MicroRNAs potentially targeting DDR-related genes are differentially expressed upon exposure to γ-rays during seed germination in wheat.

DNA damage response (DDR), a complex network of cellular pathways that cooperate to sense and repair DNA lesions, is regulated by several mechanisms, including microRNAs. As small, single-stranded RNA molecules, miRNAs post-transcriptionally regulate their target genes by mRNA cleavage or translation inhibition. Knowledge regarding miRNAs influence on DDR-associated genes is still scanty in plants. In this work, an in silico analysis was performed to identify putative miRNAs that could target DDR sensors, signal transducers and effector genes in wheat. Selected putative miRNA-gene pairs were tested in an experimental system where seeds from two wheat mutant lines were irradiated with 50 Gy and 300 Gy gamma(γ)-rays. To evaluate the effect of the treatments on wheat germination, phenotypic and molecular (DNA damage, ROS accumulation, gene/miRNA expression profile) analyses have been carried out. The results showed that in dry seeds ROS accumulated immediately after irradiation and decayed soon after while the negative impact on seedling growth was supported by enhanced accumulation of DNA damage. When a qRT-PCR analysis was performed, the selected miRNAs and DDR-related genes were differentially modulated by the γ-rays treatments in a dose-, time- and genotype-dependent manner. A significant negative correlation was observed between the expression of tae-miR5086 and the RAD50 gene, involved in double-strand break sensing and homologous recombination repair, one of the main processes that repairs DNA breaks induced by γ-rays. The results hereby reported can be relevant for wheat breeding programs and screening of the radiation response and tolerance of novel wheat varieties.

Effects of UV-B Radiation Exposure on Transgenerational Plasticity in Grain Morphology and Proanthocyanidin Content in Yuanyang Red Rice.

The effect of UV-B radiation exposure on transgenerational plasticity, the phenomenon whereby the parental environment influences both the parent's and the offspring's phenotype, is poorly understood. To investigate the impact of exposing successive generations of rice plants to UV-B radiation on seed morphology and proanthocyanidin content, the local traditional rice variety 'Baijiaolaojing' was planted on terraces in Yuanyang county and subjected to enhanced UV-B radiation treatments. The radiation intensity that caused the maximum phenotypic plasticity (7.5 kJ·m-2) was selected for further study, and the rice crops were cultivated for four successive generations. The results show that in the same generation, enhanced UV-B radiation resulted in significant decreases in grain length, grain width, spike weight, and thousand-grain weight, as well as significant increases in empty grain percentage and proanthocyanidin content, compared with crops grown under natural light conditions. Proanthocyanidin content increased as the number of generations of rice exposed to radiation increased, but in generation G3, it decreased, along with the empty grain ratio. At the same time, biomass, tiller number, and thousand-grain weight increased, and rice growth returned to control levels. When the offspring's radiation memory and growth environment did not match, rice growth was negatively affected, and seed proanthocyanidin content was increased to maintain seed activity. The correlation analysis results show that phenylalanine ammonialyase (PAL), cinnamate-4-hydroxylase (C4H), dihydroflavonol 4-reductase (DFR), and 4-coumarate:CoA ligase (4CL) enzyme activity positively influenced proanthocyanidin content. Overall, UV-B radiation affected transgenerational plasticity in seed morphology and proanthocyanidin content, showing that rice was able to adapt to this stressor if previous generations had been continuously exposed to treatment.

Genome-Wide Profile of Mutations Induced by Carbon Ion Beam Irradiation of Dehulled Rice Seeds.

As a physical mutagen, carbon ion beam (CIB) irradiation can induce high-frequency mutation, which is user-friendly and environment-friendly in plant breeding. In this study, we resequenced eight mutant lines which were screened out from the progeny of the CIB-irradiated dehulled rice seeds. Among these mutants, CIB induced 135,535 variations, which include single base substitutions (SBSs), and small insertion and deletion (InDels). SBSs are the most abundant mutation, and account for 88% of all variations. Single base conversion is the main type of SBS, and the average ratio of transition and transversion is 1.29, and more than half of the InDels are short-segmented mutation (1-2 bp). A total of 69.2% of the SBSs and InDels induced by CIBs occurred in intergenic regions on the genome. Surprisingly, the average mutation frequency in our study is 9.8 × 10-5/bp and much higher than that of the previous studies, which may result from the relatively high irradiation dosage and the dehulling of seeds for irradiation. By analyzing the mutation of every 1 Mb in the genome of each mutant strain, we found some unusual high-frequency (HF) mutation regions, where SBSs and InDels colocalized. This study revealed the mutation mechanism of dehulled rice seeds by CIB irradiation on the genome level, which will enrich our understanding of the mutation mechanism of CIB radiation and improve mutagenesis efficiency.

