Sources Of Cytoplasmic Male Sterility Research Articles

Usefulness of alien sterilizing cytoplasms for the hybrid breeding of triticale (xTriticosecale Wittmack): preliminary results.

To be useful for cereal breeding, cytoplasmic male sterility (CMS) should express the complete sterility of maternal lines and the full restoration of the male fertility of F1 hybrids. The most reliable source of sterilizing cytoplasm for triticale is Triticum timopheevi; however, due to the low frequency of efficient non-restorer genotypes for this cytoplasm, new sources of CMS are needed. In this study, aside from T. timopheevi (T) cytoplasm, three alternative CMS sources were tested: Pampa (P) from Secale cereale L., Aegilops sharonensis (A), and Ae. ventricosa (V). The suitability of these cytoplasms for breeding was assessed based on the male fertility/sterility of F1 hybrids obtained through the manual pollination of CMS maternal lines with 36 triticale cultivars and breeding strains. About half of the hybrids with each type of cytoplasm were fully fertile and produced more than 30 grains per bagged spike. The highest percentage was found in hybrids with P cytoplasm (58.33%) and the lowest in hybrids with A cytoplasm (44.44%). Male sterility was observed in hybrids with P cytoplasm (16.67%) and A cytoplasm (16.67%) but not in hybrids with T or V cytoplasm. In terms of practical aspects, male sterility systems with P or A cytoplasm exhibit similarity in their ability to restore male fertility that differ from the T and V cytoplasms. Although all studied cytoplasms exhibited some disadvantages for breeding purposes, none should be definitively classified as unacceptable for future breeding programs regarding the development of triticale hybrid cultivars.

A Single Nucleotide Polymorphism Unique to the Galanthum-CMS of Onion

Different sources of cytoplasmic male sterility (CMS) are used to produce hybrid onion seed. The most commonly used source of CMS in onion is S cytoplasm (S-CMS), and male fertility is restored by a dominant allele at the nuclear male-fertility restoration locus (Ms). Male-sterile plants possess S cytoplasm and have the homozygous recessive genotype at Ms; seed propagation of male-sterile plants is possible by crossing with a male-fertile maintainer plant or inbred possessing normal (N) male-fertile cytoplasm and the homozygous recessive at the Ms locus (N msms). Some commercially important onion populations possess S-CMS and high frequencies of the dominant Ms allele, eliminating the possibility to develop maintainer lines. An alloplasmic source of CMS (Gal-CMS) was developed by backcrossing the cytoplasm of Allium galanthum into the nuclear background of onion. The advantage of Gal-CMS is that the dominant allele at Ms does not restore male fertility, making this source of CMS useful for the development of male-sterile lines from populations possessing S cytoplasm and dominant allele(s) at Ms. In this research, a single nucleotide polymorphism unique to the cytoplasms of A. galanthum and Gal-CMS was identified, useful to distinguish Gal-CMS from other onion cytoplasms.

Development of mitochondrial simple sequence repeat markers to simultaneously distinguish cytoplasmic male sterile sources in cotton.

Deleterious effects on anther development andmain economy traits caused by sterile genes or cytoplasms are one of the important genetic characteristics of cytoplasmic male sterility (CMS) systems in cotton, which severely hinder the large-scale application of "three-line" hybrids in production. Therefore, distinct characterization of each cytoplasmic type is mandatory to improve the breeding efficiency of cotton hybrids. In this study, four isonuclear-alloplasmic cotton male sterile lines withG. hirsutum (CMS-(AD)1), G. barbadense (CMS-(AD)2), G. harknessii (CMS-D2), and G. trilobum (CMS-D8) cytoplasms were first created by multiple backcrosses with common genotype Shikang126. Then, 64 pairs of mitochondrial simple sequence repeat (mtSSR) markers were designed to explore the mitochondrial DNA diversities among four isonuclear-alloplasmic cotton male sterile lines, and a total of nine pairs of polymorphic mtSSR molecular markers were successfully developed. Polymorphism analysis indicated that mtSSR59 marker correlated to the atp1 gene could effectively divide the CMS-D2, CMS-(AD)1, and CMS-(AD)2 in one category while the CMS-D8 in another category. Further cytological observation and determination of ATP contents also confirmed the accurate classification of CMS-D2 and CMS-D8 lines. Moreover, the mtSSR59 marker was successfully applied in the marker-assisted selection (MAS) for breeding new male sterile lines and precise differentiation or purity identification of different CMS-based "three-line" and conventional cotton hybrids. This study provides new technical measures for classifying various cytoplasmic sterile lines, and our results will significantly improve the efficiency of there-line hybrid breeding in cotton.

