Stomatal guard cells are specialized epidermal cells regulating gas exchange. The ability to open or close in response to external and internal cues makes stomata a dynamic and fascinating system. Stomatal closure upon infection ensures restriction of pathogen entry into the plant and forms an essential component of innate immunity. The opening or closure of stomata is dependent on the turgidity or flaccidity of guard cells, respectively, facilitated by several signaling components, including reactive oxygen species, nitric oxide (NO) and Ca²⁺. Among these, NO is the most extensively studied gasotransmitter. Its pivotal role in stomatal closure by modulating various downstream components as well as regulation of crucial proteins by post-translational modifications makes NO an essential factor. Two more gasotransmitters, carbon monoxide and hydrogen sulfide, also trigger stomatal closure. Other gaseous molecules, like ethylene, methane, sulfur dioxide, ozone, and CO₂, can modulate stomatal closure, but they are not considered strictly as gasotransmitters due to specific criteria. We review the signaling events in guard cells triggered by these gasotransmitters leading to stomatal closure. We point out the dual role of NO to promote stomatal closure and stomatal opening. Both NO and H₂S help in reinforcing the innate immunity against pathogen attack. Although there is extensive information on the mechanism of NO action on stomata, the enzymatic source of NO or CO is still ambiguous. Similarly, research is warranted to establish the relative importance of and interactions among the three main gasotransmitters. Further studies on gasotransmitters would answer the ambiguity about their functions and confirm if they can act independently.

Over the past few decades, rice (Oryza sativa L.) has remained a fundamental staple crop and a primary nutritional energy source for nearly 3.5 billion people worldwide, particularly in Asia. With the global population projected to reach 9.6 billion by 2050, rice production must significantly increase to meet the escalating food demand. However, salinity stress poses a major abiotic challenge that severely hampers plant growth and productivity. Soil salinization, driven by climate change and rising temperatures, leads to an excessive accumulation of salts in the soil (Sári et al., 2023). This phenomenon disrupts plant physiology through water deficit, cytotoxic effects of Na⁺ and Cl⁻ ion accumulation, and nutrient imbalances (Isayenkov and Maathuis, 2019). In coastal regions, salinity stress is further intensified by seawater intrusion into groundwater reserves (Muhardi et al., 2020), while in arid and semi-arid areas, low rainfall limits salt leaching, resulting in excessive salt accumulation (Karolinoerita and Yusuf, 2020). Exposure to salinity stress induces the overproduction of reactive oxygen species (ROS), a group of highly reactive free radicals that can damage essential cellular components, including DNA, proteins, lipids, and pigments, ultimately impairing plant function (Ghosh et al., 2021). To mitigate these detrimental effects, plants activate various adaptive responses (Huong et al., 2020), including the upregulation of antioxidant enzyme systems (Jan et al., 2019), which play a crucial role in ROS scavenging and oxidative stress alleviation. These responses involve both well-developed enzymatic and non-enzymatic scavenging pathways or detoxification systems to counter the destructive effects of ROS that include the enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and so forth (Hasanuzzaman et al., 2011).

Plants have developed adaptive strategies to cope with environmental stresses, but mechanisms effective under one stress may be counterproductive under others. This study investigates the effect of moderate drought stress pretreatment on the resistance of Brassica napus to Leptosphaeria maculans, the pathogen causing blackleg disease. B. napus plants were exposed to varying durations of drought stress, followed by a 24-h recovery period before inoculation with L. maculans. The results demonstrate a priming effect of the drought pretreatment, with a reduction in necrotic lesions in cotyledons compared to non-stressed controls. The most pronounced effect was observed in plants that underwent a 68-h drought pretreatment, resulting in a 45% reduction in disease symptoms. The transcriptions of 17 genes involved in B. napus defence against pathogen infection and drought stress were monitored. This revealed the involvement of the salicylic acid signaling pathway, indicated by increased expression of PR1 and PR2 marker genes. Additionally, drought stress marker genes were upregulated. These findings provide insight into the mechanisms of plant adaptation to combined biotic and abiotic stresses, which is essential for sustainable agriculture in a changing environment.

