Male Fertile Lines Research Articles

A CRISPR/Cas9-induced male-sterile line facilitating easy hybrid production in polyploid rapeseed (Brassica napus).

Rapeseed is a globally significant oilseed crop cultivated to meet the increasing demand for vegetable oil. In order to enhance yield and sustainability, breeders have adopted the development of rapeseed hybrids as a common strategy. However, current hybrid production systems in rapeseed have various limitations, necessitating the development of a simpler and more efficient approach. In this study, we propose a novel method involving the targeted disruption of Defective in Anther Dehiscence1 of Brassica napus (BnDAD1), an essential gene in the jasmonic acid biosynthesis pathway, using CRISPR/Cas9 technology, to create male-sterile lines. BnDAD1 was found to be dominantly expressed in the stamen of rapeseed flower buds. Disrupting BnDAD1 led to decreased levels of α-linolenic acid and jasmonate in the double mutants, resulting in defects in anther dehiscence and pollen maturation. By crossing the double mutant male-sterile lines with male-fertile lines, a two-line system was demonstrated, enabling the production of F 1 seeds. The male-sterile trait of the bndad1 double mutant lines was maintainable by applying exogenous methyl jasmonate and subsequently self-pollinating the flowers. This breakthrough holds promising potential for harnessing heterosis in rapeseed and offers a simpler and more efficient method for producing hybrid seeds.

Transcriptome analysis reveals the potential lncRNA-mRNA modules involved in genetic male sterility and fertility of Chinese cabbage (brassica rapa L. ssp. pekinensis).

Long non-coding RNAs (lncRNAs) play a crucial role in regulating gene expression vital for the growth and development of plants. Despite this, the role of lncRNAs in Chinese cabbage (Brassica rapa L. ssp. pekinensis) pollen development and male fertility remains poorly understood. In this study, we characterized a recessive genic male sterile mutant (366-2S), where the delayed degradation of tapetum and the failure of tetrad separation primarily led to the inability to form single microspores, resulting in male sterility. To analyze the role of lncRNAs in pollen development, we conducted a comparative lncRNA sequencing using anthers from the male sterile mutant line (366-2S) and the wild-type male fertile line (366-2F). We identified 385 differentially expressed lncRNAs between the 366-2F and 366-2S lines, with 172 of them potentially associated with target genes. To further understand the alterations in mRNA expression and explore potential lncRNA-target genes (mRNAs), we performed comparative mRNA transcriptome analysis in the anthers of 366-2S and 366-2F at two stages. We identified 1,176 differentially expressed mRNAs. Remarkably, GO analysis revealed significant enrichment in five GO terms, most notably involving mRNAs annotated as pectinesterase and polygalacturonase, which play roles in cell wall degradation. The considerable downregulation of these genes might contribute to the delayed degradation of tapetum in 366-2S. Furthermore, we identified 15 lncRNA-mRNA modules through Venn diagram analysis. Among them, MSTRG.9997-BraA04g004630.3C (β-1,3-glucanase) is associated with callose degradation and tetrad separation. Additionally, MSTRG.5212-BraA02g040020.3C (pectinesterase) and MSTRG.13,532-BraA05g030320.3C (pectinesterase) are associated with cell wall degradation of the tapetum, indicating that these three candidate lncRNA-mRNA modules potentially regulate pollen development. This study lays the foundation for understanding the roles of lncRNAs in pollen development and for elucidating their molecular mechanisms in regulating male sterility in Chinese cabbage.

Development and Investigation of HRM Markers to Discriminate Two Ogura Cytoplasmic Male Sterility Restorer Genes in Radish

Ogura male sterile cytoplasm is widely used for radish breeding. In this study, high-resolution melting (HRM) markers associated with Rft and Rfo, major restorer-of-fertility genes in Ogura cytoplasmic male sterility (CMS) in radish, were developed. Genetic mapping was carried out using F2 populations derived from crosses between male-sterile Ogura CMS lines and male-fertile lines. Identification of the Rft and Rfo loci was achieved through SNP-based genotyping and linkage grouping. HRM markers were subsequently developed based on flanking sequences of SNPs linked to these loci. For the Rft gene, a set of 117 SNPs was selected within a candidate region on chromosome 5, and 14 HRM markers were successfully developed. Genotyping of F2 showed high correlation between three markers and the phenotype. Regarding the Rfo gene, a set of 27 HRM markers was designed based on flanking sequences of SNPs located on chromosomes 9 and 0. Genotyping in the Rfo segregating population identified a single marker, RSRF27, that accurately distinguished the male sterility phenotype. Validation of the developed markers was performed in populations containing both Rft and Rfo genes, confirming their utility for genotyping and demonstrating that these two genes independently contribute to male sterility recovery. Overall, this study provides HRM markers that can be used for genotyping Rft and Rfo and contributes to a deeper understanding of male sterility restoration mechanisms in Ogura CMS.

