Cytoplasmic Male Sterile Lines Research Articles

Exploiting sterility and fertility variation in cytoplasmic male sterile vegetable crops.

Cytoplasmic male sterility (CMS) has long been used to economically produce hybrids that harness growth vigor through heterosis. Yet, how CMS systems operate within commercially viable seed production strategies in various economically important vegetable crops, and their underlying molecular mechanisms, are often overlooked details that could expand the utility of CMS as a cost-effective and stable system. We provide here an update on the nature of cytoplasmic-nuclear interplay for pollen sterility and fertility transitions in vegetable crops, based on the discovery of components of nuclear fertility restoration and reversion determinants. Within plant CMS systems, pollen fertility can be rescued by the introduction of nuclear fertility restorer genes (Rfs), which operate by varied mechanisms to countermand the sterility phenotype. By understanding these systems, it is now becoming feasible to achieve fertility restoration with Rfs designed for programmable CMS-associated open reading frames (ORFs). Likewise, new opportunities exist for targeted disruption of CMS-associated ORFs by mito-TALENs in crops where natural Rfs have not been readily identified, providing an alternative approach to recovering fertility of cytoplasmic male sterile lines in crops. Recent findings show that facultative gynodioecy, as a reproductive strategy, can coordinate the sterility and fertility transition in response to environmental cues and/or metabolic signals that reflect ecological conditions of reproductive isolation. This information is important to devising future systems that are more inherently stable.

DNA methylation of

In wheat (Triticum aestivum L.), S-type cytoplasmic male sterile (S-CMS) lines can mainly transform from sterility to fertility at the mononuclear pollen stage. Observations from microscopy revealed an inhibition of starch accumulation within the pollen grain, suggesting that an alteration in carbohydrate metabolism or assimilate supply may be involved in S-CMS pollen abortion. We measured levels of various carbohydrates and activities of key enzymes of sucrose metabolism at the mononuclear pollen stage in anthers collected from an S-CMS line and its maintainer line and found that nonreducing sugars increased in S-CMS anthers. Sucrose accounted for part of the nonreducing sugar accumulation. The activity of invertase declined significantly, whereas sucrose synthase activity during starch accumulation in pollen showed no significant change in S-CMS anthers at the mononuclear pollen stage. The results suggest that sucrose conversion and inhibition of invertase were probably responsible for the pollen abortion. Because there is a high correlation between the rate of ethylene evolution and sucrose content, ethylene anabolism was determined. TaACS2 regulates sucrose metabolism in pollen probably through catalysing the synthesis of ethylene precursor 1-aminocyclopropane-1-carboxylic acid in wheat. In this study, ethylene production of anthers underwent accumulation, revealed by gas chromatography, and expression levels of TaACS2 were upregulated in the S-CMS line, as determined by quantitative real-time PCR. We investigated the DNA methylation pattern of TaACS2 in the core promoter region using bisulfite genomic sequencing, and lower methylation was observed in the S-CMS line. These results suggest that DNA methylation of the TaACS2 gene may be involved in the sterility–fertility transition by regulating the synthesis of ethylene in S-CMS anthers.

Heterotic groups for identifying of suitable combiners in sunflower using top-cross

The study was conducted in order to identify the suitable parental inbred lines using top cross method for improvement of new sunflower F1 single cross hybrids at research field of Seed and Plant Improvement Institute in Karaj, Iran during two Crop season (2018 and 2019). Experimental materials consisted of 31 restore lines and 43 cytoplasmic male sterile lines which were crossed with A1221 and R14 as the testers respectively. The developed F1 hybrids were evaluated for GCA of three breeding objectives i.e. flowering time, plant height and grain yield during two years replicated trials. Cluster analysis revealed two heterotic groups in which the restorer lines; R22, R24 and R38 (Grain yield of 33, 32 and 31 g head-1 respectively) and three CMS lines; A32, A370 and A110 (Grain yield of 47, 44 and 43 g head-1 respectively) were identified as the suitable restorer and cytoplasmic male sterile line for improvement of new sunflower single cross hybrids. Evaluation of specific combing ability of the resulted combinations will reveal the efficiency of this selection in the following generation.

Combined Transcriptome and Proteome Analysis of Anthers of AL-type Cytoplasmic Male Sterile Line and Its Maintainer Line Reveals New Insights into Mechanism of Male Sterility in Common Wheat.

