Dominant Male Sterility Research Articles

An epi-allele of SMS causes Sanming dominant genic male sterility in rice.

Male sterility is an important trait in rice for hybrid rice (Oryza sativa) breeding. However, the factors involved in dominant male sterility are largely unknown. Here, we identified a gene from Sanming dominant genic male sterile rice, named Sanming dominant male sterility (SMS), and reported that an epi-allele of this locus contributes to male sterility. Segregation analysis attributed dominant male sterility to a single locus, SMS, which we characterized using a male-sterile near isogenic line (NIL) of rice cultivar 93-11. The SMS locus was heterozygous in the male-sterile 93-11 NIL, containing an epi-allele identical to that in 93-11, and an epi-allele identical to that in rice cultivar Nipponbare, which we refer to as SMS9 and SMSN, respectively. SMS9 is silent and hyper-methylated, whereas SMSN is expressed and hypo-methylated in the 93-11 NIL. Overexpressing SMSN led to male sterility. Mutations in SMS rescued the male sterility of the 93-11 NIL. Interestingly, we observed the duplication of SMSN in Nipponbare, but did not observe the duplication of SMS9 in 93-11. Together, these findings suggest that the reduced methylation and enhanced expression of the SMSN epi-allele in the 93-11 NIL is responsible for its role in conferring dominant male sterility.

A natural mutation in the promoter of Ms-cd1 causes dominant male sterility in Brassica oleracea

Male sterility has been used for crop hybrid breeding for a long time. It has contributed greatly to crop yield increase. However, the genetic basis of male sterility has not been fully elucidated. Here, we report map-based cloning of the cabbage (Brassica oleracea) dominant male-sterile gene Ms-cd1 and reveal that it encodes a PHD-finger motif transcription factor. A natural allele Ms-cd1PΔ−597, resulting from a 1-bp deletion in the promoter, confers dominant genic male sterility (DGMS), whereas loss-of-function ms-cd1 mutant shows recessive male sterility. We also show that the ethylene response factor BoERF1L represses the expression of Ms-cd1 by directly binding to its promoter; however, the 1-bp deletion in Ms-cd1PΔ−597 affects the binding. Furthermore, ectopic expression of Ms-cd1PΔ−597 confers DGMS in both dicotyledonous and monocotyledonous plant species. We thus propose that the DGMS system could be useful for breeding hybrids of multiple crop species.

Anther-specific expression of OsRIP1 causes dominant male sterility in rice.

Anther-specific expression of OsRIP1 causes dominant male sterility in rice.

Spontaneous movement of a retrotransposon generated genic dominant male sterility providing a useful tool for rice breeding.

Male sterility in plants provides valuable breeding tools in germplasm innovation and hybrid crop production. However, genetic resources for dominant genic male sterility, which hold great promise to facilitate breeding processes, are extremely rare in natural germplasm. Here we characterized the Sanming Dominant Genic Male Sterility in rice and identified the gene SDGMS using a map-based cloning approach. We found that spontaneous movement of a 1978-bp long terminal repeat (LTR) retrotransposon into the promoter region of the SDGMS gene activates its expression in anther tapetum, which causes abnormal programmed cell death of tapetal cells resulting in dominant male sterility. SDGMS encodes a ribosome inactivating protein showing N-glycosidase activity. The activation of SDGMS triggers transcription reprogramming of genes responsive to biotic stress leading to a hypersensitive response which causes sterility. The results demonstrate that an ectopic gene activation by transposon movement can give birth to a novel trait which enriches phenotypic diversity with practical utility.

Improvement of Salinity Tolerance in Water-Saving and Drought-Resistance Rice (WDR)

Rice is one of the most economically important staple food crops in the world. Soil salinization and drought seriously restrict sustainable rice production. Drought aggravates the degree of soil salinization, and, at the same time, increased soil salinity also inhibits water absorption, resulting in physiological drought stress. Salt tolerance in rice is a complex quantitative trait controlled by multiple genes. This review presents and discusses the recent research developments on salt stress impact on rice growth, rice salt tolerance mechanisms, the identification and selection of salt-tolerant rice resources, and strategies to improve rice salt tolerance. In recent years, the increased cultivation of water-saving and drought-resistance rice (WDR) has shown great application potential in alleviating the water resource crisis and ensuring food and ecological security. Here, we present an innovative germplasm selection strategy of salt-tolerant WDR, using a population that is developed by recurrent selection based on dominant genic male sterility. We aim to provide a reference for efficient genetic improvement and germplasm innovation of complex traits (drought and salt tolerance) that can be translated into breeding all economically important cereal crops.