Cytosine methylation plays an important role in plant development by regulating gene expressions. However, few studies have investigated methylation changes during the tissue differentiation and development of perennial plants. Here, the fluorescence-labeled methylation-sensitive amplified polymorphism method was used with eight primer combinations to detect methylation in leaves and xylem obtained at the stages of inflorescence emergence (IE), ovary start growth, and fruit maturity (FM) in two pecan (Carya illinoinensis) cvs. Pawnee and Stuart. The results show that the total methylation in the xylem was generally higher than in the leaves at each stage. Substantial methylation variations were observed at the amplified sites in pecan tissues at the various stages. The methylation patterns changed between the leaf and xylem, with frequencies from 44.97 to 67.01 % over the three stages in the two cultivars, among which the variation frequency between the tissues at the FM stage was the highest for each cultivar. The frequencies of methylation variation between the leaf samples at any two stages ranged from 31.86 to 45.88 %, with higher variation frequencies between the xylem samples (40.90 - 59.44 %) for each cultivar, which is consistent with the comparative results of polymorphism rates between the leaf and xylem over the three stages. Cluster analysis and principal coordinate analysis suggest that the xylem at the IE and FM stages had relatively distant epigenetic relationships with other tissue samples as a whole. This study reveals the patterns of methylation variation and methylation relationships among pecan tissues undergoing different developmental processes, implying the important roles of methylation in tissue differentiation and development of trees. These results lay a theoretical foundation for elucidating the regulatory mechanisms of methylation involved in tree development.

The purpose of this study was to show the extent of phenotypic plasticity of the grass Deschampsia caespitosa from four habitats with different soil properties by comparing selected leaf traits and content of silicon and other elements. Morphological, biochemical, and optical properties were examined in leaves, but content of silicon and other elements also in soil samples. Plant-available silicon in the soil was determined following extraction in CaCl₂. Bulk element analysis was conducted using X-ray fluorescence spectrometry. The habitats of D. caespitosa differed significantly according to soil structure, which resulted in significantly different leaf traits, including leaf optical properties and content of minerals. There was no correlation between leaf silicon and plant-available or total soil silicon, while positive correlation was seen between leaf calcium and total soil calcium. In addition, plant-available silicon showed strong positive correlation with leaf calcium and phosphorus. The majority of D. caespitosa leaf and soil properties differed significantly among habitats.

The class III PRX family is a class of heme-containing oxidases and plays important roles in response to abiotic stress in plants. The responses to abiotic stresses could be regulated by phytohormones like abscisic acid (ABA) and methyl jasmonate (MeJA). In this research, 11 CsPRXs genes in tea plant (Camellia sinensis) were cloned and analyzed. Based on the similarity of the sequences, they were classified into 5 sub-groups. According to the results of reverse transcription PCR, CsPRX55 presented the highest expression in roots compared to stems and leaves of both tea cultivars LJ43 and Baiye 1. Besides, the expressions of CsPRX12 and CsPRX73 were highest in roots, while CsPRX4, CsPRX47, and CsPRX72 were highest in stems of 'Baiye 1'. But most of CsPRXs showed the highest expressions in leaves of 'LJ43'. CsPRXs appeared different expression patterns under drought stress of tea plants which were pre-treated with ABA or MeJA for three days. In 'LJ43' and 'Baiye 1', there were 3 CsPRXs and 7 CsPRXs up-regulated by exogenous ABA and MeJA, respectively. However, CsPRX4 and CsPRX16 were down-regulated in 'LJ43' treated with ABA and MeJA. It suggested that CsPRXs possessed diverse functions in response to hormones and abiotic stress. In 'LJ43', the activity of peroxidase (POD) was increased when pre-treated by ABA and MeJA, and the highest activity appeared after 24 and 12 h, respectively. In 'Baiye 1', the activity of POD was also increased, however, when pre-treated by MeJA, the peak-time of POD activity was at 24 h. But the change had no obvious rule after ABA treatment. Exogenous ABA or MeJA may play a role in protecting tea plants suffered from drought stress via regulating some CsPRXs expressions and increasing POD activity.

Roots are important for plant anchoring, water and nutrient absorption, and other physiological processes. Gravity is a primary determinant of the spatial distribution of plant roots in the soil. Therefore, in-depth understanding of the molecular mechanisms and biochemical networks of root responses to gravity has both theoretical and practical significance in guiding the genetic improvement of plants. Gravitropism, the process through which plants sense the direction of gravity and respond by making the roots grow downward and the stem grow upward, has been widely studied in roots. The perception of gravity and the gravitational growth of roots, key steps in root growth and development, are regulated by auxins and other factors. Here, we review the latest progress in the regulation of root gravitropism by hormone signals and environmental factors from a molecular perspective, and look forward to the direction of future research on root gravitropism.