Investigation of biological-rhythm patterns: physiological and biochemical effects in herbaceous plants exposed to low-level chronic radiation - part 1: nonirradiated seeds.

HYPOTHESIS: Because reactive oxygen species are involved in the regulation of biological rhythms, we hypothesized that intra-annual variability of seed progeny quality at low doses of ionizing radiation (LDIRs) would differ from that of background plants. MATERIALS AND METHODS: We conducted 12 consecutive experiments using the roll culture method by germinating seeds (monthly for 3 weeks) of six herbaceous plant species (Bromus inermis, Geum aleppicum, Plantago major, Rumex confertus, Silene latifolia, and Taraxacum officinale) growing under conditions of chronic radiation in the East Ural Radioactive Trace (EURT). We assessed physiological (seed viability and abnormality frequency) and biochemical (low-molecular-weight antioxidants, LMWAs) parameters of seedlings. RESULTS: Total absorbed dose rates of maternal plants (TADRplants) and seed embryos (TADRseeds) in the EURT exceeded background levels by 1-3 and 1-2 orders of magnitude, respectively. Nonlinear dependencies on TADR were mainly characteristic of physiological and biochemical parameters. For most populations of the studied species (B. inermis, G. aleppicum, R. confertus, and S. latifolia), seedling survival and root length decreased in the autumn-winter period, while the frequency of abnormal seedlings increased. The content of LMWAs could be ranked as R. confertus > B. inermis > G. aleppicum > S. latifolia, in good agreement with the presence of anthocyanin pigmentation in the plants. The lowest synthesis of antioxidants in seedlings was observed in winter. A high LMWA content promoted growth and reduced the frequency of abnormal seedlings. CONCLUSIONS: These results underscore a multistage nature of the impact of LDIRs on intra-annual biological rhythms in plants. High heterogeneity in reference group 'wild grasses' and diversity of their radiobiological effects should help to develop methods of radiation protection for natural ecosystems and facilitate approaches used by the International Commission on Radiological Protection.HighlightsAbsorbed dose rates for six plant species in the East Ural Radioactive Trace (EURT) area range from 0.11 to 73.89 µGy h-s (plants) and 0.11 to 6.88 µGy h-s (seed embryos).Intra-annual rhythms of physiological and biochemical parameters in the EURT zone differ from those in background seedlings.Plants in the EURT area exhibit a wide range of trait variability, asynchrony of the manifestation of the effects, nonlinear dose-response relations, and hormesis.A high content of low-molecular-weight antioxidants (LMWAs) is associated with low frequency of developmental abnormalities and high viability of seed progeny.

The effect of germinated black lentils on cookie quality by applying ultraviolet radiation and ultrasound technology.

Black lentils contain protein, carbohydrates, dietary fiber, minerals, and vitamins, as well as phytochemicals and various bioactive compounds. Ultraviolet (UV) radiation and ultrasound (US) methods are innovative technologies that can be used to increase the efficiency of the germination process in grains and legumes. To improve the nutritional value and bioactive compounds of the cookies, black lentils germinated by applying UV radiation and US technology were used in the cookie formulation. Before the germination process, UV, US, and their combination (UV+US) were applied, and pretreated and unpretreated germinated black lentil flours were used at a level of 20% in the cookie formulation. The results revealed that pretreatment application increased the total phenolic content and antioxidant activity more than the lentil sample germinated without any treatment. In addition, the pretreatments applied further reduced the amount of phytic acid in black lentils and the lowest phytic acid content was obtained with the UV-US combination. Compared to cookies containing unpretreated germinated black lentil flour, higher L* values and lower a* values were obtained in the cookie samples containing pretreated germinated black lentil flour. Cookies containing all pretreated germinated lentils generally exhibited higher Ca and K content. This study demonstrated that UV radiation and US improved the nutritional value and bioactive components of the germinated black lentil flour and the cookies in which it was used, compared to the black lentils germinated without any treatment. PRACTICAL APPLICATION: Pretreatment of black lentils with UV/US application before germination resulted in a greater increase in total phenolic content and antioxidant activity compared to the control sample. The applied pretreatments caused a further decrease in the amount of phytic acid in black lentil samples. Black lentils germinated with the UV+US combination revealed higher Ca, Fe, K, and Mg content compared to the sample germinated without any treatment.

