Development Of New Varieties Research Articles

In Vitro Plant Regeneration of Sulla coronaria from Floral Explants as a Biotechnological Tool for Plant Breeding

Sulla coronaria L. Medik., a biennial forage legume typical of the Mediterranean basin, plays a significant role in foraging systems due to its high nutritional value, ability to increase ruminant live weight, and potential to reduce methane emissions. However, its allogamous nature complicates genetic improvement and the development of new varieties with desired traits. Given these challenges, this study aims to develop, for the first time, a successful protocol for the in vitro meristematic shoot regeneration of S. coronaria. The experiment utilizes four different flower explants (anther with filament, ovary, petals, and whole immature flower) collected from twenty distinct S. coronaria biotypes with three plant growth regulator (PGR) combinations and under both light and dark conditions. In terms of the regeneration response, the key factors appear to be the combinations of PGRs and the type of explant used. The interactions between all the factors do not seem to be significant.

PHENOTYPIC DIVERSITY OF SWEET POTATO (IPOMOEA BATATAS[L.]LAM.) GERMPLASMUSING QUANTITATIVE TRAITS: A PRE- BREEDING STUDY IN TOGO

Objective: Sweet potato is a root and tuber crop which contribute to food security in Togo. However, little scientific data exists on the genetic variability of cultivars grown in Togo, although this information is a prerequisite for development of new varieties. The objective of this study was to explore the phenotypic diversity within Togos sweet potato cultivars. Materials and Methods: The germplasm is composed of sixty five (65) cultivars from Togo and sixteen (16) exotic varieties introduced from Burkina Faso breeding unit. The experiment was laid out in a 9 x 9 lattice square design with three replicates. In total, sixteen (16) quantitative traits were evaluated using the sweet potato ontology as described by CIP. Results:Descriptive statistics, ANOVA and PCA revealed high variability for traits such as root yield, dry matter content, aboveground biomass, stem length, internode length and stem diameter. Cluster analysis performed on the basis of the Euclidean distance between cultivars using Ward method as aggregation criterion has revealed four phenotypic clusters. Clusters I and II are composed of varieties with low root yield (12.95 and 15.87 t.ha-1) and high dry matter content (29.68 and 26.86%). Clusters III and IV are made of varieties exhibiting high aboveground biomass (37.74 and 50.75 t.ha-1), high fresh root yield (16.06 and 20.18 t.ha-1) and low dry matter content (24.62 and 23.84%). The variability observed in this gene bank constitutes a basis for genetic improvement programmes of sweet potato in Togo.

African Horned Melon (Cucumis metuliferus): Climate‐Resilient Crop and Gene Donor in the Breeding of Major Cucurbits

ABSTRACTAfrican horned melon (Cucumis metuliferus E. Meyer ex Naudin, 2n = 2x = 24) is an under‐researched and under‐utilised cucurbit crop primarily grown for its nutritious fruit. In its centre of diversity, the crop is valued for its relatively high tolerance to insect pests, diseases, drought and heat stress. It is a potential opportunity crop and a valuable source of genes to major Cucumis species, including cucumber (Cucumis sativas L.) and melon (C. melo L.). Its climate resilience and nutrient‐rich fruit provide niche market opportunities. Hence, production and value‐adding will make African horned melon a crop of choice globally. There is a need for an in‐depth investigation into the genetic diversity, breeding and food composition of the crop. Therefore, the objective of this review was to provide perspectives on the production and breeding status of African horned melon to appraise its genetic value for human welfare, strategic production, genetic conservation and breeding of market‐preferred varieties, including closely related Cucumis species. The first section described the botany, production status, germplasm resources and characterisation based on phenotypic and genetic markers. This is followed by breeding progress for biotic and abiotic stress tolerance, utilities and challenges of gene transfer and potential rootstock to Cucumis species, especially cucumber and melon. The review summarised the main breeding goals and approaches, including mutation breeding to fast‐track the development of new varieties. Information presented in the review will guide cultivar design in African horned melon or related cucurbits, aiming for superior agronomic and nutritional quality traits and tolerance to biotic and abiotic stresses.

