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The cytoplasm of Aegilops kotschyi is known for the induction of male sterility and haploidy in wheat. Both systems originally appeared rather simple, but manipulation of the standard chromosome constitution of the nuclear genome revealed additional interactions. This study shows that while there is little or no allelic variation at the main fertility restorer locus Rfmulti on chromosome arm 1BS, additional genes may also be involved in the nuclear-mitochondrial genome interactions, affecting not only male fertility but also the growth rate, from pollen competition for fertilization and early endosperm divisions all the way to seed size and plant maturity. Some of these effects appear to be of a sporophytic nature; others are gametophytic. Induction of parthenogenesis by a rye inducer in conjunction with the Ae. kotschyi cytoplasm is well known. However, here we show that the cytoplasmic-nuclear interactions affect all aspects of double fertilization: producing maternal haploids from unfertilized eggs, diploids from fertilized eggs or synergids, embryo-less kernels, and fertilized eggs without fertilization of the double nucleus in the embryo sack. It is unclear how frequent the inducers of parthenogenesis are, as variation, if any, is obscured by suppressors present in the wheat genome. Genetic dissection of a single wheat accession revealed five distinct loci affecting the rate of maternal haploid production: four acting as suppressors and one as an enhancer. Only when the suppressing haplotypes are confirmed may it be possible to the identify genetic variation of haploidy inducers, map their position(s), and determine their nature and the mode of action.

SUMMARY: Cytoplasmic male sterility (CMS) is an agronomically significant trait that causes dysfunction in pollen and anther development. It is often observed during successive backcrossing between distantly related species. Here, we show that Asian japonica cultivars (Oryza sativa) exhibit CMS when the nucleus is replaced with that of the African rice Oryza glaberrima. The CMS line produced stunted anthers and did not set any seeds. Mitochondrial orf288 RNA was detected in the anthers of CMS lines but not in fertility restorer lines. The mitochondrial genome‐edited japonica rice that was depleted of orf288 did not exhibit male sterility when backcrossed with O. glaberrima. These results demonstrate that orf288 is a CMS‐causing gene. As orf288 commonly occurs in the mitochondrial genomes of japonica rice, these results indicate that common japonica rice cultivars possess a cryptic CMS‐causing gene hidden in their mitochondrial genomes. [ABSTRACT FROM AUTHOR]

Summary: Germplasm resources serve as the foundations of advancements in breeding and are crucial for maintaining food security. Wild rice species of the genus Oryza include rich sources of genetic diversity and high adaptability, making them a substantial resource for rice breeding. The discovery of wild‐type cytoplasmic male sterility resources enabled the achievement of the 'three lines' goal in hybrid rice, significantly increasing rice yields. The application of resistance alleles from wild rice enables rice production to withstand losses caused by stress. Reduced genetic diversity due to rice breeding poses a significant limitation to further advances and can be alleviated through a systematic use of wild genetic resources that integrate geographic, climatic and environmental data of the original habitat, along with extensive germplasm collection and identification using advanced methods. Leveraging technological advancements in plant genomics, the understanding of genetic mechanisms and the application of artificial intelligence and gene editing can further enhance the efficiency and accuracy of this process. These advancements facilitate rapid isolation and functional studies of genes, and precise genome manipulation. This review systematically summarizes the utilization of superior genes and germplasm resources derived from wild rice sources, while also exploring the collection, conservation, identification and utilization of further wild rice germplasm resources. A focus on genome sequencing and biotechnology developments is leading to new breeding and biotechnology opportunities. These new opportunities will not only promote the development of rice varieties that exhibit high yields, superior stress resistance and high quality but also expand the genetic diversity among rice cultivars. [ABSTRACT FROM AUTHOR]

The interaction of plant mitochondrial and nuclear genetic systems is exemplified by mitochondria-encoded cytoplasmic male sterility (CMS) under the control of nuclear restorer-of-fertility genes. The S type of CMS in maize is characterized by a pollen collapse phenotype and a unique paradigm for fertility restoration in which numerous nuclear restorer-of-fertility lethal mutations rescue pollen function but condition homozygous-lethal seed phenotypes. Two nonallelic restorer mutations recovered from Mutator transposon-active lines were investigated to determine the mechanisms of pollen fertility restoration and seed lethality. Mu Illumina sequencing of transposon-flanking regions identified insertion alleles of nuclear genes encoding mitochondrial ribosomal proteins RPL6 and RPL14 as candidate restorer-of-fertility lethal mutations. Both candidates were associated with lowered abundance of mitochondria-encoded proteins in developing maize pollen, and the rpl14 mutant candidate was confirmed by independent insertion alleles. While the restored pollen functioned despite reduced accumulation of mitochondrial respiratory proteins, normal-cytoplasm plants heterozygous for the mutant alleles showed a significant pollen transmission bias in favor of the nonmutant Rpl6 and Rpl14 alleles. CMS-S fertility restoration affords a unique forward genetic approach to investigate the mitochondrial requirements for, and contributions to, pollen and seed development. [ABSTRACT FROM AUTHOR]

Key message: We report the mitochondrial genome of 39 diploid potatoes and identify a candidate ORF potentially linked to cytoplasmic male sterility in potatoes. Potato (Solanum tuberosum L.) holds a critical position as the foremost non-grain food crop, playing a pivotal role in ensuring global food security. Diploid potatoes constitute a vital genetic resource pool, harboring the potential to revolutionize modern potato breeding. Nevertheless, diploid potatoes are relatively understudied, and mitochondrial DNA can provide valuable insights into key potato breeding traits such as CMS. In this study, we examine and assemble the mitochondrial genome evolution and diversity of 39 accessions of diploid potatoes using high-fidelity (HiFi) sequencing. We annotated 54 genes for all the investigated accessions, comprising 34 protein-coding genes, 3 rRNA genes, and 17 tRNA genes. Our analyses revealed differences in repeats sequences between wild and cultivated landraces. To understand the evolution of diploid maternal lineage inheritance, we conducted phylogenetic analysis, which clearly distinguished mitochondrial from nuclear gene trees, further supporting the evidence-based of clustering between wild and cultivated landraces accessions. Our study discovers new candidate ORFs associated with CMS in potatoes, including ORF137, which is homologous to other CMS in Solanaceae. Ultimately, this work bridges the gap in mitochondrial genome research for diploid potatoes, providing a steppingstone into evolutionary studies and potato breeding. [ABSTRACT FROM AUTHOR]

The value of red sugar beet in medical treatment, nutrition, and health care, as well as for the extraction of natural pigment, is now recognized, necessitating the selection of optimal red sugar beet varieties. However, the self-bred varieties in China are all multi-embryo varieties, with very few single embryo hybrid varieties. The use of heterosis breeding requires sterile and maintainer lines; while, the domestic red beet resources and the cytoplasmic and nuclear fertility of imported red beet varieties (lines) are unknown. In this study, we identified 50 red sugar beet varieties (lines), including both domestic and international lines, using specific TR1 primers acting on a variable number of mitochondrial tandem repeat (VNTR) loci, and s17 and o7 primers associated with the nuclear fertility Rf1 and Rf2 sites to investigate the cytoplasmic and nuclear fertility-associated genotypes of 50 red sugar beet varieties (lines). The results showed that among the 50 red sugar beet varieties tested, the proportion of fertile cytoplasm (N-type) was 54%; while, the proportion of infertile cytoplasm (S-type) was 40%. The proportion of cytoplasmic hybridization between the sterile (S-type) and fertile (N-type) types was 6%. In the genotypic identification of the Rf1 and Rf2 loci related to nuclear fertility, the highest proportion in the Rf1 locus was the homozygous 1.8 kbp genotype, accounting for 94%. Double-restriction endonuclease analysis was performed on the PCR products amplified from s17. The varieties (lines) with a homozygous 5/5 pattern after double restriction endonuclease analysis accounted for the largest proportion, namely, 88%. The band pattern with the highest proportion in the Rf2 locus was a homozygous 1.4 kbp pattern, accounting for 42%, while the homozygous 2.6 kbp type accounted for 6%. Two or more heterozygous bands accounted for a total of 52%. The results provide a preliminary understanding of the cytoplasmic and nuclear fertility-related genotypes of 50 red sugar beet varieties (lines), and combine both cytoplasmic and nuclear fertility for a comprehensive analysis of the fertility of red sugar beet varieties (lines), providing a reference for the breeding of red sugar beet heterosis varieties. [ABSTRACT FROM AUTHOR]

