Cytoplasmic Male Sterile Lines Research Articles

Re-Sequencing the Mitochondrial Genome Unveils a Novel Isomeric Form of NWB CMS Line in Radish and Functional Verification of Its Candidate Sterile Gene

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 9731 bp long repeat sequences and 508 bp short repeat sequences. 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.

The R2R3 MYB gene TaMYB305 positively regulates anther and pollen development in thermo-sensitive male-sterility wheat with Aegilops kotschyi cytoplasm.

The loss of TaMYB305 function down-regulated the expression of jasmonic acid synthesis pathway genes, which may disturb the jasmonic acid synthesis, resulting in abnormal pollen development and reduced fertility. The MYB family, as one of the largest transcription factor families found in plants, regulates plant development, especially the development of anthers. Therefore, it is important to identify potential MYB transcription factors associated with pollen development and to study its role in pollen development. Here, the transcripts of an R2R3 MYB gene TaMYB305 from KTM3315A, a thermo-sensitive cytoplasmic male-sterility line with Aegilops kotschyi cytoplasm (K-TCMS) wheat, was isolated. Quantitative real-time PCR (qRT-PCR) and promoter activity analysis revealed that TaMYB305 was primarily expressed in anthers. The TaMYB305 protein was localized in the nucleus, as determined by subcellular localization analysis. Our data demonstrated that silencing of TaMYB305 was related to abnormal development of stamen, including anther indehiscence and pollen abortion in KAM3315A plants. In addition, TaMYB305-silenced plants exhibited alterations in the transcriptional levels of genes involved in the synthesis of jasmonic acid (JA), indicating that TaMYB305 may regulate the expression of genes related to JA synthesis and play an important role during anther and pollen development of KTM3315A. These results provide novel insight into the function and molecular mechanism of R2R3-MYB genes in pollen development.

Commercial suitability and characterization of newly developed Erucastrum canariense (Can) sterile cytoplasm based cytoplasmic male sterile (CMS) lines in Indian cauliflower

The study presents the first to characterize novel Erucastrum canarianse Webb and Berthel (or Can) sterile cytoplasm-based CMS lines in Indian cauliflower (Brassica oleracea var. botrytis L.) and investigating their commercial suitability. Eleven Can-based CMS lines were examined for 12 agro-morphological and yield traits,18 floral traits, four seed yield traits together with three each of the Ogura (source: wild Japanese Radish) and Tour (Source: Brassica tournefortii) cytoplasms. All of the recorded floral and seed traits showed significant (P > 0.05) differences between the CMS lines of each group. Agro-morphological and yield traits in CMS lines and their maintainers, however, were non-significantly different. All the Can- and Ogura-based CMS lines showed flowering and appropriate seed formation by natural cross-pollination. Only two Tour cytoplasm-based CMS lines, Tour (DC-41-5) and Tour (DC-67), produced the smallest malformed flowers and stigma. The highest seed yield per plant in CMS lines was in Ogu (DC-98-4) and the lowest in Tour (DC-67). P14 and P15, two polymorphic mtDNA markers, were discovered for the Can CMS system for early detection. Five primers (ITS5a-ITS4, atpF-atpH, P16, rbeL and trnL), along with their maintainers, were sequenced and aligned to detect nucleotide changes including as additions and or deletions at different positions. The newly introduced E. canariense sterile cytoplasm-based CMS system in cauliflower is the subject of the first comprehensive report, which emphasises their potential as a further stable and reliable genetic mechanism for hybrid breeding.

PMAT: an efficient plant mitogenome assembly toolkit using low-coverage HiFi sequencing data.

