Pollen Sterility Research Articles

Overexpression of a pear B-class MADS-box gene in tomato causes male sterility

B-class MADS-box genes are sufficient for the specification of petals and stamens; however, the role of <italic>Tomato MADS-box protein 6</italic> (<italic>TM6</italic>) in seed formation in pear remains largely unknown. In this study, <italic>PbTM6a</italic> and <italic>PbTM6b</italic>, characterized as negative regulators of the response to GA₄₊₇, were identified as classic B-class MADS-box genes. Additionally, both of the genes encoding proteins carried the highly conserved MADS-box domain, and showed high expression levels in anther, petal and filament of 'Dangshansu'. Overexpression of <italic>PbTM6a</italic> in tomato reduced the number of seeds per fruit. Analysis of the anatomical structure of floral organs revealed that the reduction in seed number in transgenic fruits might be attributed to an obstacle of pollen release due to strongly formed stomium and limited ovary space of ovule development. Moreover, triphenyl tetrazolium chloride (TTC) staining and <italic>in vitro</italic> germination tests of pollen grains indicated that <italic>PbTM6a</italic> overexpression reduced pollen viability and germination rates. Reciprocal crosses showed that the reduction in seed number in transgenic fruits was dominantly caused by the decreased fertility of pollen grains. Subsequent scanning electron microscopy showed that sterile pollen grains were caused by abnormal pollen grains. Additionally, the reduced levels of jasmonic acid (JA), abscisic acid (ABA), indole-3-acetic acid (IAA) and gibberellin A3 (GA3) in transgenic stamens contributed to the development of sterile pollen. Collectively, our results reveal the role of <italic>PbTM6a</italic> genes in controlling male infertility and broaden our understanding of the mechanism underlying the function of B-class MADS-box genes in pear.

The pollen as bioindicator of the genotoxicity of environment

In recent years the male gametes of plants are used for biotesting in ecotoxicology. High proportion of sterile pollen is the indicator of environmental pollution and the presence of mutagens, which cause genetic disturbances. The viability of pollen of Gorodkov’s rowan (Sorbus gorodkovii Pojark) and Scots pine (Pinus sylvestris L.) in the vicinity of environmentally hazard enterprises of the Arctic cities of the Murmansk region have been studied. The following parameters were considered: the number of fertile and sterile pollen and their percentage ratio, the sterility index, and palynotoxic effect of the pollution. High content of the abortive pollen of S. gorodkovii (55–65%), the sterility index (2.1–2.4) and the palynotoxic effect (38.2–50%) indicates the mutagenicity and genotoxicity of the emissions of the Murmansk thermal power plants, that leads to the formation of sterile male gametes. High level of sterility of P. sylvestris pollen (42.5–50.7%), the index of sterility (1.4–1.7) and the palynotoxic effect (19.1–29.8%) indicates, that emissions of the mining and processing plant "Apatit" containes the mutagenic chemicals that have a genotoxic effect on the pine male gametophyte. The pollen of plants can be used for bioindication of environment as the indicator of the impact of gametopathogenic factors.

Development and chromosomal characterization of interspecific hybrids between common buckwheat (Fagopyrum esculentum) and a related perennial species (F. cymosum).

Common buckwheat (Fagopyrum esculentum) is an annual self-incompatible plant that is widely grown. The genus Fagopyrum comprises more than 20 species, including F. cymosum, a perennial that, unlike common buckwheat, is highly resistant to excess water. In this study, we developed interspecific hybrids between F. esculentum and F. cymosum via embryo rescue, to improve undesirable traits of common buckwheat, such as low tolerance to excess water. The interspecific hybrids were confirmed by genomic in situ hybridization (GISH). We also developed DNA markers to confirm the identity of the hybrids and if genes derived from each genome were inherited by the next generation. Observations of pollen indicated that the interspecific hybrids were essentially sterile. Unpaired chromosomes and abnormal segregation during meiosis were likely responsible for the pollen sterility of the hybrids. These findings could facilitate buckwheat breeding to produce lines that can withstand harsh environments with wild or related species in the genus Fagopyrum.

