Pollination Control Research Articles

COMPARING OUTSTANDING PAPAYA LINES FOR SELECTING AND PRESERVING IMPROVED CHARACTERS

Objective: To evaluate outstanding and adapted papaya lines derived from selection to conserve desirable characteristics. Design/methodology/approach: 23 lines of the 'Maradol' type were evaluated at Antunez Michoacan, Mexico. Initially, the plants' height, stem circumference, number of leaves, and first fruit height were recorded. During their development, outstanding plants were identified, and their self-pollinating was promoted. In the fruits, their polar and equatorial circumference, shape index, weight, width and pulp firmness, and soluble solids were assessed. Results: The plants' development was different, their variability between lines allowed identifying morphological characteristics of interest. Only 10 lines had this condition. The number of fruits formed over covered flower buds and collected fruits on formed fruits was reduced. The fruits´ characterization, except for their soluble solids, showed differences. Multivariate analysis indicated variability associated with each principal component. Limitations on study/implications: Currently in Mexico, there are few papaya varieties, the 'Maradol' variety being dominant, and vulnerable to phytosanitary problems over time. However, developing varieties and seed production is challenging and the pollination control of the plants necessarily intervenes. Findings/conclusions: Out of 23 assessed papaya lines, only 43.48 % reported outstanding plants. Inside these lines, between 5 and 10 % of the plants were chosen. In the developmental progress from the covered flower buds’ stage to formed and collected fruits, only 28 % of fruits were obtained. The selected lines showed fruit variability.

New Nonwoven Fabrics for Pollination Control Bags for Oil Palm

Oil palm hybridisation requires the isolation of inflorescences with pollination control bags (PCBs) for which polyester duraweb® PCBs are used at the Dami Oil Palm Research Station in Papua New Guinea. For widening the choices of nonwoven PCBs we compared the performance of PCBs from three new types of nonwoven fabrics with the standard duraweb® PCB on 9-year-old clonal palms in one of the Dami SUPERFAMILY® seed gardens. The station typically experiences a humid climate and received weekly total rainfall ranging from 53 to 228 mm (total rainfall 1035 mm) during the reproductive phase in March and April 2020, when the trial was conducted. Analyses of variance of a number of traits such as time taken to install the bags, bag intactness, spine damage and water absorption of bags, bunch weight, healthy and total seed number and weight, seed health score, and 100-seed weight were all non-significant. The average number of healthy seeds per bunch was 1120 seeds with mean weight of 376 g per 100 seeds. Blank pollinations showed equal pollen-proofing ability among all bags without any noticeable insect entry. This study, for the first time, has identified three other nonwoven fabric PCBs with no statistical differences from the control duraweb® bags for most of the important traits, and provides new alternatives to reduce the dependency on only one type of fabric which, when in short supply, could adversely affect the plant breeding and seed production programmes.

Indicators of efficiency in operational crosses of Eucalyptus dunnii and hybrids in Montes del Plata: Current progress and challenges

One of the main goals of a tree breeding program is to increase forest productivity, adaptation and profitability of forest plantations. Eucalyptus dunnii is a main species used for pulp production in Uruguay. Montes del Plata (MdP) is one of the largest forest companies in Uruguay and has been focused on the development, testing and deployment of E. dunnii clones to establish commercial plantations in Uruguay. This poster refers to the generation of control-pollinated families, as the starting point of MdP clonal strategy. Control pollination (CP) is a tool in genetic breeding programs that enables to recombine selected genotypes with desired traits to maximize gain in the medium to long term. The selection trait for pulpwood objective is tons of cellulose per tree (ADt); consequently, growth, frost tolerance, health, and wood properties are relevant for parent selection. Ongoing work shows a fruitfully performance of E. dunnii. In the south-east region of Uruguay the species have one flowering period per year, with an average flowering time occurring between the last fortnight of February and the first half of May. Developed protocols for pollen harvesting and methods for crossing are used. The survival of pollinated flowers resulting in fruits has shown to vary with parental species. Average survival rates are 20 to 35%. The main loss of crop happens during the first 4 months after pollinating, weighting —in average— a loss of 40% of the pollinated flowers. The species fruit crop occurs one year after CP. The number of seed per fruit varies with the parental species. E. dunnii × E. dunnii crosses yield in average 6.4 seeds per fruit. However, we have seen a reduction in seeds per fruit in hybrid crosses, where E. dunnii is pollinated with another species, mostly E. globulus, E. grandis and E. dorrigoensis. Seed crops are sawn in the nursery and start an individual clonal selection based on rooting protocols. Clones that fulfill the rooting constraints go to field trials. This is presented in another poster proposal. Main challenges for the future are to maintain a wide genetic diversity in the breeding population, early flowering, and continuous improvement on CP techniques.

