings were less efficient than the intraspecific cross-pollinations of P. sylvestris and P. mugo individuals. Both species were found to intercross readily with individuals of their putative hybrid swarm, P. mugo exhibiting a higher hybridological affinity towards putatively hybrid individuals than P. sylvestris. Validation of the hybrids confirmed the paternal inheritance of chloroplast DNA (cpDNA) in the combination P. sylvestris × P. mugo only. Surprisingly, in the reciprocal crossing P. mugo × P. sylvestris, maternal inheritance of cpDNA was revealed. Obtained results offer a new insight into the direction and intensity of gene flow within the hybrid swarms of Scots pine and mountain dwarf pine.

31. 梨新品種の交配親和性に関する調査(談話会年次講演会講演要旨昭和36年度)

31. 梨新品種の交配親和性に関する調査(談話会年次講演会講演要旨昭和36年度)

PERSILANGAN INTERSPESIFIK ANGGREK HITAM (Coelogyne pandurata) DENGAN ANGGREK MUTIARA (Coelogyne asperata)

Black orchid (Coelogyne pandurata) and Pearl orchid (Coelogyne asperata) are endemic orchid from Kalimantan forest, shape and color suitable as ornamental flower. Many people collected the orchids from the wild for commercial purpose but not much effort on their propagation. To prevent population decreased, propagation and production of new varities via interspesific hybridisation need to be done. An important step required in plant breeding is to obtain cross compatiblity. Cross compatibility of some orchids from Indonesia are not known, including compatibility of Coelogyne pandurata x Coelogyne asperata. Information on compatibility and fertility is very important to produce good quality seed as propagation material. In this research pollination was performed on orchid plants at 2 until 5 day after flowering and pollination was done in the morning. There are three replicates for each pollination. Pollination was done with C. pandurata (black orchid) as male parent and C. asperata (pearl orchid) as female parent. The results showed that successful pollination was obtained from pollination at 2 days after flowering. Seed capsule was harvested at 3 months after pollination but not yet perfectly ripe. Seed germination employed in vitro method on Vacin & Went (VW) and VW with modification media. Seed from C. pandurata x C. asperata abled to germinate on VW media with addition of 0,1 mg/l auxin and 0.1 mg/l cytokinin and germinated 9 weeks after planting.

Using laterally compatible cross sections to infer fault growth and linkage models in foreland thrust belts

We investigate changes in shortening, displacement and fold geometry to understand the detailed along-strike structural variation within fold-thrust belts, and infer thrust growth and linkage mechanisms. Field observations from the Vercors in SE France are used to characterise deformation style in the region. Parallel cross sections are constructed, analysed and used to create shortening and thrust displacement profiles from the northern to southern Vercors. Sections show changes in structural style and shortening accommodation from thrust-dominated in the north to fold-dominated in the south. The total shortening distance in the Vercors does not change significantly along strike (3400–4650 m), however displacements along individual thrust zones do vary significantly and displacement profiles show a range in displacement gradients (16–107 m/km). Despite relatively simple shortening patterns in the Vercors, sections show a more complex 3D internal structure of the fold-thrust belt. Thrust displacements and geometries suggest both large-scale thrust zones and small-scale thrusts are soft linked, transferring displacement along strike through transfer zones. Short, soft-linked thrust segments indicate an intermediate stage of thrust growth and linkage, well documented for normal fault systems, which form prior to the formation of thrust branches and hard-linked displacement transfer.

