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Cytoplasmic male-sterile line CMS ANN3 was discovered from a wild annual Helianthus annuus L. accession PI 413180. A single dominant fertility restoration (Rf) gene for CMS ANN3 was identified in PI 413180, P 21, RHA 801, RCMG 1, and RHA 280, designated as Rf9. This study reports the mapping of the Rf9 locus using an F2 population of 160 individuals. Bulked segregant analysis with SSR primers identified two polymorphic SSR markers in linkage group 3 of the sunflower genetic map. A linkage map of Rf9 was constructed with 16 markers including 11 SSR/STS and five SNP markers, covering a genetic distance of 87.3 cM. The Rf9 gene is located between a co-dominant marker ORS1114 and a dominant marker NSA002021, with a distance of 4.1 and 1.0 cM, respectively. The physical distance between the two closest flanking markers corresponds to 1.44 and 2.05 Mb on the HA 412-HO and XRQ assemblies, respectively. The closely linked marker for Rf9 will facilitate marker-assisted selection in breeding programs, which provides a basis for further characterization of this gene, and for studying the mechanism between cytoplasmic male sterility and Rf genes. The mapping of the Rf gene will also be useful for studying Rf gene suppression and nuclear–cytoplasm interactions. [ABSTRACT FROM AUTHOR]

Sunflower (Helianthus annuus L.; 2n = 2x = 34) is an important annual oilseed crop cultivated worldwide due to its good oil quality and wider adaptability to different climatic and soil conditions. In the recent past, powdery mildew (Golovinomyces cichoracearum (DC.) V.P. Heluta.) disease has evolved as a significant constraint for yield and quality production in sunflower crop. Hence, we developed a F2 mapping population from a cross between the powdery mildew resistant parent IR6 and powdery mildew susceptible parent COSF 15B to identify quantitative trait loci (QTL) associated with powdery mildew resistance in sunflower. F2:4 recombinant lines of this population were screened along with parents and scored for powdery mildew resistance during Dec–Feb 2021–2022. Percent disease index (PDI) was calculated from the data taken 75 days after sowing (DAS) using a 0–9 score scale. Genetic linkage map was constructed with 92 SSR markers which covered 1053.3 cM. The QTL analysis resulted in the detection of one QTL in LG10 for PDI. It has 2.54 LOD and accounted for 12.25% phenotypic variation. The flanking markers viz., ORS684 and ORS1110 have a flanking distance of 1.7 cM. These flanking markers were validated in a set of 16 genotypes consisting of 6 susceptible, 4 moderate resistant and 6 resistant lines. The results confirmed that the flanking markers ORS684 and ORS1110 were validated and explained 24% and 28% phenotypic variation, respectively. Hence, it may be concluded that markers ORS684 and ORS1110 can be effectively utilized for marker assisted breeding programme to develop the sunflower lines resistant to powdery mildew. The candidate gene analysis revealed many candidate genes involved in plant pathogen defense mechanism (mostly R gene families) viz., leucine-rich repeat domain, serine/threonine-protein kinase, 14–3–3 protein, aspartic peptidase, ABC transporter, TIR domain, and t-SNARE coiled-coil which are highly associated with powdery mildew resistance. [ABSTRACT FROM AUTHOR]

