Fertility Restorer Lines Research Articles

Cryptic cytoplasmic male sterility-causing gene in the mitochondrial genome of common japonica rice.

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.

Estimation of heterosis on CGMS based pigeonpea

Thirty-five hybrids generated from seven cytoplasmic male sterile lines and five fertility restorer lines were tested for determining heterosis. All studied traits except pod length, number of seeds per pod, and leaf area showed significant variations between the parents indicating a sufficient variability amongthe parents (lines and testers). The mean sum of squares of the hybrids suggested high heterosis for studied traits except for test weight and number of branches per plant. The findings showed noteworthy and affirmative relative heterosis for eaj hybrid. Top three hybrids viz. CMS GT 1615 A × GTR 105 (28.34% and 38.97%), CMS GT 1615 A × GTR 18 (24.36% and 34.66%) and CMS GT 1615 × GTR 23 (22.23% and 32.35%) identified for seed yield and its contributing traits on the basis of standard heterosis against standard checks GTH 1 and GT 101, respectively. These can be exploited commercially for heterosis breeding in pigeonpea.

Understanding the role of P-type ATPases in regulating pollen fertility and development in pigeonpea.

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.

Pollination Potentiality of Honey Bee (Apis cerana Fab.) in Sunflower Hybrid (DRSH-1) Seed Production

The study was conducted at Main Agricultural Research Station, UAS, Raichur during rabi 2020-21 to utilize honey bees in sunflower hybrid seed production. Totally, thirty species of floral visitors were recorded on parental lines of sunflower hybrid (DRSH-1), among them 15 were hymenopterans, 7 lepidopterans, 5 coleopterans and 3 dipterans. Apis cerana was predominant pollinator (17.91±6.72 bees/ 5 capitula/ 5 min) on CMS parental line (ARM-243), followed by A. dorsata and least was A. florea. The peak foraging activity of A. dorsata was recorded at 0900-1000 hr with 24 bees, A. cerana recorded two peak foraging activity, one at 1100-1200 hr (29 bees) and another at 1600-1700 hr (18 bees) and A. florea recorded at 1000-1100 hr (10 bees). The maximum Shannon-Wiener index of diversity (H=1.32) of floral visitors on CMS line under open condition was recorded at 0800-0900 hr of the day and least (H=0.84) was at 1600-1700 hr. In case of fertility restorer line (6D-1) maximum Shannon-Wiener index was recorded at 1600-1700 hr (1.24). A. cerana under caged condition (three colonies per acre) without pollen load on CMS line were recorded highest mean number of nectar foragers (65±22.60 bees), followed by A. dorsata, A. cerana and A. florea foragers from natural colonies in open pollination condition. Whereas, highest mean number of nectar foragers (42.25±23.59) with pollen load in A. cerana under caged condition (three colonies per acre) were recorded, followed by A. dorsata, A. cerana and A. florea. Nectar foragers with pollen load on CMS line play an important role in transfer of pollen grains from restorer line to CMS line and carry out effective pollination. A. florea with and without pollen load spent more foraging duration (13.17 and 25.20 sec/capitulum respectively) on CMS line, followed by A. cerana and least in case of A. dorsata in open pollination. Bees without pollen load spent significantly greater nectar foraging duration as compared with bees with pollen load, both in caged and open pollination situations. Significantly highest seed yield per hectare (839.53 kg), per cent filled seeds (95.80 %), test weight (5.41 g), volume weight (46.41 g/100 ml), kernel percentage (66.09 %), highest kernel to husk ratio (1.94) and highest seed quality and associated parameters were recorded in hand + open pollinated plots, followed by the A. cerana @ 3 colonies per acre treated plots, hand pollination, open pollination and least seed quality parameters were recorded in control treatment.

Refinement of Rf1-gene localization and development of the new molecular markers for fertility restoration in sunflower.