Cytoplasmic male sterility (CMS) plays an essential role in hybrid seeds production. In wheat, orf279 was reported as a CMS gene of AL-type male sterile line (AL18A), but its sterility mechanism is still unclear. Therefore, transcriptomic and proteomic analyses of the anthers of AL18A and its maintainer line (AL18B) were performed to interpret the sterility mechanism. Results showed that the electron transport chain and ROS scavenging enzyme expression levels changed in the early stages of the anther development. Biological processes, i.e., fatty acid synthesis, lipid transport, and polysaccharide metabolism, were abnormal, resulting in pollen abortion in AL18A. In addition, we identified several critical regulatory genes related to anther development through combined analysis of transcriptome and proteome. Most of the genes were enzymes or transcription factors, and 63 were partially homologous to the reported genic male sterile (GMS) genes. This study provides a new perspective of the sterility mechanism of AL18A and lays a foundation to study the functional genes of anther development.

Organelle genome assembly uncovers the dynamic genome reorganization and cytoplasmic male sterility associated genes in tomato

To identify cytoplasmic male sterility (CMS)-associated genes in tomato, we determined the genome sequences of mitochondria and chloroplasts in three CMS tomato lines derived from independent asymmetric cell fusions, their nuclear and cytoplasmic donors, and male fertile weedy cultivated tomato and wild relatives. The structures of the CMS mitochondrial genomes were highly divergent from those of the nuclear and cytoplasmic donors, and genes of the donors were mixed up in these genomes. On the other hand, the structures of CMS chloroplast genomes were moderately conserved across the donors, but CMS chloroplast genes were unexpectedly likely derived from the nuclear donors. Comparative analysis of the structures and contents of organelle genes and transcriptome analysis identified three genes that were uniquely present in the CMS lines, but not in the donor or fertile lines. RNA-sequencing analysis indicated that these three genes transcriptionally expressed in anther, and identified different RNA editing levels in one gene, orf265, that was partially similar to ATP synthase subunit 8, between fertile and sterile lines. The orf265 was a highly potential candidate for CMS-associated gene. This study suggests that organelle reorganization mechanisms after cell fusion events differ between mitochondria and chloroplasts, and provides insight into the development of new F1 hybrid breeding programs employing the CMS system in tomato.

Genetic architecture, physio-biochemical characterization and identification of elite cytoplasmic male sterile (pt-CMS) based combiners in developing antioxidant-rich carrot

AbstractExistence of genetic divergence, appropriate characterization of breeding lines for economically important traits and determining parents with favourable alleles is the crux of crop genetic improvement programmes. This study is the first report of unravelling genetics and potential of petaloid-type cytoplasmic male sterile (pt-CMS) lines in carrot. Ten pt-CMS lines were crossed with 10 inbreds in line × tester mating fashion to generate 100 testcross progenies. Nutritional profiling of the 100 testcrosses progenies along with 20 parental types was carried out for two consecutive years for eight important traits to identify superior combiners. The pooled analysis revealed that the carotenoid content in root is under the genetic control of major genes (oligogenic). The pooled analysis revealed less than unity value of σ2A/D and σgca2/σsca2 for majority of the traits depicting preponderance of non-additive gene effects. The pt-CMS lines KT-28A, Kt-62A, KT-80A and KT-95A were identified as good combiners for carotenoids. The cross combination, KT-98A × KS-50 identified as the best heterotic combiner for CUPRAC and FRAP content over the years. Similarly, the combinations, KT-62A × KS-21, KT-80A × New Kuroda and KT-62A × KS-59 were found promising across the years for developing nutritionally rich F1 hybrids. The interaction analysis among the different antioxidant traits and plant pigments unveiled the scope of simultaneous improvement.

Combining ability estimation for yield and its components of sunflower inbred lines

The objective of this investigation was to determine the combining ability for yield and its components in sunflower A- line by tester matting design among seven cytoplasmic male sterile lines and five restorer lines were selected to product 35 crosses. Parents and crosses were evaluated during the summer of 2017 year. Results indicated that the mean squares due to parents, crosses, parent's vs crosses except for days to 50% flowering and number of seeds plant-1. Lines, testers, and line x tester were significant for all studied traits. A14 and A31 of A- lines and Rf1 and Rf20 of Rf testers proved to the best general combiners for seed yield plant-1 and the most of its attributes. Moreover, the best cross combinations were of A4 × Rf14, A6 × Rf14, A31 × Rf8, A28 × Rf20, A23 × Rf20, A1 × Rf1 and A14 × Rf11 which performed better than other developed hybrids in the view of seed yield plant-1 and one or more of its attributes. The ratio of σ2 GCA/σ2 SCA was less than unity for all the traits indicating that non-additive gene effects played an important role in the inheritance of these traits. The biplot graphic allowed a rapid and effective overview of general combining ability (GCA) and specific combining ability (SCA) effects of inbred lines, best lines, and testers as well as their performance in crosses.