In plant breeding, polyploidization is an established technique to obtain superior phenotypic characteristics. In seed propagated agricultural crops, seed treatments with antimitotic agents are often used to obtain chromosome doubling. Here, we developed a method to induce polyploidization in clonally propagated fodder grasses Lolium, Festuca, and the intergeneric hybrid Festulolium. The aim was to obtain specific genotypes at both the diploid and tetraploid levels. We evaluated different types of plant explants, and the effects of the type, concentration, and application mode of three antimitotic agents (oryzalin, colchicine, and trifluralin) on the survival rate and the polyploidization efficiency. The treatment of greenhouse-grown tillers with antimitotics only resulted in mixoploids, while tissue culture propagated plants were successfully polyploidized. A shock pretreatment, using a high concentration of an antimitotic agent during a short period, successfully induced tetraploids in all three genera. Additionally, supplementing the tissue culture medium with a lower dosage of an antimitotic agent during minimal four weeks after the shock pretreatment further promoted polyploidization. By our methods, we were able to generate diploid and tetraploid plants with an identical genomic constitution but different ploidy allowing investigation of the effects of polyploidization on plant physiology and gene regulatory networks.

Lettuce is one of our most important leaf vegetables that can be cultivated safely in organic farming, which is not only pesticide-free, but also aims to maintain and stimulate the presence of naturally occurring beneficial organisms, such as algae, mosses, bacteria, or arbuscular mycorrhiza (AM) fungi. These organisms are all beneficial for soil life and nutrient decomposition. The positive effects of beneficial microorganisms could be enhanced by mulching which is a widely used practice in organic farming. Mulching may also increase soil nutrient substance after decomposition and inhibit weed growth. In our experiment, we sought to determine the effect of different mulching techniques (alfalfa, rye, black foil) on AM root colonisation, leaf chlorophyll (Chl) content, and on peroxidase (POD) activity in Lactuca sativa plants and observe whether there are correlations between these parameters. Results show natural mulching has a positive effect on mycorrhiza fungi root colonisation and therefore lowers the stress in lettuce plant. On the other hand, there was no significant correlation between root colonisation and Chl content. As POD enzymes are directly linked to enzymatic browning, the high colonisation rate of AM may consequently lower post-harvest browning in lettuce.

Phosphorus is a key limiting factor for plant growth. Several approaches are developed to mitigate the impact of P shortage on plants and to the selection of crops with high P mobilizing capacity from P-deficient soils. In this work, four Medicago truncatula genotypes (A17, TN8.20, TN1.11, and TN6.18) were compared for their efficiency to cope with P limiting conditions using several criteria. Significant differences between genotypes, P deficiency treatments, and the interaction of genotypes with P deficiency treatments were found. P limitation resulted in an important decrease in shoot biomass, P content, P use efficiency, and photosynthetic parameters. A significant variability was found between the four genotypes, with A17 and TN8.20 being the most tolerant genotypes to P deficiency. This was consistent with the better ability of these genotypes to acidify rhizosphere and stimulate the activity of acid phosphatase and its relative gene (MtPAP1). The expression of P transporter genes (MtPT1, MtPT3, and MtPT5) was induced by P deficiency, however, the overexpression of those genes was more pronounced in tolerant genotypes. Overall, our data indicate that A17 and TN8.20 are more efficient in mobilizing P under limiting conditions and could be cultivated in P-deficient soils as forage crops.

Strigolactones (SL) are crucial plant hormones that regulate plant growth. We investigated genetic and metabolic changes in tobacco axillary flower buds following application of GR24 (SL synthetic analogue), administered 2 and 6 days later. The results indicated that GR24 effectively inhibited the growth of axillary buds. RNA sequencing revealed 1 781 differentially expressed genes in axillary buds after 6 days of GR24 treatment compared to untreated controls. Among them, 882 genes were up-regulated following GR24 treatment, suggesting substantial number of genes experienced significant changes in expression following GR24 treatment. Four carbohydrate metabolites exhibited altered abundance after 6 days of GR24 treatment; one increased and three decreased. In this study, GR24 induces substantial changes in the transcriptome and metabolome of tobacco axillary buds, with the starch and sucrose metabolic pathways and the phenylpropane biosynthesis pathway playing essential roles in the regulation of tobacco axillary bud development. Transcriptomic and metabolomic analyses highlighted that GR24 treatment significantly modulated the starch and sucrose metabolic pathways and the phenylpropane biosynthesis pathway. Our results suggest that the metabolic pathways of starch and sucrose and the biosynthesis pathway of phenylpropane play important roles in the regulation of growth and development of tobacco axillary buds by GR24.