Complete mitochondrial genomes (mitogenomes) of plants are valuable resources for nucleocytoplasmic interactions, plant evolution, and plant cytoplasmic male sterile line breeding. However, the complete assembly of plant mitogenomes is challenging due to frequent recombination events and horizontal gene transfers. Previous studies have adopted Illumina, PacBio, and Nanopore sequencing data to assemble plant mitogenomes, but the poor assembly completeness, low sequencing accuracy, and high cost limit the sampling capacity. Here, we present an efficient assembly toolkit (PMAT) for de novo assembly of plant mitogenomes using low-coverage HiFi sequencing data. PMAT has been applied to the de novo assembly of 13 broadly representative plant mitogenomes, outperforming existing organelle genome assemblers in terms of assembly accuracy and completeness. By evaluating the assembly of plant mitogenomes from different sequencing data, it was confirmed that PMAT only requires 1× HiFi sequencing data to obtain a complete plant mitogenome. The source code for PMAT is available at https://github.com/bichangwei/PMAT. The developed PMAT toolkit will indeed accelerate the understanding of evolutionary variation and breeding application of plant mitogenomes.

Identification of heterosis and combining ability in the hybrids of male sterile and restorer sorghum [Sorghum bicolor (L.) Moench] lines.

In sorghum [Sorghum bicolor (L.) Moench], combining ability and heterosis analysis are commonly used to evaluate superior parental lines and to screen for strongly heterotic hybrids, which helps in sorghum variety selection and breeding. In this context, combining ability and heterosis analysis were assessed using 14 restorer lines and seven cytoplasmic male sterile (CMS) lines in 2019 and 2020. The analysis of variance of all cross combinations had highly significant differences for all characters studied, which indicated a wide variation across the parents, lines, testers, and crosses. Combining ability analysis showed that the general combining ability (GCA) and specific combining ability (SCA) of the different parents were differed significantly among different traits. Most combinations with high SCA also showed high GCA in their parent lines. The heritability in the narrow sense of grain weight per panicle and grain yield was relatively low, indicating that the ability of these traits to be directly inherited by offspring was weak, that they were greatly affected by the environment. The better-parent heterosis for plant height, grain weight per panicle, panicle length, and 1000-grain weight was consistent with the order of mid-parent heterosis from strong to weak. The GCA effects of two lines 10480A, 3765A and three testers 0-30R, R111, and JY15R were significant for the majority of the agronomic traits including grain yield and might be used for improving the yield of grains in sorghum as parents of excellent specific combining ability. Seven strongly heterotic F1 hybrids were screened; of these, hybrids 3765A × R111, 1102A × L2R, and 3765A × JY15R showed significant increases in seed iristectorigenin A content and will feature into the creation of new sorghum varieties rich in iristectorigenin A.

Safflower heterosis for yield and its contributed characters

Twenty two hybrids were tested using line x tester design involving two cytoplasmic male sterile lines during rabi 2018, using Randomized block design with three replications. Twenty two along with three checks 'A-1,PBNS-12, PKV Pink' were evaluated at the field of Oilseeds Research Unit, Dr. PDKV, Akola during rabi 2019- 2020 to estimate extent of heterosis in safflower genotypes.Among all the crosses, AKS CMS 2A x GMU 1183 (46.15 % and 44.30%) exhibited highly significant and positive average heterosis for number of seeds/plant over mid and better parent. crosses, AKS CMS 2A x GMU 184 (49.26% and 34.44%) exhibited highly significant and positive average heterosis for 100 seed weight, whereas, cross AKS CMS 2A x GMU 5149 (15.28% and 9.32%) exhibited highly significant and positive average heterosis for volume weight. The highest heterosis and heterobeltiosis in desirable direction were recorded for seed yield/plant in AKS CMS 2A x GMU 1654 (246.96%) and the cross AKS CMS 3A x GMU 1183 (206.75%) showed highest and significantly positive standard heterosis over the checks i.e. PKV PINK, AKS 207 and PBNS-12. 