Development and evaluation of a new winter bread wheat variety Rubin Dona according to the main economically valuable traits

Relevance. The development of new varieties and their rapid introduction into production remains the most effective resource for improving productivity, energy saving, profitability and competitiveness. The purpose of the current study was to develop the winter bread wheat variety Rubin Dona and evaluate its productivity and basic adaptive, technological, and baking properties.Methods. The current study was carried out in the fields of research crop rotation of the department of winter wheat breeding and seed production in 2018–2023. The variety was developed by the method of intravarietal hybridization using the productive and adaptive variety Nakhodka as a maternal form and the high-quality strong wheat variety Donskaya Yubileynaya as a paternal form and a subsequent individual selection.Results. There has been established that the variety Rubin Dona has a high and stable level of productivity. For 6 years of competitive variety testing the mean productivity of the variety sown in green manure fallow was 9.45 t/ha with the minimum of 6.77 t/ha and the maximum of 11.80 t/ha, compared to the standard variety Ermak with 8.80, 6.06 and 11.21 t/ha, respectively. The variety Rubin Dona sown after various forecrops also demonstrates a reliable and stable productivity increase to the standard, 0.67 t/ha after maize for grain, 0.79 t/ha after peas, 0.62 t/ha after sunflower, 0.77 t/ha after winter wheat. There has been revealed that the advantage of the new variety, which provides high and stable yields, is its high environmental resistance to regional soil and climatic conditions such as drought, low temperatures, spring frosts, diseases, and lodging. The variety has lower indicators of the coefficient of variation, factor of stability (FS), yield range (d) with a high level of realization of productivity potential in comparison with both the standard variety Ermak and the highly productive variety Razdolie, which has a contrasting periods of heading and ripening. The technological and baking properties of the new variety are of high quality and meet the requirements of GOST-9353-2016 referring to the first class. Since 2023, by decision of the State Commission of the Russian Federation for testing and protection of breeding achievements, the variety has been included in the State List of the varieties approved for use in the Central Blackearth (5) and Lower Volga (8) regions.

Grain Appearance Quality of Parental and \(F_2\) Segregating Populations of Aus Rice (Oryza sativa L.)

Longer grain length with smaller grain breadth, length-breadth ratio and 1000-grain weight is considered desirable character for the development of fine grain premium quality rice. In the present experiment, grain appearance quality of 15 F2 families and 10 parental genotypes were determined to select fine grain rice. The maximum mean value for thousand seed weight was found from the genotypes P2 (29.32g), P1 (28.89g), and F2 generations of P2 x P5 (32.77g), P2 x P1 (27.30g), P1 x P4 (26.04g) and were considered as high yielders in terms of grain weight. The highest mean values for grain length were found from the genotypes P6 (9.95 mm; grain breadth 2.23 mm), P7 (9.36 mm; grain breadth 2.62 mm), and F2 generations of P6 x P7 (9.46 mm; grain breadth 2.44 mm), P3 x P6 (9.40 mm; grain breadth 2.18 mm), P7 x P6 (9.37 mm; grain breadth 2.29 mm), P7 x P3 (9.36 mm; grain breadth 2.33 mm). The F2 progenies of the cross P1 x P4 (7.79 to 11.61 mm) and P6 x P3 (7.69 to 11.11 mm) showed extremes performance for grain length indicating transgressive segregation for this trait. The superior genotypes with desirable grain characters could be selected from transgressive segregation of F2 families for the development of new varieties of fine grain rice.

Low-dose 60Co-γ-ray irradiation promotes the growth of cucumber seedlings by inducing CsSAUR37 expression.

Cucumber (Cucumis sativus L.) is a major vegetable crop grown globally, with a cultivation history of more than 3000years. The limited genetic diversity, low rate of intraspecific variation, and extended periods of traditional breeding have resulted in slow progress in their genetic research and the development of new varieties. Gamma (γ)-ray irradiation potentially accelerates the breeding progress; however, the biological and molecular effects of γ-ray irradiation on cucumbers are unknown. Exposing cucumber seeds to 0, 50, 100, 150, 200, and 250Gy doses of 60Co-γ-ray irradiation, this study aimed to investigate the resulting phenotype and physiological characteristics of seedling treatment to determine the optimal irradiation dose. The results showed that low irradiation doses (50-100Gy) enhanced root growth, hypocotyl elongation, and lateral root numbers, promoting seedling growth. However, high irradiation doses (150-250Gy) significantly inhibited seed germination and growth, decreasing the survival rate of seedlings. More than 100Gy irradiation significantly decreased the total chlorophyll content while increasing the malondialdehyde (MDA) and H2O2 content in cucumber. Transcriptome sequencing analysis at 0, 50, 100, 150, 200, and 250Gy doses showed that gene expression significantly differed between low and high irradiation doses. Gene Ontology enrichment and functional pathway enrichment analyses revealed that the auxin response pathway played a crucial role in seedling growth under low irradiation doses. Further, gene function analysis revealed that small auxin up-regulated gene CsSAUR37 was a key gene that was overexpressed in response to low irradiation doses, promoting primary root elongation and enhancing lateral root numbers by regulating the expression of protein phosphatase 2Cs (PP2Cs) and auxin synthesis genes.