Mesembryanthemum crystallinum is a model halophyte that switches from C₃ photosynthesis to Crassulacean acid metabolism (CAM) upon extreme abiotic stresses. This study aimed to investigate alkalinity-induced root transcriptome profiling in M. crystallinum. M. crystallinum seedlings were treated with 50 mM sodium bicarbonate (NaHCO₃; pH 7.5) and 90 mM NaHCO₃ (pH 9.5) for 7 d, respectively. Alkalinity-induced differentially expressed genes (DEGs) were identified and annotated. Functional enrichment analysis was performed for DEGs. The expression of genes related to response to stress and CAM were analyzed and compared. Comparing with control, 50 and 90 mM NaHCO₃ treatments induced 4 027 and 25 403 DEGs in M. crystallinum roots, respectively. Among these DEGs, 832 and 131 DEGs were consistently upregulated and downregulated by both stresses, respectively. These genes were associated with multiple biological processes related to response to abiotic stresses. Alkaline stress upregulated genes encoding heat shock proteins and ethylene-related genes, but downregulated genes encoding glutathione S-transferases. Also, genes that encode phosphoenolpyruvate carboxylases, phosphoenolpyruvate carboxylase kinase 1, and malate dehydrogenases related to malate accumulation were upregulated by alkalinity. This study indicated that alkaline stress affected the genes related to stress responses, metabolism, and malate accumulation in the roots of M. crystallinum.

Bacterial diseases of vegetable crops cause significant losses of yield and substantially decrease food quality. For sustainable development of agriculture, it is highly important to use the most effective strategies for the protection of vegetable crops from bacterial diseases which allows the creation of resistant cultivars and their introduction in regions with an increased risk of damage by phytopathogenic bacteria. This paper reviews the most widespread bacterial diseases of tomatoes, the mechanisms of interaction of plants with phytopathogenic bacteria, and the advantages of the biotechnological strategies over traditional and marker-associated breeding for creation of the resistant tomato cultivars. The current research progress on the use of biotechnological approaches such as cell selection, genetic engineering, genome editing, and gene silencing is summarized, with a special emphasis on the advantages and limitations of these methods.

In plants, calcineurin B-like proteins (CBLs) and CBL-interacting protein kinases (CIPKs) regulate Ca2+ signalling and so responses to biotic and abiotic stresses. However, the details of specific CIPKs functions in various stress responses are poorly understood. Here, we report roles of dicot and monocot CIPK2 genes in response to salinity and heavy metals. Arabidopsis thaliana AtCIPK2 was found to be universally expressed in different tissues and organs and furthermore induced by salinity. Overexpression of AtCIPK2 or Tibetan Plateau wild barley (Hordeum spontaneum) HsCIPK2 in Arabidopsis alleviated toxic effects of NaCl and mercury on seed germination and root growth. Similarly, reduced toxic effects of copper and cadmium on seed germination, but not on root growth, were observed in these transgenic lines. Live-cell fluorescence imaging analysis revealed that HsCIPK2 was predominantly distributed in the cytoplasm and nucleus and weakly localized at the plasma membrane (PM), but its PM association was rapidly enhanced upon exposure to high salinity and mercury. These results suggest an involvement of CIPK2 in plant tolerance to salinity and mercury and provide a new insight into physiological functions of CIPKs in plant response to heavy metals.

Despite the accumulating evidence showing the essential role of pentatricopeptide repeat (PPR) proteins in organellar biogenesis and plant development in Arabidopsis thaliana and maize (Zea mays), the functions of most PPR proteins in rice (Oryza sativa) are still unknown. A former study demonstrated that the mitochondria-localized Arabidopsis PPR19 is crucial for mitochondrial function and normal plant growth and development. In this study, we characterized the functional role of a rice ortholog (LOC_Os12g04110) of Arabidopsis PPR19 protein. The loss-of-function osppr19 mutant displayed delayed seed germination and stunted root and seedling growth compared with wild-type. The height of the osppr19 mutant was significantly shorter, and the grain mass of the mutant was lower than that of the wild-type. The osppr19 mutant carried few filled grains and a higher number of aborted seeds than the wild-type. The structures of mitochondria in the osppr19 mutant were abnormal, and more reactive oxygen species were accumulated in the mutant, suggesting defective mitochondrial biogenesis and function in the osppr19 mutant. Importantly, the amount of mature mitochondrial transcripts was significantly decreased in the mutant. Taken together, these results suggest that the mitochondrial OsPPR19 is essential for mitochondrial biogenesis and function, which is crucial for plant growth and development of rice grain.

Excess water is an abiotic stress in plants, but the level at which excess water becomes varies widely between plant species. We conducted a two growing season replicated excess flooding experiment that was planted with 24 accessions of perennial ryegrass which had been vegetatively propagated to ensure equal representation of genotypes within an accession, both cultivars and ecotypes, from various geographical origins. The excess water treatment applied over the winter periods was achieved with irrigation. Yields increased in the winter-flooded treatment in contrast to the non-artificial watered control treatment significantly in 2017. In 2018 the same trend could be seen, but was not significant. Differences in composition of macro- and micronutrient profiles were observed. Sulphur was the only element with highly significantly increased concentration (0.25%) in flooded samples compared to control. Phosphorus, copper, iron, manganese, and molybdenum decreased statistically significantly under flooded conditions. In conclusion, perennial ryegrass is coping extremely well with excess water supplied over the winter period and can utilise it effectively in spring.