Safflower heterosis for yield and its contributed characters

Safflower (Carthamus tinctorius L.) is one of the major edible oilseed crops grown in winter season in India. The first safflower hybrid released in India for commercial cultivation in all safflower growing regions was based on genetic male sterility system. Twenty two hybrids were tested using line x tester design involving two cytoplasmic male sterile lines during rabi 2018, using Randomized block design with three replications. Twenty two along with three checks 'A-1, PBNS-12, PKV Pink' were evaluated at the field of Oilseeds Research Unit, Dr. PDKV, Akola during rabi 2019-2020 to estimate extent of heterosis in safflower genotypes. Among all the crosses, AKS CMS 2A x GMU 1183 (46.15 % and 44.30%) exhibited highly significant and positive average heterosis for number of seeds per plant over mid and better parent. crosses, AKS CMS 2A x GMU 184 (49.26% and 34.44%) exhibited highly significant and positive average heterosis for 100 seed weight, whereas, cross AKS CMS 2A x GMU 5149 (15.28% and 9.32%) exhibited highly significant and positive average heterosis for volume weight. The highest heterosis and heterobeltiosis in desirable direction were recorded for seed yield per plant in AKS CMS 2A x GMU 1654 (246.96. %) and the cross AKS CMS 3A x GMU 1183 (206.75%) showed highest and significantly positive standard heterosis over the checks i.e. PKV PINK, AKS 207 and PBNS-12.Biotechnological tools, such as genetic engineering need to be perfected for incorporation of mitochondrial male sterility causing factor of sunflower into safflower to develop safflower hybrids which can be more easily produced.

Transcriptomics reveals a core transcriptional network of K-type cytoplasmic male sterility microspore abortion in wheat (Triticum aestivum L.)

BackgroundCytoplasmic 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.ResultsIn 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.ConclusionsWe 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.

Copy number variation of the restorer Rf4 underlies human selection of three-line hybrid rice breeding

Cytoplasmic male sterility (CMS) lines are important for breeding hybrid crops, and utilization of CMS lines requires strong fertility restorer (Rf) genes. Rf4, a major Rf for Wild-Abortive CMS (CMS-WA), has been cloned in rice. However, the Rf4 evolution and formation of CMS-WA/Rf system remain elusive. Here, we show that the Rf4 locus emerges earlier than the CMS-WA gene WA352 in wild rice, and 69 haplotypes of the Rf4 locus are generated in the Oryza genus through the copy number and sequence variations. Eight of these haplotypes of the Rf4 locus are enriched in modern rice cultivars during natural and human selections, whereas non-functional rf4i is preferentially selected for breeding current CMS-WA lines. We further verify that varieties carrying two-copy Rf4 haplotype have stronger fertility restoration ability and are widely used in three-line hybrid rice breeding. Our findings increase our understanding of CMS/Rf systems and will likely benefit crop breeding.

Maintainer/restorer identification for different CMS lines in sunflower (Helianthus annuus L.)

Thirty one uniform and stable germplasm accessions of economic importance of sunflower were crossed with five cytoplasmic male sterile lines viz., CMS-234A, CMS-17A, CMS-338A, CMS-851A and ARM-243A in a Line x Tester fashion to study their maintainer or restorer reaction during kharif-2012 in a Randomized Block Design in two replications. The accessions TSG-22, TSG-24, ID-7, SCG-37, RHA-464 and ID-25 acted asrestorersfor allfive CMS lines. It was found that ID-33 of the restorer for ARM-243A was maintainer for other CMS lines. The use of stable germplasm with restorer behaviour in heterosis breeding programmes and those with maintainer behaviour in the development of new CMS lines through conversion has been suggested. The identification of new restorers to the good combiner CMS sources assembled should receive priority for hybrid synthesis.

Flavonoid Biosynthesis Pathway May Indirectly Affect Outcrossing Rate of Cytoplasmic Male-Sterile Lines of Soybean.

