Male Sterility Trait Research Articles

Morphological Characterization of a New and Easily Recognizable Nuclear Male Sterile Mutant of Sorghum (Sorghum bicolor).

Sorghum (Sorghum bicolor L. Moench) is one of the most important grain crops in the world. The nuclear male sterility (NMS) trait, which is caused by mutations on the nuclear gene, is valuable for hybrid breeding and genetic studies. Several NMS mutants have been reported previously, but none of them were well characterized. Here, we present our detailed morphological characterization of a new and easily recognizable NMS sorghum mutant male sterile 8 (ms8) isolated from an elite inbred BTx623 mutagenized by ethyl methane sulfonate (EMS). Our results show that the ms8 mutant phenotype was caused by a mutation on a single recessive nuclear gene that is different from all available NMS loci reported in sorghum. In fertile sorghum plants, yellow anthers appeared first during anthesis, while in the ms8 mutant, white hairy stigma emerged first and only small white anthers were observed, making ms8 plants easily recognizable when flowering. The ovary development and seed production after manual pollination are normal in the ms8 mutant, indicating it is female fertile and male sterile only. We found that ms8 anthers did not produce pollen grains. Further analysis revealed that ms8 anthers were defective in tapetum development, which led to the arrest of pollen formation. As a stable male sterile mutant across different environments, greenhouses, and fields in different locations, the ms8 mutant could be a useful breeding tool. Moreover, ms8 might be an important for elucidating male gametophyte development in sorghum and other plants.

Cytoplasmic male sterility and prospects for its utilization in potato breeding, genetic studies and hybrid seed production

Increasing interest in cytoplasmic male sterility (CMS) and the search for pollen fertility restorer (Rf) genes in potato have arisen due to a new strategy in breeding of this important crop which is based on the development of heterotic hybrids produced by crossing of inbred diploid lines. The paper reviews the main results of the studies on the CMS-Rf genetic systems in different crop species, the modern methods and approaches of investigating the molecular mechanisms of CMS and pollen fertility restoration, and also the available published data on the status of these studies on potato. The nature of the chimeric mitochondrial genes associated with CMS is considered; the peculiarities of the structure and functions of pollen fertility restorer genes are discussed.Examples of CMS-Rf genetic systems in crop species including representatives of the Solanaceae family are presented. The main results of the research on the molecular mechanisms of CMS and fertility restoration obtained in the postgenomic era for various crop species using methods of transcriptomic and proteomic analyses are provided. As in many plant species, CMS in potato is of a hybrid origin. The results are presented of investigating the genetic control of male sterility in potato that have been carried out using conventional approaches (hybridological analysis) and that led to the formation of the concept of ‘genetic-cytoplasmic male sterility’ in some species of the Petota section of the Solanum genus. The characteristics of potato cytoplasmic types carrying male sterility factors are discussed. According to the modern classification of Hosaka and Sanetomo (2012) these types include T/beta, W/gamma, and D, each distinguished by the specific phenotypic appearance of male sterility traits and also by the frequency of their occurrence in the breeding gene pool and in various potato species. The results of the studies on developing DNA markers for identifying different cytoplasmic types in potato are presented.

Comparative genomic analysis of the compound Brassica napus Rf locus.