Main conclusion: A comprehensive understanding of the nucleocytoplasmic interactions that occur between genes related to the restoration of fertility and cytoplasmic male sterility (CMS) provides insight into the development of hybrids of important crop species. Modern biotechnological techniques allow this to be achieved in an efficient and quick manner. Heterosis is paramount for increasing the yield and quality of a crop. The development of hybrids for achieving heterosis has been well-studied and proven to be robust and efficient. Cytoplasmic male sterility (CMS) has been explored extensively in the production of hybrids. The underlying mechanisms of CMS include the role of cytotoxic proteins, PCD of tapetal cells, and improper RNA editing of restoration factors. On the other hand, the restoration of fertility is caused by the presence of restorer-of-fertility (Rf) genes or restorer genes, which inhibit the effects of sterility-causing genes. The interaction between mitochondria and the nuclear genome is crucial for several regulatory pathways, as observed in the CMS–Rf system and occurs at the genomic, transcriptional, post-transcriptional, translational, and post-translational levels. These CMS–Rf mechanisms have been validated in several crop systems. This review aims to summarize the nucleo-mitochondrial interaction mechanism of the CMS–Rf system. It also sheds light on biotechnological interventions, such as genetic engineering and genome editing, to achieve CMS-based hybrids. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) is a mitochondrial-encoded trait that confers reproductive defects in males but not in females or any vegetative function. Why CMS is so often found in plants should be investigated from the viewpoint of mitochondrial phylogeny. Beta vulgaris, including the wild subspecies maritima and cultivated subspecies vulgaris (e.g., sugar beet), is known to be mitochondrially polymorphic, from which multiple CMS mitochondria have been found, but their evolutionary relationship has been obscure. We first refined the B. vulgaris reference mitochondrial genome to conduct a more accurate phylogenetic study. We identified mitochondrial single-nucleotide polymorphic sites from 600 B. vulgaris accessions. Principal component analysis, hierarchical clustering analysis, and creation of a phylogenetic tree consistently suggested that B. vulgaris mitochondria can be classified into several groups whose geographical distribution tends to be biased toward either the Atlantic or Mediterranean coasts. We examined the distribution of CMS-associated mitochondrial genes from Owen, E- and G-type CMS mitochondria. About one-third of cultivated beets had Owen-type CMS, which reflects the prevalence of using Owen-type CMS in hybrid breeding. Occurrence frequencies for each of the three CMS genes in wild beet were less than 4%. CMS genes were tightly associated with specific mitochondrial groups that are phylogenetically distinct, suggesting their independent origin. However, homologous sequences of the Owen type CMS gene occurred in several different mitochondrial groups, for which an intricate explanation is necessary. Whereas the origin of cultivated beet had been presumed to be Greece, we found an absence of Owen-type mitochondria in Greek accessions. [ABSTRACT FROM AUTHOR]

Maize (Zea mays) represents one of the most successful uses of heterosis among crops. Hybrid maize seeds can be produced by crossing a male-sterile female parent with a male parent as the pollen donor to achieve high seed purity at low cost. Cytoplasmic male sterility (CMS) has been widely used for maize hybrid seed production. Recently, several hybrid seed production technologies based on genic male sterility (GMS) genes have been developed. In addition, the identification of environment-sensitive genic male sterility (EGMS) genes provides opportunities for the two-line system to be applied in maize hybrid seed production. In this review, we systematically summarize the male-sterile genes and molecular mechanisms of male sterility in maize. Future prospects for the study of maize male sterility are highlighted. Future research will enhance our understanding of the molecular regulatory networks of male sterility and promote the process of maize hybrid seed production using male sterile lines. [ABSTRACT FROM AUTHOR]

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an important component of agri‐food system in areas experiencing drought and high temperature and for increasing the resilience to climatic stresses and addressing malnutrition. The purpose of this review is to examine strategies for improving productivity, stress resilience, and nutritional quality of pearl millet and to understand its consumption pattern. Genetic diversification of hybrid parental lines remains strategically important to breed diverse, disease‐resistant and drought‐tolerant hybrids. Resistance to diseases, tolerance to drought, and high temperature and greater contents of iron and zinc are targeted in improving hybrid parental lines. Lodging resistance, compact panicles, panicle exertion, and improved seed set are universal traits, whereas duration, tillering ability, seed color, and seed size have a strong regional preference. The strategy of developing high‐yielding and disease‐resistant hybrids with adaptation to challenged agro‐ecologies has led to increase in yield from 303 to 1219 kg/ha between 1960 and 2020. Yield and stress resilience are to be increased further using conventional breeding and new tools like genomic selection, speed breeding, genome editing, and precision phenotyping. Mainstreaming grain nutritional traits, viz., iron and zinc contents in genetic improvement are essential to develop high‐yielding and nutrient‐rich pearl millet. There is need to enhance the consumption of pearl millet by strengthening existing value‐chain, providing consumer a choice of diverse range of food products, creating awareness about its health benefits and promotion through government schemes. Core Ideas: Pearl millet has an important role in increasing climatic resilience of agri‐food system and reducing malnutrition.Strategies of enhancing yield focused on hybrid development, disease resistance, and genetic diversification.Use of adapted germplasm and elite materials proved effective in amalgamating drought tolerance and productivity.In future, yield is to be increased along with resilience using conventional, genomics‐assisted, and speed breeding.There is need to enhance the consumption of nutritious pearl millet by strengthening value‐chain and creating awareness. Plain Language Summary: Pearl millet is an important component of agri‐food system in areas experiencing drought and high temperature. It would have a greater role in future for increasing the resilience to climate stresses and as nutrient‐rich crop for addressing malnutrition. The purpose of this review is to examine strategies for improving productivity, environmental resilience, and nutritional quality of pearl millet and to understand its consumption dynamics. Yield improvement remains a top priority in breeding high‐yielding cultivars. Strategies of enhancing yield were influenced by availability of new knowledge and opportunities. Programs up to 1960s focused on the development of open‐pollinating varieties using a diverse range of genetic resources. Discovery of cytoplasmic male sterility (CMS), availability of stable male‐sterile lines, and effective restorers created new opportunities to exploit heterosis at the commercial scale through the development of hybrids that provided 15%–20% yield advantage over traditional cultivars. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) is important for commercial hybrid seed production. However, it is still not used in eggplant (Solanum melongena L.), and corresponding regulatory genes and mechanisms of action have not been reported. We report CMS line 327A, which was derived from the hybridization between cultivated and wild eggplants. By looking at different stages of anther development under a microscope, we saw that the 327A anther's tapetum layer vacuolized during meiosis, which caused abortion. To investigate the 327A CMS regulatory genes, the mitochondrial genomes of 327A and its maintainer line 327B were assembled de novo. It was found that 15 unique ORFs (Open Reading Frame) were identified in 327A. RT-PCR and RT-QPCAR tests confirmed that orf312a and orf172a, 327A-specific ORFs with a transmembrane domain, were strongly expressed in sterile anthers of 327A. In addition, orf312a has a chimeric structure with the ribosomal protein subunit rpl16. Therefore, orf312a and orf172a can be considered strong candidate genes for CMS. Concurrently, we analyzed the characteristics of CMS to develop a functional molecular marker, CMS312, targeting a future theoretical basis for eggplant CMS three-line molecular breeding. [ABSTRACT FROM AUTHOR]

Male sterility (MS) caused by aborted pollen is a vital germplasm resource. In this study, metabolomic, transcriptomic, and proteomic analyses were performed to investigate the molecular regulatory mechanism of cytoplasmic male sterility (CMS) in the flower buds of the male sterile line 09-05A and its maintainer line, 09-05B, of Brassica juncea. Our metabolomic analysis revealed that 41 metabolites involved in pollen development and male fertility formation were differentially accumulated between 09-05A and 09-05B at the bi-nucleate stage of B. juncea. Integrated omics indicated that the expression of key genes and proteins in the amino acid and phenylpropanoid metabolic pathways was remarkably downregulated in the flower buds of 09-05A. Furthermore, the abnormal expression of key transcription factor (TF) genes related to tapetum development and pollen wall formation may affect pollen development in the 09-05A CMS line. The results indicated that the downregulated expression level of critical genes and proteins in amino acid metabolism; phenylpropanoid synthesis; and TF genes, such as shikimate kinase, phenylalanine ammonia-lyase, and MYB103, may have led to impaired tapetum and pollen wall development, thereby causing pollen abortion in 09-05A. This study provides new insights into the metabolic and molecular regulatory mechanisms underlying the formation of CMS in B. juncea and lays a foundation for detailed studies on the identity and characteristics of MS-related genes. [ABSTRACT FROM AUTHOR]