Analysis of genotype-by-environment interaction effect in barley genotypes using AMMI and GGE biplot methods

Genotype-by-environment interaction (GEI) analysis play a key role in any breeding program involving the development of new varieties for cultivation across various environments or in a specific region. The additive main effects and multiplicative interaction (AMMI) method and the GGE biplot are the two main statistical tools that have emerged to analyze GEI in multi-environment trials (METs). The main goal of the present study was to identify the best-performing and stable barley genotypes for the warm regions of Iran. For this purpose, 18 new advanced barley genotypes were investigated in five warm locations in Iran during two cropping seasons (2021–2023). In all experiments, test genotypes were evaluated in a randomized complete block design (RCBD) with three replications. Based on results, grain yield was significantly dependent on environments (E), genotypes (G), and GEI. The GEI effect was further divided into three principal component axes (IPCAs). The AMMI method identified genotypes G3, G9, G10, and G14 as ideal genotypes due to their low IPCA scores and high performances. In the GGE biplot analysis, the initial two PCAs accounted for 49.36 % of the total variation of grain yield, including both G and GEI effects. Based on averaged two-year data, genotypes G3, G4, G10, and G14 showed particular adaptability in the Zabol and Moghan regions. Moreover, the ranking of test environments showed good discriminatory and representative abilities for the Zabol and Moghan regions, so these environments constituted a mega-environment in Iran's warm climate. The genotype ranking indicated G3, G10 and G14 genotypes as the superior genotypes with the highest grain yield and stability in different test environments. Moreover, these results were confirmed by the results obtained by WAASB and WAASBY biplots. In conclusion, genotypes G3, G10 and G14 can be suggested for commercial usage and cultivation in various regions in Iran's warm climate.

Root hairs: an underexplored target for sustainable cereal crop production.

To meet the demands of a rising human population, plant breeders will need to develop improved crop varieties that maximize yield in the face of increasing pressure on crop production. Historically, the optimization of crop root architecture has represented a challenging breeding target due to the inaccessibility of the root systems. Root hairs, single cell projections from the root epidermis, are perhaps the most overlooked component of root architecture traits. Root hairs play a central role in facilitating water, nutrient uptake, and soil cohesion. Current root hair architectures may be suboptimal under future agricultural production regimes, coupled with an increasingly variable climate. Here, we review the genetic control of root hair development in the world's three most important crops-rice, maize, and wheat-and highlight conservation of gene function between monocots and the model dicot species Arabidopsis. Advances in genomic techniques including gene editing combined with traditional plant breeding methods have the potential to overcome many inherent issues associated with the design of improved root hair architectures. Ultimately, this will enable detailed characterization of the effects of contrasting root hair morphology strategies on crop yield and resilience, and the development of new varieties better adapted to deliver future food security.