Arabidopsis thaliana L. ecotype Dijon-G (Di-G) showed a different symptom development during pathogenesis compared to ecotype Columbia-0 (Col-0). Previously, it has been shown that Di-G has a higher susceptibility to necrotrophic fungus Alternaria brassicicola than Col-0. In this study, Di-G showed enhanced disease susceptibility to necrotrophic fungi Botrytis cinerea, Sclerotinia sclerotiorum, and Sclerotium rolfsii known to secrete oxalic acid (OA) as a pathogenicity factor. Treatment with 50 and 100 mM OA resulted in a more leaf tissue collapse in Di-G than in Col-0. The OA also up-regulated expression of the salicylic acid (SA)-inducible pathogenesis-related gene 1 (PR1) and down-regulated expression of the jasmonic acid/ethylene-inducible defensin PDF1.2 gene in Di-G. By contrast, Di-G was resistant to hemibiotrophic fungus Colletotrichum higginsianum and biotrophic Turnip crinkle virus (TCV) infections. Application of 0.5 mM SA resulted in a higher accumulation of endogenous SA and in a preferential expression of SA-responsive genes in Di-G. Salicylic acid accelerated OA-triggered plant cell death and attenuated PDF1.2 expression in Di-G. These results suggest that the enhanced susceptibility of Di-G to necrotrophic pathogen infections might be mediated by attenuated JA-ethylene defence signalling and/or heightened SA-related defence signalling. Interaction of SA-signalling with OA secretion might be also involved in the enhanced susceptibility of Di-G.

Woody plants faced multiple abiotic stresses in forest plantation that can influence their growth and development. Dalbergia odorifera T. Chen is a vulnerably endangered tree species, and references about its responses to abiotic stresses are very rare in literature. Furthermore, the mechanisms underlying the abiotic stress tolerance in plants induced by exogenous glycine betaine (GB) remains unclear. Indeed, the alternative oxidase (AOX) is one of the major components of antioxidant enzymatic machinery, and there are no studies that focused on the effects of GB on the amount of AOX protein in plants under drought or cold stresses. Thus, the aim of this study was to investigate the effect of exogenous GB on the phenotype, osmoprotectants, photosynthetic pigments, and antioxidant systems in D. odorifera under cold and drought stresses. The layout of the trial was a factorial experiment in a completely randomized design using two factors including abiotic stress (drought and cold) and GB. Moreover, the principal component analysis based on the measured parameters manifested how the selected ROS scavengers were dispersed throughout the treatments. The results showed huge beneficial impacts of GB on the phenotypic traits of D. odorifera; GB also influences positively the antioxidant machinery, photosynthetic pigments, redox-homeostasis, and water status in D. odorifera seedlings under both stresses. Moreover, exogenous GB affects more the AOX pathway in D. odorifera under cold stress than under drought stress.

It is common knowledge that R2R3-MYB transcription factors play significant roles in plant biological and physiological processes, especially in the phenylpropanoid metabolism pathway. The cultivated strawberry (Fragaria × ananassa Duch.) is an octoploid (2n = 8x = 56) species from the Rosaceae family and it is also an important fruit crop species. However, the function of R2R3-MYB genes in strawberry remains largely unknown. Here, based on the genome of the cultivated strawberry cv. Reikou, 66 FanMYB genes were found and systematically analyzed. RNA-seq analysis revealed that some FanMYBs exhibited tissue-specific expressions and were methyl jasmonate (MeJA)-responsive. Phylogenetic relationships and protein-protein interaction analysis suggested that 13 FanMYBs were likely associated with phenylpropanoid metabolism. Out of these genes, FanMYB22, FanMYB36, FanMYB47, FanMYB49, and FanMYB63 were post-transcriptionally regulated by miR858 according to the degradome data analysis, suggesting the conservation and complex regulation network in F. × ananassa. Current findings provide a useful resource for future research on the function of FanMYBs and the regulatory mechanism of the phenylpropanoid pathway in strawberry.

Salinity is one of the major abiotic constraints to agriculture. The physiological and molecular mechanisms of salt tolerance have been studied in plants for many years. The regulation of osmosis and ion homeostasis is crucial. A lot of important components involved in plant responses to salt stress have been identified. Among them, ion transporters and channels take an essential role in ion homeostasis, mainly for Na⁺, Cl^-, and K⁺. Until now, many cation antiporters important for salt tolerance in plants have been characterized. Among them, the monovalent cation/proton antiporters (CPA) family is one of the most important families, including sodium proton exchangers (NHXs), K⁺-efflux antiporters (KEAs), and cation/H⁺ exchangers (CHXs). Here, the current knowledge of the plant CPA family in responses to salt stress was reviewed. The regulation mechanisms were also included and discussed.