Genetic analysis of the 1000 grain weight trait in interlinear hybrids of winter rye (secale cereale l.)

The aim of the study is to quantify the contribution of additive, dominant and epistatic dispersions to the overall genetic variation of the 1000 grain weight trait to increase the efficiency of breeding heterotic hybrids of winter rye. The experiments were carried out at the experimental base of the Federal Research Center «Nemchinovka» (Moscow region). The starting material was 10 male sterile homozygous inbred lines carrying the Pump-type cytoplasm. These lines were crossed with two male fertile test lines: mf H-842 and mf H-1247. Test crosses were carried out in 2019 on two isolated plots according to the topcross scheme. The resulting hybrids and their parent forms were tested in 2020 and 2021 on plots of 8 m2 in two-fold repetition. The test for epistasis and decomposition of the genetic varianсе into additive and dominant components was carried out by the method of Jinks J., Perkins L.M., Brees E.L. (1969). The data show that the additive interaction of genes, as well as incomplete dominance, plays the main role in determining the trait of granularity. A stable ratio of these interactions was established over the years: the proportion of additive effects varied at the level of 83.9-84.7%, and the proportion of dominant effects at the level of 15.3-16.1%. The indicator of the degree of dominance √(H1/D) was less than one and varied slightly over the years. It follows from this that dominant alleles affecting gross grain do not completely suppress the effect of their recessive alleles. For this reason, simple interlinear hybrids inherit an intermediate phenotype compared to the parent forms. The most coarse-grained hybrids were obtained by crossing lines ms H-1054, ms H-649 and ms H-1090 with the coarsegrained tester mf H-1247. It is concluded that, in the synthesis of commercial rye hybrids, it is necessary to strive to ensure that all parent forms are gross-grained. To obtain such lines it is advisable to use methods of recurrent selection as well as convergent and cumulative breeding.

Rate of crop-weed hybridization in Sorghum bicolor × Sorghum halepense is influenced by genetic background, pollen load, and the environment.

The potential for gene flow between cultivated species and their weedy relatives poses agronomic and environmental concerns, particularly when there are opportunities for the transfer of adaptive or agronomic traits such as herbicide resistance into the weedy forms. Grain sorghum (Sorghum bicolor) is an important crop capable of interspecific hybridization with its weedy relative johnsongrass (Sorghum halepense). Previous findings have shown that triploid progenies resulting from S.bicolor×S.halepense crosses typically collapse with only a few developing into mature seeds, whereas tetraploids often fully develop. The objective of this experiment was to determine the impact of S.bicolor genotype and pollen competition on the frequency of hybridization between S.bicolor and S.halepense. A total of 12 different cytoplasmic male sterile S.bicolor genotypes were compared with their respective male fertile lines across 2 years, to assess the frequency of hybridization and seed set when S.halepense served as the pollinator parent. Results indicate significant differences in the frequency of interspecific hybridization among the S.bicolor genotypes, and pollen fertility in S.bicolor reduced the rate of this interspecific hybridization by up to two orders of magnitude. Further, hybridization rates greatly varied across the two study environments. Results are helpful for developing appropriate gene flow mitigation strategies and indicate that gene flow could be reduced by the selection of appropriate seed parents for sorghum hybrids.

Lateral metabolome study reveals the molecular mechanism of cytoplasmic male sterility (CMS) in Chinese cabbage