Seed productivity of alloplasmic lines of Beta patula and B. maritima with sterile cytoplasm under the conditions of apozygotic reproduction

Purpose. Revealing the effect of the cytoplasmic genome of replaced lines with the plasma of wild species Beta patula and B. maritima L., and apozygotic lines A4–A8 with the cytoplasm of S vulgaris Owen on the main factors of apozygotic reproduction, seed productivity, germination, monogermity and sterility as affected by the genetic origin of breeding material.
 Methods. The research was carried out in the Cytogenetics Laboratory (IBCSB), the Laboratory for Apomixis and Polyploidy of the Yaltushkiv EBS, and the Laboratory for Adaptive Breeding (Veselyi Podil EBS). Apozygotic seeds were obtained under a pollen-free regime according to the IBCSB’s Methods for Spatial Isolation and Parchment Insulators. Each seed bearer plant phenotype was determined during the flowering period by pollen sterility and partial flowering. Classification of plants was performed according to Owen (1945), with identifying plants of CMS-0, Type CMS-1, and CMS-2 types. The Monogermity of seed plants was assessed visually by the presence of separate fruits on the central shoots. In 2021, the roots of the replaced lines of the Veselyi Podil EBS were planted under the conditions of a pollen-free regime in the experimental field of the IBCSB. Seed production under apozygositic conditions was studied, taking into account the number of set fruits per 10-cm segment with 5 replications for each seed bearer. Germination was determined on the 10th day and germination vigour on the 5th day.
 Results. New sources of cytoplasmic male sterility (CMS) were obtained in the cytogenetics laboratory based on a genetic model of crossbreeding analysis, using differentiation and tools according to the marker-linked genes of hypocotyl color R+r-, and one / two-year development cycle B+b-. The analyzers for the nature of sugar beet sterility were sterility maintainers, dominant homozygotes for recessive genes of anthocyanin color, development cycle, partial fertility and sterility (NBeta vulgaris Sxxzz rr bb). Monogerm pollen-sterile lines with an apomictic way of seed reproduction (Yaltushkiv EBS) (A4–A8 Beta vulgaris Sxxzz rr), selected for the dominant color of the hypocotyl R+r-, stabilized for the trait of monogermity, 100% sterility and 2x gene ploidy, were characterized by low seed productivity. High rates of apozygotic seed development (80 to 96.4% of the number of set flowers) were observed against the background of the sterile cytoplasm of Beta maritima (Turkey). In the CMS BC4S patula line, the number of set apozygotic seeds ranges from 34 ± 0.3 to 39 ± 0.42, and the indicators of degenerated flowers under apozygotic regime varied from 31.2 to 54.3%. Isolated were seed plants with high self-reproduction, such as BC4S maritima Turkey, k.2/1, k.6/2, k.6/3 and k.3/4, k.9/4 on the background of new plasma of wild species of B. patula. The phenomenon of high self-reproduction of seeds (up to 98.5−96.4% of set flowers) was detected in line 21-011 CHS BC5S patula, which was comparable with hybrids and sterility maintainers (97.5−93.1%), which is determined by a special interaction of the beet nuclear genome of sugar beet and new plasma of wild species of the genus Beta L.
 Conclusions. The apomictic way of seed reproduction ensures the shortening of the breeding scheme for sugar beet due to high seed reproduction of mother parent in substituted lines with new plasma and differentiation by gametophytic reduction of parthenogenesis using morphological marker traits.