(1) Background: Cytoplasmic male sterility (CMS) is important for exploiting heterosis. Soybean (Glycine max L.) has a low outcrossing rate that is detrimental for breeding sterile lines and producing hybrid seeds. Therefore, the molecular mechanism controlling the outcrossing rate should be elucidated to increase the outcrossing rate of soybean CMS lines; (2) Methods: The male-sterile soybean lines JLCMS313A (with a high outcrossing rate; HL) and JLCMS226A (with a low outcrossing rate; LL) were used for a combined analysis of the transcriptome (RNA-seq) and the targeted phenol metabolome; (3) Results: The comparison between HL and LL detected 5946 differentially expressed genes (DEGs) and 81 phenolic metabolites. The analysis of the DEGs and differentially abundant phenolic metabolites identified only one common KEGG pathway related to flavonoid biosynthesis. The qRT-PCR expression for eight DEGs was almost consistent with the transcriptome data. The comparison of the cloned coding sequence (CDS) regions of the SUS, FLS, UGT, and F3H genes between HL and LL revealed seven single nucleotide polymorphisms (SNPs) only in the F3H CDS. Moreover, five significant differentially abundant phenolic metabolites between HL and LL were associated with flavonoid metabolic pathways. Finally, on the basis of the SNPs in the F3H CDS, one derived cleaved amplified polymorphic sequence (dCAPS) marker was developed to distinguish between HL and LL soybean lines; (4) Conclusions: The flavonoid biosynthesis pathway may indirectly affect the outcrossing rate of CMS sterile lines in soybean.

A small heat shock protein GmHSP18.5a improves the male fertility restorability of cytoplasmic male sterility-based restorer line under high temperature stress in soybean

Small heat shock protein (sHSP) is involved in high temperature (HT) stress response. However, the function of sHSPs in regulating male fertility of soybean under HT stress remains largely unknown. Here, we identified a sHSP gene, GmHSP18.5a, which was responded to HT stress during flowering in cytoplasmic male sterility (CMS)-based restorer line of soybean. Moreover, GmHSFA6b turned out to directly activated the expression of GmHSP18.5a by binding to the heat shock cis-element in its promoter. Overexpression of GmHSP18.5a increased male fertility in transgenic Arabidopsis, soybean CMS-based restorer line and its hybrid F1 with CMS line under HT stress. Reactive oxygen species (ROS) content detection revealed that GmHSP18.5a promoted the ROS scavenging ability of Arabidopsis inflorescence and soybean flower bud under HT stress. Enzyme activity assay and gene expression analysis indicated that GmHS18.5a mainly increased the activity of antioxidant enzymes and the expression level of ROS metabolism-related genes under HT stress. Our results indicated that GmHSP18.5a improved the male fertility restorability of CMS-based restorer line in soybean by regulating ROS metabolic pathway and reducing ROS accumulation. Our findings not only revealed the molecular mechanism of sHSP regulating the male fertility of soybean under HT stress, but also provided a theoretical basis for creating strong restorer line with thermotolerance.

Genome-Wide Dissection of Quan 9311A Breeding Process and Application Advantages

Germplasm resource innovation is a crucial factor for cultivar development, particularly within the context of hybrid rice breeding based on the three-line system. Quan 9311A, a cytoplasmic male sterile (CMS) line, has been successfully cultivated using rice restoration materials and extensively empolyed as a female parent in hybrid breeding program in China. This line was developed by crossing the CMS line Zhong 9A with a two-line restorer line 93-11, with the intention of eliminating the restoring ability of 93-11 while retaining the sterility gene WA352c from Zhong 9A. Quan 9311A effectively amalgamates the most favorable agronomic traits from both parental lines. In this study, the relationship between phenotypic characteristics and the known functional genes of Quan 9311A were analyzed using the rice genome navigation analysis technology based on whole-genome sequencing. The findings revealed that Quan 9311A harbors multiple superior alleles from both 93-11 and Zhong 9A, providing exceptional agronomic traits that were unavailable in earlier CMS lines. Despite the removal of the fertility restorer gene Rf3 from 93-11, numerous chromosomal segments from 93-11 persist in the Quan 9311A genome. Furthermore, the hybrid rice Quanyousimiao (QYSM) and the restorer line Wushansimiao (WSSM) were used as examples to illustrate the important role of Quan 9311A as the female parent in heterosis. It was found that QYSM carries a great number of superior alleles, which accounts for its high grain yield and wide adaptability. These insights not only advanced the utilization of hybrid rice pairing groups but also provided guidance for future breeding endeavors. The study introduced innovative concepts to further integrate genomics with traditional breeding techniques. Ultimately, Quan 9311A signifies a significant milestone in rice breeding technology, opening up novel avenues for hybrid rice development.