Establishment of new convenient two-line system for hybrid production by targeting mutation of OPR3 in allopolyploid Brassica napus

Abstract The two-line pollination control system, which usually depends on the utilization of thermosensitive or photoperiod genic male-sterile lines, has been widely used in various crops. However, this system is susceptible to instability issues caused by uncontrollable weather fluctuations. A stable and handy two-line pollination control system is highly desirable in many crop species for heterosis exploitation. Oxophytodienoic acid reductase 3 (OPR3) was proven to be involved in jasmonate biosynthesis. In the present study, CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat) was utilized to mutate two OPR3 homologs in Brassica napus. After two OPR3 homologs were simultaneously mutated, mutants exhibited complete male sterility, and fertility could be easily restored by exogenous MeJA treatment. Hybrids produced from crosses between the opr3 sterile lines and normal varieties exhibited heterosis. This new two-line system based on OPR3 mutation provides higher stability and convenience than traditional systems. By using exogenous MeJA treatment to restore fertility, the system enables more precise control of male fertility transition, which has great potential to significantly contribute to the maneuverable production of hybrid seeds in rapeseed as well as other Brassica species crops.

Dose effects of restorer gene modulate pollen fertility in cotton CMS-D2 restorer lines via auxin signaling and flavonoid biosynthesis.

Dose effects of Rf1 gene regulated retrieval mechanism of pollen fertility for CMS-D2 cotton. Cytoplasmic male sterility conditioned by Gossypium harknessii cytoplasm (CMS-D2) is an economical pollination control system for producing hybrid cotton seeds compared to artificial and chemical emasculation methods. However, the unstable restoring ability of restorer lines is a main barrier in the large-scale application of "three-line" hybrid cotton in China. Our phenotypic investigation determined that the homozygous Rf1Rf1 allelic genotype had a stronger ability to generate fertile pollen than the heterozygous Rf1rf1 allelic genotype. To decipher the genetic mechanisms that control the differential levels of pollen fertility, an integrated metabolomic and transcriptomic analysis was performed at two environments using pollen grains of four cotton genotypes differing in Rf1 alleles or cytoplasm. Totally 5,391 differential metabolite features were detected, and 369 specific differential metabolites (DMs) were identified between homozygous and heterozygous Rf1 allelic genotypes with CMS-D2 cytoplasm. In addition, transcriptome analysis identified 2,490 differentially expressed genes (DEGs) and 96 unique hub DEGs with dynamic regulation in this comparative combination. Further integrated analyses revealed that several key DEGs and DMs involved in indole biosynthesis, flavonoid biosynthesis, and sugar metabolism had strong network linkage with fertility restoration. In vitro application of auxin analogue NAA and inhibitor Auxinole confirmed that over-activated auxin signaling might inhibit pollen development, whereas suppressing auxin signaling partially promoted pollen development in CMS-D2 cotton. Our results provide new insight into how the dosage effects of the Rf1 gene regulate pollen fertility of CMS-D2 cotton.

Incompatibility Systems in Fruit Crops: Applications and Achievements

The method of pollination is crucial for fruit crop breeding since it affects the genetic makeup, type of gene action, ease of pollination control, and stability of varieties after release. There are a number of processes that encourage cross-pollination, but self-incompatibility (SI) is particularly significant since it is exploited in the production of hybrid seeds. SI is the practice of not allowing fertile (functioning) male and female gametes from the same plant to fuse together. Since ancient times, breeders and growers have successfully used SI as a tool to modify domesticated crops. Self-incompatibility may have an array of causes, including those that are physical, physiological, biochemical, and molecular, but on a broader scale, it appears that all of these components interact to regulate it. According to molecular investigations, at least two genes in the S-locus regulate the SI, one of which functions as a male and one as a female determinant. Self-incompatibility has several different uses, including marker-assisted breeding through SI genotyping, agricultural production and quality improvement, and the creation of hybrids to get over intra- and interspecific reproductive obstacles.

