Irradiance is one of the main limiting factors affecting the production of pepper (Capsicum annuum L.) in facility production. It is therefore important to measure the growth of pepper seedlings under low irradiance and to understand how to relieve low radiation stress. In this study, pepper seedlings were cultivated under low irradiance and were treated with gibberellic acid (GA₃) and paclobutrazol (PP333). Agronomic and physiological characteristics of the pepper seedlings were analyzed. Under low irradiance, the plant height, leaf area, and the chlorophyll (Chl) and malondialdehyde (MDA) content of pepper seedlings were higher than under normal irradiance, while the content of proline, and soluble protein and Chl a/b ratio of pepper seedlings were lower than those under normal irradiance; exogenous GA₃ had a similar effect. When PP333 was applied to the seedlings, abnormal growth was mitigated. The effects of exogenous GA₃ and PP333 on Chl fluorescence parameters were also analyzed. Under low irradiance, the maximum quantum yield reduction of photosystem (PS II) (F_v/F_m) increased significantly, and the reaction center initiated the corresponding defense mechanism for timely dissipation of excess excitation energy to reduce the damage to the plant. These results showed that spraying gibberellin under normal irradiance conditions had similar effects on pepper seedlings as under low irradiance conditions. Exogenous PP333 relieved the growth reduction by increasing the content of Chl and soluble protein and enhancing some photosynthetic parameters. These results suggest that exogenous PP333 can alleviate the abnormal growth of pepper under low radiation stress.

With the drastic changes in global climate and the increasing frequency of extreme weather events, abiotic stress poses a significant threat to future food crop production and is a major contributor to crop yield reduction (Ahmad et al., 2010). Wheat, one of the world's primary food crops, is susceptible to both abiotic and biotic stresses at all stages of its growth and development. Numerous studies have indicated that drought stress severely limits the growth and productivity of wheat (Xue et al., 2014; Faran et al., 2019). Therefore, understanding the effects of drought stress on wheat grain germination and developing strategies to mitigate the inhibition of germination caused by drought are crucial for enhancing wheat yield.

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).

To study the effects of cadmium and lead on the growth of blueberry (Vaccinium ashei Reade) plantlets in vitro and on the activity of peroxidase (POD) and superoxide dismutase (SOD) of blueberry shoots, Cd²⁺ and Pb²⁺ were added separately to a cultivation medium. The results show that 0.01 mM Cd²⁺ significantly inhibited the growth of blueberry shoots, and the height and fresh mass of the shoots were significantly lower than those of the control; 0.05 mM Cd²⁺ significantly inhibited the proliferation of the shoots; the inhibitory effect on the growth and proliferation of blueberry in vitro was enhanced with the increase of Cd²⁺ concentration. Also Pb²⁺ (0.10 - 1.00 mM) significantly decreased the proliferation of the shoots, but it did not decrease significantly the shoot height and fresh mass. After 20 d of Cd or Pb treatments, the POD and SOD activities of the shoots increased with the increase of their concentrations, and when the concentration was 1.00 mM, the POD and SOD activities were significantly higher than in the control; the effect of Pb²⁺ on POD and SOD activities was generally stronger than that of Cd²⁺. The upregulation of activities of antioxidative enzymes played an effective role in acclimatization to these stresses, especially to Pb stress.

Tomato spotted wilt virus (TSWV; species Orthotospovirus tomatomaculae, family Tospoviridae) (Kuhn et al., 2023), is a negative strand RNA-virus containing envelope structures, which makes it unique among plant viruses (de Haan et al., 1991). TSWV ranks among the most destructive plant viruses worldwide. First described in Australia in 1919, TSWV has since attained a global distribution, infecting over 1 000 plant species across more than 85 families, including key agricultural crops such as tomato (Solanum lycopersicum), pepper (Capsicum annuum), groundnut (Arachis hypogaea), and various ornamentals (Parrella et al., 2003; Pappu et al., 2009). Infected plants typically exhibit chlorotic or necrotic spots, wilting, stunted growth, and in severe cases, complete crop failure, resulting in considerable economic losses, particularly in Solanaceous and Asteraceous crops (Roselló et al., 1996; Latham and Jones, 1998).

