Doubled haploid (DH) techniques remain valuable tools for wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) genetic improvement, and DH populations are used extensively in breeding and research endeavors. Several techniques are available for DH production in wheat and barley. Here, we describe two simple, robust anther culture methods used to produce more than 15,000 DH wheat and barley lines annually in Australia.

Plant cell, tissue, and organ cultures (PCTOC) have been used as experimental systems in basic research, allowing gene function demonstration through gene overexpression or repression and investigating the processes involved in embryogenesis and organogenesis or those related to the potential production of secondary metabolites, among others. On the other hand, PCTOC has also been applied at the commercial level for the vegetative multiplication (micropropagation) of diverse plant species, mainly ornamentals but also horticultural crops such as potato or fruit and tree species, and to produce high-quality disease-free plants. Moreover, PCTOC protocols are important auxiliary systems in crop breeding crops to generate pure lines (homozygous) to produce hybrids for the obtention of polyploid plants with higher yields or better performance. PCTOC has been utilized to preserve and conserve the germplasm of different crops or threatened species. Plant genetic improvement through genetic engineering and genome editing has been only possible thanks to the establishment of efficient in vitro plant regeneration protocols. Different companies currently focus on commercializing plant secondary metabolites with interesting biological activities using in vitro PCTOC. The impact of omics on PCTOC is discussed.

Interspecific F1 hybrids between Asian (Oryza sativa) and African rice (Oryza glaberrima) exhibit severe sterility caused by the accumulation of hybrid sterility genes/loci at 15 or more loci. The mechanisms underlying the hybrid sterility genes are largely unknown; however, a few genes associated with the killer-protector system, which is the system most frequently associated with hybrid sterility genes, have been identified. We previously produced fertile plants as tetraploids derived from diploid interspecific F1 hybrids through anther culture; therefore, it was suggested that hybrid sterility could be overcome following tetraploidization. We investigated whether tetraploid interspecific plants produced by crossing are fertile and tested the involvement of hybrid sterility genes in the process. Fertile tetraploid interspecific F1 hybrid plants were obtained by crossing 2 tetraploids of O. sativa and O. glaberrima. To elucidate the relationships between pollen fertility and the hybrid sterility loci in the tetraploid F1 microspores, we performed genetic analyses of the tetraploid F2 hybrids and diploid plants obtained from the microspores of tetraploid interspecific hybrids by anther culture. The result suggested that the tetraploid interspecific hybrids overcame pollen and seed infertility based on the proportion of loci with the killer-protector system present in the tetraploids. The heterozygous hybrid sterility loci with the killer-protector system in the tetraploid segregate the homozygous killed allele (16.7-21.4%), with more than three-quarters of the gametes surviving. We theoretically and experimentally demonstrated that fertile rice progenies can be grown from tetraploid interspecific hybrids.

Doubled haploid technology is a valuable biotechnological approach in plant breeding that enables one to quickly create new varieties through the single-stage production of homozygous lines. The aim of this study was to assess the indicators of in vitro androgenesis in the anther culture of the initial breeding material of varieties and combinations of F1 and F2 and to identify promising accessions with good responsiveness. For that purpose, the plant material that proved promising for the breeding programs of Siberian Research Institute of Plant Production and Breeding (SibRIPPСоздание удвоенных гаплоидов – ценный биотехнологический подход в селекции растений, по- зволяющий ускоренно создавать новые сорта за счет одноэтапного получения гомозиготных линий. Целью настоящего исследования было проведение оценки показателей андрогенеза in vitro в культуре пыльников исходного селекционного материала сортов и комбинаций F1 и F2 и выявление перспективных образцов с хо- рошей отзывчивостью. В работе использован растительный материал, перспективный для селекционных про- грамм Сибирского научно-исследовательского института растениеводства и селекции – филиала ИЦиГ СО РАН. Десять сортов мягкой пшеницы и гибриды F1 и F2 девяти комбинаций скрещивания оценивали по основным параметрам андрогенеза in vitro: числу новообразований, числу альбиносов и зеленых растений-регенерантов и всех регенерировавших растений. Индукцию андрогенеза in vitro проводили в культуре пыльников на пита- тельной среде Chu (N6), в качестве регулятора роста использовали 1 мг/л 2.4-Д. У изучаемых образцов обна- ружен различный ответ на индукцию андрогенеза in vitro. Отмечен максимальный выход новообразований у гибридов F2 Новосибирская 15 × Лютесценс ШТ-335. Наибольшее количество зеленых растений-регенерантов обнаружено у F1 Новосибирская 15 × Лютесценс ШТ-335. По результатам дисперсионного анализа установлено достоверное ( p < 0.01) влияние генотипа на изучаемые признаки. Выявлены сорта с хорошей отзывчивостью в культуре пыльников (Новосибирская 15) и с отсутствием отзывчивости к андрогенезу in vitro (Новосибир- ская 31). Сорт Новосибирская 16 характеризовался низкой регенерационной способностью новообразова- ний. Среди гибридов значительный гетерозисный эффект отмечен по признаку «число новообразований на 100 пыльников» в комбинациях Новосибирская 15 × Лютесценс ШТ-335, Новосибирская 15 × Лютесценс 111/09, Загора Новосибирская × Обская 2. Сорт Новосибирская 15 рекомендован к включению в скрещивания как сорт, обеспечивающий высокую отзывчивость в андрогенезе in vitro гибридов. Применение технологии удвоенных гаплоидов позволило быстро создать DH-линии на основе изучаемого материала.