Chemical emasculation in cowpea (Vigna unguiculata (L.) Walp.) and dicotyledonous model species using trifluoromethanesulfonamide (TFMSA)

Hybridization plays an indispensable role in creating the diversity associated with plant evolution and genetic improvement of crops. Production of hybrids requires control of pollination and avoidance of self-pollination for species that are predominantly autogamous. Hand emasculation, male sterility genes or male gametocides have been used in several plant species to induce pollen sterility. However, in cowpea (Vigna unguiculata (L.) Walp), a self-pollinated cleistogamous dryland crop, only hand emasculation is used, but it is tedious and time-consuming. In this study, male sterility was effectively induced in cowpea and two dicotyledonous model species (Arabidopsis thaliana (L.) Heynh. and Nicotiana benthamiana Domin) using trifluoromethanesulfonamide (TFMSA). Pollen viability assays using Alexander staining showed that 30 ml of 1000 mg/l TFMSA with two-time treatments of one-week interval at the early stage of the reproductive phase under field or greenhouse conditions induced 99% pollen sterility in cowpea. TFMSA treatment induced non-functional pollen in diploid A. thaliana at two-time treatment of 10 ml of 125–250 mg/l per plant and N. benthamiana at two-time treatment of 10 ml of 250–1000 mg/l per plant. TFMSA-treated cowpea plants produced hybrid seeds when used as the female parent in crosses with non-treated plants used as male parents, suggesting that TFMSA had no effect on female functionality in cowpea. The ease of TFMSA treatment and its effectiveness to induce pollen sterility in a wide range of cowpea genotypes, and in the two model plant species tested in this study, may expand the scope of techniques for rapid pollination control in self-pollinated species, with potential applications in plant breeding and plant reproduction science.

Increasing seed set and pollen proofing in Brassica juncea and Brassica napus through novel non-woven synthetic pollination control bags

ABSTRACT Brassica juncea and B. napus species are predominantly self-pollinated. Parchment paper or muslin cloth bags are used for controlled selfed or cross-seed production. We evaluated three non-woven synthetic pollination control bags (PCBs) for two years as replacement for the commonly used PCBs. The new synthetic PCBs were fully pollen proof since the molecular marker analysis of the random seeds set on two cytoplasmic male sterile (CMS) lines isolated with PCBs were all maternally originated. DWB03 bags returned 47% significantly more seeds per bud than the parchment paper bags. Larger DWB03 bags showed 38% higher mean seed yield (g/plant) than the muslin cloth bags. Re-used DWB03 bags were statistically on par with new bags for the seed yield per plant. On average, DWB03 bags produced 57% more hybrid seed set on CMS lines than the muslin cloth bags. The micro-climate in DWB03 bags appeared to be more conducive for good seed set as compared to the outside and muslin cloth bags. Non-woven PCBs offer better options for replacing paper or muslin cloth bags in the breeding of Brassicas.

Effects of hedgerows on the preservation of spontaneous biodiversity and the promotion of biotic regulation services in agriculture: towards a more constructive relationships between agriculture and biodiversity

ABSTRACT Central to the agroecological transition is biodiversity, which, once restored in agroecosystems, should provide multiple ecosystem services that result from the interactions between different organisms. However, the diversity of expected services raises questions about the capacity of agroecosystems to simultaneously provide many of them as well as the possible existence of synergies and antagonisms. In particular, the relationships between crop-associated biodiversity (i.e. biodiversity in action in crops) and spontaneous biodiversity (i.e. biodiversity not directly related to agriculture) remain unclear. In this article, we analyse the impact of hedgerows on the preservation of spontaneous biodiversity, on the promotion of biotic regulation services such as pollination and pest control in agriculture, and on the interactions between spontaneous and associated biodiversity. Our analysis of the scientific literature shows that hedgerows are unique assets for the preservation of spontaneous biodiversity, while they also provide biotic regulation services to adjacent crops but only under specific conditions, which need to be better understood. We propose a functional conceptual framework of the ecological effects of hedgerows on associated biodiversity and we highlight the possible synergistic and antagonistic effects related to hedgerow characteristics and the life-history traits of the organisms under consideration. Our analysis therefore seeks to overcome the cleavage between associated biodiversity and spontaneous biodiversity. This approach is in keeping with a more harmonious relationship between agriculture and biodiversity.