Improvement ability of male parent by gibberellic acid application to enhancing the outcrossing of cytoplasmic male sterility rice lines

<p class="042abstractstekst">The study quantified the effect of gibberellic acid (GA<sub>3</sub>) as a pre-flowering treatment for male parent Giza 178 R and the influence of male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) for two Cytoplasmic Male Sterility (CMS) lines (‘IR69625’ and ‘G46’) on hybrid rice seed production. The main plots were occupied by CMS lines while; GA3 application for male parent Giza 178R were arranged in the sub plots and male to female ratio was arranged in the sub-sub plots. The results indicated that, the, duration of floret opening, angle of floret opening, filaments exsertion, filaments length<strong>, </strong>anther length, plant height and number of tiller hill<sup>-1 </sup>of male parent Giza 178R were significantly at 300 g GA<sub>3</sub> ha<sup>-1</sup> concentration. Plant height, panicle exsertion, panicle length, flag leaf angle and 1000-grain mass of CMS were not significantly affected by the GA<sub>3</sub> application for male parent and male to female ratio, while, number of fertile panicles hill<sup>-1</sup>, panicle mass, seed set, seed yield and harvest index of CMS lines were highly significantly affected. The highest seed yield (2.880 and 2.950 t ha<sup>-1</sup>) was obtained by CMS line IR69625A using 300 g GA<sub>3</sub> ha<sup>-1</sup> of male parent Giza 178R with male to female ratio of 2R:14A during both seasons.</p>

Improvement ability of male parent by gibberellic acid application to enhancing the outcrossing of cytoplasmic male sterility rice lines

The study quantified the effect of gibberellic acid (GA3) as a pre-flowering treatment for male parent Giza 178 R and the influence of male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) for two Cytoplasmic Male Sterility (CMS) lines (‘IR69625’ and ‘G46’) on hybrid rice seed production. The main plots were occupied by CMS lines while; GA3 application for male parent Giza 178R were arranged in the sub plots and male to female ratio was arranged in the sub-sub plots. The results indicated that, the, duration of floret opening, angle of floret opening, filaments exsertion, filaments length, anther length, plant height and number of tiller hill-1 of male parent Giza 178R were significantly at 300 g GA3 ha-1 concentration. Plant height, panicle exsertion, panicle length, flag leaf angle and 1000-grain mass of CMS were not significantly affected by the GA3 application for male parent and male to female ratio, while, number of fertile panicles hill-1, panicle mass, seed set, seed yield and harvest index of CMS lines were highly significantly affected. The highest seed yield (2.880 and 2.950 t ha-1) was obtained by CMS line IR69625A using 300 g GA3 ha-1 of male parent Giza 178R with male to female ratio of 2R:14A during both seasons.

The main restorer Rf3 of maize S type cytoplasmic male sterility encodes a PPR protein that functions in reduction of the transcripts of orf355

Male sterile lines, especially cytoplasmic male sterile (CMS) lines, are extensively used in commercial hybrid seed production. Therefore a better understanding of the genetic basis of fertility restoration for CMS is important for the utility of heterosis in crops. In general, restorer of fertility (Rf) is controlled by one or two major genomic genes, and most of the Rf genes encode proteins containing P type pentatricopeptide repeat (PPR) motifs (Wang et al., 2006; Hu et al., 2012; Tang et al., 2014; Liu et al., 2016).

Combining ability, floral biology, and seed producibility of promising cytoplasmic male-sterile (CMS) lines for hybrid rice development