Sunflower is one of the most important oil crops in Ethiopia in terms of edible oil and holds significant promise for improvement and development improved varieties. The present study was initiated to study the genetic diversity and performance of sunflower genotypes that enables to harness its seed yield and oil content improvement by using 25 genotypes including two standard checks namely Russian black and Oissa at Holeta Agricultural research center by using simple lattice design. The genotypes characterized for different agro-morphological traits and oil content. The analyses of variances have revealed highly significant difference among the genotypes for all the characters. The data revealed that sufficient variability was present among sunflower genotypes considered under this study. High Phenotypic coefficient variation, Genotypic coefficient variation and estimates of heritability (broad sense) were obtained for seed yield, oil content, oil yield, and thousand seed weight while the above parameters were found to be less compared to characters. High heritability accompanied with high genetic advance, as per percentages of mean was observed in case of seed yield, oil content, oil yield per plot, harvest index, head diameter and plant height suggesting importance of additive genetic action in the inheritance of these characters. While, high heritability coupled with moderate genetic advance was observed for days to maturity and days to 50% flowering, seed yield per plant, leaf number and reproductive phase. These indicate that the traits were controlled by additive gene action. Days to maturity, oil yield, seed yield per plant, head diameter and reproductive phase revealed positive association and had positive direct effect of seed yield. Based on genetic distance (D2 value), the genotypes under this study were grouped into two clusters indicating wider genetic diversity among the genotypes. Among the two clusters, cluster II represented the largest genotypes (18) followed by cluster I (4) genotypes and cluster S1, S2, and S3 genotypes. The clustering pattern indicated the absence of relationship between genetic diversity and geographical origin of genotypes. The maximum inter-cluster distance was observed between cluster I (D2 = 6.85). Out of the thirteen traits four significant principal components (PCs) exhibited more than 1 Eigen value and showed about 80.2% variability among the genotypes studied. The first PC accounted 41% of the variances that implies greater proportion of variable information explained by PC1. This indicates that any improvement of these characters would result in a substantial increment of seed yield. [ABSTRACT FROM AUTHOR]

Bird attack is a serious limitation to sunflower yield in several regions of the world, but it could also cause selection. The wild Helianthus annuus, naturalized in several regions of the world, hybridizes with the crop and produces crop-wild offspring. It is unknown how the selective force of seed predation by birds could drive evolution after a hybridization event. After two generations of natural selection exerted by birds (mostly by Eared Dove and Monk Parakeets), achene and plant traits of the crop-wild hybrid progeny were compared with the same hybrid progeny without any selection by birds. After two generations of bird selection the achene width, thickness and weight decreased by an average of 18.5, 26.7 and 49.2 %, respectively. Also in response to bird selection there was a correlated increase in the plant height, stem diameter, number of heads and a reduction in head diameter and the number of achenes per head. The phenotype of crop-wild plants selected by birds resembles wild plants, whereas the plants without any selection were intermediate between the parents. These results indicate that selection exerted by birds could result in the rapid evolution of crop-wild sunflower populations. [ABSTRACT FROM AUTHOR]

Haploidisation is a biotechnological method used to obtain plants with improved traits that are of use to humans. Lettuce ( Lactuca sativa L.), a well-known and popular leafy vegetable, is consumed worldwide. Its haploid form would provide a good basis for producing a pure line of plants (doubled haploids) allowing new varieties to be regenerated. The main aim of this work was to develop an effective haploidisation method for this economically important species. In order to stimulate the development of haploid embryos of lettuce based on our previous experience, we conducted in vivo distant pollination with fresh pollen grains of Helianthus annuus L. or H. tuberosus L. Because the haploid proembryos obtained after pollination did not develop further (despite the presence of cellular endosperm), we implemented the technique of in vitro culture of an isolated embryo sacs (surrounded by endothelium) with parthenogenetic embryos on various, modified Murashige and Skoog media. During the in vitro culture, we observed the formation of callus tissue and, after subsequent cultures of calluses, 23 haploid L. sativa plants were regenerated. The haploid status of the regenerated plantlets was confirmed by estimation of the genome size by flow cytometry, chromosome counting in root tips, stomata cell size and by disturbances in pollen formation resulting from abnormal microsporogenesis. This paper contains the complete protocol for obtaining haploid plants of L. sativa. [ABSTRACT FROM AUTHOR]