Flower Development of Heterodichogamous Juglans mandshurica (Juglandaceae).

Juglans mandshurica is a monoecious heterodichogamous species with protogynous and protandrous mating strategies that occur at a 1:1 ratio and are randomly distributed in the population. The inconsistent male and female flowering periods of the same mating type result in an imbalance of the ratio of male and female flowers, contributing to the low yield of this species. However, little more is known about its floral development. Following three consecutive years of observations, histological analysis, and scanning electron microscopy, we found that the morphological and anatomical development of the male and female flowers were synchronous. The male floral morphological development of J. mandshurica was divided into seven phases, while that of the female flower was nine. Four stages were shared between the male and female flower’s anatomical development. Our findings indicate that there was minimal overlap between sexual functions within the same mating type, guaranteeing synchronization, mutual non-interference, outcrossing, and avoidance of self-fertilization. These results provide a theoretical basis for the improvement of fruit yield and quality through the reasonable allocation of protogynous and protandrous individuals in a population, and for artificial pollination control. Further, these findings lay a foundation for further research on the genetic mechanisms and environmental effects on flower development of heterodichogamous J. mandshurica.

Eficiência dos visitantes florais na polinização da Anonna squamosa L.

RESUMO: Annonaceae apresenta grande destaque no mundo, com alto potencial na produção de frutos para fins comerciais. A polinização é um serviço ambiental de extrema importância, tanto para os ecossistemas quanto para a agricultura, essencial para o aumento no pegamento dos frutos. Com o presente estudo objetivou-se avaliar a riqueza, comportamento e a eficiência dos polinizadores da pinha, no município de Belém – Alagoas. Foram realizadas 11 visitas na área de estudo, totalizando 40h de esforço amostral, para a observação de visitantes florais nos períodos matutinos e noturnos. Para avaliar a formação de frutos, foram realizados os tratamentos de eficiência de polinizador, autopolinização manual (geitonogamia), polinização cruzada (manual) além da polinização natural (controle). Foram observadas três espécies de coleópteros visitando as flores de Annona squamosa L. Apenas 0,5% das flores da polinização natural (controle) formaram frutos, já na avaliação da eficiência dos polinizadores, ocorreu conversão de 45% das flores em frutos. Na geitonogamia e polinização cruzada formaram 76% e 96% dos frutos, respectivamente. Dos animais que foram observados interagindo com as flores da Annona squamosa no município, apenas os besouros se comportaram como polinizadores, pois contataram as estruturas reprodutivas das flores. O desaparecimento dos polinizadores dos cultivos da Annona squamosa, afeta diretamente a formação dos frutos, sendo a cultura dependente deste serviço. A utilização de agroquímicos e a ausência da vegetação nativa são a causa na ausência dos polinizadores da Annona squamosa.
 PALAVRAS-CHAVE: Pinha, polinização, agricultura familiar.

Unexpected Diversity in Regenerating Sites Stresses the Importance of Baselines: A Case Study With Bats (Order Chiroptera) on the Osa Peninsula, Costa Rica