BackgroundChinese cabbage is one of the most widely grown leafy vegetables in China. Cytoplasmic male sterility (CMS) is a maternally inherited trait that produces abnormal pollen during anther development, which is commonly seen in cruciferous vegetables. However, the molecular mechanism of Chinese cabbage CMS is not clear. In this study, the metabolome and hormone profiles of Chinese cabbage male sterile line (CCR20000) and sterile maintainer line (CCR20001) were analyzed in flower buds during normal stamen development and abnormal stamen development, respectively.ResultsA total of 556 metabolites were detected based on UPLC-MS/MS detection platform and database search, and the changes of hormones such as auxin, cytokinins, abscisic acid, jasmonates, salicylic acid, gibberellin acid and ethylene were analyzed. The results showed that compared with the male fertile line (MF), the male sterile line (MS) significantly decreased the content of flavonoids and phenolamides metabolites in the stamen dysplasia stage, accompanied by a large accumulation of glucosinolate metabolites. Meanwhile, the contents of GA9, GA20, IBA, tZ and other hormones in MS were significantly lower than those in MF strains. Further, by comparing the metabolome changes of MF and MS during stamen dysplasia, it was found that flavonoid metabolites and amino acid metabolites were distinctly different.ConclusionsThese results suggest that flavonoids, phenolamides and glucosinolate metabolites may be closely related to the sterility of MS strains. This study provides an effective basis for further research on the molecular mechanism of CMS in Chinese cabbage.

Assessment of combinational ability of inbred lines of winter rye by the topcross method

Dentification perspective on combinational ability of the inbred lines of winter rye is an important stage in hybrid breeding. The purpose of researches - to estimate the general and specific combinational ability of the inbred lines of winter rye by a method of full top crossings. As a maternal form 30 homozygous lines of rye bearing sterile cytoplasm Pampas type served. As testers 4 male fertile homozygous lines used : mfН-1432, mfН-1423, mfН-1147 and mfН-1842. Test crossings carried out in 2019 on spatially the isolated plots. In total 120 simple interlinear hybrids of F1 were received. Their test carried out in 2020 on plots 8,0 m2 in 2 repetitions at norm of seeding of 500 grains on 1 m2. As the standard used population variety Valdai. Productivity of hybrids F1 varied from 5,08 to 7,55 t/hectare at average productivity in experience 6,27t/hectare. Hybrids with participation of the line msH-1185-1 were the most yielding. Their productivity varied from 6,92 to 7,48 t/hectare depending on a tester. Frequency of hybrids of F1 with authentically high competitive heterosis made 20 of 120 or 16,7 %. In dispersion of a sign of productivity the essential contribution was made both the general (GCA), and specific (SCA) combinational ability. However fell to the share of effects GCA 91,2 % of all dispersion of productivity, and to SCA share - 6,9 %. The high relation variances by GCA/SCA is pointed to rather high genetic divergence by the inbred lines taken for crossing. Authentically high GCA showed 7 sterile lines: ms H-1185-1, msH-1185-2, msН-1179, msН-1238, msН-700, msН-48, msН-1247. Among lines testers of the best on GCA there was mfН-1147. High effects of SCA showed the msН-451, msН-577, msН-842, msH-1185-2 and msН-1190 lines, and also testers of mfН-1432 and mfН-1423. It is characteristic that average productivity of hybrids with participation of lines with high GCA was authentically above, than average productivity of hybrids with participation of lines from high SCA (6,76 t/hectare against 6,24 t/hectare, tfact=3,38> t05=2,22). Significantly low GCA possessed 9 sterile lines. Positive correlation between effects of GCA lines and level of their own productivity is revealed (r=0,59, t fact =2,30> t 05=2,22)

Cytoplasmic Male Sterility Incidence in Potato Breeding Populations with Late Blight Resistance and Identification of Breeding Lines with a Potential Fertility Restorer Mechanism.

Cytoplasmic male sterility (CMS) in potato is a common reproductive issue in late blight breeding programs since resistant sources usually have a wild cytoplasmic background (W or D). Nevertheless, in each breeding cycle male fertile lines have been observed within D- and T-type cytoplasms, indicating the presence of a fertility restorer (Rf) mechanism. Identifying sources of Rf and complete male sterility to implement a CMS-Rf system in potato is important since hybrid breeding is a feasible breeding strategy for potato. The objective of this study was to identify male fertile breeding lines and potential Rf candidate lines in the CIP late blight breeding pipeline. We characterized male fertility/sterility-related traits on 142 breeding lines of known cytoplasmic type. We found that pollen viability is not a reliable estimate of male sterility in diverse backgrounds. Breeding lines of the T-type cytoplasmic group had higher levels of male fertility than breeding lines of the D-type cytoplasmic group. With the help of pedigree records, reproductive traits evaluations and test crosses with female clones of diverse background, we identified four male parental lines segregating for Rf and three female parental lines that generated 100% male sterile progeny. These identified lines and generated test cross progenies will be valuable to develop validation populations for mitochondrial or nuclear markers for the CMS trait and for dihaploid generation of Rf+ lines that can be later employed in diploid hybrid breeding.