BACKGROUND: The development of the plant in vitro techniques has brought about the variation identified in regenerants known as somaclonal or tissue culture-induced variation (TCIV). S-adenosyl-L-methionine (SAM), glutathione (GSH), low methylated pectins (LMP), and Cu(II) ions may be implicated in green plant regeneration efficiency (GPRE) and TCIV, according to studies in barley (Hordeum vulgare L.) and partially in triticale (× Triticosecale spp. Wittmack ex A. Camus 1927). Using structural equation models (SEM), these metabolites have been connected to the metabolic pathways (Krebs and Yang cycles, glycolysis, transsulfuration), but not for triticale. Using metabolomic and (epi)genetic data, the study sought to develop a triticale regeneration efficiency statistical model. The culture\'s induction medium was supplemented with various quantities of Cu(II) and Ag(I) ions for regeneration. The period of plant regeneration has also changed. The donor plant, anther-derived regenerants, and metAFLP were utilized to analyze TCIV concerning DNA in symmetric (CG, CHG) and asymmetric (CHH) sequence contexts. Attenuated Total Reflectance-Fourier Transfer Infrared (ATR-FTIR) spectroscopy was used to gather the metabolomic information on LMP, SAM, and GSH. To frame the data, a structural equation model was employed.
RESULTS: According to metAFLP analysis, the average sequence change in the CHH context was 8.65%, and 0.58% was de novo methylation. Absorbances of FTIR spectra in regions specific for LMP, SAM, and GSH were used as variables values introduced to the SEM model. The average number of green regenerants per 100 plated anthers was 2.55.
CONCLUSIONS: The amounts of pectin demethylation, SAM, de novo methylation, and GSH are connected in the model to explain GPRE. By altering the concentration of Cu(II) ions in the medium, which influences the amount of pectin, triticale\'s GPRE can be increased.

BACKGROUND: Traditional breeding methods have long been employed worldwide for the evaluation and development of pepper cultivars. However, these methods necessitate multiple generations of screening, line development, evaluation, recognition, and crossing to obtain highly homozygous lines. In contrast, in vitro anther-derived microspore culture represents a rapid method to generate homozygous lines within a single generation. In the present study, we have optimized a protocol for microspore embryogenesis from anther cultures of pepper hybrids Orobelle and Bomby.
RESULTS: We achieved early and successful embryo formation from both genotypes by subjecting the buds to a cold pretreatment at 4 °C for 4 days. Our optimized culture medium, comprised of MS medium supplemented with 4 mg/L NAA, 1 mg/L BAP, 0.25% activated charcoal, 2.6 g/L gelrite, 30 g/L sucrose, and 15 mg/L silver nitrate, exhibited the highest efficiency in embryo formation (1.85% and 1.46%) for Orobelle and Bomby, respectively. Furthermore, successful plant regeneration from the anther derived microspore embryos was accomplished using half-strength MS medium fortified with 2% sucrose and 0.1 mg/L 6-benzylaminopurine (BA), solidified with 2.6 g/L gelrite. The ploidy status of the microspore-derived plantlets was analyzed using flow cytometry technique. Notably, the haploid plants exhibited distinct characteristics such as reduced plant height, leaf length, leaf width, and shorter internode length when compared to their diploid counterparts derived from seeds.
CONCLUSIONS: Our findings highlight the potential of anther culture and microspore embryogenesis as an advanced method for accelerating pepper breeding programs, enabling the rapid production of superior homozygous lines.

Anther culture (AC) is a valuable technique in rice breeding. However, the genetic mechanisms underlying anther culturability remain elusive, which has hindered its widespread adoption in rice breeding programs. During AC, microspores carrying favorable alleles for AC are selectively regenerated, leading to segregation distortion (SD) of chromosomal regions linked to these alleles in the doubled haploid (DH) population. Using the AC method, a DH population was generated from the japonica hybrid rice Shenyou 26. A genetic map consisting of 470 SNPs was constructed using this DH population, and SD analysis was performed at both the single- and two-locus levels to dissect the genetic basis underlying anther culturability. Five segregation distortion loci (SDLs) potentially linked to anther culturability were identified. Among these, SDL5 exhibited an overrepresentation of alleles from the female parent, while SDL1.1, SDL1.2, SDL2, and SDL7 displayed an overrepresentation of alleles from the male parent. Furthermore, six pairs of epistatic interactions (EPIs) that influenced two-locus SDs in the DH population were discovered. A cluster of genetic loci, associated with EPI-1, EPI-3, EPI-4, and EPI-5, overlapped with SDL1.1, indicating that the SDL1.1 locus may play a role in regulating anther culturability via both additive and epistatic mechanisms. These findings provide valuable insights into the genetic control of anther culturability in rice and lay the foundation for future research focused on identifying the causal genes associated with anther culturability.