SEXUAL POLYMORPHISM OF &lt;i&gt;RANUNCULUS ACRIS&lt;/i&gt; (RANUNCULACEAE) IN THE MOSCOW REGION

The gynodioecy of the polycarpic Ranunculus acris L. was studied in the Moscow Region. This plant has three types of flowers that differ in androecium structure: perfect flowers (with fertile stamens and carpels), partially male-sterile ones (some of the stamens become staminodes to form sterile pollen), and pistillate ones (an extreme reduction of stamens and the complete absence of fertile pollen). These three types of flowers form a size gradient from the largest perfect to the smallest pistillate ones. Each flower type is formed on separate plants. The share of plants with perfect flowers in 10 studied coenopopulations varied from 43.9 to 53.0%, that of the plants with partially male-sterile flowers from 45.5 to 54.4%. Plants with pistillate flowers are extremely rare (1.5–2.0%). Over three years of observations (2020–2022), we found that the sexual forms of the plants did not change the sex of their flowers, and the sex ratio in the coenopopulations remained stable, without significant fluctuations.

Seed productivity of alloplasmic lines of Beta patula and B. maritima with sterile cytoplasm under the conditions of apozygotic reproduction

Purpose. Revealing the effect of the cytoplasmic genome of replaced lines with the plasma of wild species Beta patula and B. maritima L., and apozygotic lines A4–A8 with the cytoplasm of S vulgaris Owen on the main factors of apozygotic reproduction, seed productivity, germination, monogermity and sterility as affected by the genetic origin of breeding material.&#x0D; Methods. The research was carried out in the Cytogenetics Laboratory (IBCSB), the Laboratory for Apomixis and Polyploidy of the Yaltushkiv EBS, and the Laboratory for Adaptive Breeding (Veselyi Podil EBS). Apozygotic seeds were obtained under a pollen-free regime according to the IBCSB’s Methods for Spatial Isolation and Parchment Insulators. Each seed bearer plant phenotype was determined during the flowering period by pollen sterility and partial flowering. Classification of plants was performed according to Owen (1945), with identifying plants of CMS-0, Type CMS-1, and CMS-2 types. The Monogermity of seed plants was assessed visually by the presence of separate fruits on the central shoots. In 2021, the roots of the replaced lines of the Veselyi Podil EBS were planted under the conditions of a pollen-free regime in the experimental field of the IBCSB. Seed production under apozygositic conditions was studied, taking into account the number of set fruits per 10-cm segment with 5 replications for each seed bearer. Germination was determined on the 10th day and germination vigour on the 5th day.&#x0D; Results. New sources of cytoplasmic male sterility (CMS) were obtained in the cytogenetics laboratory based on a genetic model of crossbreeding analysis, using differentiation and tools according to the marker-linked genes of hypocotyl color R+r-, and one / two-year development cycle B+b-. The analyzers for the nature of sugar beet sterility were sterility maintainers, dominant homozygotes for recessive genes of anthocyanin color, development cycle, partial fertility and sterility (NBeta vulgaris Sxxzz rr bb). Monogerm pollen-sterile lines with an apomictic way of seed reproduction (Yaltushkiv EBS) (A4–A8 Beta vulgaris Sxxzz rr), selected for the dominant color of the hypocotyl R+r-, stabilized for the trait of monogermity, 100% sterility and 2x gene ploidy, were characterized by low seed productivity. High rates of apozygotic seed development (80 to 96.4% of the number of set flowers) were observed against the background of the sterile cytoplasm of Beta maritima (Turkey). In the CMS BC4S patula line, the number of set apozygotic seeds ranges from 34 ± 0.3 to 39 ± 0.42, and the indicators of degenerated flowers under apozygotic regime varied from 31.2 to 54.3%. Isolated were seed plants with high self-reproduction, such as BC4S maritima Turkey, k.2/1, k.6/2, k.6/3 and k.3/4, k.9/4 on the background of new plasma of wild species of B. patula. The phenomenon of high self-reproduction of seeds (up to 98.5−96.4% of set flowers) was detected in line 21-011 CHS BC5S patula, which was comparable with hybrids and sterility maintainers (97.5−93.1%), which is determined by a special interaction of the beet nuclear genome of sugar beet and new plasma of wild species of the genus Beta L.&#x0D; Conclusions. The apomictic way of seed reproduction ensures the shortening of the breeding scheme for sugar beet due to high seed reproduction of mother parent in substituted lines with new plasma and differentiation by gametophytic reduction of parthenogenesis using morphological marker traits.