Biodiversity of interspecific hybrids of the genus <i>Allium</i> L.

Relevance. Interspecific hybridization in the genus Allium L. is the best way to increase biodiversity by introgression of desired traits within the genus. This is valuable for signs such as resistance to diseases and pests, accumulation of important metabolites, obtaining new sources of cytoplasmic male sterility. The creation based on interspecific hybridization of fundamentally new plant forms with unique genetic material makes it possible to expand the selection of genotypes that are valuable in practical terms.Methods. To characterize the breeding material, the plants of interspecific allium hybrids were evaluated using morphological and phytopathological analyses. The analysis of plants of interspecific hybrids of the genus Allium L. from various inbred offspring from BC1-2 combinations of crossing species A. cepa × A. vavilovii and A. cepa × A. fistulosum by breeding characteristics was carried out. Plants were studied by weight, color, bulb shape, number, height of seed stalks, seed productivity and resistance to downy mildew.Results. The biodiversity of plants was revealed: by weight, shape, color of the bulb; by resistance to downy mildew of plants of the first year of vegetation and seed plants; by the number, height of seed stalk; by seed productivity. Plants of interspecific allium hybrids formed bulbs weighing up to 120 g, white, yellow, brown and red, elliptical, broadly elliptical, round and transversely elliptical bulb shape. Phytopathological assessment of allium plants of the first year of vegetation and seed plants revealed diversity in inbred offspring with resistance to peronosporosis. In the combination of crossing species A. cepa × A. vavilovii plants of the first year of vegetation had the largest number of resistant plants to downy mildew (up to 66.7%). According to the seed productivity of plants, depending on the combination of crossing, inbreeding generation and backcross, highly fertile plants with increased seed setability (up to 2.0 g /plant) were identified. The conducted studies have demonstrated an increase in the biodiversity of allium plants obtained based on interspecific hybridization, backcrosses and inbreeding.

Utilization of wild species for diversifying the cytoplasmic male sterility source of sunflower (Helianthus annuus L.) hybrids

Abstract The present investigation is directed at improving sunflower using hybrids having diverse cytoplasmic male sterile (CMS) sources from Helianthus annuus and H. argophyllus. The aim is to develop and identify promising lines and hybrids with a high combining ability and to obtain highly productive oilseed sunflower hybrids having diverse CMS sources. Five diversified CMS lines and 10 testers were crossed in a line × tester mating design to develop 50 F1 hybrids for genetic analysis. The pooled analysis of variance revealed significant differences among hybrids for the traits studied. The mean squares of lines and testers from crosses and GCA variance components revealed the prevalence of additive variances and additive gene action. The mean squares of lines × tester interactions were also significant for all the traits considered. The significance of lines × tester interactions and SCA variance components indicated that SCA is also important in the expression of traits and demonstrated the role of dominant and epistatic genes in controlling the various traits. Among the diverse CMS lines, ARG-6-3-1-4was identified as the best general combiner for stem diameter, volume weight, seed yield, hull content and oil content. While, the line ARG-2-1-2 was the best general combiner for days to 50 per cent flowering, head diameter, 100 seed weight and seed filling per cent. The tester M17-R was observed to be the best general combiner for earliness and volume weight, while RHA 93 was the best general combiner for plant height, seed yield and oil content. The crossMUT-2-8-3-2 × GKVK 3 was found to be a good specific combiner for stem diameter, 100 seed weight, seed yield, seed filling percentage and oil content while, ARG-6-3-1-4 × GKVK 3 was a good specific combiner for days to 50% flowering, plant height and 100 seed weight. The highest standard heterosis for seed yield was observed in the hybrid MUT-2-8-3-2 × GKVK 3 followed by ARG-2-1-2 × LTRR 822 while for oil content the highest was seen in the cross ARG-6-3-1-4 × RHA95-C-1 and thus these hybrids can be exploited for sunflower improvement and diversifying the cytoplasmic male sterile sources of this valuable oilseed crop.