Introduction: Background and Research Aims:Assessing biodiversity recovery is key to determine whether the objectives of habitat restoration for conservation are met. Many restoration initiatives use cross-sectional comparisons of wildlife communities to infer restoration impact instead of longitudinal assessments from a baseline state. Using an indicator of biodiversity in the neotropics— bats— we demonstrate how assessing community diversity and composition in an area targeted for restoration prior to implementation, and when compared to surrounding intact forest, provides the groundwork to track changes in the community post-restoration.MethodsWe assessed bat communities by 1) using mist-net surveys to identify species in the family Phyllostomidae (leaf-nosed bats), and 2) conducting acoustic surveys to identify non-phyllostomid species (aerial insectivores).ResultsFor both groups, we found that areas targeted for restoration had similar diversity as the surrounding forest, but the two habitat types differed in community composition. Phyllostomids were captured at higher rates in forest, but aerial insectivores were detected at higher rates in restoration habitat.ConclusionOur baseline assessment revealed unexpected diversity in areas targeted for restoration. The presence of all trophic groups in restoration habitat suggests that bats provide key ecosystem services in the restoration process, such as through seed dispersal, pollination and insect pest control. Implications for Conservation: Conducting a baseline survey of bats in areas targeted for restoration demonstrated that the community was not species poor at the baseline and was different from the surrounding forest, allowing us to better track restoration success and the effects of different restoration treatments.

Characterization of tribenuron-methyl-induced male sterility in Brassica juncea L.

Significant heterosis has been documented in Brassica juncea L. that are grown as agriculturally important oilseeds, vegetables and condiments crops. Male sterility induced by chemical hybridizing agents is an important pollination control system in hybrid crop breeding. Herein, we show that tribenuron-methyl (TBM), a sulfonylurea herbicide, is an effective male gametocide in B. juncea when used at a very low dosage. In the present study, foliar application of various rates of TBM induced a significant increase in pollen sterility in B. juncea (90.57–100%). TBM-treated plants exhibited reductions in size of floral organ and yield components; however, lower dose of TBM (0.075 g a.i. ha–1) did not cause a significant reduction in seed yield per plant. Tapetum cells of TBM-treated plants were hypertrophied and degenerated earlier, and abnormal meiosis was observed at the meiotic stage. A significant decrease of acetohydroxyacid synthase (AHAS) activities was detected in buds of plants treated with 0.10 g a.i. ha–1 TBM, and RT-qPCR analysis showed that TBM exposure perturbed AHAS expression in small buds, which support that TBM induces male sterility in B. juncea by targeting AHAS expression. Our results suggest that TBM could be used as an efficient chemical hybridization agent in B. juncea, which has practical implications for the application of hybrid breeding in B. juncea.

Deficiencies in the formation and regulation of anther cuticle and tryphine contribute to male sterility in cotton PGMS line

BackgroundMale sterility is a simple and efficient pollination control system that is widely exploited in hybrid breeding. In upland cotton, CCRI9106, a photosensitive genetic male sterile (PGMS) mutant isolated from CCRI040029, was reported of great advantages to cotton heterosis. However, little information concerning the male sterility of CCRI9106 is known. Here, comparative transcriptome analysis of CCRI9106 (the mutant, MT) and CCRI040029 (the wild type, WT) anthers in Anyang (long-day, male sterile condition to CCRI9106) was performed to reveal the potential male sterile mechanism of CCRI9106.ResultsLight and electron microscopy revealed that the male sterility phenotype of MT was mainly attributed to irregularly exine, lacking tryphine and immature anther cuticle. Based on the cytological characteristics of MT anthers, anther RNA libraries (18 in total) of tetrad (TTP), late uninucleate (lUNP) and binucleate (BNP) stages in MT and WT were constructed for transcriptomic analysis, therefore revealing a total of 870,4 differentially expressed genes (DEGs). By performing gene expression pattern analysis and protein-protein interaction (PPI) networks construction, we found down-regulation of DEGs, which enriched by the lipid biosynthetic process and the synthesis pathways of several types of secondary metabolites such as terpenoids, flavonoids and steroids, may crucial to the male sterility phenotype of MT, and resulting in the defects of anther cuticle and tryphine, even the irregularly exine. Furthermore, several lipid-related genes together with ABA-related genes and MYB transcription factors were identified as hub genes via weighted gene co-expression network analysis (WGCNA). Additionally, the ABA content of MT anthers was reduced across all stages when compared with WT anthers. At last, genes related to the formation of anther cuticle and tryphine could activated in MT under short-day condition.ConclusionsWe propose that the down-regulation of genes related to the assembly of anther cuticle and tryphine may lead to the male sterile phenotype of MT, and MYB transcription factors together with ABA played key regulatory roles in these processes. The conversion of fertility in different photoperiods may closely relate to the functional expression of these genes. These findings contribute to elucidate the mechanism of male sterility in upland cotton.