Cold Stress Response Mechanisms in Anther Development.

Unlike animals that can escape threats, plants must endure and adapt to biotic and abiotic stresses in their surroundings. One such condition, cold stress, impairs the normal growth and development of plants, in which most phases of reproductive development are particularly susceptible to external low temperature. Exposed to uncomfortably low temperature at the reproductive stage, meiosis, tapetal programmed cell death (PCD), pollen viability, and fertilization are disrupted, resulting in plant sterility. Of them, cold-induced tapetal dysfunction is the main cause of pollen sterility by blocking nutrition supplements for microspore development and altering their timely PCD. Further evidence has indicated that the homeostatic imbalances of hormones, including abscisic acid (ABA) and gibberellic acid (GA), and sugars have occurred in the cold-treated anthers. Among them, cold stress gives rise to the accumulation of ABA and the decrease of active GA in anthers to affect tapetal development and represses the transport of sugar to microspores. Therefore, plants have evolved lots of mechanisms to alleviate the damage of external cold stress to reproductive development by mainly regulating phytohormone levels and sugar metabolism. Herein, we discuss the physiological and metabolic effects of low temperature on male reproductive development and the underlying mechanisms from the perspective of molecular biology. A deep understanding of cold stress response mechanisms in anther development will provide noteworthy references for cold-tolerant crop breeding and crop production under cold stress.

Evaluation of pollen morphology of Passiflora species and hybrids (Passifloraceae)

Passiflora L. is a diverse genus of mostly New World species, many of which are still evolving to overcome the challenges of competition, predation, and habitat expansion. Pollen collected from 195 Passiflora L. taxa across six subgenera; Astrophea (DC.) Mast., Decaloba (DC.) Rchb., Deidamioides (Harms) Killip, Passiflora, Tetrapathaea (DC.) P.S. Green) and Tryphostemmatoides (Harms) Killip and 40 F1 hybrids (cultivars) were examined using Scanning Electron Microscopy (SEM) and low temperature SEM. Passiflora pollen grains are divided into two major morphological groups: species with three pairs (6 apertures) of colpi found in species in subgenera Astrophea, Deidamioides, Passiflora and Tryphostemmatoides, and those with six pairs (12 apertures) of colpi found in most species from subgenus Decaloba (Tetrapathea unknown). This study shows polymorphism and surface anomalies in the morphology of pollen grains of some species. Pollen from many Passiflora F1 hybrids were examined: many have a high percentage of sterile pollen grains, others in section Dysosmia DC. and Tacsonia Juss. in subgenus Passiflora recorded a minimal percentage of sterile grains. This may be a key evolutionary advantage as several species in these groups are now recorded as invasive weeds with worldwide distribution. The term, “sticky pollen” is revealed to be the pre-germination of pollen grains without stigmatic contact. The success of some invasive species to outcompete native flora and thrive in extreme environments is in part due to the evolution of their pollen, with the absence of pollen deformation following hybridization events promoting hybrid fitness. Pollen grain morphological evidence supports keeping three endemic Australian Passiflora species in subgenus Decaloba as a unique group.