In cereal breeding, in vitro androgenesis methods are frequently applied to achieve doubled haploid (DH) plants. The aim of this study was to determine the effects of genotype (three registered varieties and eight F1 crossing combinations) and induction medium (W14mf and P4mf) on anther cultures (ACs) of triticale (×Triticosecale Wittmack). Androgenesis was induced in the treatment of each tested genotype, and the genotype significantly influenced the efficiency of AC, including in embryo-like structures (ELSs), albinos, green plantlets, and transplanted plantlets. The utilized medium also had a significant effect on the number of ELSs, albinos, and transplanted plantlets. Both media were suitable for AC in triticale DH plant production. The efficiency of AC was higher when using the P4mf medium (103.7 ELS/100 anthers, 19.7 green plantlets/100 anthers) than when using the W14mf medium (90.0 ELS/100 anthers, 17.0 green plantlets/100 anthers). However, the green plantlet regeneration efficiency of microspore-derived structures was 18.0% when using the W14mf medium, while this value was 15.9% in the case of ELSs induced with the P4mf medium. After nursery seed evaluation and propagation (DH1), the genetic homogeneity of the offspring generation (DH2) was tested using a molecular genetic method. Most of the tested DH lines showed homogeneity and were progressed into a breeding program after agronomic selection. Some DH lines showed inhomogeneity, which could be explained by the outcross inclination of triticale. We would like to call breeders\' attention to the outcross character of triticale and emphasize the vigilant propagation and maintenance of the triticale DH lines in breeding programs. Due to the outcross nature of triticale, even in self-pollinated genotypes, breeders should focus on careful maintenance, along with isolation in the case of line propagations, in triticale breeding programs.

Rice blast caused by Magnaporthe oryzae is one of the most serious rice diseases worldwide. The early indica rice thermosensitive genic male sterile (TGMS) line HD9802S has the characteristics of stable fertility, reproducibility, a high outcrossing rate, excellent rice quality, and strong combining ability. However, this line exhibits poor blast resistance and is highly susceptible to leaf and neck blasts. In this study, backcross introduction, molecular marker-assisted selection, gene chipping, anther culture, and resistance identification in the field were used to introduce the broad-spectrum blast-resistance gene R6 into HD9802S to improve its rice blast resistance. Six induction media were prepared by varying the content of each component in the culture medium. Murashige and Skoog\'s medium with 3 mg/L 2,4-dichlorophenoxyacetic acid, 2 mg/L 1-naphthaleneacetic acid, and 1 mg/L kinetin and N6 medium with 800 mg/L casein hydrolysate, 600 mg/L proline, and 500 mg/L glutamine could improve the callus induction rate and have a higher green seedling rate and a lower white seedling rate. Compared to HD9802S, two doubled haploid lines containing R6 with stable fertility showed significantly enhanced resistance to rice blast and no significant difference in spikelet number per panicle, 1000-grain weight, or grain shape. Our findings highlight a rapid and effective method for improving rice blast resistance in TGMS lines.

Catharanthus roseus L. (G.) Don is the most widely studied plant because of its high pharmacological value. In vitro culture uses various plant parts such as leaves, nodes, internodes and roots for inducing callus and subsequent plant regeneration in C. roseus. However, till now, little work has been conducted on anther tissue using plant tissue culture techniques. Therefore, the aim of this work is to establish a protocol for in vitro induction of callus by utilizing anthers as explants in MS (Murashige and Skoog) medium fortified with different concentrations and combinations of PGRs. The best callusing medium contains high α-naphthalene acetic acid (NAA) and low kinetin (Kn) concentrations showing a callusing frequency of 86.6%. SEM-EDX analysis was carried out to compare the elemental distribution on the surfaces of anther and anther-derived calli, and the two were noted to be nearly identical in their elemental composition. Gas chromatography-mass spectrometry (GC-MS) analysis of methanol extracts of anther and anther-derived calli was conducted, which revealed the presence of a wide range of phytocompounds. Some of them are ajmalicine, vindolinine, coronaridine, squalene, pleiocarpamine, stigmasterol, etc. More importantly, about 17 compounds are exclusively present in anther-derived callus (not in anther) of Catharanthus. The ploidy status of anther-derived callus was examined via flow cytometry (FCM), and it was estimated to be 0.76 pg, showing the haploid nature of callus. The present work therefore represents an efficient way to produce high-value medicinal compounds from anther callus in a lesser period of time on a larger scale.