Abstract Background Understanding the mechanism of male sterility is crucial for producing hybrid seeds and developing sterile germplasm resources. However, only a few cytoplasmic male sterility (CMS) lines of cotton have been produced due to several challenges, like inadequate variation of agronomic traits, incomplete sterility, weak resilience of restorer lines, and difficulty in combining strong dominance. Therefore, the morphological and cytological identification of CMS in cotton will facilitate hybrid breeding. Results Two F2 segregating populations of cotton were constructed from cytoplasmic male sterile lines (HaA and 01A, maternal) and restorer lines (HaR and 26R, paternal). Genetic analysis of these populations revealed a segregation ratio of 3:1 for fertile to sterile plants. Phenotypic analysis indicated no significant differences in traits of flower bud development between sterile and fertile plants. However, sterile plants exhibited smaller floral organs, shortened filament lengths, and anther atrophy on the flowering day in comparison with the fertile plants. When performed scanning electron microscopy (SEM), the two F2 populations revealed morphological variations in the anther epidermis. Cellular analysis showed no significant differences in pollen development before pollen maturation. Interestingly, between the pollen maturation and flowering stages, the tapetum layer of sterile plants degenerated prematurely, resulting in abnormal pollen grains and gradual pollen degradation. Conclusion The results of this study suggest that fertility-restoring genes are controlled by a single dominant gene. Sterile plants exhibit distinctive floral morphology, which is characterized by stamen atrophy and abnormal anthers. Pollen abortion occurs between pollen maturity and flowering, indicating that premature tapetum degradation may be the primary cause of pollen abortion. Overall, our study provides a theoretical basis for utilizing CMS in hybrid breeding and in-depth investigation of the dominant configuration of cotton hybrid combinations, mechanisms of sterility, and the role of sterile and restorer genes.

Abstract Hybrid development is one of the most promising strategies for boosting crop yields. Parental lines used to create hybrids must have good per se performance and disease resistance for developing superior hybrids. Indian wheat line HD3209 was developed by introducing the rust resistance genes Lr19/Sr25 into the background of popular wheat variety HD2932. The wheat line HD3209 carrying Lr19/Sr25 has been successfully and rapidly converted to the CMS line A-HD3209, with 96.01% background genome recovery, based on selection for agro-morphological traits, rust resistance, pollen sterility, and foreground and background analyses utilizing SSR markers. The converted CMS line A-HD3209 was completely sterile and nearly identical to the recurrent parent HD3209. Based on high per se performance and rust resistance, the study concludes that the derived CMS line A-HD3209 is promising and can be employed successfully in hybrid development.

Abstract Background Cytoplasmic male sterility (CMS) has greatly improved the utilization of heterosis in crops due to the absence of functional male gametophyte. The newly developed sporophytic D1 type CMS (CMS-D1) rice exhibits unique characteristics compared to the well-known sporophytic CMS-WA line, making it a valuable resource for rice breeding. Results In this research, a novel CMS-D1 line named Xingye A (XYA) was established, characterized by small, transparent, and shriveled anthers. Histological and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays conducted on anthers from XYA and its maintainer line XYB revealed that male sterility in XYA is a result of delayed degradation of tapetal cells and abnormal programmed cell death (PCD) of microspores. Transcriptome analysis of young panicles revealed that differentially expressed genes (DEGs) in XYA, compared to XYB, were significantly enriched in processes related to chromatin structure and nucleosomes during the microspore mother cell (MMC) stage. Conversely, processes associated with sporopollenin biosynthesis, pollen exine formation, chitinase activity, and pollen wall assembly were enriched during the meiosis stage. Metabolome analysis identified 176 specific differentially accumulated metabolites (DAMs) during the meiosis stage, enriched in pathways such as α-linoleic acid metabolism, flavone and flavonol biosynthesis, and linolenic acid metabolism. Integration of transcriptomic and metabolomic data underscored the jasmonic acid (JA) biosynthesis pathway was significant enriched in XYA during the meiosis stage compared to XYB. Furthermore, levels of JA, MeJA, OPC4, OPDA, and JA-Ile were all higher in XYA than in XYB at the meiosis stage. Conclusions These findings emphasize the involvement of the JA biosynthetic pathway in pollen development in the CMS-D1 line, providing a foundation for further exploration of the molecular mechanisms involved in CMS-D1 sterility.

Cytoplasmic male sterility (CMS) is of major agronomical relevance in hybrid breeding. In gametophytic CMS, abortion of pollen is determined by the grain genotype, while in sporophytic CMS, it is determined by the mother plant genotype. While several CMS mechanisms have been dissected at the molecular level, gametophytic CMS has not been straightforwardly accessible. We used the gametophytic Sha-CMS in Arabidopsis to characterize the cause and process of pollen abortion by implementing in vivo biosensing in single pollen and mitoTALEN mutagenesis. We obtained conclusive evidence that orf117Sha is the CMS-causing gene, despite distinct characteristics from other CMS genes. We measured the in vivo cytosolic ATP content in single pollen, followed pollen development, and analyzed pollen mitochondrial volume in two genotypes that differed only by the presence of the orf117Sha locus. Our results showed that the Sha-CMS is not triggered by ATP deficiency. Instead, we observed desynchronization of a pollen developmental program. Pollen death occurred independently in pollen grains at diverse stages and was preceded by mitochondrial swelling. We conclude that pollen death is grain-autonomous in Sha-CMS and propose that mitochondrial permeability transition, which was previously described as a hallmark of developmental and environmental-triggered cell death programs, precedes pollen death in Sha-CMS. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility has been a popular genetic tool in development of hybrids. The molecular mechanism behind maternal sterility varies from crop to crop. An understanding of underlying mechanism can help in development of new functional CMS gene in crops which lack effective and stable CMS systems. In crops where seed or fruit is the commercial product, fertility must be recovered in F1 hybrids so that higher yield gains can be realized. This necessitates the presence of fertility restorer gene (Rf) in nucleus of male parent to overcome the effect of sterile cytoplasm. Fertility restoring genes have been identified in crops like wheat, maize, sunflower, rice, pepper, sugar beet, pigeon pea etc. But in crops like eggplant, bell pepper, barley etc. unstable fertility restorers hamper the use of Cytoplasmic genic male sterility (CGMS) system. Stability of CGMS system is influenced by environment, genetic background or interaction of these factors. This review thus aims to understand the genetic mechanisms controlling mitochondrial-nuclear interactions required to design strong and stable restorers without any pleiotropic effects in F1 hybrids. [ABSTRACT FROM AUTHOR]