Development of the PARMS Marker of the Dominant Genic Male Sterility (DGMS) Line and Its Utilization in Rapeseed (Brassica napus L.) Breeding.

The 8029AB line is a dominant genic male sterility (DGMS) two-type line in Brassica napus L., which can be used in a three-line approach for the seed production of rapeseed hybrids. Genetic analyses have demonstrated that the sterility of 8029A is controlled by a single dominant nuclear gene (BnMS5e) interacting with one recessive gene (BnMS5c). Six pairs of penta-primer amplification refractory mutation system (PARMS) markers were designed according to the sequence of BnMS5a, BnMS5c and BnMS5e. Two pairs of these PARMS markers were successfully identified and validated. The PARMS markers MS5-1Fc/MS5-1Ft/MS5-1R12 could distinguish BnMS5c from BnMS5a/BnMS5e, and the PARMS markers MS5-2Ft/MS5-2Fa/MS5-1R12 could genotype BnMS5a and BnMS5c/BnMS5e. The combination of these two pairs of PARMS markers could be used to identify the presence or absence of BnMS5a/BnMS5c/BnMS5e effectively. Consequently, marker-assisted selection can be carried out in the early generation to shorten the breeding period and improve the breeding efficiency.

Breeding with dominant genic male-sterility genes to boost crop grain yield in the post-heterosis utilization era

Global food security is facing severe challenges from an ever-growing population, limited resources, and various stresses. Dominant genic male sterility (DGMS) technology combined with modern breeding strategies may create novel cultivation models with ~50% DGMS F1 hybrids for field production of cross-pollinated crops, boosting crop grain yield to ensure global food security and sustainable agriculture in the post-heterosis utilization era.

Molecular regulation of ZmMs7 required for maize male fertility and development of a dominant male-sterility system in multiple species.

Understanding the molecular basis of male sterility and developing practical male-sterility systems are essential for heterosis utilization and commercial hybrid seed production in crops. Here, we report molecular regulation by genic male-sterility gene maize male sterility 7 (ZmMs7) and its application for developing a dominant male-sterility system in multiple species. ZmMs7 is specifically expressed in maize anthers, encodes a plant homeodomain (PHD) finger protein that functions as a transcriptional activator, and plays a key role in tapetal development and pollen exine formation. ZmMs7 can interact with maize nuclear factor Y (NF-Y) subunits to form ZmMs7-NF-YA6-YB2-YC9/12/15 protein complexes that activate target genes by directly binding to CCAAT box in their promoter regions. Premature expression of ZmMs7 in maize by an anther-specific promoter p5126 results in dominant and complete male sterility but normal vegetative growth and female fertility. Early expression of ZmMs7 downstream genes induced by prematurely expressed ZmMs7 leads to abnormal tapetal development and pollen exine formation in p5126-ZmMs7 maize lines. The p5126-ZmMs7 transgenic rice and Arabidopsis plants display similar dominant male sterility. Meanwhile, the mCherry gene coupled with p5126-ZmMs7 facilitates the sorting of dominant sterility seeds based on fluorescent selection. In addition, both the ms7-6007 recessive male-sterility line and p5126-ZmMs7M dominant male-sterility line are highly stable under different genetic germplasms and thus applicable for hybrid maize breeding. Together, our work provides insight into the mechanisms of anther and pollen development and a promising technology for hybrid seed production in crops.