BackgroundThe plant trait of cytoplasmically-inherited male sterility (CMS) and its suppression by nuclear restorer-of-fertility (Rf) genes can be viewed as a genetic arms race between the mitochondrial and nuclear genomes. Most nuclear Rf genes have been shown to encode P-type pentatricopeptide repeat proteins (PPRs). Phylogenetic analysis of P-class PPRs from sequenced plants genomes has shown that Rf-proteins cluster in a distinct clade of P-class PPRs, RFL-PPRs, that display hallmarks of positive evolutionary selection. Genes encoding RFL-PPRs (RFLs) within a given plant genome tend to be closely related both in sequence and position, but a detailed understanding of how such species-specific expansion occurs is lacking. In the canola, (oilseed rape) species Brassica napus, previous work has indicated the nuclear restorer genes for the two native forms of CMS, Rfn (for nap CMS) and Rfp (pol CMS), represent alternate haplotypes, or alleles, of a single nuclear locus.ResultsFine genetic mapping indicates that Rfn does indeed localize to the same genomic region as Rfp. We find this region is enriched in RFL genes, three of which, based on their position and expression, represent potential candidates for Rfn; one of these genes, designated PPR4, is a preferred candidate in that it is not expressed in the nap CMS line. Comparison of the corresponding regions of the genomes of B. rapa, B. oleracea, Arabidopsis thaliana and A. lyrata provides insight into the expansion of this group of RFL genes in different lines of evolutionary descent.ConclusionsUnlike other nuclear restorer loci containing multiple RFL genes, the RFL genes in the Rf region of B. napus are not present in tandem arrays but rather are dispersed in genomic location. The genes do not share similar flanking non-coding regions and do not contain introns, indicating that they have duplicated primarily through a retrotransposition-mediated process. In contrast, segmental duplication has been responsible for the distribution of the 10 sequences we annotated as RFL genes in the corresponding region of the A. lyrata genome. Our observations define the Brassica Rf locus and indicate that different mechanisms may be responsible for the proliferation of RFL genes even among closely related genomes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3117-0) contains supplementary material, which is available to authorized users.

PAP3 Regulates Stamen but Not Petal Development in Capsicum annuum L.

Pepper flowers are hermaphroditic; the plant's male sterility trait is characterized by its inability to produce pollen grains. In the ABC model of flower development, B-function genes play roles in petal and stamen development in the angiosperm. In this study, a B-class gene designated as PAP3 (GenBank accession no. HM104635) was isolated in pepper. The gene encoded 226 amino acids and shared high similarity with the MADS-box protein family, with a conservative MADS domain and semiconservative K domain. Furthermore, the expression of PAP3 was abundant only in petals and anthers but not in leaves. A functional study employing virus-induced gene silencing (VIGS) showed that knockdown of PAP3 led to the shriveling of pollen grains and male sterility; however, it did not affect petal development. These results suggest an essential role for PAP3 in the development of the pepper stamen and in contributing to the variation of floral traits.

Determination of male strobilus developmental stages by cytological and gene expression analyses in Japanese cedar (Cryptomeria japonica).

The molecular mechanisms that control male strobilus development in conifers are largely unknown because the developmental stages and related genes have not yet been characterized. The determination of male strobilus developmental stages will contribute to genetic research and reproductive biology in conifers. Our objectives in this study were to determine the developmental stages of male strobili by cytological and transcriptome analysis, and to determine the stages at which aberrant morphology is observed in a male-sterile mutant of Cryptomeria japonica D. Don to better understand the molecular mechanisms that control male strobilus and pollen development. Male strobilus development was observed for 8 months, from initiation to pollen dispersal. A set of 19,209 expressed sequence tags (ESTs) collected from a male reproductive library and a pollen library was used for microarray analysis. We divided male strobilus development into 10 stages by cytological and transcriptome analysis. Eight clusters (7324 ESTs) exhibited major changes in transcriptome profiles during male strobili and pollen development in C. japonica Two clusters showed a gradual increase and decline in transcript abundance, respectively, while the other six clusters exhibited stage-specific changes. The stages at which the male sterility trait of Sosyun was expressed were identified using information on male strobilus and pollen developmental stages and gene expression profiles. Aberrant morphology was observed cytologically at Stage 6 (microspore stage), and differences in expression patterns compared with wild type were observed at Stage 4 (tetrad stage).