Epigenetic Dynamics and Regulation of Plant Male Reproduction.

Flowering plant male germlines develop within anthers and undergo epigenetic reprogramming with dynamic changes in DNA methylation, chromatin modifications, and small RNAs. Profiling the epigenetic status using different technologies has substantially accumulated information on specific types of cells at different stages of male reproduction. Many epigenetically related genes involved in plant gametophyte development have been identified, and the mutation of these genes often leads to male sterility. Here, we review the recent progress on dynamic epigenetic changes during pollen mother cell differentiation, microsporogenesis, microgametogenesis, and tapetal cell development. The reported epigenetic variations between male fertile and sterile lines are summarized. We also summarize the epigenetic regulation-associated male sterility genes and discuss how epigenetic mechanisms in plant male reproduction can be further revealed.

Production of Doubled Haploid through Anther Culture of the Male-Fertile Lines in the CMS System of Eggplant with the Cytoplasm of <i>Solanum grandifolium</i>

To produce doubled haploid homozygous male-sterile line of eggplant with the cytoplasm of Solanum grandifolium, anther culture of the male-fertile (MF) BC5 in the S. grandifolium induced CMS system was done. Anthers were cultured in an embryo induction medium and were heated to 35℃ for 3 d in the dark and then transferred to 25℃ under a 16 h photoperiod. After 20 d the anthers were transferred to a germination medium. The presence of pollen in the anther, number of chromosomes in the root tip cells, size of the stomatal guard cells and pollen fertility of the regenerated plants were investigated. The frequency of embryo formation in the MF line was 1.02%. From the embryos, one regenerated plant showed pollen non-formation type male sterility. Root tip chromosome number and stomatal guard cell size confirmed that the regenerated male-sterile plant is a microspore originated doubled haploid through spontaneous chromosome doubling. The present study demonstrates the first successful production of a doubled haploid homozygous male-sterile line in a CMS system of eggplant with the cytoplasm of S. grandifolium. Therefore, this material could be a useful breeding material for eggplant and improve the speed of conventional breeding.

Proteomic analysis of differential anther development from sterile/fertile lines in Capsicum annuum L.

BackgroundPepper (Capsicum annuum L.) is a major cash crop throughout the world. Male sterility is an important characteristic in crop species that leads to a failure to produce functional pollen, and it has crucial roles in agricultural breeding and the utilization of heterosis.ObjectivesIn this study, we identified many crucial factors and important components in metabolic pathways in anther and pollen development, and elucidated the molecular mechanism related to pollen abortion in pepper.MethodsPepper pollen was observed at different stages to detect the characteristics associated with male sterility and fertility. The phytohormone and oxidoreductase activities were detected in spectrophotometric and redox reaction assays, respectively. Proteins were extracted from male sterile and fertile pepper lines, and identified by TMT/iTRAQ (tandem mass tags/isobaric tags for relative and absolute quantitation) and LC-MS/MS (liquid chromatograph-mass spectrometer) analysis. Differentially abundant proteins (DAPs) were analyzed based on Gene Ontology annotations and the Kyoto Encyclopedia of Genes and Genomes database according to |fold change)| > 1.3 and P value < 0.05. DAPs were quantified in the meiosis, tetrad, and binucleate stages by parallel reaction monitoring (PRM).ResultsIn this study, we screened and identified one male sterile pepper line with abnormal cytological characteristics in terms of pollen development. The peroxidase and catalase enzyme activities were significantly reduced and increased, respectively, in the male sterile line compared with the male fertile line. Phytohormone analysis demonstrated that the gibberellin, jasmonic acid, and auxin contents changed by different extents in the male sterile pepper line. Proteome analysis screened 1,645 DAPs in six clusters, which were mainly associated with the chloroplast and cytoplasm based on their similar expression levels. According to proteome analysis, 45 DAPs were quantitatively identified in the meiosis, tetrad, and binucleate stages by PRM, which were related to monoterpenoid biosynthesis, and starch and sucrose metabolism pathways.ConclusionsWe screened 1,645 DAPs by proteomic analysis and 45 DAPs were related to anther and pollen development in a male sterile pepper line. In addition, the activities of peroxidase and catalase as well as the abundances of phytohormones such as gibberellin, jasmonic acid, and auxin were related to male sterility. The results obtained in this study provide insights into the molecular mechanism responsible for male sterility and fertility in pepper.