Male sterile (MS) plants fail to produce functional anthers, pollen, or male gametes. This condition is useful in sunflower hybrid seed production. A MS form identified in an invasive population of H. annuus located in Las Malvinas was characterized by 37 morphological variables, six mitochondrial genes ( atpA, atp6, coxIII, orfb, orfB and orfC) associated with cytoplasmic male sterility (CMS), five SSR loci associated with ms9, ms10, and ms11 nuclear male sterility genes, and the HRGO2 marker associated with the Rf1 fertility restoration gene for CMS-PET1. Restoration of MS condition was evaluated through crosses with 13 sunflower inbred lines. Las Malvinas site was described regarding its population size, spatial distribution, and male sterility occurrence. Ten years after the first observation, population size was over 250,000 individuals. The adoption of this species as ornamental plant in home gardens has contributed its expansion. The low frequency of MS plants found in natural conditions (0.4 %) is concordant with a CMS form in combination with restoration genes. Wild individuals harboring the CMS-PET1 cytoplasm and individuals carrying a different mitochondrial genome were found. The Rf1 restorer gene for CMS-PET1 was not detected. The new type of male sterility was different than CMS-PET1 in pollen morphology; absence of orfC; and different response to crosses with inbred lines. Molecular differences were found with CMS-RES1 and CMS-MAX1. The male sterility could not be explained by differences in the cytoplasmic or nuclear regions studied. The new MS form will expand the genetic diversity available for commercial hybrid sunflower production. [ABSTRACT FROM AUTHOR]

Major improvement in sunflower breeding requires heterotic hybrids which can be achieved by tapping combining ability of F hybrids developed from crossing of two genetically diverse female lines with male testers. Six lines and three testers were crossed in a line × tester mating design, thus 18 F hybrids were developed for genetic analysis. The objectives of this research were (i) to determine combining ability of female and male lines through line × tester analysis for developing rewarding sunflower hybrids and (ii) to estimate additive and non-additive genes controlling phenological, seed yield and oil traits. The experiment was carried-out in randomized complete block design with four replications. The combined analysis revealed that genotypes performed differently over the years for all the characters with the exception of leaves per plant and 1,000-achene weight, however genotypes × year interactions were non-significant for all the traits except plant height. The non-significant interactions hence indicated that the genotypes were quite consistent in the performance over the years. The significant differences (p < 0.01) among the parents, crosses and parents versus crosses were also observed. The significant mean squares due to lines and testers both determine the general combining ability (GCA) revealed the prevalence of additive variances and additive genes influencing the traits. While the significance of lines × tester interactions indicated the importance of specific combining ability (SCA) of parents and demonstrated the importance dominance or non-additive variances and genes. The major role of dominant genes was found because the degree of dominance was greater than unity. These results indicated the preponderance of dominant gene action and the feasibility of hybrid sunflower development. GCA estimates revealed that female lines HO-I, T-4-0319 and PAC-0505 and testers PAC-0306 and PAC-64-A were good general combiners for early maturity, seed yield and oil content. SCA estimates determined the suitability of F hybrids and the hybrids T-4-0319 × SF-187, HO-I × PAC-0306, Peshawar-93 × SF-187 manifested higher positive SCA effects for seed yield and oil content while they recorded negative but desirable SCA effects for phenological traits and plant height. [ABSTRACT FROM AUTHOR]

Safflower ( Carthamus tinctorius L.) seeds contain a high proportion of tocopherols (>90 %) in the α-tocopherol form. A mutant with a high concentration of γ-tocopherol (>85 %) was identified in germplasm of wild safflower ( Carthamus oxyacanthus M. Bieb.) that showed strong introgression of C. tinctorius, which allowed selection of individuals of both species with high concentrations of either α- or γ-tocopherol. The trait is controlled by a γ-tocopherol methyltransferase (γ-TMT) locus. The objective of this research was to identify γ-TMT sequence mutations associated with the high γ-tocopherol trait. Full length genomic and cDNA sequences of the γ-TMT gene were obtained from plants of C. tinctorius and C. oxyacanthus with both tocopherol profiles. Sequences from high γ-tocopherol plants showed an 11 bp deletion in exon 6 of the γ-TMT gene that disrupted the reading frame and created a premature stop codon, resulting in a predicted protein with a drastically altered amino acid sequence downstream the frameshift site. The data suggested that the frameshift mutation was underlying the γ-TMT loss of function mutant allele that determines the high γ-tocopherol phenotype. The characterized sequence change of 11 bp deletion could be used directly as a functional marker for introgression of the high γ-tocopherol trait into elite safflower cultivars. [ABSTRACT FROM AUTHOR]