Compatibility study using hybridization procedure among Pleurotus genotypes and authentication by enzyme expression and ITSR of rDNA

Cross compatibility and authentication of hybrid genotypes among species of Pleurotus were studied using lignocellulotic enzymes production and Internal transcribed spacer (ITS) of rDNA. Schematic procedure of hyphal anastomosis hybridization between the species of Pleurotus was employed in this study. Formation of clamp connexion, changes in morphological hyphal arrangement and general increased in the enzymes production by the hybrid strains over their wild types is an evidence for the compatibility of crossed genotypes. Highest produced enzyme was manganese peroxidase by hybrid LN 97 with 3.25 Uml–1, followed by laccase with 3.06 Uml–1 obtained in LN 91 (hybrid). Lignin peroxidase was the least enzyme produced, but with better performance in hybrid LN 97 (2.75 Uml–1). Dendrogram of relationship among the genotypes revealed two major clusters. Cluster II contained singleton (LN 95), hybrid strain which totally separated from both parents. Most strains clustered away from their parents, authenticating the hybrids produced. Current study shows the Pleurotus employed for this investigation are cross compatible with high expression of heterosis in hybrid strains relative to the parents on the basis of enzymes produced. This technique could serve as a good tool in breeding programs for Pleurotus strain improvement.

Inter-specific and Inter-generic Hybridization Compatibility of Eriobotrya Species (Loquat) and Related Genera

We studied the cross-compatibility among 91 inter-specific combinations and 21 inter-generic combinations in 7 Eriobotrya plants and 2 related genera (Raphiolepis indica Lindl. and Photinia serrulata Lindl.) using emasculation, bagging, and artificial pollination. Our results showed that 28 of the 91 inter-specific combinations set no fruit, which means nearly 30% of the combinations were incompatible. In the remaining 63 combinations, most showed partial cross-compatibility, and a few showed complete cross compatibility. Eriobotrya plants were incompatible with plants from their related genera (R. indica Lindl. and P. serrulata Lindl.). Backcrossing produced 5 compatible combinations, which could set fruits and produce F1 progeny but only after embryo rescue. Fruit setting ratios varied among various species used as male or female parents. E. prinoides Rehd. & Wils., common loquat (E. japonica) and Eriobotrya × daduheensis, used as female parents resulted in an average fruit-setting ratio of 36.2%–58.2%. E. deflexa Nakai and its two forms, and E. elliptica Lindl. as female parents resulted in 2.9%–16.3% average fruit-setting ratio; however, the fruit set ratio was higher (22.4%–43.1%) if they were used as male parents. Failure of E. deflexa f. koshunensis Nakai × E. prinoides Rehd. & Wils. hybrids to set fruit could be attributed to sporophytic incompatibility.

Mitochondrial genome sequences from wild and cultivated barley (Hordeum vulgare).

BackgroundSequencing analysis of mitochondrial genomes is important for understanding the evolution and genome structures of various plant species. Barley is a self-pollinated diploid plant with seven chromosomes comprising a large haploid genome of 5.1 Gbp. Wild barley (Hordeum vulgare ssp. spontaneum) and cultivated barley (H. vulgare ssp. vulgare) have cross compatibility and closely related genomes, although a significant number of nucleotide polymorphisms have been reported between their genomes.ResultsWe determined the complete nucleotide sequences of the mitochondrial genomes of wild and cultivated barley. Two independent circular maps of the 525,599 bp barley mitochondrial genome were constructed by de novo assembly of high-throughput sequencing reads of barley lines H602 and Haruna Nijo, with only three SNPs detected between haplotypes. These mitochondrial genomes contained 33 protein-coding genes, three ribosomal RNAs, 16 transfer RNAs, 188 new ORFs, six major repeat sequences and several types of transposable elements. Of the barley mitochondrial genome-encoded proteins, NAD6, NAD9 and RPS4 had unique structures among grass species.ConclusionsThe mitochondrial genome of barley was similar to those of other grass species in terms of gene content, but the configuration of the genes was highly differentiated from that of other grass species. Mitochondrial genome sequencing is essential for annotating the barley nuclear genome; our mitochondrial sequencing identified a significant number of fragmented mitochondrial sequences in the reported nuclear genome sequences. Little polymorphism was detected in the barley mitochondrial genome sequences, which should be explored further to elucidate the evolution of barley.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3159-3) contains supplementary material, which is available to authorized users.