The discovery of a wild abortive-type (WA) cytoplasmic male sterile (CMS) line and breeding its restorer line have led to the commercialization of three-line hybrid rice, contributing considerably to global food security. However, the molecular mechanisms underlying fertility abortion and the restoration of CMS-WA lines remain largely elusive. In this study, we cloned a restorer gene, Rf20 , following a genome-wide association study analysis of the core parent lines of three-line hybrid rice. We found that Rf20 was present in all core parental lines, but different haplotypes and structural variants of its gene resulted in differences in Rf20 expression levels between sterile and restored lines. Rf20 could restore pollen fertility in the CMS-WA line and was found to be responsible for fertility restoration in some CMS lines under high temperatures. In addition, we found that Rf20 encodes a pentatricopeptide repeat protein that competes with WA352 for binding with COX11. This interaction enhances COX11's function as a scavenger of reactive oxygen species, which in turn restores pollen fertility. Collectively, our study suggests a new action mode for pentatricopeptide repeat proteins in the fertility restoration of CMS lines, providing an essential theoretical basis for breeding robust restorer lines and for overcoming high temperature-induced fertility recovery of some CMS lines. Cytoplasmic male sterility (CMS) is an important genetic tool for breeding and exploiting hybrid vigor in crops. Rf genes can make CMS lines fertile. Song et al. show that structural variations of a new fertility restorer gene, Rf20 , underlie the restoration of wild abortive-type CMS in rice. Mechanistically, RF20 can compete with WA352 for binding with COX11 to enhance the scavenging of reactive oxygen species for the fertility restoration. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) arises from the incompatibility between the nucleus and cytoplasm as typical representatives of the chimeric structures in the mitochondrial genome (mitogenome), which has been extensively applied for hybrid seed production in various crops. The frequent occurrence of chimeric mitochondrial genes leading to CMS is consistent with the mitochondrial DNA (mtDNA) evolution. The sequence conservation resulting from faithfully maternal inheritance and the chimeric structure caused by frequent sequence recombination have been defined as two major features of the mitogenome. However, when and how these chimeric mitochondrial genes appear in the context of the highly conserved reproduction of mitochondria is an enigma. This review, therefore, presents the critical view of the research on CMS in plants to elucidate the mechanisms of this phenomenon. Generally, distant hybridization is the main mechanism to generate an original CMS source in natural populations and in breeding. Mitochondria and mitogenomes show pleomorphic and dynamic changes at key stages of the life cycle. The promitochondria in dry seeds develop into fully functioning mitochondria during seed imbibition, followed by massive mitochondria or mitogenome fusion and fission in the germination stage along with changes in the mtDNA structure and quantity. The mitogenome stability is controlled by nuclear loci, such as the nuclear gene Msh1. Its suppression leads to the rearrangement of mtDNA and the production of heritable CMS genes. An abundant recombination of mtDNA is also often found in distant hybrids and somatic/cybrid hybrids. Since mtDNA recombination is ubiquitous in distant hybridization, we put forward a hypothesis that the original CMS genes originated from mtDNA recombination during the germination of the hybrid seeds produced from distant hybridizations to solve the nucleo-cytoplasmic incompatibility resulting from the allogenic nuclear genome during seed germination. [ABSTRACT FROM AUTHOR]

Background: Understanding the mechanism of male sterility is crucial for producing hybrid seeds and developing sterile germplasm resources. However, only a few cytoplasmic male sterility (CMS) lines of cotton have been produced due to several challenges, like inadequate variation of agronomic traits, incomplete sterility, weak resilience of restorer lines, and difficulty in combining strong dominance. Therefore, the morphological and cytological identification of CMS in cotton will facilitate hybrid breeding. Results: Two F2 segregating populations of cotton were constructed from cytoplasmic male sterile lines (HaA and 01A, maternal) and restorer lines (HaR and 26R, paternal). Genetic analysis of these populations revealed a segregation ratio of 3:1 for fertile to sterile plants. Phenotypic analysis indicated no significant differences in traits of flower bud development between sterile and fertile plants. However, sterile plants exhibited smaller floral organs, shortened filament lengths, and anther atrophy on the flowering day in comparison with the fertile plants. When performed scanning electron microscopy (SEM), the two F2 populations revealed morphological variations in the anther epidermis. Cellular analysis showed no significant differences in pollen development before pollen maturation. Interestingly, between the pollen maturation and flowering stages, the tapetum layer of sterile plants degenerated prematurely, resulting in abnormal pollen grains and gradual pollen degradation. Conclusion: The results of this study suggest that fertility-restoring genes are controlled by a single dominant gene. Sterile plants exhibit distinctive floral morphology, which is characterized by stamen atrophy and abnormal anthers. Pollen abortion occurs between pollen maturity and flowering, indicating that premature tapetum degradation may be the primary cause of pollen abortion. Overall, our study provides a theoretical basis for utilizing CMS in hybrid breeding and in-depth investigation of the dominant configuration of cotton hybrid combinations, mechanisms of sterility, and the role of sterile and restorer genes. [ABSTRACT FROM AUTHOR]

The flowering period of rice significantly impacts variety adaptability and yield formation. Properly shortening the reproductive period of rice varieties can expand their ecological range without significant yield reduction. Targeted genome editing, like CRISPR/Cas9, is an ideal tool to fine-tune rice growth stages and boost yield synergistically. In this study, we developed a CRISPR/Cas9-mediated multiplex genome-editing vector containing five genes related to three traits, Hd2, Ghd7, and DTH8 (flowering-stage genes), along with the recessive rice blast resistance gene Pi21 and the aromatic gene BADH2. This vector was introduced into the high-quality japonica rice variety in Zhejiang province, Jiahe212 (JH212), resulting in 34 T0 plants with various effective mutations. Among the 17 mutant T1 lines, several displayed diverse flowering dates, but most exhibited undesirable agronomic traits. Notably, three homozygous mutant lines (JH-C15, JH-C18, and JH-C31) showed slightly earlier flowering dates without significant differences in yield-related traits compared to JH212. Through special Hyg and Cas marker selection of T2 plants, we identified seven, six, and two fragrant glutinous plants devoid of transgenic components. These single plants will serve as sib lines of JH212 and potential resources for breeding applications, including maintenance lines for indica–japonica interspecific three-line hybrid rice. In summary, our research lays the foundation for the creation of short-growth-period CMS (cytoplasmic male sterility, CMS) lines, and also provides materials and a theoretical basis for indica–japonica interspecific hybrid rice breeding with wider adaptability. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) C-type cytoplasmic male sterility (CMS-C) is a highly used CMS system for maize commercial hybrid seed production. Rf4 is the major dominant restorer gene for CMS-C. Inbreds were recently discovered which contain the restoring Rf4 allele yet are unable to restore fertility due to the lack of an additional gene required for Rf4's restoration. To find this additional gene, QTL mapping and positional cloning were performed using an inbred that contained Rf4 but was incapable of restoring CMS-C. The QTL was mapped to a 738-kb interval on chromosome 2, which contains a Pentatricopeptide Repeat (PPR) gene cluster. Allele content comparisons of the inbreds identified three potential candidate genes responsible for fertility restoration in CMS-C. Complementation via transformation of these three candidate genes showed that PPR153 (Zm00001eb114660) is required for Rf4 to restore fertility to tassels. The PPR153 sequence is present in B73 genome, but it is not capable of restoring CMS-C without Rf4. Analysis using NAM lines revealed that Rf4 requires the presence of PPR153 to restore CMS-C in diverse germplasms. This research uncovers a major CMS-C genetic restoration pathway and can be used for identifying inbreds suitable for maize hybrid production with CMS-C cytoplasm. [ABSTRACT FROM AUTHOR]

The P-type ATPase superfamily genes are the cation and phospholipid pumps that transport ions across the membranes by hydrolyzing ATP. They are involved in a diverse range of functions, including fundamental cellular events that occur during the growth of plants, especially in the reproductive organs. The present work has been undertaken to understand and characterize the P-type ATPases in the pigeonpea genome and their potential role in anther development and pollen fertility. A total of 59 P-type ATPases were predicted in the pigeonpea genome. The phylogenetic analysis classified the ATPases into five subfamilies: eleven P1B, eighteen P2A/B, fourteen P3A, fifteen P4, and one P5. Twenty-three pairs of P-type ATPases were tandemly duplicated, resulting in their expansion in the pigeonpea genome during evolution. The orthologs of the reported anther development-related genes were searched in the pigeonpea genome, and the expression profiling studies of specific genes via qRT-PCR in the pre- and post-meiotic anther stages of AKCMS11A (male sterile), AKCMS11B (maintainer) and AKPR303 (fertility restorer) lines of pigeonpea was done. Compared to the restorer and maintainer lines, the down-regulation of CcP-typeATPase22 in the post-meiotic anthers of the male sterile line might have played a role in pollen sterility. Furthermore, the strong expression of CcP-typeATPase2 in the post-meiotic anthers of restorer line and CcP-typeATPase46, CcP-typeATPase51, and CcP-typeATPase52 in the maintainer lines, respectively, compared to the male sterile line, clearly indicates their potential role in developing male reproductive organs in pigeonpea. [ABSTRACT FROM AUTHOR]