Combining ability is one of the most important information breeders use to identify superior inbred lines on the basis of their performance in hybrid combinations. The objectives of our study were (i) to quantify the importance of general combining ability (GCA) and specific combining ability (SCA) variances for seed yield, oil content and oil yield; and (ii) estimate GCA and SCA effects of seed yield, oil content and oil yield of inbred lines developed from advanced cycle pedigree breeding populations in sunflower. A total of 109 female S 3 cytoplasmic male sterile (CMS) lines from four bi-parental populations in advanced cycle pedigree breeding were crossed with two testers to form 218 testcross hybrids (TCHs). The TCHs were then evaluated in three environments. Variance component analysis results showed predominance of σ 2gca over σ 2sca for seed yield and oil yield indicating that superior TCHs can be identified based on positive and significant GCA effects of the female lines. For oil content σ 2sca was predominant over σ 2gca indicating that selecting for TCHs with high oil content would be best among line × tester combinations and not among female S 3CMS lines per se. The proportion of GCA and SCA effects in the best five TCHs in each breeding population also confirmed the predominance of GCA effects over SCA effects for seed yield and oil yield while for oil content both GCA and SCA effects appear to be important, with SCA effects having more influence than GCA. The best selection strategy would therefore be to capture the GCA in the early stages of inbreeding and then SCA for the few unique combinations when lines are almost fixed. [ABSTRACT FROM AUTHOR]

The genetic base of sunflower elite lines is very narrow, due to many years of selection and breeding. To broaden the genetic diversity of the cultivated sunflower, in 1995 73 wild sunflower populations were crossed with 3 cultivated lines (Testers), and 219 hybrid offspring's were evaluated in the field. GCA and SCA effects were computed suggesting for all traits a genetic potential for improvement through selection. Study of the hybrids revealed that the wild accessions bear different genetic abilities to combine with the testers for traits of morphological architecture, phenology and yield (seed weight and seed oil). The variance due to GCA and SCA showed that gene action was additive for days to flowering, branching and plant height. Genotypes derived from the same geographic origin may have either good or poor general combing ability. The correlation between GCA and per se genotype performance was positive for all traits except for seed oil content. This was the first attempt to evaluate wild-cultivated hybrids in sunflower on a large scale and will be the starting point for the management of hybrid Helianthus annuus populations for breeding. GCA and SCA estimations will facilitate the definition of strategies to manage and exploit the natural diversity for this crop. [ABSTRACT FROM AUTHOR]

Quantitative resistance to sunflower downy mildew was studied on inbred lines and hybrids not carrying efficient major gene resistance, in field trials in one to four sites over 3 years. Hybrids from factorial crosses showed that inheritance is under additive control and comparison with reactions of parental inbred lines gave narrow sense heritabilities of 27–57%. Analysis of a polymorphic recombinant inbred line population without efficient major gene resistance indicated that two highly significant Quantitative Trait Loci (QTL) explained 42% of variation in field reaction to downy mildew. These QTL were mapped on linkage groups 8 and 10, and do not appear related to any of the known major resistance gene clusters. Possible bases of this type of resistance and its use in breeding are discussed. [ABSTRACT FROM AUTHOR]