Restoration ability of newly developed restorer gene pool inbreds on two different CMS sources in sunflower (Helianthus annuus L.)

Classical cytoplasmic male sterility (PET-1) discovered by Leclercq and a few restorer lines are being utilized for commercial hybrid seed production in sunflowers over the world since 1972. The utilisation of a single source of male sterility results in a high level of vulnerability to biotic and abiotic stresses. The goal of this study was to identify new fertility restorers for two different cytoplasmic male sterile sources, i.e., PET-1 (COSF-6A, COSF-7A, CMS-38A, ARM-248A) and CMS PEF (FMS-852A). Five CMS lines were crossed with newly developed drought tolerant 10 inbred lines in Line x Tester fashion and an evaluation of test cross progenies was conducted. All the inbreds were categorized into complete, partial restorers and maintainers through cytological observation. Six inbreds, viz., RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 behaved as restorers for all the CMS lines and restored fertility, while RGP-222 and 298R inbreds maintained sterility. The CMS line, FMS-852A was maintained by four inbreds indicating the involvement of different gene(s), while six inbreds, RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 were restored its fertility. None of the inbreds behaved as partial restorers for any of the CMS lines. The fertility restoration ranged from 91.4 to 97.4 per cent in different cross combinations. In the present study, pollen fertility of up to 80 per cent was observed for the PET-1 source. However, only 60 per cent of the pollen fertility was observed for CMS fallax. From the study, it was evident that among the two CMS sources, restorers for PET-1 and PEF were available. Efforts should be made to utilize CMS PEF for the production of more productive sunflower hybrids resistant to biotic and abiotic stresses. Keywords: CMS sources, Inbreds, Maintainer, Restorer, Sunflower

The Gossypium anomalum genome as a resource for cotton improvement and evolutionary analysis of hybrid incompatibility.

Cotton is an important crop that has been the beneficiary of multiple genome sequencing efforts, including diverse representatives of wild species for germplasm development. Gossypium anomalum is a wild African diploid species that harbors stress-resistance and fiber-related traits with potential application to modern breeding efforts. In addition, this species is a natural source of cytoplasmic male sterility and a resource for understanding hybrid lethality in the genus. Here, we report a high-quality de novo genome assembly for G. anomalum and characterize this genome relative to existing genome sequences in cotton. In addition, we use the synthetic allopolyploids 2(A2D1) and 2(A2D3) to discover regions in the G. anomalum genome potentially involved in hybrid lethality, a possibility enabled by introgression of regions homologous to the D3 (Gossypium davidsonii) lethality loci into the synthetic 2(A2D3) allopolyploid.

A Study on Sources of Cytoplasmic Genetic Male Sterility, Heterosis, and Combining Ability in Pearl Millet

A Study on Sources of Cytoplasmic Genetic Male Sterility, Heterosis, and Combining Ability in Pearl Millet

Identification of stable restorers for diverse cytoplasmic source in Sorghum [Sorghum bicolor (L.) Moench.

In sorghum [Sorghum bicolor (L.) Moench.], milo is the lone source of cytoplasmic male sterility (CMS) extensively used in production of commercial hybrids. The hazards of such a narrow cytoplasmic base are apparent and consequently new diverse sources like A2, A3, A4, maldandi, VZM and G1 were identified. However, the commercial exploitation of these sources has not been possible because of the difficulty in fertility restoration on these sources. The present study was, therefore, undertaken to test different sorghum germplasm lines for their fertility restoration/maintenance on maldandi and milo cytoplasm. Twenty-five diverse accession were selected from minicore collection and crossed with two male sterile lines viz., 104A (milo) and M 31-2A (maldandi). The resulting F1s were classified as fertility restorers and maintainers based on seed set on bagged ear heads. The restoration studies indicated that 2 lines on maldandi and 6 on milo cytoplasm showed strong fertility restoration (> 90 % seed set).