CRUZAS SIMPLES PROGENITORAS E HÍBRIDO TRILINEAL DE MAÍZ H-53 AE: DENSIDADES Y PRODUCTIVIDAD

<p><strong>Background</strong>. The use of improved seeds in Mexico is limited. To increase its use and improve its supply, it is necessary to promote the generation of micro-enterprises; for this, the Universidad Nacional Autónoma de México (UNAM) and Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) work in a coordinated manner on the development of new varieties. <strong>Objective</strong>. To determine the seed productivity by effect of the population density of the trilinear hybrid of H-53 AE maize and its simple progenitor crosses in two environments of Valles Altos. <strong>Methodology</strong>. In the spring-summer cycle of 2014, in Cuautitlán Izcalli and Texcoco, State of Mexico, three genotypes were evaluated: the simple female cross androsterile (M53AE x M59) and fertile version (M53F x M59), as well as the trilineal hybrid H-53 AE. Population densities were 55,000, 70,000, and 85,000 ha<sup>-1</sup> plants, respectively. The variables evaluated were male and female flowering, plant and ear height, volumetric weight, weight of 200 grains, ear length, grains per row, dry matter percentage, and grain percentage. The experimental design employed a factorial design with random complete blocks, and the Tukey method was used for mean comparison. <strong>Results</strong>. The simple crosses, androsterile and fertile, exceeded the performance of the hybrid trilineal H-53 AE (7280 Kg ha<sup>-1</sup>). The population density where genotypes expressed a higher yield was 70, 000 ha<sup>-1</sup> plants, with 8602 Kg ha<sup>-1</sup>, significantly different to 7813 Kg ha<sup>-1</sup>, and 7748 Kg ha<sup>-1</sup> for 85,000 and 55, 000 ha<sup>-1</sup> plants, respectively. <strong>Implications</strong>. Further analysis of other environmental factors should be carried out to strengthen the recommendation of the evaluated trilinear hybrid. <strong>Conclusion. </strong>The best responses were presented in the population density of 70,000 plants ha<sup>-1</sup>, and the highest average yield of three genotypes and three population densities with 8768 Kg ha<sup>-1</sup> was in the FESC environment (Cuautitlán Izcalli).</p>

Exploring nut quality traits in almond varieties: a comparative study of local and foreign cultivars and their F1 hybrid offsprings

Almonds are one of the most popular and widely consumed tree nuts in the world, prized for their taste, texture, and nutritional benefits. However, the quality and characteristics of almonds can vary significantly depending on the variety and growing conditions. In this context, a comparative study was conducted to explore the nut quality traits of almond local and foreign cultivars, as well as their F1 hybrid offspring resulting from crossbreeding. “Nut quality” is a dynamic concept changing based on consumer needs and perceptions that reflect sociocultural evolution. The aim of this study was to identify the most promising almond varieties and hybrids based on some nut quality traits including macro–micro elements and tocopherol contents. To accomplish this goal, samples were collected from local (Gulcan 2 and Nurlu) and foreign (Lauranne and Guara) almond cultivars, as well as F1 hybrid offspring resulting in two cross-breading (“Gulcan 2 × Lauranne” and “Guara × Nurlu”), and conducted a comprehensive analysis using high-performance liquid chromatography and atomic absorption spectroscopy. Our results showed that the nut quality traits of almonds can vary significantly among different cultivars and hybrids, with some varieties and hybrids exhibiting superior characteristics compared to others. These findings provide important insights into the potential for improving almond quality through crossbreeding and the development of new varieties with improved characteristics which can help inform breeding programs and improve the quality of almonds available in the market.

Efficient isolated microspore culture protocol for callus induction and plantlet regeneration in japonica rice (Oryza sativa L.)

BackgroundIsolated microspore culture is a useful biotechnological technique applied in modern plant breeding programs as it can produce doubled haploid (DH) plants and accelerate the development of new varieties. Furthermore, as a single-cell culture technique, the isolated microspore culture provides an excellent platform for studying microspore embryogenesis. However, the reports on isolated microspore culture are rather limited in rice due to the low callus induction rate, poor regeneration capability, and high genotypic dependency. The present study developed an effective isolated microspore culture protocol for high-frequency androgenesis in four japonica rice genotypes. Several factors affecting the isolated microspore culture were studied to evaluate their effects on callus induction and plantlet regeneration.ResultsLow-temperature pre-treatment at 4 ℃ for 10–15 days could effectively promote microspore embryogenesis in japonica rice. A simple and efficient method was proposed for identifying the microspore developmental stage. The anthers in yellow-green florets located on the second type of primary branch on the rice panicle were found to be the optimal stage for isolated microspore culture. The most effective induction media for callus induction were IM2 and IM3, depending on the genotype. The optimal concentration of 2, 4-D in the medium for callus induction was 1 mg/L. Callus induction was negatively affected by a high concentration of KT over 1.5 mg/L. The differentiation medium suitable for japonica rice microspore callus comprised 1/2 MS, 2 mg/L 6-BA, 0.5 mg/L NAA, 30 g/L sucrose, and 6 g/L agar. The regeneration frequency of the four genotypes ranged from 61–211 green plantlets per 100 mg calli, with Chongxiangjing showing the highest regeneration frequency.ConclusionsThis study presented an efficient protocol for improved callus induction and green plantlet regeneration in japonica rice via isolated microspore culture, which could provide valuable support for rice breeding and genetic research.