Study on the specificity of some molecular markers related to the cytoplasmic male sterility trait of vietnamese Chi Thien chilli pepper cultivar (Capsicum frutescens)

Cytoplasmic male sterility (CMS) is an important trait in the production of F1 hybrid seed of chili peppers. The creation and detection of CMS and maintainer lines by conventional methods require a lot of time and effort, and the accuracy is influenced by many factors. Therefore, the application of molecular markers is necessary to increase the efficiency of breeding. In this research, we investigated the specificity of four primer sets, coxIISCAR, atp6SCAR, RfSCAR and coxTri-M1 related to CMS trait in different lines of Chi Thien cultivar that is planted widely in Vietnam. The results showed that three of the four sets of primers (coxIISCAR, RfSCAR and coxTri-M1) could discriminate exactly the CMS and the maintainer lines, the two most important lines for the production of F1 hybrid seeds. These results showed the feasibility of the application of these primer sets to increase the effectiveness of the chili peppers breeding process in Vietnam.

Hybridization Using a New Male-sterile Germplasm as the Female Parent in Chinese Jujube

This study identified a new male-sterile germplasm of Chinese jujube, named male-sterile No. 2 (JMS2), and achieved controlled hybridization using that germplasm as the female parent. The anthers of JMS2 before flower bud opening became shrunken, dingy yellow and much smaller than normal ones, and they changed to brown after anthesis. No pollen was observed in anthers of JMS2 and its male-sterile trait remained stable over different years. A total of 1,642 fruits were obtained from ten intra- and interspecific cross combinations via controlled hybridization from 2008 to 2012 using JMS2 as the female parent. Of those, 27.3% produced seeds, on average (0-72.6%). The rate of fruit with seed (RFS) was significantly different between cross combinations or years. Compared to other cross combinations, the RFS in the combination of JMS2 × ‘Xingguang’ (a Chinese jujube cultivar with high resistance to jujube witches’ broom disease) and JMS2 × ‘Xing16’ (a sour jujube genotype) remained high in different years and reached means of 48.7 and 58.1%, respectively. Finally, 150 plantlets were regenerated from immature embryos, and 51 of them were randomly selected and identified to be authentic hybrids using amplified fragment length polymorphism (AFLP) markers. This is the first report of hybrids obtained from a cross between Chinese jujube and sour jujube.

Molecular mapping of three nuclear male sterility mutant genes in cultivated sunflower (Helianthus annuus L.)

The nuclear male sterility (NMS) trait is a useful tool for sunflower (Helianthus annuus L.) breeding and genetic programs. Previously, we induced NMS mutants in cultivated line HA 89. The mutants possessed single recessive genes ms6, ms7, and ms8, respectively, in NMS HA 89-872, NMS HA 89-552, and NMS HA 89-747. Bulked segregant analysis based on the male-fertile and male-sterile DNA pools and 560 simple sequence repeat and insertion/deletion markers randomly selected from 17 linkage groups (LGs) were used to locate ms6 to LG16, ms7 to LG6, and ms8 to LG5. Subsequent genotyping of three F2 populations of 88, 93, and 76 individuals confirmed their map positions. Additional polymorphic markers derived from four restriction fragment length polymorphism-converted sequence-tagged site primer pairs were identified. A partial linkage map consisting of eight markers was constructed for the ms6 locus, covering a region of 69.24 cM, with markers ORS807 and ORS996 flanking the ms6 locus at distances of 7.2 and 18.5 cM, respectively. Six markers were constructed for ms7, covering a region of 53.4 cM, with ORS608 and ORS1229 flanking ms7 at distances of 2.6 and 9.5 cM, respectively. Ten markers were constructed for ms8, covering a region of 18.0 cM, with six markers below ms8 and CRT518 above flanking ms8 at distances of 7.4 and 3.8 cM, respectively. The markers and mapping information will be useful for selection of the recessive NMS genes in sunflower breeding programs.

DETERMINATION OF FERTILITY AND POLLEN VIABILITY OF BREEDING LINE OF PATTYUPAN SQUASH WITH MALE STERILITY OF FUNCTIONAL TYPE

This article describes the features of the development of male sterility trait of functional type in pattypan squash. The viability of pollen grains in different periods of vegetation was studied. The determined fertility ability of pollen can be used for hybrid seed production of different varieties of pumpkin.