Soybean is one of the most important economic crops in the world. However, the salinization of soil results in the decrease of soybean yield as it is only a moderately salt-tolerant crop. We treated three soybean cultivars with low and high concentrations of NaCl. The differentially expressed genes between the control group and the salt treatment group were identified by mRNA sequencing and analyzed by gene ontology and Kyoto encyclopedia of genes and genomes annotations. We performed weighted gene co-expression network analysis on all samples and found genes most related to the phenotype. After verifying the results of differentially expressed genes by quantitative PCR, we finally identified Glyma06G01990, Glyma08G22730, Glyma019G05140, and Glyma06G20160 as key genes affecting the soybean growth under salt stress.

Image-derived phenotyping at individual plant level can provide more accurate and more comprehensive information than manual measuring for quantitative traits related to canopy growth in field environment. Aims of this study were to: (i) assess smartphone image-derived canopy parameter at early stage of sunflower, and (ii) to evaluate performance of predictive models for morphological and biomass traits related to canopy growth using smartphone image-derived parameter. Original top-view image datasets taken with a smartphone camera were processed, and necessary information was extracted with image analysis software developed using fuzzy c-means clustering algorithm. Canopy cover rate per plant (CCR) was not only the relative value but also image-derived phenotyping feature. CCR were significantly and positively correlated (r ≧ 0.90; **P < 0.01) with plant height, total leaf area per plant, plant dry mass, aboveground plant dry and leaf dry mass, respectively. Ground measured and predicted values from linear regression model for plant height, total leaf area per plant, plant dry mass, aboveground total dry mass, leaf dry mass per plant with CCR showed an accurate prediction with high coefficients of determination (R ) of more than 0.8063, respectively. The present study documented the robustness of predictive models using several metrics.

This study investigated the impacts of acid rain stress on Akebia trifoliata and the mitigation effects of exogenous curcumin (CUR) using integrated physiological, anatomical, and transcriptomic analyses. Acid rain stress significantly decreased chlorophyll content (total chlorophyll by 64.8%), leaf epidermal thickness (upper and lower epidermis by 58.9 and 35.6%), and starch content (by 63.9%), while increasing oxidative stress markers (MDA by 82.6%; ROS production by 345.8%) and content of osmolytes (proline by 64.4%). A. trifoliata counteracted acid rain stress by enhancing superoxide dismutase (SOD) and catalase (CAT) activities, and by modifying leaf anatomical structure (increased mesophyll tissue thickness). CUR application, particularly at 50 μmol/L (CUR50), effectively alleviated damage by maintaining leaf structural integrity and promoting growth recovery. Transcriptomic analysis revealed 993 differentially expressed genes between CUR50-treated vs. acid rain-stressed plants, primarily enriched in the plant hormone signal transduction and phenylpropanoid biosynthesis pathways. These results demonstrate that CUR mitigates acid rain stress through coordinated physiological adaptations and transcriptional reprogramming of stress-responsive pathways. This study provides a theoretical basis for cultivating A. trifoliata and implementing phytoremediation strategies in acid rain-affected regions.

Barley (Hordeum vulgare L.), an important food and fodder crop, is potentially tolerant to salinity. To identify quantitative trait loci (QTLs) controlling salt tolerance, the population of 162 recombinant inbred lines (RILs) derived from F8 generation of Arigashar (an extremely salt tolerant Iranian six-rowed barley landrace) crossed with Igri (a salt semi-sensitive two-rowed cultivar) were evaluated. The growth of shoots, roots, and coleoptiles, and root numbers are four important growth characteristics severely affected by salt stress at seedling growth stages. A linkage map was constructed using 106 AFLP and SSR markers spanning six barley chromosomes including 2(2H), 3(3H), 4(4H), 7(5H), 6(6H), and 1(7H). Out of totally 26 detected QTLs, 17 QTLs were found effective for salt tolerance at 250 and 350 mM NaCl which localized on chromosomes 2H, 3H, 4H, 6H, 7H, and linkage group L1, whereas considering equivalent overlapped QTLs with a pleiotropic effect led to detection of totally 9 distinctive QTLs (QClgH2.1b, QSdgH2.1b, QSlgH2.1c, QNrgH2.1b, QTwgH2.2c, QSdg3Hb, QSlg4Hb1, QClg4Hb, and QSlg6Hc2) effective for salinity tolerance. 2(2H), 4(4H), and 6(6H) were major chromosomes harboring QTLs which effectively controlled salt tolerance in the Igri×Arigashar population. An interesting QTL, QTwg4Hc, was localized on chromosome 4H in the XE41-M61 marker distance that controls several traits including shoot and coleoptile lengths and shoot fresh mass under salt stress. A dense marker cluster around a resistance gene could offer a starting point for positional cloning.