Detection of candidate gene LsACOS5 and development of InDel marker for male sterility by ddRAD-seq and resequencing analysis in lettuce.

A new breeding method of F1 hybrid using male sterility would open an exciting frontier in lettuce breeding, a self-pollinating crop. Male sterility is a crucial trait in F1 hybrid breeding. It is essential to map the causative gene for using male sterility. The ms-S, male-sterile (MS) gene of ‘CGN17397’, was mapped to linkage group (LG) 8 by ddRAD-seq and narrowed down between two markers using two F2 populations. This region spans approximately 10.16 Mb, where 94 genes were annotated according to the lettuce reference genome sequence (version8 from ‘Salinas’). The whole-genome sequencing of the MS lines ‘CGN17397-MS’ and male-fertile (MF) lines ‘CGN17397-MF’ revealed that only one gene differed in the area of Lsat_1_v5_gn_8_148221.1, a homolog of acyl-CoA synthetase5 (ACOS5), and was deleted in the MS lines. It was reported that ACOS5 was needed for pollen wall formation and that the null mutants of ACOS5 were entirely male sterility in some plants. Thus, I concluded that Lsat_1_v5_gn_8_148221.1 designated as LsACOS5 was a biologically plausible candidate gene for the ms-S locus. By using the structural polymorphism of LsACOS5, an InDel marker was developed to select the MS trait. The results obtained here provide valuable information for the genic male-sterility in lettuce.

Transcriptome profiling of flower buds of male-sterile lines provides new insights into male sterility mechanism in alfalfa

BackgroundThe use of heterosis to produce hybrid seeds is a challenge to breeding for improved crop yield. In previous studies, we isolated a male sterile alfalfa hybrid and successfully obtained a genetically stable alfalfa male sterile line through backcrossing, henceforth named MS-4. In this study, we used RNA-seq technology to analyze the transcriptome profiles of the male sterile line (MS-4) and the male fertile line (MF) of alfalfa to elucidate the mechanism of male sterility.ResultsWe screened a total of 11,812 differentially expressed genes (DEGs) from both MS-4 and MF lines at three different stages of anther development. Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that these DEGs are mainly involved in processes such as energy metabolism, lipid and amino acid metabolism, carbohydrate metabolism, in addition to cell synthesis and aging. The results from protein–protein interaction (PPI) network analysis showed that the ribosomal protein (MS.Gene25178) was the core gene in the network. We also found that transcriptional regulation was an influential factor in the development of anthers.ConclusionsOur findings provide new insights into understanding of the fertility changes in the male sterile (MS-4) of alfalfa.

Electrophysiological, Morphologic, and Transcriptomic Profiling of the Ogura-CMS, DGMS and Maintainer Broccoli Lines.

To better serve breeding of broccoli, the electrophysiological, morphological and transcriptomic profiling of the isogenic Ogura-CMS, DGMS and their maintainer fertile lines, were carried out by scanning electron microscopy, investigation of agronomic traits and RNA-sequencing analysis. The agronomic traits of plant height, length of the largest leaf, plant spread angle, single head weight, head width and stem diameter showed stronger performance in Ogura-CMS broccoli than in DGMS line or maintainer fertile line. However, the Ogura-CMS broccoli was poorer in the seed yield and seed germination than in the DGMS line and maintainer fertile line. Additionally, the DGMS broccoli had longer maturation and flowering periods than the Ogura-CMS and maintainer fertile lines. There were obvious differences in the honey gland, happening in the male sterility and fertile lines of broccoli. Additionally, the mechanism regulating Ogura-CMS and DGMS in broccoli was investigated using florets transcriptome analyses of the Ogura-CMS, DGMS and maintainer fertile lines. As a result, a total of 2670 differentially expressed genes (DEGs) were detected, including 1054 up- and 1616 downregulated genes in the Ogura-CMS and DGMS lines compared to the maintainer fertile line. A number of functionally known genes involved in plant hormones (auxin, salicylic acid and brassinosteroid), five Mitochondrial Oxidative Phosphorylation (OXPHOS) genes of atp8, LOC106319879, LOC106324734, LOC106314622 and LOC106298585, and three upregulated genes (Lhcb1, Lhcb3 and Lhcb5) associated with the photosynthesis-antenna protein pathway, were obviously detected to be highly associated with reproductive development including flowering time, maturity and reproductive period in the Ogura-CMS and DGMS broccoli comparing to their maintainer fertile line. Our research would provide a comprehensive foundation for understanding the differences of electrophysiological, morphological and transcriptomic profiles in the Ogura-CMS, DGMS and maintainer broccoli, and as well as being beneficial to exploring the mechanism of male sterility in Brassica crops.