Mitigating salt stress by conditioning seeds with ultraviolet light (UV-C) in white oats (Avena sativa L.).

Seed conditioning with ultraviolet light (UV-C) might (1) improve crop yield and quality, (2) reduce the use of agrochemicals during cultivation, and (3) increase plant survival in high salinity environments. The aim of this study was to examine the effects of UV-C conditioning of white oat seeds at two doses (0.85 and 3.42 kJ m-2) under salinity stress (100 mM NaCl). Seeds were sown on germination paper and kept in a germination chamber at 20°C. Germination and seedling growth parameters were evaluated after 5 and 10 days. Data demonstrated that excess salt reduced germination and initial growth of white oat seedlings. In all the variables analyzed, exposure of seeds to UV-C under salt stress exerted a positive effect compared to non-irradiated control. The attenuating influence of UV-C in germination was greater at 0.85 than at 3.42 kJ m-2. Thus, data indicate that conditioning white oat seeds in UV-C light produced greater tolerance to salt stress. These findings suggest that UV-C conditioning of white oat seeds may be considered as a simple and economical strategy to alleviate salt-induced stress.

In Vitro Gamma Mutagenesis Techniques in Rice (Oryza sativa L. var. Lazarroz FL).

Gamma radiation (60Co)-induced mutagenesis offers an alternative to develop rice lines by accelerating the spontaneous mutation process and increasing the pool of allelic variants available for breeding. Ionizing radiation works by direct or indirect damage to DNA and subsequent mutations. The technique can take advantage of in vitro protocols to optimize resources and accelerate the development of traits. This is achieved by exposing mutants to a selection agent of interest in controlled conditions and evaluating large numbers of plants in reduced areas. This chapter describes the protocol for establishing gamma radiation dosimetry and in vitro protocols for optimization at the laboratory level using seeds as the starting material, followed by embryogenic cell cultures, somatic embryogenesis, and regeneration. The final product of the protocol is a genetically homogeneous population of Oryza sativa that can be evaluated for breeding against abiotic and biotic stresses.

Using Magnetic Fields to Enhance the Seed Germination, Growth, and Yield of Plants.

Geomagnetic field (GMF) protects living organisms on the Earth from the radiation coming from space along with other environmental factors during evolution, and it has affected the growth and development of plants. Many researchers have always been interested in investigating these effects in different aspects. In this chapter, we focus on the methods of using different types of magnetic fields (MFs) to investigate the dimensions of their biological effects on plants. The aim is to increase seed germination, growth characters, and yield of plants using the following methods: (1) Using MFs lower than GMF to study effects of GMF on the growth and yield of plants. (2) Using reversed magnetic fields (RMFs) lower than GMF to study its effects on the growth and development of plants during evolution. (3) Using static magnetic fields (SMFs) higher than GMF and reversed SMFs to study effects of the south (S) and north (N) magnetic pole on plants. (4) Using electromagnetic fields (EMFs) to increase and accelerate seed germination, growth, and yield of plants, and establish the status of plants against other environmental stresses. (5) Using magnetized water (MW) to improve plant seed germination, growth, and yield. (6) Using high gradient magnetic field (HGMF) to study magneto-tropism in plants. In this chapter, we recommend application of various types of MFs to study their biological effects on plants to improve crop production.

How does ionizing radiation affect amyloidogenesis in plants?