Cytological Study of Anthers for Pollen Sterility in the F7 Generation of a Rice (Oryza sativa L.) Cross

The present research work was proficiently done at the experimental plot of Birsa Agricultural University, Kanke under the rainfed conditions of Jharkhand, India during kharif 2021. The F7 generation seeds of the cross Pusa-1176 x BPT-5204 was sown as panicle to progeny rows in the seed bed nursery and thereafter transplanted into the field. In this investigation, the study has been oriented more towards the male sterility as it is more sensitive than female gametes based on the observation recorded in previous generation (F6) regarding spikelet sterility percentage. Henceforth, the study has been focussed on the microscopic study of pollen grains to validate the reason behind the cause of spikelet sterility in the panicles. To understand this phenomenon, pollen viability test was done by staining the anthers with 1% Iodine- potassium iodide in order to know the extent of fertility or sterility present in the pollen grains of the rice segregants. Through microscopic study, segregation was observed in the pollen sterility % among the families studied which might be due to the change in the environmental conditions such as temperature, photoperiod and humidity etc. The expected genetic ratio obtained was 9:3:3:1(partially sterile+highly fertile/completely fertile/ highly sterile/completely sterile) revealing that it is controlled by 2 genes since the ratio fitted in digenic ratio.

Evaluation of natural products and chemical compounds to improve the control strategy against cucumber powdery mildew

Powdery mildew, caused by Podosphaera xanthii, is a devastating disease that can wipe out a cucumber crop in optimal weather conditions. Disease control management depends mainly on fungicides to inhibit the pathogen. However, they have fatal side effects on most organisms. This study evaluated the use of natural products as safe alternatives to fungicides for controlling cucumber powdery mildew. The effectiveness and phytotoxicity of the studied products, as well as their effects on leaf anatomy and pollen fertility, were evaluated. Although the fungicide tested (Score 25% EC) was the most effective treatment, it caused the highest phytotoxicity, leaf morphological changes, and pollen sterility. All the treatments used significantly reduced disease severity under greenhouse and field conditions, except for Spirulina, which recorded the lowest efficacy rate. Lemon oil, garlic oil, and Blight stop achieved the desired goal of controlling the disease and improving the plant’s physiological state. Therefore, we recommend using any of them to control cucumber powdery mildew, except for Spirulina, which we recommend as a biofertilizer.

Winter wheat cytogenetic variability under the action of a chemical supermutagen

The analysis of cytogenetic activity is a key component in determining prospects of future hereditary variability after, subject to a certain mutagenic factor, primarily identifying the significance of the genotype-mutagenic interaction, the correctness of the selected concentrations for more thorough screening of some development parameters. Winter wheat seeds of eight varieties (Balaton, Borovytsia, Zeleny Gai, Zoloto Ukrainy, Kalancha, Niva Odeska, Polyanka, Pochayna) were subjected to ЕМS (ethylmethansulfonate) at the concentrations of 0.025%, 0.05%, 0.10% The exposure lasted for 24 hours. Cytogenetic analysis was carried out for pollen fertility; we also examined the rates and spectras of chromosomal rebuildings in proper cell devision phases in relation to plant gcnotype and concentration of the mutagen. The experiment was aimed at identification of interrection between geotype, concentration of mutagen and mutagen nature, determining genome response to mutagen action. Such indicators of cytogenetic activity as the total rate of chromosomal abnormalities, fragments and double fragments, single and double bridges, micronucleus and lagging chromosomes were studied. The selected concentrations of the mutagen significantly influenced all the analyzed parameters, they can be attributed to the optimal and high range of concentrations according to the nature of the impact on bread wheat. We determined that in the case of the mutagenic action, the genotype had a significantly lesser effect on the nature and rate of individual aberrations than an increase in the concentration, while having a significant effect on the rate of increase in pollen sterility. The mutagen was characterized by a significantly lower site-specificity at the cellular level than other chemical supermutagens, manifesting only in the correlation between individual types of aberrations, but not in the character of the increase in their number. The key parameter to identify the activity of this agent was the frequency of fragments and double fragments, their ratio with bridges.