Efficacy of hybrid seed production through natural pollinators employing male sterility: Case study of ridge gourd [Luffa acutangula (Roxb.) L.] CGMS system

Potential of natural pollinators and manually assisted pollination for producing F1 hybrid seeds of ridge gourd hybrid ‘KRH 1’ was evaluated under open field condition for two seasons by growing male sterile line (KAU-LA-MS-101) and monoecious male fertile line (LA-102) in alternate rows. Investigation was carried out at the Department of Vegetable Science, College of Agriculture, Vellanikkara, Thrissur, India. Species diversity of the pollinators, peak foraging time of the pollinators, number of floral visits by pollinating bees and number of bees visiting a flower during stigma receptivity were recorded. Nectary glands of male and female flowers of KAU-LA-MS-101 and LA 102 were measured. Seed yield and seed quality related traits were also recorded following standard protocol. Male sterile plants produce small male flowers with tiny nectary glands when compared to that of LA- 102, but female flowers of male sterile line have larger nectary glands. Stingless bee (Tetragonula sp.), was the pollinator observed in the field during anthesis time with peak activity after 5.30 pm. Number of fruits, number of seeds per fruit and average seed weight were significantly different between male sterile line and monoecious male fertile line LA-102. Pollination efficiency of bees found to be high when compared to manual hands in terms of quality of seeds produced from male sterile plants. However manual hands proved to be better for inducing more number of seeds per fruit. Total seed yield per plant depends on the total number of fruits developed and pollination by bees induces the development of more flowers to maturity, thereby ensuring competitive seed yield. Seed yield per plant exhibited significant positive correlation with seed length, shoot length, root length, fresh weight, vigour index I and germination velocity index. Present investigation revealed the potential of male sterile line developed in ridge gourd for hybrid seed production. Alternate planting of fertility restorer line with the MS line and allowing open pollination with the assistance of bees will reduce the labour charge involved in hybrid seed production and quality seed can be made available at a competitive rate.

Transcriptome Profiling Reveals Molecular Changes during Flower Development between Male Sterile and Fertile Chinese Cabbage (Brassicarapa ssp. pekinensis) Lines.

Male sterility exists widely in flowering plants and is used as a fascinating tool by breeders for creating hybrid varieties. Herein, stamen samples from male sterile CCR20000 and male fertile CCR20001 lines during two developmental stages were employed to elucidate the molecular changes during flower development in fertile and sterile Chinese cabbage lines. RNA-seq revealed weak transcriptional activity in the sterile line, which may have led to the abnormal stamen development. The differentially expressed genes were enriched in plant hormone, carbon metabolism, and biosynthesis of amino acid pathways. Important genes with opposite patterns of regulation between the two lines have been associated with the male sterility trait. Members of the transcription factor families such as AP2, MYB, bHLH, and WRKY were highly active in the regulation of structural genes involved in pollen fertility. This study generated important genomic information to support the exploitation of the male sterility trait in Chinese cabbage breeding programs.

Deciphering the dynamic gene expression patterns of pollen abortion in a male sterile line of Avena sativa through transcriptome analysis at different developmental stages

BackgroundMale sterility (MS) has important applications in hybrid seed production, and the abortion of anthers has been observed in many plant species. While most studies have focused on the genetic factors affecting male sterility, the dynamic gene expression patterns of pollen abortion in male sterile lines have not been fully elucidated. In addition, there is still no hybrid oat that is commercially planted due to the lack of a suitable system of male sterility for hybrid breeding.ResultsIn this study, we cultivated a male sterile oat line and a near-isogenic line by crossbreeding to elucidate the expression patterns of genes that may be involved in sterility. The first reported CA male sterile (CAMS) oat line was used for cross-testing and hybridization experiments and was confirmed to exhibit a type of nuclear sterility controlled by recessive genes. Oat stamens of two lines were sampled at four different developmental stages separately. Paired-end RNA sequencing was performed for each sample and generated 252.84 Gb sequences. There were 295,462 unigenes annotated in public databases in all samples, and we compared the histological characteristics and transcriptomes of oat stamens from the two oat lines at different developmental stages. Our results demonstrate that the sterility of the male sterile oat line occurs in the early stage of stamen development and is primarily attributable to abnormal meiosis and the excessive accumulation of superoxide.ConclusionsTo the best of our knowledge, this study is the first to decipher the dynamic expression profiles of pollen abortion CAMS and CA male fertile (CAMF) oat lines, which may represent a valuable resource for further studies attempting to understand pollen abortion and anther development in oats.