PURPOSE: Ionizing radiation is a harsh environmental factor that could induce plant senescence. We hypothesized that radiation-related senescence remodels proteome, particularly by triggering the accumulation of prion-like proteins in plant tissues. The object of this study, pea (Pisum sativum L.), is an agriculturally important legume. Research on the functional importance of amyloidogenic proteins was never performed on this species. MATERIALS AND METHODS: Pea seeds were irradiated in the dose range 5-50 Gy of X-rays. Afterward, Fourier-transform infrared spectroscopy (FTIR) was used to investigate changes in the secondary structure of proteins in germinated 3-day-old seedlings. Specifically, we evaluated the ratio between the amide I and II peaks. Next, we performed protein staining with Congo red to compare the presence of amyloids in the samples. In parallel, we profiled the detergent-resistant proteome fraction by ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS). Differentially accumulated proteins were functionally analyzed in MapMan software, and the PLAAC tool was used to predict putative prion-like proteins. RESULTS: We showed a reduced germination rate but higher plant height and faster appearance of reproductive organs in the irradiated at dose of 50 Gy group compared with the control; furthermore, we demonstrated more ß-sheets and amyloid aggregates in the roots of stressed plants. We detected 531 proteins in detergent-resistant fraction extracted from roots, and 45 were annotated as putative prion-like proteins. Notably, 29 proteins were significantly differentially abundant between the irradiated and the control groups. These proteins belong to several functional categories: amino acid metabolism, carbohydrate metabolism, cytoskeleton organization, regulatory processes, protein biosynthesis, and RNA processing. Thus, the discovery proteomics provided deep data on novel aspects of plant stress biology. CONCLUSION: Our data hinted that protein accumulation stimulated seedlings' growth as well as accelerated ontogenesis and, eventually, senescence, primarily through translation and RNA processing. The increased abundance of primary metabolism-related proteins indicates more intensive metabolic processes triggered in germinating pea seeds upon X-ray exposure. The functional role of detected putative amyloidogenic proteins should be validated in overexpression or knockout follow-up studies.

Evaluation of morpho-physiological responses and genotoxicity in Eruca sativa (Mill.) grown in hydroponics from seeds exposed to X-rays.

Due to its potential applications in cultivated plants, ionizing radiation (IR) and its effect on organisms is increasingly studied. Here we measured the effects of ionizing radiation on Eruca sativa by analyzing plants from irradiated seeds (1 and 10 Gy) grown in hydroponics. We measured several morpho-physiological traits and genotoxicity. Radiation stress induced a noticeable variability of the morpho-physiological traits highlighting decreased plant vigor. Shoot length and leaf number were significantly higher in 1 Gy-treated samples, whereas root length was significantly higher in 10 Gy treated plants. Stomata number significantly increased with IR dose, whereas both pigment and Rubisco content decreased under radiation stress. Phenol content significantly increased in 1 Gy treated samples, otherwise from total antioxidants, which were not different from control. Most results could find a feasible explanation in a hormesis-like pattern and in a decreased plant vigor under radiation stress. IR induced genotoxic damage, evaluated by ISSR markers, in 15 day old leaves; specifically, a severe decrease in the genome template stability was observed. However, a partial recovery occurred after 2 weeks, especially under the lowest dose (i.e., 1 Gy), suggesting that DNA damage detection and repair mechanisms are active. Pigment content and genotoxic damage may serve as proxies for evaluating plant responses to IR stress, since they show univocal dose-dependent trends. The use of more checkpoints for analyses and more doses over a wider range, as well as the focus on different metabolites, could help elucidate plant response in terms of morpho-physiological changes.

Response of Satureja hortensis L. to gamma radiation and its impact on secondary metabolite content and biochemical characteristics.

PURPOSE: The current study investigated the effects of gamma irradiation on biochemical parameters and secondary metabolite accumulation in Summer Savory under field conditions. MATERIALS AND METHODS: The dry seeds of Summer Savory (with a moisture content of 12%) were exposed to gamma radiation at the doses of 20, 40, 60, 80, and 100 Gy. Non-irradiated seeds (0 Gy) were used as control. RESULTS: Our findings showed that gamma radiation at low doses (20-40 Gy) had no effect on biochemical parameters and secondary metabolites accumulation in S. hortensis. These parameters are steadily and significantly increased by raising gamma irradiation doses from 40 to 100 Gy. The highest amount of chlorophyll a and b, carotenoids, anthocyanin, and total phenolic and flavonoid content were observed in 80 and 100 Gy treatments. Plants exposed to 80 and 100 Gy treatments accumulated the maximum amounts of rosmarinic acid and caffeic acid, respectively. Furthermore, the analysis of S. hortensis essential oil revealed that gamma radiation significantly alters its components. Carvacrol, α-Pinene, and α-Thujene levels raised dramatically compared to control with an increase in gamma irradiation dose from 20 to 100 Gy, while Thymol and α-Terpinene levels lowered. CONCLUSIONS: Our results showed that treatment of Summer Savory seeds with gamma radiation at 80 and 100 Gy doses could significantly be raised biochemical parameters and secondary metabolites accumulation under field conditions. The current study showed that gamma irradiation could be used as a pre-sowing elicitor to improve the quantity and quality of phytochemicals in Summer Savory.