Ornithine decarboxylase regulates putrescine-related metabolism and pollen development in Atropa belladonna

Polyamines, including putrescine, spermidine, and spermine, play critical roles in cell physiology by different forms. As a rate-limiting enzyme that converts ornithine to putrescine, ornithine decarboxylase (ODC, EC 1.1.1.37) has been studied in detail in animals and microorganisms, but its specific functions are poorly understood in plants. In this study, the metabolic and developmental roles of the ODC gene were studied through RNAi-mediated suppression of the ODC gene (AbODC) in A. belladonna. Suppression of AbODC reduced the production of precursors of medicinal tropane alkaloids, including putrescine and N-methylputrescine, as well as hyoscyamine and scopolamine. In AbODC-RNAi roots, the production of putrescine and spermidine in free form was reduced, but in the AbODC-RNAi leaves, the content of free polyamines was not altered. In the roots/leaves of AbODC-RNAi plants, the production of conjugated and bound polyamines was reduced. In addition, suppression of the ODC gene resulted in reduction of polyamines and pollen sterility in AbODC-RNAi flowers. In floral organs, GUS-staining results indicated that AbODC was domainantly expressed in pollen. In summary, ornithine decarboxylase not only plays a key role in regulating the biosynthesis of diverse forms of polyamines and medicinal tropane alkaloids, but also participates in pollen development.

Stable and reproducible expression of bacterial ipt gene under the control of SAM-specific promoter (pKNOX1) with interference of developmental patterns in transgenic Peperomia pellucida plants.

Reproducible and stable transgene expression is an important goal in plant basic research and applications. Hence, we report the first stable expression of bacterial transgenes in medicinal plant, Peperomia pellucida (L.) Kunth. Two key elements relevant to the dynamic expression of the bacterial cytokinin biosynthesis gene, ipt (isopentenyltransferase) were examined. First, by designing a specific expression cassette driven by a tissue-specific promoter for the required levels of gene expression in the particular function of development, and second by using P. pellucida as a model plant due to its short developmental cycle that supported expedient tracking of transgene expression in the progeny. Transgenic frequencies of ipt gene obtained from different expression cassettes of pKNOX1 for tissue-specific promoter in shoot apical meristem were compared with the cauliflower mosaic virus (CaMV35S) promoter (p35S), a constitutive promoter investigated for T3 generation. It was clearly shown that transgenic plants with pKNOX1 showed percentage of survivals in T3 at about 2.2 folds more than those of p35S-transgenic. Transgenic P. pellucida under controllable expression of pKNOX1 showed increased leaf and seed size with a high percentage of fertile seed, whereas transgenic plants with p35S showed phenotypic features of bushy and small leaves, sterile pollen and lower reproductive fitness. Quantitative examination of ipt-positive gene expression in T3 generation of transformants with pKNOX1 were 100% (line k-14) and 50% (line k-20), while 33.3% was observed in transgenic line c-11 with p35S. Interestingly, the endogenous cytokinin biosynthesis gene (ipt3) was significantly upregulated (2-3 folds higher) in pKNOX1-transformants. The overall relative mRNA expression of bacterial ipt gene and overproducing of cytokinin contents (t-ZR and 2-iP) detected in p35S-transformants caused abnormality and low percentages of transgene reproducible Interestingly, pKNOX1-transgenic plants tended to maintain chlorophyll contents 4-5 folds and extending the developmental cycle to 12.4 weeks (wk), which was 2 folds more than wildtype (5.8 wk) and p35S-transformants (7.4 wk). The promotor effect on stable and reproducible transgene-expressions demonstrated prominent features of P. pellucida and also empowered further omics studies.