BackgroundA combining ability analysis is a useful tool of plant breeders in screening and identifying promising parental lines with high potential for developing competitive rice hybrids. Also, one important factor that strongly determines the suitability of commercial utilization of hybrid rice parental lines is their extent of seed producibility.MethodsIn this study, the combining ability, floral biology and seed producibility of cytoplasmic male sterile (CMS) lines were investigated to identify good combiners with good seed production potential. The Line × Tester analysis was used to determine the general combining abilities (GCA) of hybrid rice parental lines, and Specific Combining Abilities (SCA) of the different hybrid combinations. A correlation analysis was also done to determine floral traits that influence the outcrossing rate of the CMS lines. There were 4 CMS lines, 6 restorer lines, 24 hybrid combinations and 1 check variety in a randomized complete block Design (RCBD) with 3 replicates.ResultsResults indicated that CMS lines IR79128B and IR102758B were good combiners and the most promising restorer lines were D2031-7-1-2R, Hanareumbyeo 2, and XTR036-54-10R. Based on specific combining ability test, the most promising combination was entry 10 (IR58025A/D2013-7-1-2R). It has the highest yield of 7496 kg ha−1, a high positive SCA score of 570.54, and highest standard heterosis of 12.9%. Based on floral traits, IR79128B was the most promising with a high positive GCA score of 186.93, panicle exertion rate of 74.8%, and a high outcrossing rate of 51%. There was a significant positive association between outcrossing rate, duration of floral opening, panicle exertion rate, and general combining ability.ConclusionThe floral traits found to be significantly associated with outcrossing rate are useful selection criteria not only for identifying economically usable CMS lines but also for developing new and promising parental lines and hybrids. These CMS lines do not only give heterotic combinations but are also commercially producible, the two most important factors to the success of any hybrid rice breeding program.

The effects of Rf5 and Rf6 on fertility restoration in Honglian-type cytoplasmic male sterile (CMS) lines of japonica rice (Oryza sativa L. ssp. japonica).

The online version contains supplementary material available at 10.1007/s11032-021-01256-7.

QTL Mapping of a Novel Genomic Region Associated with High Out-Crossing Rate Derived from Oryza longistaminata and Development of New CMS Lines in Rice, O. sativa L.

High seed cost due to poor seed yield severely limits the adoption of hybrid rice by farmers. Increasing the out-crossing rate is one of the key strategies to increase hybrid seed production. Out-crossing rate is highly influenced by the size of female floral traits, which capture pollen grains from male donor plants. In the current study, we identified 14 QTLs derived from the perennial wild rice Oryza longistaminata by composite interval mapping for five key floral traits: stigma length (five), style length (three), stigma breadth (two), stigma area (one), and pistil length (three). QTL analysis and correlation studies revealed that these stigma traits were positively correlated and pleiotropic to the stigma length trait. We selected the major-effect QTL qSTGL8.0 conferring long stigma phenotype for further fine mapping and marker-assisted selection. The qSTGL8.0 (~ 3.9 Mb) was fine mapped using newly developed internal markers and was narrowed down to ~ 2.9 Mb size (RM7356–RM256 markers). Further, the flanking markers were validated in a segregating population and in progenies from different genetic backgrounds. The markers PA08-03 and PA08-18 showed the highest co-segregation with the stigma traits. The qSTGL8.0 was introgressed into two cytoplasmic male sterile (CMS) lines, IR58025A and IR68897A, by foreground, background, and trait selection approaches. The qSTGL8.0 introgression lines in CMS backgrounds showed a significantly higher seed setting rate (2.5–3.0-fold) than the original CMS lines in test crosses with their corresponding maintainer lines. The newly identified QTLs especially qSTGL8.0, will be quite useful for increasing out-crossing rate and this will contribute to increase seed production and decrease seed cost.

Global gene expression analysis of pigeonpea with male sterility conditioned by A2 cytoplasm.

Cytoplasmic male sterility(CMS), a maternally inherited trait, provides a promising means to harness yield gains associated with hybrid vigor. In pigeonpea [Cajanus cajan (L.) Huth], nine types of sterility-inducing cytoplasm have been reported, of which A2 and A4 have been successfully deployed in hybrid breeding. Unfortunately, molecular mechanism of the CMS trait is poorly understood because of limited research invested. More recently, an association between a mitochondrial gene (nad7) and A4 -CMS has been demonstrated in pigeonpea; however, the mechanism underlying A2 -CMS still remains obscure. The current investigation aimed to analyze the differences in A2 -CMS line (ICPL 88039A) and its isogenic maintainer line (ICPL 88039B) at transcriptome level using next-generation sequencing. Gene expression profiling uncovered a set of 505 genes that showed altered expression in response to CMS, of which, 412 genes were upregulated while 93 were downregulated in the fertile maintainer line vs. the CMS line. Further, gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) network analyses revealed association of CMS in pigeonpea with four major pathways: glucose and lipid metabolism, ATP production, pollen development and pollen tube growth, and reactive oxygen species (ROS) scavenging. Patterns of digital gene expression were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) of six candidate genes. This study elucidates candidate genes and metabolic pathways having potential associations with pollen development and male sterility in pigeonpea A2 -CMS. New insights on molecular mechanism of CMS trait in pigeonpea will be helpful to accelerate heterosis utilization for enhancing productivity gains in pigeonpea.