Stress memory in two generations of Plantago major from radioactive and chemical contaminated areas after the cessation of exposure.

HYPOTHESIS: The differences in viability, root length, and pro/antioxidant features of Plantago major seedlings identified in seed progeny formed in areas of radioactive and chemical contamination can persist in subsequent generations after the elimination of the stress. MATERIALS AND METHODS: The seed mixtures of F1 generation were collected from P. major natural populations (P plants) growing for a long time in the East Ural Radioactive Trace, the Karabash Copper Smelter zone, and background area. The seeds of F2 generation were obtained from F1 generation plants grown on experimental plots with 'clean' agricultural background; F3 generation was grown from F2 generation on the same plots. The viability of seed progeny was estimated by survival rate and root length. Pro/antioxidant features were determined spectrophotometrically by malondialdehyde content, superoxide dismutase and catalase activities, and total content of low molecular weight antioxidants in seedlings. RESULTS AND CONCLUSIONS: The hypothesis about the persistence of effects from chronic exposure to ionizing radiation and chemical contamination in the generations' sequence of P. major after the removal of stress was confirmed only partially. The data obtained indicated that changes in the prooxidant and antioxidant features of plants in response to low doses of ionizing radiation can persist for at least in two generations after the stress removal. In the case of long-term exposure to chemical contaminants, we observed the persistence of the effect in a succession of generations only on the morphological indicator of root length.

Evaluating the role of gamma irradiation to ameliorate salt stress in corn.

PURPOSE: Salt stress is a significant issue in corn cultivation leading to corn yield reduction, especially in the arid and semi-arid regions. Nuclear technologies, along with other standard methods, can be used as an efficient method for mitigating salt stress effects on plants. MATERIALS AND METHODS: In this research, gamma irradiation (GI) was studied on seeds in the salt stress amelioration of corn in laboratory and field conditions. A total of five doses of gamma rays (25, 50, 100, 150 and 200 Gy) were applied to corn seeds (SC.703) at the laboratory under saline and control conditions. The best gamma-ray treatment (25 Gy) was selected for studying corn under salt stress in the field condition. RESULTS: The length of the radicle, seminal roots and shoot, dry weight of radicle, and seminal roots were affected by salt stress (p <.001). However, GI affected only the radicle and seminal root length (p < .001). The radicle length was decreased as much as 3, 11, 17, 25, and 27% in 25, 50, 100, 150 and 200 Gy of GI, respectively. In addition, the seminal root length was decreased in all GI treatments except 25 Gy (p < .05). Plants derived from seeds exposed to GI (25 Gy) had a higher chlorophyll content of 1, 17, and 29% at V3 (third leaf stage), R1 (silk stage, p < .001), and R4 (dough stage, p < .001), respectively. In GI treatment, the soluble carbohydrate content was significantly higher (p < .001) at all three measurement stages and the soluble protein was significantly higher (p < .001) only at the R4 stage. Moreover, proline content was higher in GI (25 Gy) at V3 (58%, p < .05) and R1 (98%, p < .001) treatment stages. CONCLUSION: Since plants from gamma-irradiated seeds had a greater plant weight and their economic traits (cob and grain weight) were higher compared to control plants under salt stress conditions, it can be concluded that a low dose of GI may ameliorate the effect of salt stress on the corn plants.

Beneficial effects of gamma-irradiation of quinoa seeds on germination and growth.