Ability to restore male fertility is important trait for sunflower breeding. The most commonly used fertility restoration gene in the production of sunflower hybrids is Rf1. The localization of Rf1 on the linkage group 13 has been previously shown, however, its exact position, its sequence and molecular mechanism for fertility restoration remain unknown. Therefore, several markers linked to Rf1 gene, commonly used for MAS, don't always allow to identify the genotype of plants. For this reason, the search for new markers and precise localization of the Rf1 gene is an urgent task. Based on previously identified single nucleotide polymorphisms (SNPs) at LG13, significantly associated with the ability to restore male fertility, two markers have been developed that have performed well after careful evaluation. These markers, together with other Rf1 markers, were applied for genotyping 72 diversity panel accessions and 291 individuals of F2 segregating population, obtained from crossing the cytoplasmic male sterility (CMS) AHO33 and restorer RT085HO lines. The analysis revealed no recombinants between Rf1 gene and SRF833 marker, the distance between Rf1 and SRF122 marker was 1.0cM. Data obtained made it possible to specify the localization of the Rf1 gene and reduce the list of candidate genes to the 3 closely linked PPR-genes spanning a total of 59 Kb. However, it cannot be ruled out that analysis of the candidate region in the genome of fertility restorer lines can reveal new candidate genes in this locus that are absent in the cytoplasmic male sterility maintainer reference sequence.

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).

Genomic survey of high-throughput RNA-Seq data implicates involvement of long intergenic non-coding RNAs (lincRNAs) in cytoplasmic male-sterility and fertility restoration in pigeon pea.

Long-intergenic non-coding RNAs (lincRNAs) originate from intergenic regions and have no coding potential. LincRNAs have emerged as key players in the regulation of various biological processes in plant development. Cytoplasmic male-sterility (CMS) in association with restorer-of-fertility (Rf) systems makes it a highly reliable tool for exploring heterosis for producing commercial hybrid seeds. To date, there have been no reports of lincRNAs during pollen development in CMS and fertility restorer lines in pigeon pea. Identification of lincRNAs in the floral buds of cytoplasmic male-sterile (AKCMS11) and fertility restorer (AKPR303) pigeon pea lines. We employed a computational approach to identify lincRNAs in the floral buds of cytoplasmic male-sterile (AKCMS11) and fertility restorer (AKPR303) pigeon pea lines using RNA-Seq data. We predicted a total of 2145 potential lincRNAs of which 966 were observed to be differentially expressed between the sterile and fertile pollen. We identified, 927 cis-regulated and 383 trans-regulated target genes of the lincRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the target genes revealed that these genes were specifically enriched in pathways like pollen and pollen tube development, oxidative phosphorylation, etc. We detected 23 lincRNAs that were co-expressed with 17 pollen-related genes with known functions. Fifty-nine lincRNAs were predicted to be endogenous target mimics (eTMs) for 25 miRNAs, and found to be associated with pollen development. The, lincRNA regulatory networks revealed that different lincRNA-miRNA-mRNA networks might be associated with CMS and fertility restoration. Thus, this study provides valuable information by highlighting the functions of lincRNAs as regulators during pollen development in pigeon pea and utilization in hybrid seed production.

Identification and characterization of a fertility restorer line in Bhut Jolokia

Identification and characterization of a fertility restorer line in Bhut Jolokia

Population structure and genetic diversity of a germplasm for hybrid breeding in rye (Secale cereale L.) using high-density DArTseq-based silicoDArT and SNP markers

Investigating genetic structure and diversity is crucial for the rye hybrid breeding strategy, leading to improved plant productivity and adaptation. The present study elucidated the population structure and genetic diversity of 188 rye accessions, comprising 94 pollen fertility restoration lines (RF) and 94 cytoplasmic male-sterile (CMS) lines with Pampa sterilizing cytoplasm using SNP and silicoDArT markers from the diversity array technology (DArT)-based sequencing platform (DArTseq). Expected heterozygosity (He) and Shanon’s diversity (I) indexes varied slightly between marker systems and groups of germplasms (He = 0.34, I = 0.51 for RF and CMS lines genotyped using SNPs; He = 0.31, I = 0.48, and He = 0.35, I = 0.53 for RF and CMS using silicoDArTs, respectively). ANOVA indicated moderate variation (7%) between RF and CMS breeding materials. The same parameter varied when chromosome-assigned markers were used and ranged from 5.8% for 5R to 7.4% for 4R. However, when silicoDArT markers were applied, the respective values varied from 6.4% (1R) to 8.2% (3R and 4R). The model-based (Bayesian) population structure analysis based on the total marker pool identified two major subpopulations for the studied rye germplasm. The first one (P1) encompasses 93 RF accessions, and the second one (P2) encompasses 94 CMS and one RF accession. However, a similar analysis related to markers assigned to selected chromosomes failed to put plant materials into any of the populations in the same way as the total marker pool. Furthermore, the differences in grouping depended on marker types used for analysis.