Detection of True Hybrids in Pearl Millet Cross Combinations by Employing SSR Molecular Markers

Pearl millet (Pennisetum glaucum L. R. Br.), a crucial staple food and significant cereal crop, is gaining prominence due to its versatile applications as feed, food, and fodder. Heterosis of this crop has been extensively harnessed to increase productivity. Hybrid variants exhibit superior grain and stover yields compared to open-pollinated varieties.Top of Form The primary aim of this investigation was to evaluate and confirm authentic hybrids within three resultant F1 progenies. The assessment of parents and F1 hybrids was carried out during the Kharif 2021for the purpose of accurate discrimination and rapid verification of true hybrids by employing 20 SSR molecular markers. The experimental materials consisted of three distinct cytoplasmic male sterile (CMS) lines including ICMA 843-22, ICMA 04999, and ICMA 02333, used as female parents along with three fertility restorers, viz., ICMR 01004, ICMR 20233, and ICMR 20342, were utilized as male parents. The analysis of SSR profiles was based on distinctive banding patterns, resulting in unique profiles for the hybrids. The amplified fragment sizes ranged between 90 to 300 base pairs (bp), effectively enabling the differentiation of authentic hybrids. Within the specific crosses, the percentage of polymorphism was determined 75% for the cross ICMA 843-22 × ICMR 01004, 80% for the cross combination  ICMA 04999 × ICMR 20233, and 75% for the cross ICMA 02333 × ICMR 20342. The true hybrids were calculated using hybrid purity percentage formula using heterozygous banding patten among total plants evaluated. Among a total of 100 F1 plants, 85, 86, and 88 plants were accurately identified as true hybrids in the respective crosses i.e., ICMA 843-22 × ICMR 01004, ICMA 04999 × ICMR 20233, and ICMA 02333 × ICMR 20342. The identified markers hold significant potential for applications such as hybridity test, genetic purity assessments, diverse germplasm identification, and DNA fingerprinting endeavors in future.

Male sterility in plants: an overview of advancements from natural CMS to genetically manipulated systems for hybrid seed production.

The male sterility system in plants has traditionally been utilized for hybrid seed production. In last three decades, genetic manipulation for male sterility has revolutionized this area of research related to hybrid seed production technology. Here, we have surveyed some of the natural cytoplasmic male sterility (CMS) systems that existed/ were developed in different crop plants for developing male sterility-fertility restoration systems used in hybrid seed production and highlighted some of the recent biotechnological advancements in the development of genetically engineered systems that occurred in this area. We have indicated the possible future directions toward the development of engineered male sterility systems. Cytoplasmic male sterility (CMS) is an important trait that is naturally prevalent in many plant species, which has been used in the development of hybrid varieties. This is associated with the use of appropriate genes for fertility restoration provided by the restorer line that restores fertility on the corresponding CMS line. The development of hybrids based on a CMS system has been demonstrated in several different crops. However, there are examples of species, which do not have usable cytoplasmic male sterility and fertility restoration systems (Cytoplasmic Genetic Male Sterility Systems-CGMS) for hybrid variety development. In such plants, it is necessary to develop usable male sterile lines through genetic engineering with the use of heterologous expression of suitable genes that control the development of male gametophyte and fertile male gamete formation. They can also be developed through gene editing using the recently developed CRISPR-Cas technology to knock out suitable genes that are responsible for the development of male gametes. The present review aims at providing an insight into the development of various technologies for successful production of hybrid varieties and is intended to provide only essential information on male sterility systems starting from naturally occurring ones to the genetically engineered systems obtained through different means.