The capacity of extracellular self-DNA (esDNA) to inhibit growth is getting more research attention as this could be explored for several purposes, including the development of specific bioherbicides. While the inhibitory effect has been studied in several dicotyledon species, little is known about the effects and subsequent signaling processes in monocots. Here, we measured the growth, counted the number of lateral and crown roots, determined greenness index, quantified the production of O₂^.- and H₂O₂, and determined the expressions of genes encoding antioxidant enzymes (SODs and CATs) in rice (Oryza sativa L.), a model plant of monocots. After 7 d of germination, rice roots were exposed to 0, 75, and 150 µg cm^-3 of esDNA. Inhibitory effect was found to be negatively correlated to esDNA concentration, as indicated by the length of primary roots. Interestingly, this negative effect was only observed in the directly exposed organ (root) but not in the length of shoot or fresh mass of the whole seedling. The percentage of greenness index of leaves and number of crown and lateral roots were also similar across treatments. However, esDNA exposure to root increased production of O₂^.- and H₂O₂ in the root. At the molecular level, the response was characterized by the decreased expression of the antioxidant genes SOD3, CATB, and CATC. These findings suggest that esDNA inhibits rice growth locally in, e.g. in treated roots, and the responses involve increased production of ROS and suppression of antioxidants. This study could be the basis for determining the combination of concentration and period of exposure that might significantly inhibit total growth of monocot weeds with a minimum effect on the crop.

Bacterial leaf blight (BLB) is a common disease that affects rice development and yield. The effects of major nutrients, especially nitrogen, on rice BLB susceptibility have been considered when devising rational fertilization strategies. However, the defense mechanism of rice against BLB under phosphate (Pi)-deficient conditions remains uncertain. Jasmonic acid (JA) is a phytohormone produced by rice plants to respond to abiotic and biotic stresses. Here, the involvement of the JA pathway in rice response to Xanthomonas oryzae pv. oryzae (Xoo) under low Pi was investigated in two contrasting rice cultivars G299 and G22. Expressions of JA-related genes under low Pi and Pi-related genes under JA treatment were assessed. The resistant capacity of G299 and G22 against Xoo infection was also investigated. In the JA-sensitive and Pi-sensitive cv. G299, JA-related genes were highly expressed under low Pi, and low Pi-responsive genes were strongly upregulated under JA treatment. Neither JA nor Pi pathways were activated in the JA-tolerant and low Pi-tolerant cv. G22. Low Pi strongly enhanced rice resistance to Xoo in cv. G299. Our study demonstrated that Pi deficiency confers rice resistance to Xoo. The JA pathway modulates the response to low Pi, depending on the cultivar. Pi-response genes are involved in Pi stress and may participate in the regulation of overall plant growth under various abiotic stresses. These findings provide new insights into the interaction between phosphate deficiency and the JA pathway and the subsequent effect on plant disease resistance.

Seedling greening upon irradiance is essential for the survival of plant after germination. Here, we studied the role of nitric oxide (NO) in regulating the accumulation of chlorophyll during greening of Arabidopsis seedlings, and we also investigated the changes of ATP in the chloroplast and cytoplasm during greening by using a fluorescent protein sensor (Ateam 1.03-nD/nA) based on fluorescence resonance energy transfer (FRET) and the effects of NO on the changes of ATP content. The results showed that the content of NO, chlorophyll, and ATP in the chloroplast and cytoplasm increased with the increase of greening time. L-NAME, an inhibitor of NO, not only decreased the accumulation of chlorophyll content but also reduced the ATP content in the chloroplast and cytoplasm during the greening of Arabidopsis seedlings. Therefore, these experiments indicate that the accumulation of chlorophyll and changes of ATP during greening of etiolated Arabidopsis seedlings are mediated by nitric oxide.