Heterotic Effect of Different Cytoplasmic Combinations in Sunflower Hybrids Cultivated Under Diverse Irrigation Regimes.

The sunflower hybrids hold a narrow cytoplasmic diversity. Besides, the heterotic effect of wild cytoplasmic combinations of sunflower on important traits under water stress has not been explored in detail. Here, we evaluated the different sunflower cytoplasmic combinations in sunflower hybrids using cytoplasmic male sterile (CMS) sources as female parents. We used a total of sixteen sunflower genotypes representing twelve CMS lines from wild and conventional sources along with four restorer lines. Twelve CMS lines were crossed with four restorer lines to develop a total of 48 F1 hybrid combinations. The hybrids were evaluated under two different environments (i.e., regular irrigation and water stress) for morphophysiological, yield, and biochemical traits over two years. Heterotic effect for various CMS sources was evaluated on all of the three possible scales, namely, better-parent heterosis (BPH), mid-parent heterosis (MPH), and heterosis as percent of check (PSH-996). For better-parent and mid-parent heterosis, the CMS sources Helianthus annuus, Helianthus argophyllus, and Helianthus debilis demonstrated positive better-parent heterosis for seed yield, oil content, and oleic acid irrespective of the environment. However, the hybrid combinations of different sources when using the genotype RCR8297 as the restorer parent recorded maximum average returns. Furthermore, chlorophyll meter (SPAD) reading positively correlated with days to 50% flowering, days to maturity, plant height, and number of leaves per plant in both the environments. Overall, this study identified and compared the heterotic effect of the different cytoplasmic combinations in sunflower under water stress as well as under normal irrigation environments.

Mapping of the New Fertility Restorer Gene Rf-PET2 Close to Rf1 on Linkage Group 13 in Sunflower (Helianthus annuus L.).

The PET2-cytoplasm represents a well characterized new source of cytoplasmic male sterility (CMS) in sunflower. It is distinct from the PET1-cytoplasm, used worldwide for commercial hybrid breeding, although it was, as PET1, derived from an interspecific cross between Helianthus. petiolaris and H. annuus. Fertility restoration is essential for the use of CMS PET2 in sunflower hybrid breeding. Markers closely linked to the fertility restorer gene are needed to build up a pool of restorer lines. Fertility-restored F1-hybrids RHA 265(PET2) × IH-51 showed pollen viability of 98.2% ± 1.2, indicating a sporophytic mode of fertility restoration. Segregation analyses in the F2-population of the cross RHA 265(PET2) × IH-51 revealed that this cross segregated for one major restorer gene Rf-PET2. Bulked-segregant analyses investigating 256 amplified fragment length polymorphism (AFLP) primer combinations revealed a high degree of polymorphism in this cross. Using a subset of 24 AFLP markers, three sequence-tagged site (STS) markers and three microsatellite markers, Rf-PET2 could be mapped to the distal region of linkage group 13 between ORS1030 and ORS630. Three AFLP markers linked to Rf-PET2 were cloned and sequenced. Homology search against the sunflower genome sequence of HanXRQ v1r1 confirmed the physical location of Rf-PET2 close to the restorer gene Rf1 for CMS PET1. STS markers were mapped that can now be used for marker-assisted selection.