Combined transcriptome and proteome analyses between the cytoplasmic male sterile line and its maintainer line in Welsh onion (Allium fistulosum)

AbstractCytoplasmic male sterility (CMS) is dispensable for research of heterosis and investigation of nuclear–cytoplasmic interaction in Welsh onion. The molecular mechanism of the cytoplasmic male sterile line and its maintainer line was investigated by combined transcriptome and proteome analyses in Welsh onion. The 410,585 full‐length non‐chimeric (FLNC, full‐length readsnon‐Chimeric) sequences were obtained, and AS events and lncRNAs were identified by full‐length transcriptome. Towards a comprehensive understanding and identification of related genes for male sterility, the transcriptome and proteome sequencing were utilized to explore the differences between the cytoplasmic male sterile line and its maintainer line. The 287 differentially expressed genes (DEGs) and 49 differentially expressed proteins (DEPs) were identified, and we furthermore explored the function of genes and proteins. The heat map preliminarily demonstrated the expression change of the key genes and proteins in two cultivars. CMS‐related genes were screened form differentially expressed genes, and verified by quantitative real‐time quantitative polymerase chain reaction (qRT‐PCR). Our research found the CMS regulatory genes, proteins and related pathways. The transcriptome and proteome datasets contribute to accelerate the development of CMS gene clones and functional genomics research on Welsh onions.

Development of alloplasmic male sterile lines and their assessment for heterotic potential in eggplant (Solanum melongena L.)

ABSTRACT The use of Solanum aethiopicum as the female parent with S. melongena led to the development of a cytoplasmic-genic male sterility system (CGMS) in eggplant. The male sterility was complete and expressed as rudimentary anthers with no pollen grains. Ten backcross progenies of male sterile lines in diverse genetic backgrounds of S. melongena were characterised after BC7 generation for 14 horticultural traits. It was observed that male sterile lines and their respective maintainer parents were isogenic for all the traits, except stamen size and days to 50% flowering. The fertility of male sterile lines was restored after hybridising with plants derived from an S. melongena × S. aethiopicum cross. The fertility restoration was governed by a single dominant gene. The maternal cytoplasm of S. aethiopicum in male sterile lines and of S. melongena in maintainers and restorers was confirmed with mitochondria and chloroplast DNA-specific molecular markers. Further, to assess the heterotic potential, 10 cytoplasmic male sterility lines were crossed with three restorers to develop 30 F1 hybrids, out of which D−67A × R−6 and D−104A × R−6 were found consistently better than the standard check for yield plant−1 over two years. In this manuscript a comprehensive study on development and utilisation of an alloplasmic CGMS system in eggplant has been discussed.

Irradiated Pollen-Induced Parthenogenesis for Doubled Haploid Production in Sunflowers (Helianthus spp.).

Doubled haploid (DH) technology is a tool used to develop large numbers of inbred lines and increase the rate of genetic gain by shortening the breeding cycles. However, previous attempts to produce DH sunflower plants (Helianthus spp.) have resulted in limited success. In this research, we applied gamma-induced parthenogenesis to assist the production of DH sunflowers. The objectives of the study included (1) identifying optimal gamma ray doses for inducing DH sunflowers using two cytoplasmic male sterility (CMS) lines as female plants and two male pollinators with recognizable morphological markers, (2) selecting new male pollinators from wild sunflower varieties, and (3) testing the efficacy of the selected male pollinators using emasculated non-male sterile sunflower lines as female plants. In these experiments, pollen grains were irradiated with gamma ray doses ranging from 50 to 200 Gy. The optimal gamma ray dose for pollen grain irradiation and DH plant production was identified to be 100 Gy. In addition, a cultivated (G11/1440) and a wild-type (ANN1811) sunflower line can be used as common male pollinators for their distinctive morphological markers and wide capacity for DH induction by gamma-irradiated pollen grains.