CHALLENGES AND OPPORTUNITIES TO DESIGN FUTURE CROPS: GATEWAY TO SUSTAINABLE AGRICULTURE IN 21ST CENTURY

The global food production system is facing numerous challenges due to factors such as population growth, climate change, limited resources, and environmental preservation. To address these challenges, various strategies can be employed to develop future crops that are more productive, nutritious, and resilient. One strategy is to improve the yield potential of existing crops by developing new high-yielding cultivars. This can be achieved through the development of new varieties that can produce more grain under optimal conditions. Additionally, improving the nutritional quality of crops is important to address nutrient deficiencies. Synthetic biology and metabolic engineering methods can be used to develop crops with enhanced nutritional value. Efficient utilization of agricultural resources is another important aspect of crop improvement. This includes developing crops that use water and nutrients more efficiently, reducing the need for irrigation and fertilizers, and minimizing environmental impacts. Increasing the resistance of crops to pests, diseases, and extreme weather events can also help reduce the use of pesticides and minimize crop losses. The domestication of wild or semi-wild plants through genetic manipulation offers new opportunities for crop design. These plants may have high nutritional value, stress tolerance, and specialized metabolites that can be incorporated into cultivated crops. Similarly, the domestication of orphan or neglected plants can contribute to crop improvement by incorporating unique traits. Genetic improvement through the transfer of genes from wild relatives or other species can also enhance crop productivity. Advancements in genomics and genetic technologies can aid in the identification and transfer of beneficial alleles. Agronomic improvements, such as maximizing the effectiveness of crop protection agents and fertilizers while minimizing their environmental impact, can also contribute to crop performance. The emerging field of synthetic biology offers opportunities for developing novel biological devices and systems that can further enhance crop productivity and resilience. Overall, these strategies can help address the challenges faced by the global food production system.

Gas chromatography–mass spectrometry‐based electronic nose, glycosidically bound volatile, and alcohol‐acyltransferase activity profiles of Okinawan pineapple

SummaryA recent increase in the demand for pineapple necessitates the development of new varieties with superior flavour quality. In this study, we characterised the volatile profiles of three new Okinawan pineapple breeding lines using gas chromatography (GC)–mass spectrometry (MS)‐based electronic nose (e‐nose), glycosylated volatiles, and alcohol‐acyltransferase (AAT) activity measurements. The volatile profiles of the fruits were selected using the GC–MS‐e‐nose and visualised using multivariate statistical plots. The glycosidically bound compounds were collected by solid‐phase extraction and hydrolysed by β‐glucosidase. In total, 12 hydroxyl‐group substances, including chavicol (medicinal‐herbal aroma), geraniol (floral‐sweet), and linalool (floral‐citrus), were released from these glycosides. Crude enzymes containing AAT were extracted, and their in vitro activities in 2‐methylbutyl acetate production were highly related to their contents. These results provide information regarding volatile profiles and bounded‐aroma resources, as well as the esterification potential of new Okinawan pineapple breeding lines for use in the agro‐food industry.

Fine-mapping and primary analysis of candidate genes associated with seed coat color in mung bean (Vigna radiata L.)

Seed coat color affects the appearance and commodity quality of mung beans (Vigna radiata L.). The substances that affect mung bean seed coat color are mainly flavonoids, which have important medicinal value. Mapping the seed coat color gene in mung beans would facilitate the development of new varieties and improve their value. In this study, an F2 mapping population consisting of 546 plants was constructed using Jilv9 (black seed coat) and BIS9805 (green seed coat). Using bulk segregated analysis (BSA) sequencing and kompetitive allele-specific PCR (KASP) markers, the candidate region related to seed coat color was finally narrowed to 0.66 Mb on chromosome (Chr.) 4 and included eight candidate genes. Combined transcriptome and metabolome analyses showed that three of the eight candidate genes (LOC106758748, LOC106758747, and LOC106759075) were differentially expressed, which may have caused the differences in flavonoid metabolite content between Jilv9 and BIS9805. These findings can provide a research basis for cloning the genes related to seed coat color and accelerate molecular marker-assisted selection breeding in mung beans.

Morphological and Genetic Characterization of Maize Landraces Adapted to Marginal Hills in North-West Italy.