Phenotypic Plasticity in Morphological Traits of Abelmoschus esculentus L. Induced by Histone Deacetylase Inhibitor, Trichostatin A

Epigenetic changes such as DNA methylation and histone modifications, when meiotically inherited across generations, can act as a stable evolutionary force that is independent of any accompanying DNA mutations. Certain histone deacetylase (HDAC)-inhibiting chemicals such as Trichostatin A (TSA) and sodium butyrate are known to regulate the total acetylated histones in the genome, which is important for regulating the expression of various traits in all organisms. This study investigated all morphological variations in traits of Abelmoschus esculentus L. (okra) induced by different doses of Trichostatin A in a popular okra variety, Arka Abhay. Two sets of seeds were treated with two doses (0.4 µM and 1.2 µM) of TSA and were incubated in the chemical for three and five days, respectively, to record the effects of dose and incubation periods on various agronomic characters of okra. The treatment of TSA had a negative impact on the majority of the characters under evaluation. Total seedlings emerged, and mean shoot and root length were retarded following the TSA treatment. Extremely dwarfed plants with malformed leaves and flowers were a common observation. Pollen sterility combined with distortion of the reproductive whorls of the flowers were particularly pronounced at high doses with a prolonged incubation period. Treated plants had a significantly delayed first flowering and produced short fruits with altered morphology. Variations in seeds with respect to the number, colour and size were also recorded. Total reduction with respect to seedling parameters, total pollen production, the number of fertile pollens, plant height and other damaging effects on leaves, flowers, fruits and seeds increased as the dose and incubation period increased. Statistical analysis revealed the significant negative effect of TSA treatments on plant height, the number of ridges and locules per fruit, number of seeds per fruit and test weight. The treatment, 1.2 µM Trichostatin A incubated for three days, showed a remarkable difference as traits such as total field emergence, seedling parameters and days to first flowering plant height, number of seeds per fruit and test weight deviated from the expected trend of decreasing growth parameters as the dose and incubation period increased. The study further revealed that the treatment (1.2 µM TSA incubated for three days) can be suggested for use in okra to induce epigenetic variations without significantly compromising the growth and vigour parameters of okra.

POLLEN WALL ABORTION 1 is essential for pollen wall development in rice.

The integrity of pollen wall structures is essential for pollen development and maturity in rice (Oryza sativa L.). In this study, we isolated and characterized the rice male-sterile mutant pollen wall abortion 1 (pwa1), which exhibits a defective pollen wall (DPW) structure and has sterile pollen. Map-based cloning, genetic complementation, and gene knockout experiments revealed that PWA1 corresponds to the gene LOC_Os01g55094 encoding a coiled-coil domain-containing protein. PWA1 localized to the nucleus, and PWA1 was expressed in the tapetum and microspores. PWA1 interacted with the transcription factor TAPETUM DEGENERATION RETARDATION (TDR)-INTERACTING PROTEIN2 (TIP2, also named bHLH142) in vivo and in vitro. The tip2-1 mutant, which we obtained by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9-mediated gene editing, showed delayed tapetum degradation, sterile pollen, and DPWs. We determined that TIP2/bHLH142 regulates PWA1 expression by binding to its promoter. Analysis of the phenotype of the tip2-1 pwa1 double mutant indicated that TIP2/bHLH142 functions upstream of PWA1. Further studies suggested that PWA1 has transcriptional activation activity and participates in pollen intine development through the β-glucosidase Os12BGlu38. Therefore, we identified a sterility factor, PWA1, and uncovered a regulatory network underlying the formation of the pollen wall and mature pollen in rice.

Agronomic and Physiological Indices for Reproductive Stage Heat Stress Tolerance in Green Super Rice

Optimum growing temperature is necessary for maximum yield-potential in any crop. The global atmospheric temperature is changing more rapidly and irregularly every year. High temperature at the flowering/reproductive stage in rice causes partial to complete pollen sterility, resulting in significant reduction in grain yield. Green Super Rice (GSR) is an effort to develop an elite rice type that can withstand multiple environmental stresses and maintain yield in different agro-ecological zones. The current study was performed to assess the effect of heat stress on agronomic and physiological attributes of GSR at flowering stage. Twenty-two GSR lines and four local checks were evaluated under normal and heat-stress conditions for different agro-physiological parameters, including plant height (PH), tillers per plant (TPP), grain yield per plant (GY), straw yield per plant (SY), harvest index (HI), 1000-grain weight (GW), grain length (GL), cell membrane stability (CMS), normalized difference vegetative index (NDVI), and pollen fertility percentage (PFP). Genotypes showed high significant variations for all the studied parameters except NDVI. Association and principal component analysis (PCA) explained the genetic diversity of the genotypes, and relationship between the particular parameters and grain yield. We found that GY, along with other agronomic traits, such as TPP, SY, HI, and CMS, were greatly affected by heat stress in most of the genotypes, while PH, GW, GL, PFP, and NDVI were affected only in a few genotypes. Outperforming NGSR-16 and NGSR-18 in heat stress could be utilized as a parent for the development of heat-tolerant rice. Moreover, these findings will be helpful in the prevention and management of heat stress in rice.