Leaves of Lotus japonicus infected by powdery mildew accumulate isoflavonoids, especially vestitol and sativan as protective compounds, whereas their flavonol-glycosides or phenylpropanoic acids content were rather decreased. For a better understanding of the induction of phytoalexin production in L. japonicus, the influence of important signalling molecules, namely methyl jasmonate and salicylic acid, was tested by leaf application, up to 15 d. No effects after spraying the leaves with 0.5 mM salicylic acid were observed regarding the plant isoflavonoid content, whereas methyl jasmonate showed moderate effect on vestitol accumulation. Chitosan application led to a strong increase in vestitol content, sativan and vestitol derivative also increased. In a similar way to the effect of powdery mildew infection, the content of ferulic acid and kaempferol glycosides decreased, except for one compound, identified as kaempferol-6-deoxyhexose, that is the result of acetylation of kaempferol glycosides. The application of chitosan also led to an approximately 2.5- to 3.5-fold increase in hydrogen peroxide content, indicating the involvement of H₂O₂ in the chitosan signalling pathway. The activity of key enzyme of the phenolic biosynthesis, phenylalanine amonia lyase (PAL), was stimulated as well as the expression of 3 PAL-isogenes (LjPAL4, LjPAL6, and LjPAL9), whereas LjPAL8 decreased. Moreover, the expression of two key enzymes of vestitol and sativan biosythesis: pterocarpan reductase and isoflavone synthase were also strongly induced. The data suggest that chitosan acts as an elicitor of the fungal attack in Lotus japonicus that do not lead to a general stimulation of the metabolism of phenols, but rather to a specific induction of isoflavonoid-phytoalexine production, especially for production of vestitol.

Preventing extinction is one of the greatest challenges facing the global community. Nursery stock breeding is an effective means to restore endangered species, such as Horsfieldia hainanensis Merr., with difficulty in natural regeneration period. In this study, we investigated the optimum combination of irradiance and nitrogen for the cultivation of H. hainanensis seedlings by comparing twenty treatments with different combinations of irradiances (100, 67.5, 45.7, 15.6 % of full natural irradiance) and five levels of N supply (0, 1.8, 3.6, 5.4, 7.2 g plant^-1). We found that the growth and photosynthetic efficiency of seedlings under full irradiance were significantly inhibited compared with shaded seedlings. Under full irradiance, a lack of N resulted in reduced chlorophyll (Chl) synthesis, causing lower photosynthetic efficiency and an imbalance in metabolism. Proper shading (67.5 and 45.7 % of natural irradiance) and N addition (1.8 - 5.4 g plant^-1) promoted root development, increase Chl content and photosynthesis, and ultimately the accumulation of larger amount of biomass. The biomass of the shaded seedlings was mainly distributed to aboveground tissues, while seedlings exposed to stronger radiation accumulated greater root biomass. Therefore, the best seedling management for this species is a combination of 67.5 % of natural irradiance and moderate N supply (4.6 g plant^-1).

To obtain immediate homozygosity by androgenesis, the doubled haploid method is often used. As a result, a mapping population was created utilizing rice (Oryza sativa L.) cvs. Mahulata and IR 20 as parents in order to find QTLs/genes for drought tolerance at the vegetative stage. The effectiveness of the doubled haploids (DHs) approach, on the other hand, is largely dependent on the ability to distinguish haploids from diploids among the green regenerants. Although flow cytometry and cytological screening for pollen sterility can be used to identify haploids, these methods are expensive, time-consuming, and need a sophisticated laboratory with highly trained workers. Plant height and other spikelet features have also been used to differentiate haploids from doubled haploids. However, no systematic analysis of several morphological features for distinguishing haploids in doubled haploids has been published to date. As a result, a cost-effective approach for distinguishing haploids from true DHs obtained from anther culture is required. The goal of this work was to identify haploids using morphological features and simple microscopic examinations without the use of chemicals or complex laboratory facilities. The cross between the IR20 and Mahulata yielded a total of 198 anther culture (AC) derived plants. A group of 41 plantlets was chosen as putative haploids based on their shorter height and Cq values using qPCR-based genotyping and finally validated that, in addition to plant height, other morphological traits such as total number of leaves/plant, total number of tillers/plant, and floral characters can be used to successfully identify haploids. We report a variety of morphological signs as indicators of haploid plants, including smaller plants, higher tiller density, narrower and shorter leaf length, and partial exertion of panicle from the flag leaf sheath. Other morphological markers for identifying haploids from DHs include smaller florets and anthers, and small desiccated microspores.

Solanum nigrum L. is an annual undomesticated berry plant of Solanaceae. The fruits of S. nigrum are tiny, but there are about 25 seeds in a single fruit. The total number of seeds produced in one plant can reach more than 3 000. The height is about 30 - 40 cm, and the whole growth cycle is two months when S. nigrum was cultivated in the light incubator of the laboratory. The Agrobacterium tumefaciens-mediated transformation has been established in S. nigrum. So S. nigrum has the characteristics of model plants. AcMYB110, an R2R3-MYB transcription factor from kiwi (Actinidia spp.), was transformed into S. nigrum mediated by A. tumefaciens. The results indicated that the petals of 35S:AcMYB110 S. nigrum plants are pink compared with white petals in wild-type plants, and content of anthocyanins was significantly increased in the pericarp from young fruit to its maturity, especially in the central part of the fruit flesh. The results showed that the ectopic expression of AcMYB110 in S. nigrum is consistent with the expression of AcMYB110 in kiwi. This suggests that AcMYB110 plays a conserved role in regulating anthocyanins synthesis in fruits and can be potentially applied for improvement of the anthocyanins content in horticulture fruits breeding.