[Objective] The“three line”method is the main way to breed hybrid soybeans. At present, only a few soybean restoration genes have been cloned. Thus it will be helpful in the breeding strong restorer lines with multi genes aggregation, thereby improving the fertility stability of hybrid F1, if more new Rf genes can be discovered. [Method] Using soybean cytoplasmic male sterile line JLCMS5A and its restorer line JLR2 as materials, transcriptome sequencing technology was used to analyze the transcriptional level changes of JLCMS5A and JLR2 flower buds at different stages, and to explore the relevant genes and pathways regulating restorer of fertility and flower bud development processes. Further gene annotation, sequence difference analysis, RT-qPCR validation, phylogenetic analysis, and protein structure prediction were performed on differentially expressed genes（DEGs） with Rf gene features encoding PPR（pentatrioptide repeat）proteins to explore Rf related genes. [Result] Transcriptome sequencing identified 17 181 DEGs, of which 3 856 were related to developmental stage and 2 808 were related to fertility. GO（gene ontology）functional annotation indicated that fertility-related DEGs were mainly enriched in functional categories such as ADP binding, nucleic acid binding transcription factor activity, and protein kinase activity, while developmental stage-related DEGs were mainly enriched in functional categories such as protein heterodimerization activity, DNA replication, and DNA binding. KEGG（kyoto encyclopedia of genes and genes）enrichment analysis showed that fertility-related DEGs mainly participate in metabolic pathways closely related to protein, carbohydrates, and signal transduction, such as endoplasmic reticulum protein processing, glucoside biosynthesis, and plant hormone signal transduction. Development-related DEGs mainly participated in metabolic pathways closely related to DNA replication, mismatch repair, starch and sucrose metabolism, and cell division and energy degradation. Analysis of candidate Rf genes revealed that the Glyma.09G176400 in JLR2 may play a certain role in regulating the restorer-of-fertility process of soybean cytoplasmic male sterility. [Conclusion] 3 856 DEGs and 2 808 DEGs which respectively related to developmental stage and fertility were identified by transcriptomic techniques and molecular biological methods. Whereafter, a total of 15 DEGs encoding PPR protein were identified, which had the characteristics of restorer-of-fertility gene. Finally, a restorer-of-fertility related gene Glyma.09G176400 was excavated [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) is a very important factor to produce hybrid seeds, and the restoration of fertility involves the expression of many fertility‐related genes. Our previous study showed that the expression of CaPIPLC5 was significantly up‐regulated in pepper restorer accessions and minimally expressed in sterile accessions, speculating that CaPIPLC5 is related to the restoration of fertility. In this study, we further validated the function of CaPIPLC5 in the restoration of fertility. The results showed that CaPIPLC5 was specifically expressed in the anthers of the restorer accessions with the subcellular localization in the cytoplasm. Furthermore, the expression of CaPIPLC5 was significantly higher in restorer lines and restorer combinations than that in CMS lines and their maintainer lines. Silencing CaPIPLC5 led to the number of pollen decreased, pollen grains wrinkled, and the ratio of pollen germination reduced. In addition, the joint analysis of Yeast One‐Hybrid (Y1H) and Dual‐Luciferase (dual‐LUC) assays suggested that transcription factors such as CaARF5, CabZIP24 and CaMYB‐like1, interacted with the promoter regions of CaPIPLC5, which regulated the expression of CaPIPLC5. The present results provide new insights into the study of CaPIPLC5 involved in the restoration of fertility in pepper. [ABSTRACT FROM AUTHOR]

Gynodioecy, the coexistence of hermaphrodites with females, often reflects conflicts between cytoplasmic male sterility (CMS) genes and nuclear genes restoring male fertility. CMS is frequent in plants and has been recently discovered in one animal: the freshwater snail, Physa acuta. In this system, CMS was linked to a single divergent mitochondrial genome (D), devoid of apparent nuclear restoration. Our study uncovers a second, novel CMS-associated mitogenome (K) in Physa acuta , demonstrating an extraordinary acceleration of molecular evolution throughout the entire K mitochondrial genome, akin to the previously observed pattern in D. This suggests a pervasive occurrence of accelerated evolution in both CMS-associated lineages. Through a 17-generation introgression experiment, we further show that nuclear polymorphisms in K-mitogenome individuals contribute to the restoration of male function in natural populations. Our results underscore shared characteristics in gynodioecy between plants and animals, emphasizing the presence of multiple CMS mitotypes and cytonuclear conflicts. This reaffirms the pivotal role of mitochondria in influencing male function and in generating genomic conflicts that impact reproductive processes in animals. [ABSTRACT FROM AUTHOR]

The article presents a study which identified cost-effective alternatives to gibberellic acid for cytoplasmic male sterility (CMS) breeding. Topics discussed include treatments and doses of chemicals that can serve the same purpose in this breeding technology, data showing mean values of various metrical characters at a glance, and observations on scanning electron micrographs (SEM).

Hybrid development is one of the most promising strategies for boosting crop yields. Parental lines used to create hybrids must have good per se performance and disease resistance for developing superior hybrids. Indian wheat line HD3209 was developed by introducing the rust resistance genes Lr19/Sr25 into the background of popular wheat variety HD2932. The wheat line HD3209 carrying Lr19/Sr25 has been successfully and rapidly converted to the CMS line A-HD3209, with 96.01% background genome recovery, based on selection for agro-morphological traits, rust resistance, pollen sterility, and foreground and background analyses utilizing SSR markers. The converted CMS line A-HD3209 was completely sterile and nearly identical to the recurrent parent HD3209. Based on high per se performance and rust resistance, the study concludes that the derived CMS line A-HD3209 is promising and can be employed successfully in hybrid development. [ABSTRACT FROM AUTHOR]

Ogura cytoplasmic male sterility (CMS) is considered the rapeseed (Brassica napus L.) with the most potential to be utilized as a heterosis system worldwide, but it lacks sufficient restorers. In this study, root tip cell (RTC) mitotic and pollen mother cell (PMC) meiosis observations were compared to ensure the number of chromosomes and the formation of a chromosomal bridge using restorer lines R2000, CLR650, and Zhehuhong (a new restorer) as the experimental material. Further, molecular markers of exogenous chromosomal fragments were detected and the sequence and expression differences of restorer genes in the three lines were determined to identify the distinctive characteristics of Zhehuhong. The results showed that the number of chromosomes in Zhehuhong was stable (2n = 38), indicating that the exogenous radish chromosome segment had been integrated into the chromosome of Zhehuhong. Molecular marker detection revealed that Zhehuhong was detected at most loci, with only the RMA05 locus being missed. The exogenous radish chromosome segment of Zhehuhong differed from R2000 and CLR650. The pollen mother cells of Zhehuhong showed chromosome lagging in the meiotic metaphase I, meiotic anaphase I, and meiotic anaphase II, which was consistent with R2000 and CLR650. The restorer gene PPRB in Zhehuhong had 85 SNPs compared with R2000 and 119 SNPs compared with CLR650, indicating the distinctive characteristic of PPRB in Zhehuhong. In terms of the spatial expression of PPRB, the highest level was detected in the anthers in the three restorer lines. In addition, in terms of temporal expression, the PPRB gene expression of Zhehuhong was highest at a bud length of 4 mm. Our results clearly indicated that Zhehuhong is a new restorer line for the Ogura CMS system, which can be used further in rapeseed heterosis utilization. [ABSTRACT FROM AUTHOR]

Simple Summary: Conventional potato breeding has produced only limited genetic gain due to the polyploid nature of the crop. In recent years, hybrid potato breeding at the diploid level has been developed to overcome this limited genetic gain. In diploid potato breeding, homozygous inbred lines are developed by self-fertilization, enabling incremental improvements of the material in each generation. This type of breeding requires self-fertility, which makes hybridization of inbred lines labor-cumbersome and results in hybrids that produce many undesirable berries in the field. In many crop species, cytoplasmic male sterility is used to produce maternal inbred lines that are male sterile. In this study, we explore the antherless cytoplasmic male sterility system in potato. We identify a recessive locus that is required for sterility and we show that this trait is expressed in Phureja cytoplasm but not in Andigena or Tuberosum cytoplasm. We implemented this system in hybrid seed production and show that the resulting hybrids set far fewer berries in the field than male fertile controls. Recent advances in diploid F1 hybrid potato breeding rely on the production of inbred lines using the S-locus inhibitor (Sli) gene. As a result of this method, female parent lines are self-fertile and require emasculation before hybrid seed production. The resulting F1 hybrids are self-fertile as well and produce many undesirable berries in the field. Utilization of cytoplasmic male sterility would eliminate the need for emasculation, resulting in more efficient hybrid seed production and male sterile F1 hybrids. We observed plants that completely lacked anthers in an F2 population derived from an interspecific cross between diploid S. tuberosum and S. microdontum. We studied the antherless trait to determine its suitability for use in hybrid potato breeding. We mapped the causal locus to the short arm of Chromosome 6, developed KASP markers for the antherless (al) locus and introduced it into lines with T and A cytoplasm. We found that antherless type male sterility is not expressed in T and A cytoplasm, proving that it is a form of CMS. We hybridized male sterile al/al plants with P cytoplasm with pollen from al/al plants with T and A cytoplasm and we show that the resulting hybrids set significantly fewer berries in the field. Here, we show that the antherless CMS system can be readily deployed in diploid F1 hybrid potato breeding to improve hybridization efficiency and reduce berry set in the field. [ABSTRACT FROM AUTHOR]