Occurrence of cytogenetic effects under the action of epimutagen in winter wheat

Research on studying the features of 0.01%, 0.05%, 0.10% and 0.50% epimutagen Triton-X-305 impact at the cellular level, which means the way of identifying the viability of pollen in plants of the first generation, and cytological analysis of chromosomal aberrations in the cells of the primary meristem of germinal roots during germination of bread winter wheat seeds have been conducted. Research in this direction allows us to significantly improve the monitoring of same type of substances in the environment and to forecast the nature of their action at the DNA-level. Genotypes Podolyanka and Spivanka created by Ukrainian selection and varieties of French selection Altigo, Courtot, Lyrik, Flamenko have been studied. These genotypes were selected in order to characterize possible genotype-mutagenic interactions for a compound of complex hereditary pattern for a range of concentrations with maximum contrast taking into account the possible high site-specific effect. The main purpose of this research was to identify the specificity of impact of the agent Triton X-305 at the cellular level and identify parameters fully showing the effect of this substance on the subsequent induction of biodiversity and the enhancement of hereditary variability at the cellular level. Such indicators as pollen sterility effected by various concentrations, the total frequency of chromosomal rearrangements, the spectrum of chromosomal rearrangements, including fragments and double fragments, single and double bridges, micronuclei and lagging chromosomes have been investigated. The ratio of fragments to bridges as an indicator of the active factor nature, the number of cells with two or more rearrangements as an indicator of genetic toxicity of this substance has been established. As a result, a significantly weaker effect of the epimutagen on the overall frequency of chromosomal rearrangement has been shown unlike other factors of a mutagenic nature, at the same time changing the ratio of the obtained aberrations in favour of micronuclei and lagging chromosomes. In addition, other parameters are determined as more meaningful for identifying a specific agent of impact, and the differences in concentrations are less contrasting. There is also a less significantly decreasing fertility, however, this parameter is highly dependent on the source material. In the future, we intend to assess the variability, primarily of a hereditary nature, by the way of a visual analysis of the obtained material in subsequent generations, as well as through biochemical analysis, yield qualities analysis and morphometry of the obtained material.

Genetic characterization and fine mapping of qHMS4 responsible for pollen sterility in hybrids between Oryza sativa L. and Oryza glaberrima Steud.

The online version contains supplementary material available at 10.1007/s11032-022-01306-8.

Plant Nutrition: An Effective Way to Alleviate Abiotic Stress in Agricultural Crops.

By the year 2050, the world’s population is predicted to have grown to around 9–10 billion people. The food demand in many countries continues to increase with population growth. Various abiotic stresses such as temperature, soil salinity and moisture all have an impact on plant growth and development at all levels of plant growth, including the overall plant, tissue cell, and even sub-cellular level. These abiotic stresses directly harm plants by causing protein denaturation and aggregation as well as increased fluidity of membrane lipids. In addition to direct effects, indirect damage also includes protein synthesis inhibition, protein breakdown, and membranous loss in chloroplasts and mitochondria. Abiotic stress during the reproductive stage results in flower drop, pollen sterility, pollen tube deformation, ovule abortion, and reduced yield. Plant nutrition is one of the most effective ways of reducing abiotic stress in agricultural crops. In this paper, we have discussed the effectiveness of different nutrients for alleviating abiotic stress. The roles of primary nutrients (nitrogen, phosphorous and potassium), secondary nutrients (calcium, magnesium and sulphur), micronutrients (zinc, boron, iron and copper), and beneficial nutrients (cobalt, selenium and silicon) in alleviating abiotic stress in crop plants are discussed.