Complete organelle genomes of Sinapis arvensis and their evolutionary implications

Sinapis arvensis, belonging to the genus Sinapis of the family Brassicaceae, has good agronomic characters that make it a valuable genetic resource for crop improvement and is a cytoplasmic source of heterologous cytoplasmic male sterility (CMS). In addition, S. arvensis has played an important role in the evolution of the six major cultivated Brassica species involved in the triangle of U. Using next-generation sequencing, we assembled and revealed the gene composition of S. arvensis cytoplasmic genome. The chloroplast genome comprises 153,590 bp, with 112 individual genes, including 4 rRNA, 29 tRNA, and 79 protein-coding genes. The mitochondrial genome comprises 240,024 bp, with 54 genes, including 18 tRNA, three rRNA and 33 protein-coding genes. Genome structure and evolutionary analysis indicated that the sequences of the S. arvensis organellar genomes were more similar to those of Brassica nigra and B. carinata than to those of other Brassicaceae species. Four mitochondrial open reading frames displaying chimeric structural features and encoding hypothetical proteins with transmembrane domains may account for the infertility of Nsa CMS previously derived from somatic cell hybridization between B. napus and S. arvensis. These results will not only contribute to utilize the germplasm resource of S. arvensis, and comprehend the evolution of organelle genomes within the Brassicaceae family, but also help to identify genes conditioning the alloplasmic male sterility of Nsa CMS in B. napus.

Organization Features of the Mitochondrial Genome of Sunflower (Helianthus annuus L.) with ANN2-Type Male-Sterile Cytoplasm.

This study provides insights into the flexibility of the mitochondrial genome in sunflower (Helianthus annuus L.) as well as into the causes of ANN2-type cytoplasmic male sterility (CMS). De novo assembly of the mitochondrial genome of male-sterile HA89(ANN2) sunflower line was performed using high-throughput sequencing technologies. Analysis of CMS ANN2 mitochondrial DNA sequence revealed the following reorganization events: twelve rearrangements, seven insertions, and nine deletions. Comparisons of coding sequences from the male-sterile line with the male-fertile line identified a deletion of orf777 and seven new transcriptionally active open reading frames (ORFs): orf324, orf327, orf345, orf558, orf891, orf933, orf1197. Three of these ORFs represent chimeric genes involving atp6 (orf1197), cox2 (orf558), and nad6 (orf891). In addition, orf558, orf891, orf1197, as well as orf933, encode proteins containing membrane domain(s), making them the most likely candidate genes for CMS development in ANN2. Although the investigated CMS phenotype may be caused by simultaneous action of several candidate genes, we assume that orf1197 plays a major role in developing male sterility in ANN2. Comparative analysis of mitogenome organization in sunflower lines representing different CMS sources also allowed identification of reorganization hot spots in the mitochondrial genome of sunflower.

Intraspecific, interspecific and intergeneric hybridization of stone fruit plants

Aim. The aim to identify valuable source material from the number of intraspecific, interspecific and intergeneric hybrids of stone fruit plants to improve and expand the varietal composition of peach that meets the needs of industrial and amateur gardening. Methods. Program and methods of varietal study of fruit, berry and nut crops / Ed. G. A. Lobanov. Michurinsk, 1973. 492 p. Program and methods of selection of fruit, berry and nut crops / Ed. G. A. Lobanov. Michurinsk, 1980. 529 p. Program and methods of selection of fruit, berry and nut crops / Ed. Sedova and T. P. Ogoltsova. Orel: VNIISPK, 1999. 608 p. Results. New genotypes of peach, which are sources of cytoplasmic male sterility (CMS), were selected; large-fruited peach I4 970-89 was isolated, as a pollinator for genotypes with male sterility; in the population of hybrid seedlings F2 (peach of the world x David peach) we identified new genotypes of plants with absent characters in their original species; with resistance to powdery mildew and leaf curl, dwarf plant growth, forms with decorative double flowers, white, pink and purple-red color of the petals of the corolla, bell-shaped and rosy flower types, male sterility, pollen fertility and honey taste of the fruit inherited from his wild ancestor - David peach. Summary. Selected maternal genotypes of the original parental forms of apricot, with a character of CMS - 189-88, 249-81, 498-86. They are of breeding value for the development of new peach cultivars. Peach I4 970-89 of the Nikitsky Botanical Gardens’ breeding is a pollinator for hybrids of peach with common almond, characterized by male sterility. Valuable characters of David peach could be transferred to common peach and its cultivars as a result of natural hybridization due to their joint growth in the primary Chinese-Japanese genetic center. From wild ancestor, David peach common peach cultivars inherited such valuable characteristics as resistance to powdery mildew and leaf curl, dwarf growth of plants, shapes with decorative double flowers, white, pink and purple-red petals of the corolla campanulate and rose-like types of flower, male sterility, pollen fertility and the honey taste of the fruit.