Комплексный подход ускоренной селекции F1-гибридов ярового рапса на основе ЦМС

The breeding of F1-hybrids of spring rapeseed is the most effective approach to solving the problem of increasing rapeseed yield, as well as provides a more effective return on investment in breeding. Accelerated breeding of heterosis hybrids is provided by a complex of modern biotechnological and molecular-genetic methods. Cytoplasmic male sterility (CMS) is used to control hybridization in the industrial production of F1-hybrid seeds and for additional copyright protection. Molecular-genetic markers allow rapid determination of the type of CMC and differentiation between the lines of fertility restorers and sterility maintainers. By combining double haploid production and indoor planting for the development of maternal lines, the intensity of the breeding process can be increased by 2–3 times. In this research, we have genotyped a germplasm collection of foreign spring rape using the molecular marker ORF138 for the Ogura cytoplasm and divided the collection into two groups according to the presence or absence of the marker. Subsequently, doubled haploid lines (DHL) produced from a sample with Ogura cytoplasm were used as fertility restorer lines, and DHL from hybrids with a non-Ogura cytoplasm were used to develop female male sterile lines based on Ogura-CMC. The doubled haploid lines were evaluated in the field for the main economically valuable traits, and 30 fertility restorer lines and four male-sterile lines were hybridized to assess their combining ability. As a result, four DH lines J30, J26, J24 and Ki1ms were selected for future breeding of heterosis hybrids basedon Ogura-CMC and five promising spring rapeseed hybrids were identified according to the complex of traits and properties.

Principal component analysis and genetic divergence studies for yield and quality-related attributes of rice restorer lines

A study on genetic diversity and principal component analysis (PCA) in a set of 90 fertility restorer lines of rice was conducted to identify potential parents for producing high-yielding hybrids. The D2 statistics uncovered the maximum inter-cluster distance between the clusters having different genotypes. The genotypes PS 2, PRR 828, JR-4322-2, and JR-4322-2 belonging to these diversified gene pools may produce heterotic hybrid combinations involving the most suitable parents mentioned above. The PCA reduces dimensional complexity into nine principle axes with PC1 account maximum variable genotypes, namely, JR-1009, ANP-553, JR-1062-1, JR-1103-1, JR-1023-1, JR-1054-4, IR09N 261, JR-1008, NPT-3806, and JR-81. Considering the magnitude of genetic distance, the per cent contribution of traits towards divergence (fertile spikelet/plant and total spikelet/plant) along with the highest cluster means of these traits reflected by the genotypes belonging to clusters, IX and X. The most quality attributes were included in PC4 and PC5 containing genotypes NPT 10, R710, and JR1301. The diversified gene pool and intensive selection designed for varietal development followed by molecular characterization give a precise idea about the upcoming utilization of existing genetic diversity.