Industrial chicory genome gives insights into the molecular timetable of anther development and male sterility.

Industrial chicory (Cichorium intybus var. sativum) is a biannual crop mostly cultivated for extraction of inulin, a fructose polymer used as a dietary fiber. F1 hybrid breeding is a promising breeding strategy in chicory but relies on stable male sterile lines to prevent self-pollination. Here, we report the assembly and annotation of a new industrial chicory reference genome. Additionally, we performed RNA-Seq on subsequent stages of flower bud development of a fertile line and two cytoplasmic male sterile (CMS) clones. Comparison of fertile and CMS flower bud transcriptomes combined with morphological microscopic analysis of anthers, provided a molecular understanding of anther development and identified key genes in a range of underlying processes, including tapetum development, sink establishment, pollen wall development and anther dehiscence. We also described the role of phytohormones in the regulation of these processes under normal fertile flower bud development. In parallel, we evaluated which processes are disturbed in CMS clones and could contribute to the male sterile phenotype. Taken together, this study provides a state-of-the-art industrial chicory reference genome, an annotated and curated candidate gene set related to anther development and male sterility as well as a detailed molecular timetable of flower bud development in fertile and CMS lines.

Evaluation of Cytoplasmic Male Sterile Lines and Restorer Lines in Moricandia System for Heterosis Breeding in Indian Mustard [Brassica juncea (L.) Czern & Coss.]

This study was undertaken with the objectives of Cytoplasmic Male Sterility (CMS) assessment and study of pollen fertility restoration using five Mori based Cytoplasmic Male Sterile lines viz., Mori ‘A’ SKM 109, Mori ‘A’ SKM 125, Mori ‘A’ SKM 201, Mori ‘A’ SKM 219, Mori ‘A’ SKM 303 and eight diverse Mori based fertility restorer lines viz., Mori ‘R’ GM 2, Mori ‘R’ GM 3, Mori ‘R’ SKM 9033, Mori ‘R’ SKM 301, Mori ‘R’ Pusa Bahar, Mori ‘R’ Vardan, Mori ‘R’ Bio 902, Mori ‘R’ 1-14 to  identify good fertility restorer line and stain ability of pollen grains of sterile and fertile lines to Moricandia arvensis, cytoplasmic background of converted cytoplasmic male sterile lines of Indian Mustard [Brassica juncea (L.) Czern & Coss.] by repeated backcrossing at the Main Castor-Mustard Research station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar-385506 Banaskantha. The pollen stain ability, plant fertility status and percentage siliquae set per plant was recorded for the morphological characterization and to confirm stability of true Cytoplasmic Male Sterile (CMS) line. The experimental material comprised of fifty-four genotypes consisting of five diverse CMS lines and eight Fertility Restorer lines were crossed in line X tester mating design and resultant forty hybrids along with their thirteen parents and standard check variety (Kranti) were evaluated in randomized block experimental design. The morphological characters were studied viz., pollen fertility, Number of siliquae set per plant, per cent siliquae set per plant in field as well as laboratory tests were conducted with 2 % Aceto-carmine to confirm pollen stain ability and purity of CMS (A-lines) for male sterility and pollen fertility restorability of R-lines. There were visual differences observed for the parents (male sterile lines and fertility restorer lines), all the F1 crosses and standard check parent for pollen fertility. The male sterile lines exhibited (100%) pollen sterility and the pollen fertility restorer lines varied from 80.05 % (Mori ‘R’ Pusa Bahar) to 97.97 %(Mori ‘R’ SKM 9033).