Characterization and transcriptome analysis of a dominant genic male sterile cotton mutant

BackgroundMale sterility is an efficient trait for hybrid seed production and germplasm innovation. Until now, most studies on male sterility were on cytoplasmic and recessive genic sterility, with few on dominant genic male sterility, especially in cotton, due to lack of such mutant.ResultsWe discovered a natural male sterile (MS) Sea Island cotton (G. barbadense) mutant. Genetic analysis showed the mutation was caused by a dominant mutation in a single nuclear gene. Comparative cytological observation of anther sections from MS and wild-type (WT) uncovered cellular differences in anther at and after the tetrad stage of pollen mother cells (PMC). In the MS anthers, the outer wall of pollen grains was free of spinules, the tapetum was vacuolated and showed delayed degradation, consequently, no functional pollen grains. Comparison of transcriptomes from meiosis, tetrad, mononuclear and binuclear pollen, and pollen maturation stages identified 13,783 non-redundant differentially expressed genes (DEGs) between MS and WT. Based on the number of DEGs, analyses of enriched GO terms and KEGG pathways, it was evident that significant transcriptomic changes occurred at and after the tetrad stage, consistent with cytological observation, and that the major differences were on metabolism of starch, sucrose, ascorbate, aldarate, alanine, aspartate and glutamate, and biosynthesis of cutin, suberine and wax. WGCNA analysis identified five modules containing 920 genes highly related to anther development, especially the greenyellow module with 54 genes that was highly associated with PMC meiosis and tetrad formation. A NAC transcription factor (Gh_D11G2469) was identified as a hub gene for this module, which warrants further functional characterization.ConclusionsWe demonstrated that the MS trait was controlled by a single dominant nuclear gene and caused by delayed tapetum degradation at the tetrad stage. Comparative transcriptome analysis and gene network construction identified DEGs, enriched GO terms and metabolic pathways, and hub genes potentially associated with anther development and the MS trait. These results contribute to our understanding of dominant genic male sterility (DGMS) and provided source for innovation of cotton germplasm.

Ms3 dominant genetic male sterility for wheat improvement with molecular breeding

AbstractGenetic dominant male sterility (DMS) has not been widely used as a breeding tool in wheat (Triticum aestivum L.), although DMS‐facilitated backcross, mass selection, half‐sib selection, and S1 family recurrent selection strategies have been described, and Ms2‐facilitated recurrent selection has been used in China. Our objective was to revisit these strategies using the tools of molecular breeding. Development of a mechanism for seedling identification of sterile progeny was a key component of designing practical DMS‐facilitated molecular breeding systems. The DMS gene Ms3 was previously localized to the centromeric region of chromosome 5A. The centromeric location is an advantage because recombination rates are very low. Once identified, a broadly informative marker would reliably predict the male‐sterile phenotype. A set of 429 hybrids incorporating Ms3 were constructed, both within US hard winter wheats, and between these winter wheats and Asian spring wheats. Association of the male‐sterile phenotype with those polymorphic DNA sequence tags that localized to chromosome 5A was tested using case‐control association analysis. Two highly significant (logarithm of odds [LOD] > 30) single nucleotide polymorphism (SNP)–trait associations were obtained. One SNP was developed into a highly sensitive, reliable marker for the Ms3‐associated male‐sterile phenotype. Previously described breeding strategies using DMS were updated for trait‐targeted marker‐assisted backcrossing and gene pyramiding, S1 recurrent selection, and early‐generation genomic selection. Application of DMS to association mapping, with the particular use case of the multiparent advanced generation intercross population, is also described.

Mutation of the seminal protease gene, serine protease 2, results in male sterility in diverse lepidopterans

Sterile insect technology (SIT) is an environmentally friendly method for pest control. As part of our efforts to develop a strategy that results in engineered male-sterile strains with minimum effects on viability and mating competition, we used CRISPR/Cas9 technology to disrupt Ser2, which encodes a seminal fluid protein, in the model lepidopteran insect, Bombyx mori, and an important agricultural pest, Plutella xylostella. Disruption of Ser2 resulted in dominant heritable male sterility. Wild-type females mated with Ser2-deficient males laid eggs normally, but the eggs did not hatch. We detected no differences in other reproductive behaviors in the mutant males. These results support the conclusion that Ser2 gene is necessary for male reproductive success in diverse lepidopterans. Targeting Ser2 gene has the potential to form the basis for a new strategy for pest control.