Development of a genotyping method for onion (Allium cepa L.) male-fertility based on multiplex PCR

ABSTRACTThe most widely used source of onion cytoplasmic male-sterility (CMS) is controlled by a single nuclear gene and a cytoplasmic factor, and the sterility trait can be recovered by the dominant nuclear gene (Ms). Marker-assisted selection (MAS) has a great potential in the selection of male sterility lines and maintainer lines. In this study, two markers at the Ms loci and one cytoplasm marker were used to a develop multiplexed polymerase chain reaction (PCR) system for MAS of fertility traits in onion. Seven pairs of PCR primers were designed on the basis of the flanking sequences (F1890 and S1887) of the male-fertility restoration (Ms) locus and a mitochondrial sequence (mt472) in onion. One set of compatible primers were selected to develop a multiplex-PCR molecular marker (AcCN), which was established in forty-eight lines. The fertility types of cytoplasm and nuclear were distinguished by one-time PCR detection. The accuracy of the AcCN marker was verified in practical backcross breeding population. The AcCN marker types perfectly matched with their genotypes and phenotypes. It can be concluded that this marker is of great practical significance for MAS in the selection of onion maintainer lines.

Evaluation and selection of sources of cytoplasmic male sterility in broccoli

Broccoli is an important Brassica vegetable that shows obvious heterosis. The main method for hybrid broccoli production is to use cytoplasmic male sterility (CMS) and pollination by bees. Therefore, the evaluation and selection of high quality sources of CMS is important for broccoli breeding. We aimed to evaluate the effects of different CMS sources on the morphology and size of floral organs, the attractiveness to pollinators and yield of hybrid seeds. Using broccoli CMS lines generated from different CMS sources with the same maintainer lines, we studied morphophysiological characteristics of flowers, such as flower shape and size, nectar production and sugar content, as well as the number of bee visits and seed yield. The degree of bud abortion, floral organs shape, degree of flower opening, nectar production, bee visits, and hybrid yield differed in CMS lines with same recurrent parent. When the CMS source was same and the recurrent parents were different, the degrees of bud abortion were different among the CMS lines, while the flowering characteristics were similar. Generally, larger floral organs and higher volumes of nectar were associated with higher frequency of bee visits and higher seed yield. Based on the morphological characteristics and size of floral organs, nectar secretion, bee-attracting ability and hybrid yield, we selected four CMS sources suitable for future use in broccoli breeding. Our results will provide an important reference for breeding high-quality CMS lines in broccoli and provide valuable CMS sources for breeding other cruciferous crops.

Linkage Mapping and Genome-Wide Association Studies of the Rf Gene Cluster in Sunflower (Helianthus annuus L.) and Their Distribution in World Sunflower Collections.