The growing interest in maize landraces over the past two decades has led to the need to characterize the Italian maize germplasm. In Italy, hundreds of maize landraces have been developed, but only a few of them have been genetically characterized, and even fewer are currently employed in agriculture or for breeding purposes. In the present study, 13 maize landraces of the west Emilia-Romagna region were morphologically and genetically characterized. These accessions were sampled in 1954 from three provinces, Modena, Parma, and Piacenza, during the characterization project of Italian maize landraces. The morphological characterization of these 13 accessions was performed according to the UPOV protocol CPVO/TP2/3, examining 34 phenotypic traits. A total of 820 individuals were genotyped with 10 SSR markers. The genetic characterization revealed 74 different alleles, a FST mean value of 0.13, and a Nm mean of 1.73 over all loci. Moreover, AMOVA analysis disclosed a low degree of differentiation among accessions, with only 13% of genetic variability found between populations, supporting PCoA analysis results, where the first two coordinates explained only 16% of variability. Structure analysis, supported by PCoA, showed that only four accessions were clearly distinguished for both K = 4 and 6. Italian landraces can be useful resources to be employed in maize breeding programs for the development of new varieties, adapted to different environmental conditions, in order to increase crop resilience and expand the maize cultivation area.

Olive trees in the world. Past and present with future perspectives

The cultivation of the olive tree is of great economic importance worldwide. For the 2022-2023 harvest, were produced around 3,010,000 Mg of olive oil and 2,955,500 Mg of table olives of selected varieties, managing to establish itself in approximately 56 countries with different environments. In most of the cultivated areas only monovarietals were used, but mixtures of varieties have been recommended, which act as pollinators, avoiding reproduction problems. Furthermore, global warming also affects production efficiency and the quality of derived products. The olive grove underwent important changes due to genetic improvement. However, despite modern molecular tools, most of the work continues to be based on agronomic classical methods such as crossing and selection in progeny, delaying the development of new varieties. Models with high resolution climate projections are being used, allowing predicting the future evolution of the olive tree. Unfortunately, Brazil produces only 0.2% of its internal consumption and therefore has become the world's second largest importer after the United States to cover the growing demand. Based on this information, this review aims to discuss the adjustments in olive growing, which has been gaining more and more areas dedicated to its cultivation in Brazil.

Opening Eyes on Seedling Tuber Quality in Potato: Size Matters

For potato, diploid hybrid breeding is a novel breeding technique that speeds up the development of new varieties. A consequence of hybrid breeding is the introduction of hybrid true potato seeds as starting material. From these seeds, seedling tubers can be produced in one field season, to use as starting material for a seed or a ware crop in the following year. For breeding purposes as well as for seed crop and ware crop production, it is essential to produce seedling tubers of high quality. The production of seedling tubers is a new step in the potato production chain; therefore, we investigated the effect of tuber quality traits on plant development and yield. With similar seedling tuber weight, more eyes per seedling tuber led to more stems per plant. This was compensated by a lower number of tubers per stem resulting in an equal total tuber number and weight per plant at the end of the growing season. A higher seedling tuber weight led to a higher soil cover in the field. Hybrid potato plants grown from larger seedling tubers produced a greater total tuber weight per plant than plants grown from smaller tubers, while number of eyes and stems per tuber had no effect on final yield when using equal seedling tuber weight.

New Epigenetic Modifier Inhibitors Enhance Microspore Embryogenesis in Bread Wheat

The use of doubled haploid (DH) technology enables the development of new varieties of plants in less time than traditional breeding methods. In microspore embryogenesis (ME), stress treatment triggers microspores towards an embryogenic pathway, resulting in the production of DH plants. Epigenetic modifiers have been successfully used to increase ME efficiency in a number of crops. In wheat, only the histone deacetylase inhibitor trichostatin A (TSA) has been shown to be effective. In this study, inhibitors of epigenetic modifiers acting on histone methylation (chaetocin and CARM1 inhibitor) and histone phosphorylation (aurora kinase inhibitor II (AUKI-II) and hesperadin) were screened to determine their potential in ME induction in high- and mid-low-responding cultivars. The use of chaetocin and AUKI-II resulted in a higher percentage of embryogenic structures than controls in both cultivars, but only AUKI-II was superior to TSA. In order to evaluate the potential of AUKI-II in terms of increasing the number of green DH plants, short and long application strategies were tested during the mannitol stress treatment. The application of 0.8 µM AUKI-II during a long stress treatment resulted in a higher percentage of chromosome doubling compared to control DMSO in both cultivars. This concentration produced 33% more green DH plants than the control in the mid-low-responding cultivar, but did not affect the final ME efficiency in a high-responding cultivar. This study has identified new epigenetic modifiers whose use could be promising for increasing the efficiency of other systems that require cellular reprogramming.