Downy mildew of sunflower, caused by the Oomycete, Plasmopara halstedii is at present controlled by major resistance genes. However, the pathogen has shown a considerable capacity for changes in virulence and these resistance genes are overcome only a few years after they have been introduced into new sunflower varieties. This paper presents research for quantitative, non-race-specific resistance independent of major genes. The reaction of cultivated sunflower genotypes to field attack by downy mildew was studied over 4 years in several environments and in the presence of the two most common races in France: 703 and 710. An experimental protocol with pre-emergence irrigation was developed, making it possible to observe downy mildew reaction whatever the weather conditions. Significant levels of partial resistance were observed in about 50 inbred sunflower lines among the 800 observed. These results suggest that it should be possible to select for non-race-specific downy mildew resistance and to include it in modern varieties. However, since this non-specific resistance is partial, it may be necessary to combine it with major gene resistance. Possible strategies are discussed to obtain durable resistance to downy mildew. [ABSTRACT FROM AUTHOR]

Heat stress (HS) is a major threat to current and future crop production. Crop improvement for HS tolerance is a major tool for dealing with HS and crop wild relatives (CWR) offer the greatest variability for such improvement. Here, we evaluated the HS tolerance on four reproductive traits in cultivated and wild sunflower and tested for local adaptation to HS within the wild germplasm. Three cultivars and 23 wild populations (from native and invasive ranges) were grown in field experiments for 2 years. Flowering heads were covered with white (control) and black (HS) paper bags during seven consecutive days. Additionally, biogeographic tools were used to test for local adaptation. HS increased air temperature on black bags compared to the white ones by 9.4 °C on average and strongly decreased seed number and yield with smaller effects on head diameter and seed weight. We found large variability for HS tolerance, mainly in seed number and yield. The invasive group outperformed the cultivated and native groups in both years. Biogeographic analysis reveals a clinal variation in HS tolerance, populations from wetter (but not from warmer) environments were more tolerant to HS. In addition, the positive correlation observed between reproductive traits under control conditions and HS tolerance helps to explain the better performance of the invasive populations. We proposed the use of invasive populations for future sunflower improvements in HS tolerance and the adoption of biogeographic tools in another CWR species to identify HS tolerant populations. [ABSTRACT FROM AUTHOR]

Pre-breeding and elite breeding are two steps in creating high yielding sunflower hybrids that differ in well established procedures and selection methods. However, a methodology that bridge efficient use of introgression lines as product of pre-breeding procedures and their crossing to elite inbreed lines, is not yet very well established. Therefore, the development of cost- and time-efficient methods for the determination of best parent heterosis and the use of best inbred lines in crosses with introgression lines for obtaining high-yielding and stable hybrids is highly desirable. In this regard, sixteen Cytoplasmic Male Sterile (CMS) inbred lines (A) derived from four heterogeneous interspecific lines originating from three annual: H. debilis silvestris (DEB-SIL), H. praecox runyoni (PRA-RUN), H. deserticola (DES) and one perennial H. resinosus (RES) wild species were evaluated. Seven agronomic traits were measured over a period of 2 years and 38 DNA loci were analysed, in order to compare four different methods for the estimation of best parent heterosis (BPH). New inbred lines were characterized by Principal Component Analysis (PCA) of morphological traits and Principal Coordinate Analysis (PCoA) of molecular marker data. Line × tester mating design was used to evaluate General Combining Ability (GCA), while Genetic Distance (GC) estimated by markers was evaluated as a predictor of BPH by Locally Weighted Sequential Smoothing (LOESS). Analysis of combining ability is one of the most important tools breeders use to identify superior inbred lines on the basis of their performance in hybrid combinations. Results obtained in this research show that PCA of morphological and PCoA of molecular marker data on parental lines are generally in agreement with GCA effects for examined traits. GD versus BPH relationships indicate that intermediate to high GD between parental lines was optimal for best heterotic effects of most traits. In this study, we show that the combination of the PCA of morphological data, PCoA of molecular marker data and GD between parental lines is fast and affordable, giving the most important information for parental choice of introgression and elite lines in sunflower breeding programs. [ABSTRACT FROM AUTHOR]