Identification of brown planthopper resistance gene Bph32 in the progeny of a rice dominant genic male sterile recurrent population using genome-wide association study and RNA-seq analysis

Brown planthopper (BPH) is one of the most damaging pests of rice. Improving the resistance of rice varieties is considered a safe and effective way to control this pest. Here, a field experiment was conducted to test BPH resistance in a rice population developed by recurrent selection of a variety with dominant genic male sterility. Three high-resistance lines were identified and subjected to a genome-wide association study (GWAS), which mapped the BPH resistance gene to the short arm of chromosome 6. One highly resistant line (14CF2426) was further crossed with Taichuang Native 1 (TN1) to construct an F2 segregating population. Artificial insect infestation identified three quantitative trait loci (QTLs), which were mapped to chromosomes 1, 6, and 10; the QTL on chromosome 6 of 14CF2426 contained a known resistance gene, Bph32. Near-isogenic lines NIL-Bph32 and NIL-bph32 of Bph32 were constructed using molecular marker-assisted selection. RNA sequencing (RNA-seq) detected 1268 differentially expressed genes (DEGs) between the two near-isogenic lines. Compared with NIL-Bph32, 1064 genes were upregulated and 204 were downregulated in NIL-bph32. Gene ontology (GO) enrichment analysis detected 46 significantly enriched terms, and KEGG analysis revealed four significantly enriched metabolic pathways. This robust multi-method strategy showed that combining GWAS analysis with a dominant genic male sterile recurrent rice population can significantly improve the efficiency of gene identification. RNA-seq revealed some candidate genes with a potential regulatory function in BPH resistance, thus providing insights into the transcriptional regulatory network and the molecular mechanisms of resistance.

Development of a visible marker trait based on leaf sheath-specific anthocyanin pigmentation applicable to various genotypes in rice.

To overcome a limitation to the breeding of autogamous crops, recurrent selection using transgenic male sterility (RSUTMS) has been proposed. In this system, negatively or positively selectable marker traits are required along with dominant transgenic male sterility. Anthocyanin pigmentation is an excellent marker trait. Two regulatory genes for MYB and bHLH and a structural gene for DFR are required for anthocyanin pigmentation in rice. Therefore, to apply anthocyanin pigmentation as a marker trait in various rice genotypes, coordinated expression of the three genes is required. In this study, we developed a leaf sheath–specific promoter and introduced three genes—DFR and C1/Myb, driven by the 35S promoter, and OsB2/bHLH, driven by the leaf sheath–specific promoter—into the rice genome. Leaf sheath–specific pigmentation was confirmed in all seven genotypes tested, which included japonica and indica cultivars. Analysis of genome sequence data from 25 cultivars showed that the strategy of conferring leaf sheath–specific anthocyanin pigmentation by introduction of these three genes would be effective for a wide range of genotypes and will be applicable to RSUTMS.

Development of transgenic male-sterile rice by using anther-specific promoters identified by comprehensive screening of the gene expression profile database 'RiceXPro'.

Because genomic selection is designed for the population breeding of allogamous species, a successive outcrossing system is required for efficient use of genomic selection in autogamous crops, such as Oryza sativa L. (rice). Transgenic and dominant male-sterility is a suitable tool for efficient outcrossing of autogamous crops. Though there have been some reports of dominant male-sterile rice developed using transgenic technology, the flowering habit was substandard. Here, to isolate promoters that, when linked to a lethal gene, induce dominant male-sterility while retaining a good flowering habit, we identified 38 candidate genes with anther-specific expression by using the ‘RiceXPro’ database. We then evaluated the abilities of the near-upstream regions of these genes to induce male-sterility when linked to the lethal gene barnase and introduced into the rice cultivar ‘Nipponbare’. Seven of the 38 promoters induced clear dominant male-sterility; promoters expressed in the later stage of anther development induced male-sterility while retaining better flowering habits when compared to ones expressed in the early stage. These seven promoters could potentially be used to facilitate development of an efficient outcross-based breeding system in rice.

Development and characterization of transgenic dominant male sterile rice toward an outcross-based breeding system.