Quinoa is one of the crops well-adapted to high altitude regions that can grow relatively well under drought, humid, and high UV radiation conditions. This study was performed to investigate the effects of gamma-radiation on quinoa. Seeds were treated with various doses of 50 Gy, 100 Gy, 200 Gy, 300 Gy, 400 Gy, 600 Gy, 800 Gy, and 1000 Gy. We investigated germination, as well as plant height, chlorophyll content, and normalized difference vegetation index (NDVI) at 0, 30, 44, 58, and 88 days after transplanting (DAT) and panicle weight at 88 DAT. The plants grown from the seeds treated at radiation doses greater than 200 Gy showed reduced values in most growth and physiological characteristics. The germination rate and germination speed were higher in the 50 Gy-treated seeds than in 0 Gy-treated (control) seeds. Plant height and panicle weight were highest in the plants from 50 Gy-treated seeds. Chlorophyll content was higher in all treated samples than in the controls. NDVI value showed the highest value in 0 Gy controls and plants treated with 50 Gy. The antioxidant activity was also higher in the plants from the seeds treated with 50 Gy and 100 Gy, showing a steady increase as the radiation dose increased even at 200 Gy. The plants from seeds treated with 0 Gy showed higher expression of proteins related to photorespiration and tubulin chains. The plants from seeds treated with 50 Gy induced more stress-responsive proteins.

Effect of Extraction Procedures with Ultrasound and Cellulolytic Enzymes on the Structural and Functional Properties of Citrus grandis Osbeck Seed Mucilage.

The structural and functional properties of Citrus grandis Osbeck (CGO) seed mucilage by different extraction practices, including conventional citrate buffer, ultrasonic-assisted (UAE), enzymatic-assisted extraction (EAE) with cellulase or Celluclast® 1.5 L and various ultrasonic-assisted enzymatic extraction (UAEE) procedures were investigated. It was found that CGO seed from agricultural and processing byproducts is an excellent new source of high methoxyl pectin with quite high intrinsic viscosity (about 108.64 dL/g) and molecular weight (about 1.9 × 106) as compared with other pectin sources. UAEE with Celluclast® 1.5 L enhanced the extraction yield most pronouncedly (about 2.3 times). Moreover, the monosaccharide composition of CGO seed mucilage is least affected by EAE with Celluclast® 1.5 L. In contrast, EAE with cellulase dramatically reduces the galacturonic acid (GalA) content to less than 60 molar%, and increases the glucose (Glc) content pronouncedly (to about 40 molar%), which may be considered as an adverse effect in terms of pectin purity. Though extraction procedures involved with ultrasound and cellulolytic enzymes generally show a decrease in GalA contents, weight average molar mass and intrinsic viscosity, EAE with Celluclast® 1.5 L is least affected, followed by UAE and UAEE with Celluclast® 1.5 L. These features can be leveraged in favor of diversified applications.

Beyond the PAR spectra: impact of light quality on the germination, flowering, and metabolite content of Stevia rebaudiana (Bertoni).

BACKGROUND: Stevia rebaudiana is a high value crop due to the strong commercial demand for its metabolites (steviol glycosides) but has limited geographical cultivation range. In non-native environments with different daylength and light quality, Stevia has low germination rates and early flowering resulting in lower biomass and poor yield of the desired metabolites. In this study, artificial lighting with light-emitting diodes (LEDs) was used to determine if different light quality within and outside of the photosynthetically active radiation (PAR) range can be used to improve germination rates and yields for production of steviol glycosides for the herbal supplement and food industry. RESULTS: Plants treated with red and blue light at an intensity of 130 µmol m-2  s-1 supplemented with 5% of UV-A light under a 16-h photoperiod produced the most desirable overall results with a high rate of germination, low percentage of early flowering, and high yields of dry leaf, stevioside and rebaudioside A, 175 days after planting. CONCLUSION: While red and blue light combinations are effective for plant growth, the use of supplemental non-PAR irradiation of UV-A wavelength significantly and desirably delayed flowering, enhanced germination, biomass, rebaudioside A and stevioside yields, while supplemental green light improved yield of biomass and rebaudioside A, but not stevioside. Overall, the combination of red, blue and UV-A light resulted in the best overall productivity for Stevia rebaudiana. © 2021 Society of Chemical Industry.

Time Course Analysis of Genome-Wide Identification of Mutations Induced by and Genes Expressed in Response to Carbon Ion Beam Irradiation in Rice (Oryza sativa L.).