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

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

Diagnostic value of <i>Rf1</i> gene molecular markers in sunflower

Background. Modern production of sunflower seeds is currently based on the cultivation of high-yielding heterotic F1 hybrids from crossbreeding of lines with cytoplasmic male sterility (CMS) of PET1-type and fertility restorer lines. The paternal parent serves as a donor of the nuclear Rf1 gene functional allele, which is responsible for pollen fertility restoration in F1 plants. The detection of carriers of the Rf1 locus recessive and dominant alleles using diagnostic molecular markers accelerates breeding of female and male parental lines for creating hybrids.Materials and methods. The material for the study included 75 lines of various origins from the VIR sunflower genetic collection as well as hybrids from crosses of VIR 116A sterile line with fertile lines differing in the type of cytoplasm (fertile or sterile) and the presence of molecular markers, most of which were linked to the Rf1 locus. For marker validation, two different approaches were used: either by analyzing associations between the ability of a line to restore pollen fertility and the presence of molecular markers in its genotype, or by estimating recombination frequency between the Rf1 locus and marker loci in four segregating hybrid populations.Results. According to the obtained results, no markers demonstrated 100% efficiency in the analysis of the sample of genotypes. The ORS511 marker was most frequently observed among the lines presumably carrying the dominant allele Rf1. Pollen fertility of F1 hybrids from interline crossings was 89-99%. The segregation for fertility/sterility in F2 fitted the theoretical ratio of 3:1 expected in case of the monogenic control of the trait. The markers HRG01, HRG02 and ORS511 were linked to the fertility restoration trait, with recombination rates between Rf1 locus and markers varying in different cross combinations. The analysis of VIR 116А × VIR 740 and VIR 116А × RIL 130 hybrids showed that among the marker loci studied, the ORS511 was closest to the Rf1 locus Rf1 (recombination frequency of 2.2 and 3.3%, respectively). The recombination rate between the Rf1 and ORS511 loci equaled 7.5% in the cross VIR 116А × VIR 210 and 8.9% in VIR 116 × VIR 195.Conclusion. The markers ORS511, HRG01 and HRG02 are the most efficient for the identification of alleles of the Rf1 gene and for the marker assisted selection in hybrid populations produced involving sunflower lines from the VIR collection.

A comprehensive approach to modern aspects in sunflower selection

According to scientists of the NAAS network, the genetic potential of sunflower hybrids of Ukrainian selection is used in production by no more than 30%. Due to the reduction of the rotation period in crop rotation, crop losses from diseases increased from 10-15% to 35%, and in some favorable years for the development of diseases, losses only from rot are 70% or more. Phytopathological studies were performed on a stationary artificial infectious background of the Institute of Oilseeds NAAS during 2017-2020. We studied the biological resistance to major fungal diseases of new promising lines and hybrids of sunflower breeding institutions of NAAS (Institute of Plant Breeding Yur`eva). Synthetic artificial infectious background was formed during 16 years with forced introduction of infection during sowing of selection genotypes of sunflower. To assess the resistance of sunflower varieties to dry rot and embelization, the infectious background began to be created in 2012. Infectious material was developed in the immunity laboratory of the Institute of Oilseeds of NAAS by increasing pure cultures by the method of V.Y. White Assessment of resistance of sunflower to a number of diseases in the field was carried out according to the method of VP Mistletoe. Sowing was carried out with a seeding rate of 55 thousand / ha. According to the results of field and laboratory studies, sunflower lines and hybrids were identified, which were characterized by the duration of the growing season of the phase "seedlings-physiological maturity" in hybrids 95-110 days, in lines 85-105 days. The selected linear samples had a yield higher than the linear standard (ZL42 with a yield of 0.97 t/ha), and the studied sterile lines had a yield from 1.76 (+0.79) to 1.96 (+0.99) t/ha. Pollen fertility restorer lines had a yield at the level of 0.36 (-0.05) - 0.55 (+0.14) t/ha, when forming the yield of the control line ZL260V - 0.41 t / ha. Created hybrids based on these lines (parental components) formed a yield: Firstborn 3.34 t / ha, Tour - 3.80 t / ha, which is higher than the control hybrid Darius from 0.4 to 0.86 t / ha, respectively. The weight of 1000 seeds of sterile analogues varied in the range of 55.2 g - 56.4 g. In the lines of pollen fertility restorers in the range of 29.4-35.0 g. In the presented hybrids, the average weight of 1000 seeds was in the range of 57.0-60,1 g, while the standard Darius formed a mass of 1000 seeds within 49.0 g. The selected samples had a high percentage of fat accumulation in the seeds. This figure ranged from 49.76 (ZL96A) to 51.12% (ZL72A) among sterile analogues, while the standard sample ZL42A had an oil content of 49.26%. New selected sunflower hybrids were marked by fat content in seeds at the level of 51.88 (Prize) and 52.12% (Firstborn), while the hybrid - standard Darius also had a fairly high level of oil content, namely 48.13%. The presented lines and their hybrid combinations for the study period (2017-2020) combined relatively high resistance to powdery mildew, dry rot, embelisation and high economic performance. According to the results of a comprehensive assessment, a number of hybrids were identified. Among them are Tour, Prize and Firstborn. With such indicators, the presented hybrids are able to compete with dignity in the sunflower seed market.