Are maternal and reciprocal effects important in breeding the inter-specific hybrid between Acacia auriculiformis and A. mangium?

Controlled pollination (CP) was used to produce four reciprocal crosses of the interspecific hybrid between Acacia auriculiformis and A. mangium, and one additional reciprocal cross within each parental species. There were no reciprocal effects on seed yield index (filled seeds per 100 flowers pollinated) and germination success for filled seeds. The CP families, together with four additional CP hybrid families, one open-pollinated (OP) family from seed orchards of each parental species and a commercial Acacia hybrid (A. mangium × A. auriculiformis) clone were planted in a field trial in central Vietnam. Forty months after planting the pure-species A. mangium families, with diameter at breast height (DBH), averaging 10.8 cm, grew faster than those of A. auriculiformis (mean 8.5 cm). Nursery gate survival and mean height and diameter at breast height at 40 months of the interspecific hybrid families were not affected by crossing direction. The mean height and DBH of all hybrid families was close to the mid-point of the two parental species. Inheritance of phyllode length and breadth was non-additive; interspecific hybrid families had phyllode length and width much closer to that of A. auriculiformis than to A. mangium, however there was no consistent reciprocal effect for these traits. It is concluded that, at least for the test environment under study, crossing direction is not likely to be of practical importance in hybrid breeding of these species.

English

Three pollination control tents (PCTs) made from novel nonwoven synthetic fabrics with more open pore structure (DWB10, DWB23 and DWB24) were compared with the standard DWB01 fabric for pollen proofing in sugar beet (Beta vulgaris L.) at the research station of Lion Seed Ltd Essex, UK in 2019. PCTs of 63.5 x 63.5 cm footprint accommodated single potted plants. A completely randomised trial with five replications including an open pollinated control was conducted using cytoplasmic male sterile line 1TM37. Analysis was computed for (a) full data and (b) excluding three DWB23 defective tents. Differences among treatments were non-significant for all morphological traits except for number of secondary branches in (a) only. There was thus no micro-climatic difference among treatments for morphological traits of the 1TM37 CMS line. Among the seed related traits, 1000-seed weight and 10-day germination (%) were significant between treatments in (a) but only 1000-seed weight in (b). The mean 1000-seed weight was significantly higher for the open control than all other PCT treatment means which did not differ significantly from zero. Therefore, all four fabrics of PCTs were equally pollen proof in preventing pollen contamination. It is concluded for the first time that mini-tents of these novel nonwoven fabrics, engineered for both larger pores for air permeability and fibre architecture to prevent pollen transmission, adequately eliminated cross-pollination while maintaining ambient environmental conditions and are effective for sugar beet breeding. The PCT technology may be equally usefully deployed in other traditional, commercial and fibre crops for hybrid seed production. Key words: Sugar beet, nonwoven synthetic fabric, pollination control tent, male sterility. &nbsp

English

The practices of using isolation and distance in the seed production of open pollinated crops are fundamental concepts to ensure seed purity. We uniquely examined the effectiveness of replacing isolation plots for seed production and grass breeding with different sizes of novel nonwoven synthetic fabric pollination control tents (PCTs). Two fabrics, DWB10 and DWB24, were used along with multiple genotypes of tall fescue at Ardmore, Burneyville and Gene Autry locations in Oklahoma, USA during 2018 and 2019. Treatment effects were consistently significant in both years, but location differences were more pronounced in 2019. Interactions of treatments with locations or genotypes were not predominant. The two tent fabrics, generally, performed equally well for various traits in both years. Tent performance for both fabrics was particularly superior over control for various traits in 2019 (e.g., DWB10 tent showed a 36% increase for seed yield (SY) over the control). Introduction of fans in tents for increasing pollen flow in 2019 was not advantageous as it reduced the SY by 23%. The average temperature within tents was higher with lower average humidity than the control producing a microclimate for good yield and disease free seeds. The final germination (%) of seeds from tents and controls at 21 days was high and not much different with a minimum overall germination of 89% at Burneyville in 2018. There was no evidence of pollen contamination from tetraploid ryegrass pollen in any of the tent fabrics. Bad weather in 2018 affected the sturdiness of tents, but modifications in 2019 corrected all such mishaps. Further improvements in the structures, design and cover have since been made for field exploitation of technology in grass improvement and seed multiplication. Key words: Ryegrass, fescue grass, pollination control tents, nonwoven fabrics. &nbsp