Heavy-ion irradiation is a powerful mutagen and is widely used for mutation breeding. In this study, using whole-genome sequencing (WGS) and RNA sequencing (RNA-seq) techniques, we comprehensively characterized these dynamic changes caused by mutations at three time points (48, 96, and 144 h after irradiation) and the expression profiles of rice seeds irradiated with C ions at two doses. Subsequent WGS analysis revealed that more mutations were detected in response to 40 Gy carbon ion beam (CIB) irradiation than 80 Gy of CIB irradiation at the initial stage (48 h post-irradiation). In the mutants generated from both irradiation doses, single-base substitutions (SBSs) were the most frequent type of mutation induced by CIB irradiation. Among the mutations, the predominant ones were C:T and A:G transitions. CIB irradiation also induced many short InDel mutations. RNA-seq analysis at the three time points showed that the number of differentially expressed genes (DEGs) was highest at 48 h post-irradiation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the DEGs showed that the "replication and repair" pathway was enriched specifically 48 h post-irradiation. These results indicate that the DNA damage response (DDR) and the mechanism of DNA repair tend to quickly start within the initial stage (48 h) after irradiation.

HY5 and ABI5 transcription factors physically interact to fine tune light and ABA signaling in Arabidopsis.

KEY MESSAGE: Cross-talk between light and ABA signaling is mediated by physical interaction between HY5 and ABI5 Arabidopsis. Plants undergo numerous transitions during their life-cycle and have developed a very complex network of signaling to integrate information from their surroundings to effectively survive in the ever-changing environment. Light signaling is one of the crucial factors that govern the plant growth and development from the very first step of that is from seedling germination to the flowering. Similarly, Abscisic acid (ABA) signaling transduces the signals from external unfavorable condition to the internal developmental pathways and is crucial for regulation of seed maturation, dormancy germination and early seedling development. These two fundamental factors coordinately regulate plant wellbeing, but the underlying molecular mechanisms that drive this regulation are poorly understood. Here, we identified that two bZIP transcription factors, ELONGATED HYPOCOTYLE 5 (HY5), a positive regulator of light signaling and ABA-INSENSITIVE 5 (ABI5), a positive regulator of ABA signaling interacts and integrates the two pathways together. Our phenotypic data suggest that ABI5 may act as a negative regulator during photomorphogenesis in contrast, HY5 acts as a positive regulator of ABA signaling in an ABA dependent manner. We further showed that over-expression of HY5 leads to ABA-hypersensitive phenotype and late flowering phenotype. Taken together, our data provides key insights regarding the mechanism of interaction between ABI5-HY5 that fine tunes the stress and developmental response in Arabidopsis.

Metabolic activities and molecular investigations of the ameliorative impact of some growth biostimulators on chilling-stressed coriander (Coriandrum sativum L.) plant.

BACKGROUND: Priming of seed prior chilling is regarded as one of the methods to promote seeds germination, whole plant growth, and yield components. The application of biostimulants was reported as beneficial for protecting many plants from biotic or abiotic stresses. Their value was as important to be involved in improving the growth parameters of plants. Also, they were practiced in the regulation of various metabolic pathways to enhance acclimation and tolerance in coriander against chilling stress. To our knowledge, little is deciphered about the molecular mechanisms underpinning the ameliorative impact of biostimulants in the context of understanding the link and overlap between improved morphological characters, induced metabolic processes, and upregulated gene expression. In this study, the ameliorative effect(s) of potassium silicate, HA, and gamma radiation on acclimation of coriander to tolerate chilling stress was evaluated by integrating the data of growth, yield, physiological and molecular aspects. RESULTS: Plant growth, yield components, and metabolic activities were generally diminished in chilling-stressed coriander plants. On the other hand, levels of ABA and soluble sugars were increased. Alleviation treatment by humic acid, followed by silicate and gamma irradiation, has notably promoted plant growth parameters and yield components in chilling-stressed coriander plants. This improvement was concomitant with a significant increase in phytohormones, photosynthetic pigments, carbohydrate contents, antioxidants defense system, and induction of large subunit of RuBisCO enzyme production. The assembly of Toc complex subunits was maintained, and even their expression was stimulated (especially Toc75 and Toc 34) upon alleviation of the chilling stress by applied biostimulators. Collectively, humic acid was the best the element to alleviate the adverse effects of chilling stress on growth and productivity of coriander. CONCLUSIONS: It could be suggested that the inducing effect of the pretreatments on hormonal balance triggered an increase in IAA + GA3/ABA hormonal ratio. This ratio could be linked and engaged with the protection of cellular metabolic activities from chilling injury against the whole plant life cycle. Therefore, it was speculated that seed priming in humic acid is a powerful technique that can benefit the chilled along with non-chilled plants and sustain the economic importance of coriander plant productivity.