【Objective】It is to explore the molecular mechanism of fertility transformation in weakly restoring hybrid F1 of soybean cytoplasmic male sterility at the RNA level, then to provide valuable information on the molecular mechanism of male sterility in soybean from the perspective of fertility transition.【Method】Using weakly restoring hybrid F1（H3A× SXTH3）as the research object, and short light（plant fertility is sterile）and normal light（plant fertility is fertile）treatments were set up during the seedling stage. Mixed flower buds of different sizes were collected during the peak flowering period for transcriptome sequencing and quantitative real time PCR（RT-qPCR） analysis.【Result】Total 3 917 differentially expressed genes were screened out. After short light treatment during the seedling stage, 2134 genes were downregulated and 1 783 genes were upregulated. Bioinformatics analysis was conducted on differentially expressed genes, and gene ontology（GO）significant enrichment analysis showed that carbohydrate metabolic process, transmembrane transporter activity, and cell periphery functions played the main biological functions during fertility transition. The significant enrichment analysis of the kyoto encyclopedia of genes and genomes（KEGG）pathway showed that the main metabolic pathways for fertility transformation were pentose and glucuronate interconversions, starch and sucrose metabolism, and plant circadian rhythm. RT-qPCR analysis of 11 genes revealed that genes related to soybean cytoplasmic male sterility and pentatricopeptide repeats protein（PPR）were involved during fertility transformation of weakly restoring cytoplasmic male sterile hybrid F1 in soybean.【Conclusion】It was speculated that the fertility transformation of weakly restoring hybrid F1 was related to abnormal expressions of genes related to plant circadian rhythm, PPR, and soybean cytoplasmic male sterility, such as mitochondrial, pollen wall development, carbohydrate metabolism, sugar transport, and reactive oxygen species metabolism. Key genes in the circadian rhythm pathway change cause changes in the expression levels of PPR genes and soybean cytoplasmic male sterility related genes, then fertility transformation will occur [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is a critical staple crop globally, integral to human consumption, food security, and agricultural product stability. The quality and purity of maize seeds, essential for hybrid seed production, are contingent upon effective detasseling. This study investigates the evolution of detasseling technologies and their application in Chinese maize hybrid seed production, with a comparative analysis against the United States. A comprehensive examination of the development and utilization of detasseling technology in Chinese maize hybrid seed production was undertaken, with a specific focus on key milestones. Data from the United States were included for comparative purposes. The analysis encompassed various detasseling methods, including manual, semi-mechanized, and cytoplasmic male sterility, as well as more recent innovations such as detasseling machines, and the emerging field of intelligent detasseling driven by unmanned aerial vehicles (UAVs), computer vision, and mechanical arms. Mechanized detasseling methods were predominantly employed by America. Despite the challenges of inflexible and occasionally overlooked, applying detasseling machines is efficient and reliable. At present, China' s detasseling operations in hybrid maize seed production are mainly carried out by manual work, which is labor-intensive and inefficient. In order to address this issue, China is dedicated to developing intelligent detasseling technology. This study emphasizes the critical role of detasseling in hybrid maize seed production. The United States has embraced mechanized detasseling. The application and development of manual and mechanized detasseling were applied later than those in the United States, but latest intelligent detasseling technologies first appeared in China. Intelligent detasseling is expected to be the future direction, ensuring the quality and efficiency of hybrid maize seed production, with implications for global food security. [ABSTRACT FROM AUTHOR]

Sorghum hybrids demonstrated increased productivity and helped offset the decreasing cultivated areas, particularly in Asia. The diversity in cytoplasmic male sterility systems, stability of restorers and high yield of sorghum is an important factor for achieving food security and sustainability. In sorghum, hybrid production has been limited to A1 cytoplasmic source to date, primarily due to limited number of restorers on other cytoplasmic sources. This work aimed at filling this gap through diversifying and assessing the producibility and stability of cytoplasmic backgrounds across environments, evaluating the stability of restorers across cytoplasms and environments, and evaluating the performance of the hybrid F1 products under different water regimes across cropping seasons. The effects of genotypes and interactions between the genotypes and the tested environments were shown visually using GGE biplot, which also categorized the genotypes based on performance per se and stability. Analysis of variance revealed significant (P A1>A3 >A4. The A2 cytoplasm can therefore reliably offer seed producibility advantage to commercial seed producers. Furthermore, the which-won–where model for hybrid grain yield revealed specific adaptations of hybrid genotypes G143, G195 and G215 to first mega environment (E1 and E3), whereas G167, G110, and G112 were adapted to the second mega-environment (E2 and E4). With a GGE biplot goodness of fit of 70 % the best possible yield- and stability-based ranking of hybrid genotypes was G143, G215, G189, G200, G69, G162, G119, G54, and G81. The newly uncovered hybrid products should therefore be considered for downstream testing stages and candidates for release and commercial cultivation. Clearly, this work resulted in novel findings particularly in terms of seed producibility, universal restorers across the 4 cytoplasms and environments, and superior and stable hybrid products, all of which are expected to add value to conventional and heterosis breeding in the process of sorghum cultivar development.

Open-pollinated onion cultivars predominate in the southern region of Brazil, due to their higher adaptability to local climatic conditions, unlike commercial hybrids, which have shown a lower adaptability. Cytoplasmic male sterility (CMS) systems are employed to develop hybrid onion cultivars. Two molecular markers, 5’cob and orfA501, were used to differentiate the cytoplasm type, and the AcSKP1 marker to identify the nuclear male fertility-restoring locus (Ms). A total of 1,126 plants from the most common onion cultivars grown in southern Brazil, including Bola Precoce®, Crioula®, Valessul®, Mega®, Joia® and Princesa do Sul®, were analyzed using all the three markers. An extremely rare occurrence of the S cytoplasm was observed among the cultivars, being detected in only 1.8 % of the samples, while the T cytoplasm was the most prevalent, accounting for 56.3 % of the samples. Among the 1,126 plants analyzed, only three exhibited the S cytoplasm and were recessive for the Ms-locus (Smsms). Additionally, 49 plants with the N-cytoplasm (as per the Engelke’s classification) and recessive for the nuclear genotype (Nmsms) were identified, 45 of which were pollen producers. The male-fertility restoration occurred in 22.2 % of the crosses between Tmsms male-sterile plants and male-fertile N cytoplasmic-msms plants (as per the Engelke’s classification).