Identification of microRNAs and their gene targets in cytoplasmic male sterile and fertile maintainer lines of pigeonpea.

Comparative analysis of genome-wide miRNAs and their gene targets between cytoplasmic male sterile (CMS) and fertile lines of pigeonpea suggests a possible role of miRNA-regulated pathways in reproductive development. Exploitation of hybrid vigor using CMS technology has delivered nearly 50% yield gain in pigeonpea. Among various sterility-inducing cytoplasms (A1-A9) reported so far in pigeonpea, A2 and A4 are the two major sources that facilitate hybrid seed production. Recent evidence suggests involvement of micro RNA in vast array of biological processes including plant reproductive development. In pigeonpea, information about the miRNAs is insufficient. In view of this, we sequenced six small RNA libraries of CMS line UPAS 120A and isogenic fertile line UPAS 120B using Illumina technology. Results revealed 316 miRNAs including 248 known and 68 novel types. A total of 637 gene targets were predicted for known miRNAs, while 324 genes were associated with novel miRNAs. Degradome analysis revealed 77 gene targets of predicted miRNAs, which included a variety of transcription factors playing key roles in plant reproduction such as F-box family proteins, apetala 2, auxin response factors, ethylene-responsive factors, homeodomain-leucine zipper proteins etc. Differential expression of both known and novel miRNAs implied roles for both conserved as well as species-specific players. We also obtained several miRNA families such as miR156, miR159, miR167 that are known to influence crucial aspects of plant fertility. Gene ontology and pathway level analyses of the target genes showed their possible implications for crucial events during male reproductive development such as tapetal degeneration, pollen wall formation, retrograde signaling etc. To the best of our knowledge, present study is first to combine deep sequencing of small RNA and degradome for elucidating the role of miRNAs in flower and male reproductive development in pigeonpea.

Comparative transcriptome analysis provides insight into the molecular mechanisms of anther dehiscence in eggplant (Solanum melongena L.)

Anther dehiscence releases pollen and therefore is a key event in plant sexual reproduction. Although anther dehiscence has been intensively studied in some plants, such as Arabidopsis thaliana and rice (Oryza sativa), the molecular mechanism of anther dehiscence in eggplant (Solanum melongena) is largely unknown. To provide insight into this mechanism, we used RNA-sequencing (RNA-seq) to analyze the transcriptomic profiles of one natural male-fertile line (F142) and two male-sterile lines (S12 and S13). We assembled 88,414 unigenes and identified 3446 differentially expressed genes (DEGs). GO and KEGG analysis indicated that these DEGs were mainly involved in “metabolic process”, “catalytic activity”, “biosynthesis of amino acids”, and “carbon metabolism”. The present study provides comprehensive transcriptomic profiles of eggplants that do and do not undergo anther dehiscence, and identifies a number of genes and pathways associated with anther dehiscence. The information deepens our understanding of the molecular mechanisms of anther dehiscence in eggplant.

Heterosis for Ethanol Yield and Yield Components in Sweet Sorghum

The improvement of sweet sorghum for biofuel traits is gaining attention globally because of its promising role in the growth and sustainability of the ethanol production chain. The aim of this study was to assess the heterosis on ethanol yield and related agro-industrial traits in sweet sorghum under tropical conditions. Thirty hybrids were generated from a partial diallel scheme using three juicy stem non-sweet female lines (A) with cytoplasmic male sterility crossed with ten sweet sorghum male fertile restorer lines (R). The hybrids, parental lines, and two checks were evaluated in three environments in Brazil. Heterosis in sweet sorghum was observed for ethanol yield (ETH) and several yield components. Four hybrids showed positive heterosis on the R-line basis for ETH. The heterosis was higher for PH (plant height), GMP (green or fresh biomass production), and tons of brix per hectare. The parental A and R-lines diverged in contributing to the heterosis. The lines BR008A and CMSXS644R have been highlighted for ethanol yield and can be included in future A and R-line development.