Development of male sterile broccoli lines with raphanus sativus cytoplasm and assessment of their value for breeding purposes

ABSTRACT The aim of this study was to obtain new broccoli lines with cytoplasmic male sterility trait for the development of the modern F1 hybrids. CDT70 cauliflower line obtained in the Research Institute of Horticulture, formerly Research Institute of Vegetable Crops, Skierniewice, Poland, with the reliable cytoplasmic male sterility from Raphanus sativus (Ogu-INRA) was selected as a source of this trait. Three broccoli lines: BMi, BCr1 and BCr2 were used as donors of commercial characters in all cross combinations with sterile components. Selected fertile broccoli genotypes were characterized by good quality, uniformity and high level of self-compatibility. The breeding procedure included three consecutive back crosses of male sterile genotypes with fertile broccoli lines that lasted from 2008 to 2012. In each generation, self-compatibility level, the stability of the male sterility trait and ability for the generative propagation of back-crossed genotypes were tested in comparison with donor broccoli lines in the greenhouse. The agronomical and morphological characters of the back-crossed progeny were also evaluated in the field. As a result, three CMS broccoli lines of Bc3 generation with good quality and high seeding index, suitable for the breeding purposes, were obtained.

Cloning and Characterization of Importin α in Brassica napus L.

ABSTRACTA previously identified genic male sterile (GMS) line in Brassica napus L. (rapeseed), in which the male sterile trait is controlled by a monogenic dominant locus, has been designated as MDGMS. In this study, we cloned importin‐α‐like sequences in MDGMS and its allelic fertile line. When we compared complementary DNA (cDNA) and deduced amino acid sequences of both cloned regions, several mutations were detected between the two lines. Sequence analysis revealed that the cloned gene contains 10 exons and 9 introns, consistent with IMPa‐4 in Arabidopsis spp., and it was accordingly designated as BnIMPα (Brassica napus importin α). Splice junctions of all introns in BnIMPα follow the GT–AG rule, and the amino acid sequence of BnIMPα contains the nuclear localization signal (NLS) sequence RKKIYKTGVDADEARRRR. The BnIMPα protein possesses characteristic features of importin α, such as an importin β binding (IBB) domain, eight tandem armadillo (ARM) repeats, and two helix–turn–helix motifs (HEAT) repeats. BnIMPα ribonucleic acid interference (RNAi) resulted in sterility or reduced fertility of male and female gametes, indicating that BnIMPα is necessary for gametogenesis in B. napus. Compared with the wild‐type, RNAi plants were highly susceptible to downy mildew and viral diseases. Tissue and subcellular localization analysis indicated that BnIMPα is expressed in all plant tissues other than seeds, especially conducting tissue and stamens, and that BnIMPα is localized in the nucleus.

The Arabidopsis U–box/ARM repeat E3 ligase AtPUB4 influences growth and degeneration of tapetal cells, and its mutation leads to conditional male sterility

Pollen formation is a complex developmental process that has been extensively investigated to unravel underlying fundamental developmental mechanisms and for genetic manipulation of the male-sterility trait for hybrid crop production. Here we describe identification of AtPUB4, a U-box/ARM repeat-containing E3 ubiquitin ligase, as a novel player in male fertility in Arabidopsis. Loss of AtPUB4 function causes hypertrophic growth of the tapetum layer. The Atpub4 mutation also leads to incomplete degeneration of the tapetal cells and strikingly abnormal exine structures of pollen grains. As a result, although the Atpub4 mutant produces viable pollen, the pollen grains adhere to each other and to the remnants of incompletely degenerated tapetal cells, and do not properly disperse from dehisced anthers for successful pollination. We found that the male-sterility phenotype caused by the Atpub4 mutation is temperature-dependent: the mutant plants are sterile when grown at 22°C but are partially fertile at 16°C. Our study also indicates that the AtPUB4-mediated pathway acts in parallel with the brassinosteroid pathway in controlling developmental fates of the tapetal cells to ensure male fertility.