Unraveling the Genetic Basis of Fertility Restoration for Cytoplasmic Male Sterile Line WNJ01A Originated From Brassica juncea in Brassica napus.

Crosses that lead to heterosis have been widely used in the rapeseed (Brassica napus L.) industry. Cytoplasmic male sterility (CMS)/restorer-of-fertility (Rf) systems represent one of the most useful tools for rapeseed production. Several CMS types and their restorer lines have been identified in rapeseed, but there are few studies on the mechanisms underlying fertility restoration. Here, we performed morphological observation, map-based cloning, and transcriptomic analysis of the F2 population developed by crossing the CMS line WNJ01A with its restorer line Hui01. Paraffin-embedded sections showed that the sporogenous cell stage was the critical pollen degeneration period, with major sporogenous cells displaying loose and irregular arrangement in sterile anthers. Most mitochondrial electron transport chain (mtETC) complex genes were upregulated in fertile compared to sterile buds. Using bulked segregant analysis (BSA)-seq to analyze mixed DNA pools from sterile and fertile F2 buds, respectively, we identified a 6.25 Mb candidate interval where Rfw is located. Using map-based cloning experiments combined with bacterial artificial chromosome (BAC) clone sequencing, the candidate interval was reduced to 99.75 kb and two pentatricopeptide repeat (PPR) genes were found among 28 predicted genes in this interval. Transcriptome sequencing showed that there were 1679 DEGs (1023 upregulated and 656 downregulated) in fertile compared to sterile F2 buds. The upregulated differentially expressed genes (DEGs) were enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) lysine degradation pathway and phenylalanine metabolism, and the downregulated DEGs were enriched in cutin, suberine, and wax biosynthesis. Furthermore, 44 DEGs were involved in pollen and anther development, such as tapetum, microspores, and pollen wall development. All of them were upregulated except a few such as POE1 genes (which encode Pollen Ole e I allergen and extensin family proteins). There were 261 specifically expressed DEGs (9 and 252 in sterile and fertile buds, respectively). Regarding the fertile bud-specific upregulated DEGs, the ubiquitin–proteasome pathway was enriched. The top four hub genes in the protein–protein interaction network (BnaA09g56400D, BnaA10g18210D, BnaA10g18220D, and BnaC09g41740D) encode RAD23d proteins, which deliver ubiquitinated substrates to the 26S proteasome. These findings provide evidence on the pathways regulated by Rfw and improve our understanding of fertility restoration.

A small RNA of miR2119b from soybean CMS line acts as a negative regulator of male fertility in transgenic Arabidopsis

The miR2119 is involved in the growth, development and abiotic stress response of some legumes, including Medicago truncatula, Phaseolus vulgaris and soybean (Glycine max (L.) Merr.). Our previous small RNA sequencing analysis showed that miR2119b was up-regulated in the flower buds of soybean cytoplasmic male sterile (CMS) line compared with its maintainer line, but the role and mechanism of miR2119b in the regulation of soybean male fertility are still unclear. In this study, the gma-miR2119b and its target gene alcohol dehydrogenase 1.3b (ADH1.3b) were characterized and found to be highly expressed in the flowers of soybean CMS line and its maintainer. Transgenic Arabidopsis plants overexpressing gma-miR2119b exhibit male fertility abnormalities, including pollen fertility and germination rate decreased. Enzyme activity detection found the ADH and catalase (CAT) enzyme activities in inflorescence of gma-miR2119b overexpressed plants were lower than those of wild-type. Bioinformatics and gene expression analysis showed that gma-miR2119b/GmADH1.3b module was responsive to high temperature (HT) stress during flowering. After HT stress, the gma-miR2119b overexpressed plants showed male sterility, including shorter filament, sterile pollen, indehiscent anther and non seed. Moreover, some key genes involved in HT response and reactive oxygen species (ROS) signal regulation pathway, including heat shock protein70, galactinol synthase 1 and CAT, showed down-regulated expression in transgenic plants under HT stress, suggesting that gma-miR2119b regulates male fertility via HT-ROS signaling pathway under HT stress. It was speculated that the gma-miR2119b acted as a negative regulator of male fertility in plants by regulating ADH1, HT-induced and ROS scavenging genes expression.

Genome-wide transcriptome analysis of microspore abortion initiation in radish (Raphanus sativus L.).