Radix astragali, from the roots of Astragalus L. species, is regarded as an important traditional medicinal plant and has been widely used as a Qi-Invigorating medicine for more than 2 000 years. Considering the different metabolites or functional compounds of Radix astragali from distinct species, the underlying genetic information among the two species is important. Here, we compared the two different root transcriptomes and expression patterns of genes involved in key medicinal secondary metabolites of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao and Astragalus membranaceus (Fisch.) Bge. A total of 98 017 578 and 102 635 956 reads, including 98 294 560 and 92 494 416 high-quality reads, were obtained for A. mongholicus and A. membranaceus, respectively. In general, 73 785 (39.47%) and 60 739 (34.93%) unigenes for A. mongholicus and A. membranaceus were differentially expressed, indicating that the two species had many homologous genes. In comparison, the carbon metabolism category contained the most abundant unigenes in A. mongholicus, and it contained many more genes than those found in A. membranaceus based on the KEGG results. Genes that may participate in the biosynthesis of flavonoids, diterpenoids, triterpenoids, steroids, isoquinoline alkaloids, and carotenoids, such as CHS, F3H, GA3, and CYPs, were identified based on annotations. A total of 5 227 and 5 101 transcription factors (TFs) were identified in A. mongholicus and A. membranaceus, respectively. Three TF categories were found and showed twice as many numbers for A. mongholicus than A. membranaceus, i.e., SOH1 (4:2), LIM (18:5), and GRF (19:5), while MED7 had more unigenes in A. membranaceus (6:12). These results indicated that the different pathways may be involved in the synthesis of active ingredients in the two germplasm resources, and the data obtained will provide valuable information for further utilization and investigation of these two species.

Electric signaling pathways are important for rapid and long-distance communication within a plant. Changes in the electric potential (EP) inside plants have been observed during the propagation of electric signals. Increasing radiofrequency electromagnetic radiation (EMR) in the environment raise the question about possible effects of EMR on the EP of plants. In the present experiment, we investigated the effect of 2, 2.5, 3.5, and 5.5 GHz EMR with a maximum field intensity of 23-25 V m^-1 on the EP in emergent Myriophyllum aquaticum plants. The 2 and 5.5 GHz exposures caused significant (16 and 13 %) decreases in the standard deviation of rapid fluctuations observed in the EP. The greatest change was caused by 2.5 GHz EMR (23 % increment), although it was not statistically significant. A recovery of the EP was only after 2.5 GHz EMR exposure. The temperature of the plants was not changed by the EMR exposure. These findings confirm the frequency-dependent non-thermal effects of EMR on the EP of plants.

Ascorbic acid (AsA) and glutathione (GSH) contribute to defense responses under abiotic stresses. The present study explored the ascorbate-glutathione cycle and ascorbate regeneration under high concentration (30 mM) of cadmium in the tea plant (Camellia sinensis L.). The tea leaves showed speckles and necrosis from the third day of Cd treatment. The content of superoxide anion (O₂^.-) and hydrogen peroxide (H₂O₂) in the leaves were significantly higher until the seventh day after Cd treatment. The content of O₂^.- and H₂O₂ were the highest on the fifth day (212.7 and 153.6 % of the control, respectively). The AsA content increased (86.9 %) on the first day after Cd treatment and decreased significantly in the subsequent days, while GSH showed a reverse trend. The enzymatic activity assays showed that dehydroascorbate reductase (DHAR) and glutathione reductase (GR) involved in AsA regeneration were downregulated considerably after Cd foliar application. In contrast, the activities of ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) increased on the first day and then declined. Reverse-transcription quantitative PCR showed upregulation of glutathione synthetase (CsGSHS), γ-glutamylcysteine synthetase (Csγ-ECS), and CsMDHAR of the AsA regeneration pathway and downregulation of CsDHAR and CsGR. The expressions of GDP-L-galactose phosphorylase (CsGGP), L-galactose-1-phosphate phosphatase (CsGPP), and L-galactono- 1,4-lactone dehydrogenase (CsGaILDH) of the L-galactose pathway were also downregulated. The results indicated that AsA, which can respond to Cd stress of plants by increasing antioxidant ability, was consumed to scavenge ROS; moreover, Cd stress inhibited AsA synthesis and regeneration, which made that tea plants suffering severe damage.