Genetics of the thermosensitive genic male sterility trait in rice

UPRI 95-140 (P1), the thermosensitive genic male sterile (TGMS) line of low temperature fertility transformation type, was analyzed for its inheritance and transformation behavior. Parents, F1, F2, and six test crosses between TGMS (female parent) and UPRI 95-141 (P2), UPRI 95-165 (P3), UPRI 95-124 (P4), UPRI 95-117 (P5), and IR36 (P6) were screened in the field during the main season.

'진귤' (Citrus sunki) 의 웅성가임 연관 SCAR 마커 개발

감귤류 중 수술이 퇴화되어 웅성불임형질을 나타내는 '청견' 품종에 정상적인 수술의 형태를 가진 웅성가임인 '진귤' 품종을 교배하여 150개체의 <TEX>$F_1$</TEX> 집단을 구축하여 수술이 퇴화되는 개체와 정상인 개체를 분리하였다. 분리된 F1 개체들을 사용하여 SRAP 기법과 집단 분리 분석법(BSA)을 조합하여 웅성 가임 연관 마커 개발에 활용하였다. <TEX>$F_1$</TEX> 집단 내 150개체 중 66개체가 퇴화 수술을 갖고 있으며 웅성 가임성과 웅성 불임성의 분리비는 1:1이며 <TEX>$x^2$</TEX> 값은 2.16(p=0.05)이었다. 197개의 SRAP 프라이머 조합들 중 웅성가임 특이밴드를 형성하는 3개의 SRAP 프라이머 조합(F4/R27, F39/R60, 및 F15/R37)을 선발하였으며, 이 중 F39/R60 프라이머에 특이적으로 증폭하는 DNA단편의 염기서열을 기본으로 하여 새롭게 작성한 양방향 프라이머 조합 중 웅성 가임 계통에서만 약 1.4 Kb의 특이밴드를 증폭하는 프라이머 조합, pMS 33U/pMS 1462L를 선발하여 SCAR 마커를 개발 하였다. 이러한 결과는 개발된 SCAR 마커로 무핵성 계통들의 육종 선발에 효율성을 높일 수 있을 것으로 기대된다. In Citrus, an <TEX>$F_1$</TEX> segregation population of 150 plants was constructed from a cross between 'Kiyomi' (C. unshiu <TEX>${\times}$</TEX> C. sinensis) carrying the male sterility trait and 'Jinkyool' (C. sunki). Sequence-related amplification polymorphism (SRAP) combined with bulked segregant analysis was used to develop markers linked to male fertility. In the <TEX>$F_1$</TEX> population, 66 out of 150 seedlings had aborted anthers and the ratio of male sterile plants to fertile plants in the progenies matched the expected Mendelian segregation ratio of 1:1 (<TEX>$x^2$</TEX> =2.16 at p=0.05). From the profiling of the 197 SRAP primer sets, three SRAP primer sets (F4/R27, F39/R60, and F15/R37) that were closely linked to the target trait were identified and successfully converted into a sequence characterized amplified region (SCAR) marker for selection of male fertility in citrus. The SCAR marker, using the pMS 33U/pMS 1462L primer set specifically, produced a single 1.4-Kb fragment that was linked to male fertility. Our results suggested that this SCAR marker can be useful for marker-assisted selection of male sterile individuals in breeding <TEX>$F_1$</TEX> progenies in Citrus.

Cytological and mapping analysis of a novel male sterile type resulting from spontaneous floral organ homeotic conversion in marigold (Tagetes erecta L.)