Combined analysis of transcriptome and metabolome reveals that sugar, lipid, and phenylpropane metabolism are essential for male fertility in temperature-induced male sterile rice.

Photoperiod- and thermosensitive genic male sterility (PTGMS) rice is a vital germplasm resource consisting of two-line hybrid rice in which light and temperature strictly control their fertility changes. Variable environmental conditions present huge risks to the two-lines hybrid seed production. Explaining the regulatory mechanism of male fertility in rice PTGMS lines is an essential prerequisite to ensuring food security production. A group of near-isogenic lines (NILs) of a rice PTGMS line unique to this research group was used for this study. These lines have the same genetic background and regulate male fertility by responding to different temperature changes. Transcriptomic analysis revealed that 315 upregulated genes and 391 regulated genes regulated male fertility in response to temperature changes, and differentially expressed genes (DEGs) were mainly characterized in enrichment analysis as having roles in the metabolic pathways of sugar, lipid and phenylpropanoid. Electron microscopy analysis revealed that a lack of starch accumulation in sterile pollen grains induced by high temperature, with an abnormal exine development and a lack of inner pollen grains. Defective processes for sporopollenin synthesis, sporopollenin transport and pollen wall formation in sterile anthers were verified using qPCR. Targeted metabolomics analysis revealed that most lipids (phospholipids, sphingolipids and fatty acids) and flavonoids (flavones and flavanones) were upregulated in fertile anthers and involved in pollen wall development and male fertility formation, while lignin G units and C-type lignin were the major contributors to pollen wall development. The coding genes for trehalose 6-phosphate phosphatase, beta-1,3-glucanase, phospholipase D and 4-coumarate-CoA ligase are considered essential regulators in the process of male fertility formation. In conclusion, our results indicated that the expression of critical genes and accumulation of metabolites in the metabolism of sugar, lipid, and phenylpropanoid are essential for male fertility formation. The results provide new insights for addressing the negative effects of environmental variation on two-line hybrid rice production.

Consequence of cyclic pollen selection for heat tolerance on the performance of different generations in maize (Zea mays L.)

The reproductive stage in many crops, including maize, is very sensitive to heat stress and the genetic overlap between gametophytic and sporophytic phase gives an opportunity to select superior stress tolerant genotype at gametophytic stage. An attempt was made to evaluate the response of cyclic pollen selection in the F1 and F2 generations on the performance of F3 generation progenies for seed yield and yield contributing traits under natural heat stress conditions. In this direction three groups of F3 progenies, namely (i) pollen selection in F1 and F2 generations (GG), (ii) pollen selection only in F2 generation (CG), (iii) no pollen selection in F1 and F2 generations (CC) were screened for heat stress at Agricultural Research Station (ARS), Bheemarayanagudi. The GG progenies recorded significantly higher chlorophyll content, more number of pollen grains per anther and less pollen sterility compared to CG and CC group of progenies under heat stress. Further, the F4 progenies obtained through cyclic pollen selection (in F1, F2 and F3) were also tested for heat stress tolerance at seedling stage. The significant improvement for heat stress tolerance was recorded in F4 progenies derived through cyclic pollen selection as compared to control (no pollen selection for heat tolerance in any generation) F4 progenies. The results indicated that cyclic pollen selection in F1, F2 and F3 generations improved the heat stress tolerance of the progenies in the succeeding generations. To provide genetic evidence for the effect of pollen selection for heat tolerance, the control F2 (C) and selected F2 (G) populations were compared for the segregation of SSR markers. The selected F2 (G) population showed significant deviation from normal Mendelian ratio of 1:2:1 and showed skewness towards the alleles selected from male parent. The results provide strong evidence for an increase in the frequency of parental alleles in the progenies that impart heat stress tolerance.