Genomic selection is attracting attention in the field of crop breeding. To apply genomic selection effectively for autogamous (self-pollinating) crops, an efficient outcross system is desired. Since dominant male sterility is a powerful tool for easy and successive outcross of autogamous crops, we developed transgenic dominant male sterile rice (Oryza sativa L.) using the barnase gene that is expressed by the tapetum-specific promoter BoA9. Barnase-induced male sterile rice No. 10 (BMS10) was selected for its stable male sterility and normal growth characteristics. The BMS10 flowering habits, including heading date, flowering date, and daily flowering time of BMS10 tended to be delayed compared to wild type. When BMS10 and wild type were placed side-by-side and crossed under an open-pollinating condition, the seed-setting rate was <1.5%. When the clipping method was used to avoid the influence of late flowering habits, the seed-setting rate of BMS10 increased to a maximum of 86.4%. Although flowering synchronicity should be improved to increase the seed-setting rate, our results showed that this system can produce stable transgenic male sterility with normal female fertility in rice. The transgenic male sterile rice would promote a genomic selection-based breeding system in rice.

Recurrent selection breeding by dominant male sterility for multiple abiotic stresses tolerant rice cultivars

Recurrent selection has not been extensively applied in rice breeding practices due to lack of male sterility genes. Recently, a male sterile line (named as ‘Jiabuyu’) controlled by a novel single dominant gene was found, which provides an ideal tool for rice recurrent selection breeding. Here, two different kinds of recurrent selection populations facilitated for outcrossing by the dominant male sterile line ‘Jiabuyu’ were developed, that included one population using 31 abiotic stress tolerance introgression lines with common recipient parent as founders, and the other one using 25 popular restorers lines applied in hybrid breeding as founders. After two cycles of recurrent selection through natural outcrossing, the seeds from male fertile progeny plants were screened for higher grain yield under normal irrigated, drought, and salt-stressed natural field conditions. Finally, we identified 11 promising high-yielding lines under irrigated conditions, 12 drought-tolerant and 12 salt-tolerant lines. Among them, one line gave higher grain yield across all three conditions, three lines yielded high in both irrigated and drought conditions and another three lines gave high yields in both drought and salt-stressed conditions. The present study was a commendable attempt at utilizing recurrent selection population facilitated by dominant male sterile line to improve rice complex traits, which provided valuable lessons for other rice breeders. The developed lines are promising to be rice varieties with high yield, drought and/or salinity tolerances.

A novel dominant rice male sterility mutant, OsDMS-1, simultaneously controlled by independent loci on chromosomes 1, 2, and 3

We found a rice dominant genetic male-sterile mutant OsDMS-1 from tissue culture-regenerated offspring of Zhonghua 11 (japonica rice). Compared to Zhonghua 11, OsDMS-1 mutant anthers were narrow and pale and incapable of pollen release although the glume opened normally. Approximately 81.4% of this mutant pollen was small and malformed and could not be stained by iodine treatment. A paraffin section assay showed delayed degradation of the OsDMS-1 mutant tapetum without starch accumulation in the mutant pollen, ultimately leading to pollen abortion. Classical genetic analysis indicated that only one dominant gene controlled the sterility in the OsDMS-1 mutant. However, molecular mapping suggested three loci simultaneously control male sterility in this mutant: OsDMS-1A (on chromosome 1), flanked by InDel markers C1D4 and C1D5, OsDMS-1B (on chromosome 2), flanked by InDel markers C2D3 and C2D10, and OsDMS-1C (on chromosome 3), flanked by InDel markers 0315 and C3D3. Molecular mapping disagreed with classical genetic analysis regarding the number of genes controlling the OsDMS-1 mutant, indicating a novel mechanism underlying sterility in OsDMS-1. We present two hypotheses to explain this novel inheritance behavior: one is described as Parent-Originated Loci Tying Inheritance (POLTI); while the alternate hypothesis is described as Loci Recombination Lethal (LRL).