A male sterile line was isolated in marigold (Tagetes erecta L.) and cytological analysis determined this to be a novel genic male sterility trait (Tems). Through the use of amplified fragment length polymorphisms (AFLPs) and bulked segregant analysis (BSA), tightly linked markers of Tems were identified with a view towards a map-based cloning strategy. It was found that spontaneous homeotic conversion of floral organs was the underlying cause of the male sterility in this marigold line. Thus, petals of male sterile plants resembled sepal-like structures and the stamens were partially converted to styles, although without the full characteristics or function of the true style organs. We have constructed a fine marker-based map for the Tems gene. This is intended to provide a tool for marker assisted selection (MAS) strategies in hybrid breeding and map-based cloning strategies for the male sterility locus. We discuss the significance of this spontaneously derived genic male sterility trait relating to the homeotic conversion of floral organs in marigold.

Identification of a SCAR marker linked to a recessive male sterile gene (Tems) and its application in breeding of marigold (Tagetes erecta)

AbstractIn marigold, an F2 segregation population of 167 plants was constructed from a cross of a line (M525A) carrying the male sterility trait × an inbred line (f53f). In line M525A, the male sterility trait was controlled by the recessive gene, Tems. The intersimple sequence repeat (ISSR) and sequence‐related amplified polymorphism (SRAP) techniques combined with bulked segregant analysis were used to develop markers linked to the trait. From a survey of the 38 ISSR primers and 170 SRAP primer combinations, only one SRAP marker that was closely linked to the target trait was identified and successfully converted into sequence characterized amplified region (SCAR) marker that was located within 2.4 cM from Tems locus. The marker was validated with five other two‐type lines and in each case the male fertile plants were reliably identified. This SCAR marker therefore permits the efficient marker‐assisted selection of male sterile individuals in breeding programmes of marigold and will greatly facilitate the breeding of F1 cultivars.

Expression of sunflower cytoplasmic male sterility-associated open reading frame, orfH522 induces male sterility in transgenic tobacco plants

Sterility in the universally exploited PET1-CMS system of sunflower is associated with the expression of orfH522, a novel mitochondrial gene. Definitive evidence that ORFH522 is directly responsible for male sterility is lacking. To test the hypothesis that ORFH522 is sufficient to induce male sterility, a set of chimeric constructs were developed. The cDNA of orfH522 was cloned in-frame with yeast coxIV pre-sequence, and was expressed under tapetum-specific promoter TA29 (construct designated as TCON). For developing control vectors, orfH522 was cloned without the transit peptide under TA29 promoter (TON) or orfH522 was cloned with or without transit peptide under the constitutive CaMV35S promoter (SCOP and SOP). Among several independent transformants obtained with each of the gene cassettes, one third of the transgenics (6/17) with TCON were completely male sterile while more than 10 independent transformants obtained with each of the control vectors were fertile. The male sterile plants were morphologically similar to fertile plants, but had anthers that remained below the stigmatic surface at anthesis. RT-PCR analysis of the sterile plants confirmed the anther-specific expression of orfH522 and bright-field microscopy demonstrated ablation of the tapetal cell layer. Premature DNA fragmentation and programmed cell death was observed at meiosis stage in the anthers of sterile plants. Stable transmission of induced male sterility trait was confirmed in test cross progeny. This constitutes the first report at demonstrating the induction of male sterility by introducing orfH522 gene that could be useful for genetic engineering of male sterility.

Environmental risk assessment of genetically modified chrysanthemums containing a modified cry1Ab gene from Bacillus thuringiensis

Insect-resistant transgenic chrysanthemum plants expressing a modified cry1Ab gene of Bacillus thuringiensis were produced, and an environmental risk assessment of these plants was undertaken in preparation for release their into the field. These plants were examined for molecular profiles, morphological and growth characteristics, cross compatibility, production of allelopathic substances, and influence on soil microbes. The results showed that the insect-resistance trait of the GM chrysanthemum plants is stably integrated in the nuclear genome, and the expression of the mcbt gene did not cause significant differences in the morphological characteristics, the production of allelopathic substances, or the effect on soil microorganisms compared to non-GM chrysanthemums. However, because these plants have cross-compatibility with wild related species, they will be forbidden to be cultured in the open field under the Cartagena Protocol on Biosafety. Therefore, we are attempting to introduce a male and/or female sterility trait to GM chrysanthemums with insect resistance to reinforce their biosafety for the practical uses.