Genetic diversity analysis of fertility restorer and CMS lines of wheat (Triticum aestivum L.) by using SSR markers

Genetic diversity of 92 fertility restorer and four CMS lines were analyzed using 38 polymorphic SSR markers. A total of 102 alleles were detected which are ranged from 2 to 4 with an average of 2.68 alleles per locus. Polymorphism information content (PIC) of SSR markers ranged from 0.22 to 0.81 with an average of 0.53 per locus. The cluster analysis based on 38 polymorphic markers produced seven main clusters with 0.36 to 0.97 similarity coefficient. The highest similarity was observed between the restorer lines 919R and 920R and three restorer lines 907R, 923R, and 922R were found to be most distinct from the rest. Analysis of molecular variance revealed within and among populations variance of 97 and 3 per cent, respectively. Cluster analysis revealed the genetically distinct restorer and CMS lines that would serve as diverse parents to be exploited in future breeding programme to broaden the genetic base of wheat cultivars. Key wordsGenetic diversity, Restorer line, CMS line, SSR markers, Triticum aestivum.

Genetics Analysis of Rf Gene in Chilli Pepper (Capsicum annuum L.)

The inability to develop functional pollen is caused by cytoplasmic male sterility (CMS), a maternally inherited trait. Restorer-of-fertility (Rf), a nuclear gene, could cause normal pollen production in CMS plants, resulting in fertility in the plant. This paper aimed to study the inheritance of restoration of fertility traits in both Sweet pepper and Hot pepper. The study was conducted in the Indian agricultural research institute, Katrain regional station, India. Genetic analysis of fertility restoration was performed on the progeny of chilli and sweet pepper. KTCA 5 (cytoplasmic-genetic male sterile line-Sweet pepper), KTCA 10 (cytoplasmic-genetic male sterile line-Sweet pepper. F2 segregation population and back cross BC1 population obtained from an F1 hybrid between KTCR 15 (a fertility restorer line). The fertility of the test-crossed lines was assessed under open field conditions using pollen related criteria. The fertility restoration trait segregated in 3:1 and 1:1 F2 segregation populations and backcrossed BC1 populations respectively in both Sweet Pepper and Hot pepper backgrounds. This indicates single dominant gene inheritance of the Rfgene. There is no effect of CMS background on the restoration trait inheritance.

Productivity and quality of experimental sunflower hybrids in climatically different years

Abstract. The main purpose of sunflower breeding requires the developing of high-yielding hybrid varieties with broad ecological plasticity that would guarantee the stability of the yield and the quality of the production from them. This investigation involved 10 experimental F1 hybrid combinations developed with the participation of double haploid fertility restorer lines (DHR) obtained through the method of gamma-induced parthenogenesis in combination with embryo culture. The aim of the investigation was to study the productivity and quality of the seeds from the new experimental sunflower hybrid varieties with a view of their future use in practice. The experimental work included years 2014 and 2015, which were significantly different with regard to the climatic conditions. The experiments were carried out in the experimental field and the laboratory of the Technical University in Varna. The hybrid combinations were assessed according to the main parameters of sunflower productivity, namely seed yield (kg/ha) and oil yield (kg/ha), as well as according to the main quality parameter of sunflower seeds – oil percent in seed. Under the conditions of this investigation, the analysis of the results showed that the genotype potential of the hybrids was determining for the seed and oil yield; a relatively high effect of the year conditions was also established for the parameter oil yield. The percent of oil in seeds was determined on the basis of the genotype, and the effect of the year was considerably lower. Summing up the results from the testing of the experimental hybrids, it can be pointed out that three of the studied hybrid combinations (3607A х 112DHR, 3607A х 123DHR and 3607A х 167DHR) realized good production potential under variable agro-meteorological conditions and can find future realization in practice.