Commercial hybrid seed production in sunflower currently relies on a single cytoplasmic male sterility (CMS) source, PET1 and the major fertility restoration gene, Rf1, leaving the crop highly vulnerable to issues with genetic bottlenecks. Therefore, having multiple CMS/Rf systems is important for sustainable sunflower production. Here, we report the identification of a new fertility restoration gene, Rf7, which is tightly linked to a new downy mildew (DM) resistance gene, Pl34, in the USDA sunflower inbred line, RHA 428. The Rf7 gene was genetically mapped to an interval of 0.6 cM on the lower end of linkage group (LG) 13, while Pl34 was mapped 2.1 cM proximal to the Rf7. Both the genes are located in a cluster of Rf and Pl genes. To gain further insights into the distribution of Rf genes in the sunflower breeding lines, we used a genome-wide association study (GWAS) approach to identify markers associated with the fertility restoration trait in a panel of 333 sunflower lines genotyped with 8,723 single nucleotide polymorphism (SNP) markers. Twenty-four SNP markers on the lower end of LG13 spanning a genomic region of 2.47 cM were significantly associated with the trait. The significant markers were surveyed in a world collection panel of 548 sunflower lines and validated to be associated with the Rf1 gene. The SNP haplotypes for the Rf1 gene are different from Rf5 and the Rf7gene located in the Rf gene cluster on LG13. The SNP and SSR markers tightly flanking the Rf7 gene and the Pl34 gene would benefit the sunflower breeders in facilitating marker assisted selection (MAS) of Rf and Pl genes.

Characterization of the mitochondrial genome of the MAX1 type of cytoplasmic male-sterile sunflower

BackgroundMore than 70 cytoplasmic male sterility (CMS) types have been identified in Helianthus, but only for less than half of them, research of mitochondrial organization has been conducted. Moreover, complete mitochondrion sequences have only been published for two CMS sources – PET1 and PET2. It has been demonstrated that other sunflower CMS sources like MAX1, significantly differ from the PET1 and PET2 types. However, possible molecular causes for the CMS induction by MAX1 have not yet been proposed. In the present study, we have investigated structural changes in the mitochondrial genome of HA89 (MAX1) CMS sunflower line in comparison to the fertile mitochondrial genome.ResultsEight significant major reorganization events have been determined in HA89 (MAX1) mtDNA: one 110 kb inverted region, four deletions of 439 bp, 978 bp, 3183 bp and 14,296 bp, respectively, and three insertions of 1999 bp, 5272 bp and 6583 bp. The rearrangements have led to functional changes in the mitochondrial genome of HA89 (MAX1) resulting in the complete elimination of orf777 and the appearance of new ORFs - orf306, orf480, orf645 and orf1287. Aligning the mtDNA of the CMS sources PET1 and PET2 with MAX1 we found some common reorganization features in their mitochondrial genome sequences.ConclusionThe new open reading frame orf1287, representing a chimeric atp6 gene, may play a key role in MAX1 CMS phenotype formation in sunflower, while the contribution of other mitochondrial reorganizations seems to appear negligible for the CMS development.

Stability Analysis of Some Novel Cytoplasmic Male Sterile Sources of Sunflower and Their Hybrids

AbstractGenetic makeup along with environmental stimuli affect the expression of a trait in plants. Drought tolerance in addition to stability of characters over a wide range of environmental conditions is not well studied in sunflower. Therefore, here we have performed a stability analysis study of sunflower genotypes. The experimental material comprised of 19 lines of sunflower comprising 9 alloplasmic cms lines from different wild sources along with one common maintainer from petiolaris source, 4 cms lines and one maintainer from cultivated source (cytoplasm from H. petiolaris), 4 restorer lines and 60 F1 hybrids (developed in line x tester design). The experiment was conducted over two years i. e. spring season 2011 and spring season 2012 over the two environments one normal irrigated and another water stress environment at Punjab Agricultural University, Ludhiana, India. The data were recorded for different morphophysiology, yield and quality trais and analysis as per standard procedures. The genotype×environment interaction was further partitioned into linear and non-linear components according to Eberhart and Russel model. Eleven sunflower hybrids were found to be stable across the environments for seed yield. While, sufficient variability was also recorded for the oil content with the highest oil percentage in the cross combination ARG-2A×P100R (34.61). Overall, this study provides useful information regarding the stability of newly developed and cytoplasmically diverse sunflower hybrids under north Indian conditions.