Identification of AFLP markers linked to the epistatic suppressor gene of a recessive genic male sterility in rapeseed and conversion to SCAR markers

AbstractA recessive epistatic genic male sterility (REGMS) two‐type line, 9012AB, has been used for rapeseed hybrid seed production in China. The male sterility of 9012AB is controlled by two recessive duplicate sterile genes (ms1 and ms2) interacting with one recessive epistatic suppressor gene (esp). Homozygosity at the esp locus (espesp) suppresses the expression of the recessive male sterility trait in homozygous ms1ms1ms2 ms2 plants. In this study, we used a combination of bulked segregant analyses and amplified fragment length polymorphism (AFLP) to identify markers linked to the suppressor gene in a BC1 population. From the survey of 1024 AFLP primer combinations, eight markers tightly linked to the target gene were identified. The two closest markers flanking both sides of Esp, P9M5370 and S16M14780, had a genetic distance of 1.4 cM and 2.1 cM, respectively. The AFLP fragment from P4M8190, which co‐segregated with the target gene was converted into a sequence characterized amplified region marker. The availability of linked molecular markers will facilitate the utilization of REGMS in hybrid breeding in Brassica napus.

Estimation of stoichiometry of marker sequences of the sugar beet (Beta vulgaris) mitochondrial genome by real-time PCR

47 Plant mitochondrial genomes exhibit some features distinguishing them from the mitochondrial genomes of animals and fungi, the main of which are a large size (with the coding capacity being similar) and a complex organization. It was shown that the mitochondrial DNA fraction (mtDNA) contains concatemers, circular molecules with linear fragments, and subgenomic circular and linear variants whose stoichiometry may vary [1‐5]. The traditional representation of full-length sequences of plant mitochondrial genomes in the form of the “master” chromosome apparently does not reflect their state in vivo , because it does not take into account the lowcopy-number and recombinant sequences located in untypical environment. The trait of cytoplasmic male sterility (CMS) is related to the presence in mitochondria of a special genome type. In the case of Owen’s type of CMS in sugar beet ( Beta vulgaris ), this is the Svulg genome. This trait is expressed only in a special nuclear environment and consists in the inability of the plant to produce fertile pollen. CMS is usually caused by the formation of chimerical sequences, with this process being facilitated by a high recombination activity of plant mitochondrial genome. To date, two variants of the main chromosome of B. vulgaris mitochondrial genome have been sequenced: the N type, which ensures the formation of fertile pollen, and the Svulg -type [6, 7]. A large number of regions unique for each genome type does not make it possible to assign CMS to a loss or acquisition of a certain sequence in sugar beet. Additionally, the analysis of translation patterns of N- type and Svulg type mitochondria did not allow the CMS determinant to be determined at the protein level [8]. The relationship between CMS and selective amplification of certain subgenomic variants has been demonstrated for the haricot ( Phasoleus vulgaris ) [9]. Probably, the expression of CMS in B. vulgaris is also ensured not only by the presence of the genome (the “master” chromosome) but also by the composition and stoichiometry of subgenomic variants. In this case, the number of copies of subgenomic variants of mtDNA in the cytoplasm of sterile and fertile plants should be determined to find the relationship between CMS and the mitochondrial genome structure. In this study, we performed a comparative analysis of the number of copies of marker sequences in N -type and Svulg -type mitochondrial genomes. For this purpose, we for the first time used the real-time PCR—one of the most sensitive and precise methods of determination of the amount of certain sequences in DNA samples [10].