The article discusses a new hybrid rootstock called 'Intensia' that has been developed by the Institut de Recerca i Tecnologia Agroalimentàries (IRTA). This rootstock is well-suited for Prunus crops in Mediterranean climates and offers benefits such as reduced vigor, early bearing, and adaptation to calcareous soils. 'Intensia' also shows improved cropping efficiency and drought tolerance. The article provides information on the characteristics and performance of 'Intensia' based on trials and evaluations. It also mentions its susceptibility to iron chlorosis and root-knot nematodes. The article highlights the genetic developments in Prunus species and the role of 'Intensia' in constructing a linkage map. 'Intensia' is available and further reading references are provided. [Extracted from the article]

Hybridization is the main method for developing new breeding material, obtaining genetic variability, and combining desired traits. The purpose of the current work is to characterize new promising varieties and hybrids of sweet and grass sorghum developed by the “ARC “Donskoy” because of hybridization on a sterile and fertile basis. The study was conducted on the breeding field of the FSBSI “ARC “Donskoy”, Zernograd, Rostov region in 2021–2023. The zone is characterized by ordinary carbonate chernozem (3.2 % of humus, 10–40 mg/kg of phosphorus, 70–110 mg/kg of nitrogen, 300–500 mg per kg of soil of potassium). Meteorological conditions during the years of study (2021–2023) were contrasting: in 2022, HTC = 0.52 indicated average aridity and insufficient moisture with 0.81–0.82 in 2021 and 2023. The objects of the study were the varieties and hybrids of Sudan grass and sugar sorghum developed by the FSBSI “ARC “Donskoy”. As a result of hybridization on a sterile basis, there was developed a number of sorghumSudan hybrids (‘Jetta x Kudesnitsa’, ‘APV-1115 x Topolina’, ‘APV-1115 x FP’, ‘Dobrynya’, ‘Gordey’) and sweet sorghum hybrids (‘APV-115 x Yuzhnoye’, ‘Jetta x Severanay Vishnya’, ‘Duet’), allowing to obtain green mass yields of 51–63 and 47–49 t/ha, which was higher than the standard by 5–17 t/ha (10.8–37.0 %) and 5–7 t/ha (11.9–16.7 %) respectively. Using intervarietal hybridization, almost all varieties developed by the FSBSI “ARC “Donskoy” have been created. Among them there are the Sudan grass varieties ‘Alisa’, ‘Gratsiya’, ‘Anastasiya’, ‘Kudesnitsa’, ‘FP’ and the sweet sorghum varieties ‘Yuzhnoe’, ‘Feniks’, ‘Orfey’, ‘SK-20/334’, ‘Severanay Vishnya’ with a green mass yield of 40–48 and 34–38 t/ha, which is higher than that of standard varieties by 3–11 t/ha (8.1–29.7 %) and 7–11 t/ha (25.9–40.7 %), respectively. Thus, hybridization is the main method for developing new breeding material and combining the desired traits in new samples.

Summary: Cytoplasmic male sterility (CMS), encoded by the mitochondrial open reading frames (ORFs), has long been used to economically produce crop hybrids. However, the utilization of CMS also hinders the exploitation of sterility and fertility variation in the absence of a restorer line, which in turn narrows the genetic background and reduces biodiversity. Here, we used a mitochondrial targeted transcription activator‐like effector nuclease (mitoTALENs) to knock out ORF138 from the Ogura CMS broccoli hybrid. The knockout was confirmed by the amplification and re‐sequencing read mapping to the mitochondrial genome. As a result, knockout of ORF138 restored the fertility of the CMS hybrid, and simultaneously manifested a cold‐sensitive male sterility. ORF138 depletion is stably inherited to the next generation, allowing for direct use in the breeding process. In addition, we proposed a highly reliable and cost‐effective toolkit to accelerate the life cycle of fertile lines from CMS‐derived broccoli hybrids. By applying the k‐mean clustering and interaction network analysis, we identified the central gene networks involved in the fertility restoration and cold‐sensitive male sterility. Our study enables mitochondrial genome editing via mitoTALENs in Brassicaceae vegetable crops and provides evidence that the sex production machinery and its temperature‐responsive ability are regulated by the mitochondria. [ABSTRACT FROM AUTHOR]

Summary: A fast evolution within mitochondria genome(s) often generates discords between nuclear and mitochondria, which is manifested as cytoplasmic male sterility (CMS) and fertility restoration (Rf) system. The maize CMS‐C trait is regulated by the chimeric mitochondrial gene, atp6c, and can be recovered by the restorer gene ZmRf5. Through positional cloning in this study, we identified the nuclear restorer gene, ZmRf5, which encodes a P‐type pentatricopeptide repeat (PPR) family protein. The over‐expression of ZmRf5 brought back the fertility to CMS‐C plants, whereas its genomic editing by CRISPR/Cas9 induced abortive pollens in the restorer line. ZmRF5 is sorted to mitochondria, and recruited RS31A, a splicing factor, through MORF8 to form a cleaving/restoring complex, which promoted the cleaving of the CMS‐associated transcripts atp6c by shifting the major cleavage site from 480th nt to 344 th nt for fast degradation, and preserved just right amount of atp6c RNA for protein translation, providing adequate ATP6C to assembly complex V, thus restoring male fertility. Interestingly, ATP6C in the sterile line CMo17A, with similar cytology and physiology changes to YU87‐1A, was accumulated much less than it in NMo17B, exhibiting a contrary trend in the YU87‐1 nuclear genome previously reported, and was restored to normal level in the presence of ZmRF5. Collectively these findings unveil a new molecular mechanism underlying fertility restoration by which ZmRF5 cooperates with MORF8 and RS31A to restore CMS‐C fertility in maize, complemented and perfected the sterility mechanism, and enrich the perspectives on communications between nucleus and mitochondria. [ABSTRACT FROM AUTHOR]

In citrus breeding programs, male sterility is an important trait for developing seedless varieties. Sterility associated with the male sterile cytoplasm of Kishu mandarin (Kishu-cytoplasm) has been proposed to fit the cytoplasmic male sterility (CMS) model. However, it remains undetermined whether CMS in citrus is controlled by interactions between sterile cytoplasm and nuclear restorer-offertility (Rf) genes. Accordingly, mechanisms underlying the control of the wide phenotypic variation in pollen number for breeding germplasm should be elucidated. This study aimed to identify complete linkage DNA markers responsible for male sterility at the MS-P1 region based on fine mapping. Two P-class pentatricopeptide repeat (PPR) family genes were identified as candidates for Rf based on predicted mitochondrial localization and higher expression in a male fertile variety/selected strain than in a male sterile variety. Eleven haplotypes (HT1-HT11) at the MS-P1 region were defined based on genotyping of DNA markers. Association analysis of diplotypes at the MS-P1 region and the number of pollen grains per anther (NPG) in breeding germplasms harboring Kishu-cytoplasm revealed that the diplotypes in this region influenced NPG. Among these haplotypes, HT1 is a non-functional restorer-of-fertility (rf) haplotype; HT2, a less-functional Rf; HT3-HT5 are semi-functional Rfs; and HT6 and HT7 are functional Rfs. However, the rare haplotypes HT8-HT11 could not be characterized. Therefore, P-class PPR family genes in the MS-P1 region may constitute the nuclear Rf genes within the CMS model, and a combination of the seven haplotypes could contribute to phenotypic variation in the NPG of breeding germplasms. These findings reveal the genomic mechanisms of CMS in citrus and will contribute to seedless citrus breeding programs by selecting candidate seedless seedlings using the DNA markers at the MS-P1 region. [ABSTRACT FROM AUTHOR]

This article discusses the importance of heterosis in wheat breeding and presents the findings of a study on wheat genetics and plant breeding. The study identified promising cross combinations that exhibited significant levels of desirable heterosis for various traits, including plant height, productive tillers per plant, spike length, flag leaf area, grains per spike, 1000-grain weight, biological yield per plant, harvest index, and grain yield per plant. The results suggest that these heterotic crosses can be utilized to develop high-yielding wheat varieties and improve overall crop performance. The study also highlights the potential for incorporating marker-assisted breeding techniques in future research. [Extracted from the article]