RELATIONSHIP BETWEEN BIOCHEMICAL INDICATORS AND PHENOTYPICAL CHARACTERISTICS OF THYME (THYMUS VULGARIS L.)

Introduction. Thyme (Thymus vulgaris L.) is a sought-after medicinal crop, the raw materials of which are included in the Pharmacopoeias of several countries and are widely used in scientific medicine. Due to the presence of strong intraspecific diversity in thyme, it seems interesting to identify phenotypic characteristics that most likely indicate the presence of certain pharmacologically significant compounds. The presence of such information will allow targeted selection both in natural populations and during the hybridization of cultivars and the development of new varieties. The purpose of the work was to identify phenotypic traits indicating a high content of essential oil and thymol in thyme, the amount of phenolic compounds, flavonoids and tannins. Material and methods. Samples and varieties of thyme from different geographical origins were selected as objects. Biometric, anatomical indicators and yield were determined in the flowering phase. The essential oil content was determined by Clevenger hydrodistillation method. Component composition was determined by gas chromatography. The amount of phenolic compounds and tannins according to the Folin-Ciocalteu method in aqueous-alcoholic extract calculated as gallic acid. The determination of flavonoids in the aqueous-alcoholic extract was carried out using the spectrophotometryс method calculated as rutin. Results. As a result of the research, no signs were found indicating a high content of essential oil. Flavonoid content calculated as rutin had a negative correlation (−0.72) with stomatal density. A negative relationship was noted between the intensity of coloring of the pistil and anthers and the content of the total phenolic compounds calculated as gallic acid (0.71 and 0.72, respectively). Large stomata on both the underside and upper side of the leaf may indicate a high tannin content (0.8 and 0.88). All studied components of common thyme belonged to the thymol type, and the content of this component ranged from 37.6 to 80.8%. An increased content of thymol in essential oil is observed such signs as an elongated leaf shape (leaf index R = 0.78), lack of downward curling of the edges of the leaf blade (R = –0.78) and pronounced veins on the underside of the leaf (R = 0.92). Large stomata on the lower epidermis also indicate an increased proportion of thymol in the essential oil (R = 0.78). When analyzing the interdependence between the content of the main components of essential oil, it was noted that there is a close negative correlation between the content of p-cymene and thymol (R = –0.91) and carvacrol (R = –0.88). Conclusion. As a result of the research, phenotypic and anatomical characteristics were identified that make it possible to diagnose promising samples of common thyme, which will help speed up the selection process.

Transcriptome Analysis Reveals the Molecular Mechanisms of BR Negative Regulatory Factor StBIN2 Maintaining Tuber Dormancy.

Potato is an important food crop. After harvest, these tubers will undergo a period of dormancy. Brassinosteroids (BRs) are a new class of plant hormones that regulate plant growth and seed germination. In this study, 500 nM of BR was able to break the dormancy of tubers. Additionally, exogenous BR also upregulated BR signal transduction genes, except for StBIN2. StBIN2 is a negative regulator of BR, but its specific role in tuber dormancy remains unclear. Transgenic methods were used to regulate the expression level of StBIN2 in tubers. It was demonstrated that the overexpression of StBIN2 significantly prolonged tuber dormancy while silencing StBIN2 led to premature sprouting. To further investigate the effect of StBIN2 on tuber dormancy, RNA-Seq was used to analyze the differentially expressed genes in OE-StBIN2, RNAi-StBIN2, and WT tubers. The results showed that StBIN2 upregulated the expression of ABA signal transduction genes but inhibited the expression of lignin synthesis key genes. Meanwhile, it was also found that StBIN2 physically interacted with StSnRK2.2 and StCCJ9. These results indicate that StBIN2 maintains tuber dormancy by mediating ABA signal transduction and lignin synthesis. The findings of this study will help us better understand the molecular mechanisms underlying potato tuber dormancy and provide theoretical support for the development of new varieties using related genes.