Wheat, barley and maize genes editing using the CRISPR/Cas system

Precise editing of the genes of plant organisms with complex genomes has long been a difficult task. The CRISPR/Cas technology developed in the last decade has become one of the preferred tools for site-directed mutagenesis of plant genes and has quickly replaced the ZFN and TALEN systems. However, while the CRISPR/Cas system has proven to be an effective tool for modifying the genome of diploid species, its application to organisms such as cereals with complex and, in the case of common wheat, polyploid genomes is complicated by a number of obstacles. This review summarizes the main results obtained using the CRISPR/Cas system in such economically valuable cereals as common wheat Triticum aestivum L., barley Hordeum vulgare L., and maize Zea mays L., the genome structure of which increases the probability of the emergence of non-target mutations and reduces the specificity of editing. Every year the number of methodological publications on the directed mutagenesis of these crops, aimed at optimizing and improving the performance of the CRISPR/Cas system, increases exponentially, and the editing efficiency reaches 100% for maize and barley. The experimental articles are mainly aimed at improving the economically important traits of plants, such as improved yields, nutritional value and resistance to diseases and herbicides. Plant improvement is also associated with editing genes that affect pollination control, which is used in hybrid breeding. This creates the prerequisites for the creation of new maize, barley and wheat varieties, and for the saturation of existing ones with the necessary properties.

Cytological and genetic characterisation of dominant GMS line Shaan-GMS in Brassica napus L.

Genic male sterility (GMS) is an effective pollination control system applied in the hybrid breeding of Brassica napus L. Shaan-GMS is a spontaneous mutant of dominant GMS in B. napus. In this research, anther abortion in the homozygous two-type line 9A15AB derived from Shaan-GMS was characterised with the combined use of light microscopy and transmission electron microscopy. Results indicated that the most striking differences between the fertile and sterile plants occurred in the tapetum in the early microsporocyte stage. In sterile plants, the tapetal cells were irregularly arranged, multi-layered and occupied the growing space of microsporocytes. When entering into meiosis, the tapetum cells degraded and the cytoplasm fused. Some oval monolayer or bilayer membrane organelles existed in the tapetal cells in sterile anthers. Mitochondria in the tapetal cells were abnormal, and middle layer cells degraded early. Pollen mother cells of Shaan-GMS degenerated at the start of meiosis and ceased at the anaphase I stage, with no dyads or tetrads formed. The combined effects of the abnormal development of the tapetum, the middle layer cells and meiosis lead to male sterility in Shaan-GMS. Inheritance of male sterility of Shaan-GMS is controlled by a monogenically multiallelic locus with three different alleles (Ms, ms and Mf), with a relationship expressed as Mf > Ms and Ms > ms. The findings help lay the foundation for illustrating the mechanism of male sterility and the utilisation of Shaan-GMS in rapeseed.

Chromosome doubling of Cichorium intybus L. haploids through protoplast regeneration

Industrial chicory (Cichorium intybus L.) is mainly grown for inulin production. To enhance production and uniformity, hybrid cultivars are preferred. Therefore, a controlled pollination system and homozygous parental lines are needed. The most desirable pollination control system is cytoplasmic male sterility (CMS). A new, naturally induced CMS has been reported by Van der Veken et al. (2018). To regenerate homozygous parental lines of modern industrial chicory cultivars, different haploid inducing techniques have been compared and evaluated. The only successful method was intergeneric hybridization with Cicerbita alpina (Dore et al., 1996), yielding haploid plants. Here we show that protoplast regeneration is an efficient tool for chromosome doubling of these haploids. The presented method can be used for chromosome doubling of slowly developing haploids.