A single point mutation in Ms44 results in dominant male sterility and improves nitrogen use efficiency in maize

SummaryApplication of nitrogen fertilizer in the past 50 years has resulted in significant increases in crop yields. However, loss of nitrogen from crop fields has been associated with negative impacts on the environment. Developing maize hybrids with improved nitrogen use efficiency is a cost‐effective strategy for increasing yield sustainably. We report that a dominant male‐sterile mutant Ms44 encodes a lipid transfer protein which is expressed specifically in the tapetum. A single amino acid change from alanine to threonine at the signal peptide cleavage site of the Ms44 protein abolished protein processing and impeded the secretion of protein from tapetal cells into the locule, resulting in dominant male sterility. While the total nitrogen (N) content in plants was not changed, Ms44 male‐sterile plants reduced tassel growth and improved ear growth by partitioning more nitrogen to the ear, resulting in a 9.6% increase in kernel number. Hybrids carrying the Ms44 allele demonstrated a 4%–8.5% yield advantage when N is limiting, 1.7% yield advantage under drought and 0.9% yield advantage under optimal growth conditions relative to the yield of wild type. Furthermore, we have developed an Ms44 maintainer line for fertility restoration, male‐sterile inbred seed increase and hybrid seed production. This study reveals that protein secretion from the tapetum into the locule is critical for pollen development and demonstrates that a reduction in competition between tassel and ear by male sterility improves grain yield under low‐nitrogen conditions in maize.

A generic SSR marker closely linked to a dominant genic male sterility gene (DGMs79-399-3) in broccoli (Brassica oleracea var. italica)

As an important pollination system, male sterility has been used widely for broccoli (Brassica oleracea var. italica) hybrid production. New male sterile lines are important for broccoli breeding. We transferred the dominant genic male sterility (DGMs) 79-399-3, which was developed from a spontaneous mutation in cabbage, to broccoli. In this study, molecular markers linked to the DGMs79-399-3 gene in broccoli were identified by screening a segregating population DGMs8554 with 747 individuals, obtained by ten backcrosses (BC10) using a cabbage-dominant genic male sterility line containing DGMs79-399-3 as the donor and broccoli inbred line 8554 as the recipient. Bulked segregation analysis with respect to male sterility and fertility for the BC10 population of DGMs8554 was conducted by scanning 2585 different types of primers. Three SSR and one SCAR marker were identified, and a map surrounding DGMs79-399-3 was constructed. Two flanking markers, scaffold10312a and scaffold129_2012, were linked to the dominant male sterile DGMs79-399-3 gene at distances of 0.563 and 0.328 cM, respectively, which mapped the DGMs79-399-3 gene to a 0.891 cM range. The markers were verified in another three broccoli groups, and a generic SSR marker, scaffold10312a, was obtained with an accuracy ≥96.43 %. The markers developed here will accelerate the breeding of new elite DGMs lines in broccoli and provide a solid basis for cloning of the DGMs79-399-3 gene.

Fine mapping of a dominant thermo-sensitive genic male sterility gene (BntsMs) in rapeseed (Brassica napus) with AFLP- and Brassica rapa-derived PCR markers.

A new thermo-sensitive dominant genic male sterility (TSDGMS) line of Brassica napus was found and mapped in this paper. Our result will greatly accelerate the map-based cloning of the BntsMs gene. TE5A is a thermo-sensitive dominant genic male sterility line originating from spontaneous mutation of the inbred line TE5 in Brassica napus and provides a promising system for the development of hybrid cultivars. Genetic analysis has revealed that the BntsMs mutant is controlled by a single, dominant gene. Here, we describe the fine mapping of BntsMs using amplified fragment length polymorphism (AFLP) and intron polymorphism (IP) methodologies. We screened 1,024 primer combinations and then identified five AFLP markers linked to the BntsMs gene, two of which were successfully converted into sequence-characterised amplified region (SCAR) markers. The linkage of the markers was identified by analysing a large BC2 population of 700 recessive-fertility individuals. Two SCAR markers were found in the flanking region of the BntsMs gene at distance of 3.5 and 4.8 cm. Based on sequence information from the previously screened AFLP markers and on genome organisation comparisons of the A genome of Brassica rapa and Arabidopsis, seven IP markers linked to the BntsMs gene were developed. By analysing the 700 recessive-fertility individuals, two IP markers, IP004 and IP470, were localised to the flanking region of the BntsMs gene at a distance of 0.3 and 0.2 cm, respectively. A comparison of the B. rapa and Arabidopsis genomes revealed 27 genes of B. rapa in the flanking region of these two IP markers. It is likely that the molecular markers developed from these investigations will greatly accelerate the positional cloning of the BntsMs gene.