COMBINING ABILITY OF GRAIN SORGHUM INBRED LINES GROWN DURING OFF-SEASON

ABSTRACT The expansion of sorghum as a succession crop, after soybean, has demanded the development of new inbred lines by the breeding programs. The first step in the selection process consists of evaluating the performance per se of the inbred lines or of their hybrid combination. The purpose of this study was to determine the combining ability of sorghum inbred lines under different environment conditions of the crop production areas. The trials were carried out in the second season of 2017, under no-tillage system, in four environments, Rio Verde, Sete Lagoas, Teresina and Sinop. Thirty hybrids, resulting from the crosses of six fertility restoration lines (R) with five male-sterile lines (A) were evaluated. A randomized complete block design with three replicates was used in all experiments. The characteristics evaluated were flowering, plant height and grain yield. The environment significantly influenced the estimates of general and specific combining ability, which suggests that both effects, additive and dominant, are important in the control of these characters. The restoring lines GI.1 and G1.2 contributed to increasing the grain yield of their hybrids by over 650 kg.ha-1. Among the male-sterile lines, the best for grain yield were GII. 1 and GII.4 with contribution above 450 kg.ha-1 in the hybrids in which they participate. The hybrid combinations GI.5xGII.3 and GI.1xGII.2 stood out with potential to obtain high grain yield, associating positive aspects of the other characteristics.

Fertility restoration of Chinese wild rice-type cytoplasmic male sterility by CRISPR/Cas9-mediated genome editing of nuclear-encoded RETROGRADE-REGULATED MALE STERILITY.

Cytoplasmic male sterility (CMS) is a trait that produces nonfunctional pollen caused by the interaction between mitochondrial and nuclear genes. In Chinese-wild (CW) type CMS, CWA, in rice (Oryza sativa L.), its mitochondria enhance the expression of the nuclear gene RETROGRADE-REGULATED MALE STERILITY (RMS), which causes pollen abortion. Fertility is recovered when its expression decreases in a restorer line, CWR. The expression of RMS is controlled by the single nucleotide polymorphism (SNP) located in the promoter region 2,286 bp upstream of the start codon of RMS. However, another gene, PPR2, which encodes pentatricopeptide repeat-domain containing protein, is predicted in the reverse strand of this region and a premature stop codon is created in CWR by the SNP. To prove RMS is directly involved in restoring fertility of CW-CMS, we introduced mutations into RMS and PPR2 using CRISPR/Cas9. Fertility was recovered in the genome-edited CMS plants with reduced expression of RMS and unaltered expression of PPR2, when the mutation was introduced in the promoter regions of RMS within or outside the coding sequence (CDS) of PPR2. Fertility restoration was not obtained when the mutation was introduced within the CDS of RMS. Our results demonstrated that PPR2 is not responsible for fertility restoration, and fertility was recovered by reduced expression of RMS, providing us with a new artificial fertility restorer line for agronomical use.

General and specific combining ability in dual purpose sorghum [Sorghum bicolor (L.) Moench

The aim of this study was to evaluate the general combining ability of sorghum lines and the specific combining ability of the hybrids for yield and its related traits. Three fertility restorer lines, ten male-sterile lines, and their hybrids from line x tester mating design crosses were evaluated in RBD with three replications in four environments. Analysis was performed using the Griffing’s method of diallel (1956) for individual environments and Daljit Singh (1979) for over the environments. There was a significant effect of GCA and SCA for most of the traits evaluated, indicating the participation of additive or domi­nant genes in inheritance. The restorer line SPV 1822 and five male sterile lines ICSA 29003, ICSA 29004, ICSA 29011, ICSA 29014 and ICSA 29016 show potential for use as parents in sorghum breeding programs. Crosses ICSA 29004 × SPV 1822 and ICSA 29012 × SPV 1822 were identified for multilocation testing.