The use of male sterile lines is one of the ideal means in hybrid seed production. Despite the widespread application of Ogura cytoplasmic male sterile (CMS) lines, the molecular mechanisms remain largely unknown. In this study, histological analyses of floral buds from a CMS line 40MA and its corresponding maintainer line 40MB were conducted, which indicate that microspore abortion was initiated shortly after the tetrad stage. RNA sequencing was performed to analyze the transcriptomes of floral buds from the tetrad stage and the early microspore stages of these two lines. More than 39 million clean reads were generated for each library, and the portions mapped to the reference genome were all above 70.60%. To further analyze the differentially expressed genes (DEGs), the samples were grouped into four pairs, of which the pair of 40MA and 40MB at the early microspore stage showed the most DEGs (5100 members). According to the abnormal appearance of the tapetum cells in 40MA, a series of tapetum development related genes were screened and analyzed. In addition, a total of 623 genes with differential expressions in the tetrad stage, but not in the early microspore stage between the two lines were filtered as the microspore abortion initiation related candidates. Twelve genes were selected to validate the sequencing result by quantitative RT-PCR. In this study, we identified a number of candidate genes involved in the initiation of microspore degeneration, which may provide a new perspective to unravel the molecular mechanism of Ogura CMS.

COMBINING ABILITY AND GENETIC PARAMETERS FOR CYTOPLASMIC MALE STERILITY LINES IN Zea mays L.

This study aimed to evaluate The number of pure inbred lines of maize (Zea mays L.) carried out for two seasons (spring and autumn) of 2019 in the fields of the research station/ agricultural research station in Abo Gharib. Four cytoplasmic male sterile inbred lines (A1, A3, A5 and A7) with their maintenance lines and four genetically fertile inbreds ( Inb2, HZ3, R5 and 18) in addition to the control hybrid (Nahrain) were used. Single hybrids were produced according to line × tester system. All genotypes were planted using randomized complete block design (RCBD) in three replicates, to analyses general and specific combining ability and estimate the effects and estimation some genetic Parameters for number days of sowing to 50%, leaf area, rows number per ear, kernels number per row , 500-kernel weight and grain yield per plant. Comparison results showed that inbred lines and their single crosses presented significant differences for all studied traits. The hybrids (A1×HZ3), (A1×R5) and (A3×HZ3) scored highest yield (175.1, 172.2 and 172.1) respectively. Obtained results also recorded significant influence of GCA and SCA in most studied traits, And the values of GCA/SCA was less than one, And the percentage of broad sense heritability was high for all traits, while it was low for the narrow sense heritability for all traits as well, which led to a higher average degree of dominance than the correct one, which indicates that the traits were under the influence of the dominance and over dominance of genes, which indicates that the possibility of using superior parents in their speculations to derive Single hybrids with special combinability of field characteristics, yield and components.

Breeding for thermo-sensitive pol cytoplasmic male sterile line and its restorer with high oleic acid through molecular marker-assisted selection in Brassica napus

Breeding for thermo-sensitive pol cytoplasmic male sterile line and its restorer with high oleic acid through molecular marker-assisted selection in Brassica napus

Characterization of the Mitochondrial Genome of a Wheat AL-Type Male Sterility Line and the Candidate CMS Gene.

Heterosis utilization is very important in hybrid seed production. An AL-type cytoplasmic male sterile (CMS) line has been used in wheat-hybrid seed production, but its sterility mechanism has not been explored. In the present study, we sequenced and verified the candidate CMS gene in the AL-type sterile line (AL18A) and its maintainer line (AL18B). In the late uni-nucleate stage, the tapetum cells of AL18A showed delayed programmed cell death (PCD) and termination of microspore at the bi-nucleate stage. As compared to AL18B, the AL18A line produced 100% aborted pollens. The mitochondrial genomes of AL18A and AL18B were sequenced using the next generation sequencing such as Hiseq and PacBio. It was found that the mitochondrial genome of AL18A had 99% similarity with that of Triticum timopheevii, AL18B was identical to that of Triticum aestivum cv. Chinese Yumai. Based on transmembrane structure prediction, 12 orfs were selected as candidate CMS genes, including a previously suggested orf256. Only the lines harboring orf279 showed sterility in the transgenic Arabidopsis system, indicating that orf279 is the CMS gene in the AL-type wheat CMS lines. These results provide a theoretical basis and data support to further analyze the mechanism of AL-type cytoplasmic male sterility in wheat.