Radish (Raphanus sativus L.) is a globally significant vegetable and relies on cytoplasmic male sterile (CMS) lines for hybrid seed production. The NWB CMS type is favored over Ogura CMS for its ease in maintainer screening. Despite its varied mitochondrial configurations and unvalidated sterile gene, we re-sequenced the mitochondrial genome of NWB CMS Tibet A and verified the function of the sterility gene via genetic transformation of Arabidopsis thaliana. The mitochondrial genomes of Tibet A could be assembled into circular DNA molecules, with a mitochondrial genome size of 239,184 bp. Our analysis indicated that the specific orf463a was the CMS-associated gene in Tibet A, sharing sequence consistency with the CMS gene in DCGMS and NWB CMS YB-A. Collinearity analysis showed that the mitochondrial genomes of NWB CMS Tibet A, DCGMS, and NWB CMS YB-A share the same mitotype, with structural variations due to recombination via a 9731 bp long repeat sequence and a 508 bp short repeat sequence. Driven by the Ap3 promoter, transgenic Arabidopsis with orf463a exhibited male sterility, confirming the gene's potential role in CMS. In this study, we assembled a new isomeric form of NWB CMS mitochondrial genome and proved the function of the candidate sterile gene. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) plays a crucial role in the utilization of heterosis. The petaloid anther abortion in oil tea (Camellia oleifera Abel.) constitutes a CMS phenomenon, which is of great value for the hybrid breeding of oil tea. However, as the mechanism of its CMS is still poorly understood, it is necessary to study the cytology and physiological characteristics of anther abortion. In this study, a C. oleifera cultivar, Huashuo (HS), and its petalized CMS mutant (HSP) were used as materials to explore this mechanism. Compared with HS, cytological analysis demonstrated that HSP showed early-onset tapetum programmed cell death (PCD) and an organelle disorder phenotype during the tetrad stage. In HSP, anthers exhibited elevated levels of calcium deposition in anther wall tissues, tapetum layers, and microspores, and yet calcium accumulation was abnormal at the later stage. The contents of hydrogen peroxide and MDA in HSP anthers were higher, and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were lower than those of HS, which resulted in an excessive accumulation of reactive oxygen species (ROS). Real-time quantitative PCR confirmed that the transcription levels of CoPOD and CoCAT genes encoding key antioxidant enzymes in HSP were downregulated compared with HS in early pollen development; the gene CoCPK, which encodes a calcium-dependent protein kinase associated with antioxidase, was upregulated during the critical period. Thus, we suggest that excessive ROS as a signal breaks the balance of the antioxidant system, and along with an abnormal distribution of calcium ions, leads to the early initiation of PCD in the tapetum, and ultimately leads to pollen abortion for HSP. These results lay a cytological and physiological foundation for further studies on the CMS mechanism, and provide information for breeding male-sterile lines of C. oleifera. [ABSTRACT FROM AUTHOR]

Maize(Zea mays. L) is a globally important crop, and understanding its genetic diversity is crucial for plant breeding phylogenetic analyses and comparative genetics. While nuclear markers have been extensively used for mapping agriculturally important genes, they are limited in recognizing characteristics, such as cytoplasmic male sterility and reciprocal cross hybrids. In this study, we performed next-generation sequencing of 176samples, and the maize cultivars represented five distinct groups. A total of 89 single nucleotide polymorphisms (SNPs) and 11 insertion/deletion polymorphisms (InDels) were identified. To enable high-throughput detection, we successfully amplified and confirmed 49 SNP and InDel markers, which were defined as a Varietal Chloroplast Panel (VCP) using the Kompetitive Allele Specific PCR (KASP). The specific markers provided a valuable tool for identifying chloroplast groups. The verification experiment, focusing on the identification of reciprocal cross hybrids and cytoplasmic male sterility hybrids, demonstrated the significant advantages of VCP markers in maternal inheritance characterization. Furthermore, only a small subset of these markers is needed to provide useful information, showcasing the effectiveness of these markers in elucidating the artificial selection process of elite maize lines. [ABSTRACT FROM AUTHOR]

To ensure food security for ~ 10 billion human population in 2050 a sustainable increase in food production is indispensable. Wheat is the third most consumed cereal crop worldwide after rice and maize. It is estimated that the current wheat yield will be insufficient to cope with future needs. In the past hybrid seed production has revolutionized rice and maize production; however, wheat is still lagging behind other crops, such as rice, corn, soybeans, and canola in terms of variety/hybrid development and trait development. The potential of hybrid wheat is undeniable but these challenges need to be overcome if we want to commercialize it. Despite a century of efforts we still do not have a reliable hybrid breeding system to attempt large-scale production due to certain issues like self-pollination, polyploid nature, low variability in germplasm (less than 1% cross-pollination), and higher seed rates. Moreover, a limited number of GMS genes and their regulatory pathways has narrowed our selection; further research is required to identify and understand the genetic and molecular mechanisms involved. There are few successful examples of hybrid wheat, only 1% of its total wheat growing area is hybrid wheat. There is no simple way to produce a stable wheat hybrid, until this point no one knows how to commercialize wheat on a larger scale. The use of comparative functional genomics and biotechnological tools combined with conventional breeding is likely the possible key to guarantee a stable hybrid wheat breeding and to help overcome global food security issues. This paper would provide an overview of techniques to induce male sterility in wheat and their use in commercialized hybrid seed production systems. [ABSTRACT FROM AUTHOR]

Onion is an important vegetable crop because it adds nutritional value and diversity to food preparation. Understanding recent advancements in onion molecular genetics is essential to improve production, quality, and disease resistance. Cutting-edge genomic technologies like genetic mapping and RNA sequencing reveal important genes and pathways. The review examines the progress in utilizing various molecular markers to study genetic divergence. The exploration extends to understanding the genes and pathways responsible for bulb color and chemical composition and the genetic factors influencing bulbing, flowering, and vernalization. Additionally, the article explores quantitative trait loci associated with resistance to major damaging diseases and delves into the role of different loci in male sterility and hybrid development. The recent publication of the whole genome sequence of onions will lead to further identification of genes and understanding their roles and functions in metabolic pathways. [ABSTRACT FROM AUTHOR]

This article, published in the Plant Biotechnology Journal, discusses the use of mitoTALENs to edit the mitochondrial genome of cytoplasmic male sterile (CMS) rice. The researchers focused on a specific CMS-associated gene called WA352 and used mitoTALENs to edit it in CMS-WA rice. They found that the edited offspring showed restored pollen viability and seed setting, confirming that WA352 is the cause of CMS. The study also demonstrated the genetic stability of the edited offspring in the next generation. The results contribute to the understanding of plant mitochondrial genes and have implications for crop breeding research. [Extracted from the article]

Abstract Background Cytoplasmic male sterility (CMS) plays a crucial role in hybrid production. K-type CMS, a cytoplasmic male sterile line of wheat with the cytoplasms of Aegilops kotschyi, is widely used due to its excellent characteristics of agronomic performance, easy maintenance and easy restoration. However, the mechanism of its pollen abortion is not yet clear. Results In this study, wheat K-type CMS MS(KOTS)-90-110 (MS line) and it’s fertile near-isogenic line MR (KOTS)-90-110 (MR line) were investigated. Cytological analysis indicated that the anthers of MS line microspore nucleus failed to divide normally into two sperm nucleus and lacked starch in mature pollen grains, and the key abortive period was the uninucleate stage to dinuclear stage. Then, we compared the transcriptome of MS line and MR line anthers at these two stages. 11,360 and 5182 differentially expressed genes (DEGs) were identified between the MS and MR lines in the early uninucleate and binucleate stages, respectively. Based on GO enrichment and KEGG pathways analysis, it was evident that significant transcriptomic differences were “plant hormone signal transduction”, “MAPK signaling pathway” and “spliceosome”. We identified 17 and 10 DEGs associated with the IAA and ABA signal transduction pathways, respectively. DEGs related to IAA signal transduction pathway were downregulated in the early uninucleate stage of MS line. The expression level of DEGs related to ABA pathway was significantly upregulated in MS line at the binucleate stage compared to MR line. The determination of plant hormone content and qRT-PCR further confirmed that hormone imbalance in MS lines. Meanwhile, 1 and 2 DEGs involved in ABA and Ethylene metabolism were also identified in the MAPK cascade pathway, respectively; the significant up regulation of spliceosome related genes in MS line may be another important factor leading to pollen abortion. Conclusions We proposed a transcriptome-mediated pollen abortion network for K-type CMS in wheat. The main idea is hormone imbalance may be the primary factor, MAPK cascade pathway and alternative splicing (AS) may also play important regulatory roles in this process. These findings provided intriguing insights for the molecular mechanism of microspore abortion in K-type CMS, and also give useful clues to identify the crucial genes of CMS in wheat.

DNA methylation is widely found in higher plants and can control gene expression by regulation without changing the DNA sequence. In this study, the whole-genome methylation map of sugar beet was constructed by WGBS (whole-genome bisulfite sequencing) technology, and the results of WGBS were verified by bisulfite transformation, indicating that the results of WGBS technology were reliable. In addition, 12 differential methylation genes (DMGs) were identified, which were related to carbohydrate and energy metabolism, pollen wall development, and endogenous hormone regulation. Quantitative real-time PCR (qRT-PCR) showed that 75% of DMG expression levels showed negative feedback with methylation level, indicating that DNA methylation can affect gene expression to a certain extent. In addition, we found hypermethylation inhibited gene expression, which laid a foundation for further study on the molecular mechanism of DNA methylation at the epigenetic level in sugar beet male sterility. [ABSTRACT FROM AUTHOR]