Cd accumulation, its effects on elongation growth of maize coleoptile segments, pH changes of their incubation medium and the membrane potential of parenchymal cells were studied. The Cd content increased significantly with exposure to increasing cadmium concentrations. Coleoptile segments accumulated the metal more efficiently in the range 10-100 µM Cd, than in the range 100-1000 µM Cd. Cd at concentrations higher than 1.0 µM produced a significant inhibition of both growth and proton extrusion. 100 µM Cd caused depolarization of the plasma membrane (PM) potential in parenchymal cells. The simultaneous treatment of maize coleoptile segments by indole-3-acetic acid (IAA) and Cd, counteracted the toxic effect of Cd on growth. Moreover, our data also showed that 100 µM Cd suppressed the characteristic IAA-induced hyperpolarization of the membrane potential, causing membrane depolarization. These results indicate that the toxic effect of Cd on growth of maize coleoptile segments might be, at least in part, caused via reduced PM H⁺-ATPase activity.

Understanding the basis of the genetic variations responsible for the complex traits found in Eucalyptus cladocalyx under arid environmental conditions is crucial for designing genetic architecture studies. Forty-five half-sib families from Australia were used to identify inter-simple sequence repeat (ISSR) markers that are associated with growth (height, diameter at breast height, and stem straightness), flowering traits (flowering intensity, flowering precocity, reproductive capacity, and late flowering) and tree survival under arid conditions in southern Atacama Desert, Chile. Each DNA pellet consisted of a pool of five trees from each family. ISSR markers were associated with all the traits studied and accounted for 9.8 to 23.4 % of the phenotypic variation. Several loci were associated with more than one trait. For example, UBC_{810(450-500 bp)}, ISO_{1(600-610 bp)}, and TGT_{9(780-800 bp)} were associated with three of the traits studied. These identified genomic regions may contribute to the increase of the efficiency of the conventional tree breeding program for E. cladocalyx.

The aim of this study was to evaluate the tensile strength of the rachilla in spikelets of Polish cultivars of Festulolium braunii (K. Rich.) A. Camus during seed development and maturation. The investigations were carried out in 2009 - 2010 at the Plant Breeding, Szelejewo, Poland. The inflorescences were randomly harvested in June - July from plant collection in maintenance breeding of three Polish cultivars (Agula, Felopa, and Sulino). Using a specifically developed testing machine, tensile strength of the rachilla of individual spikelets were determined. Regardless of the F. braunii cultivar, the tensile strength of the rachilla decreased through consecutive growth stages. The highest tensile strength of the rachilla was observed during the phase of kernel watery ripe stage (BBCH 71) - it ranged from 510.1 mN in 'Agula' to 592.0 mN in 'Felopa'. At the fully ripe phase (BBCH 89), the value of this trait ranged from 19.2 mN in 'Agula' to 45.0 mN in 'Felopa'. It was also observed that in all tested cultivars of F. braunii, the spikelets located in the lower part of the spike were characterised by the highest tensile strength of the rachilla, whereas those in the upper part were characterised by the lowest values of this trait. This means that the caryopses in the spikelets located at the lower part of the inflorescence were less susceptible to shedding. Seed shedding the Polish F. braunii cultivars, especially 'Agula' and 'Sulino', may start as early dough and soft dough phases. By contrast, seed shedding 'Felopa' is moved to the later phases of seed maturation.

Growth, photosynthetic characteristics, chlorophyll (Chl) fluorescence parameters, and peroxidation of membrane lipids of Cryptotaenia japonica were studied under differing irradiances (15, 35, 60, and 100 % of full irradiance). At full irradiance, C. japonica exhibited a typical decline in net photosynthetic rate (P_N) at midday, which was not observed in the other irradiance treatments. This indicates a possible photoinhibition for C. japonica at the high irradiance. Diurnal patterns of stomatal conductance (g_s) were remarkably similar to those of P_N in each irradiance treatment, and the intercellular CO₂ concentration (c_i) had the opposite trend. C. japonica growing under 60 % of the full irradiance exhibited the highest plant height, stem diameter, leaf area, and biomass. The initial fluorescence (F₀) value was lowest at 60 % of the full irradiance. Maximal fluorescence (F_m), potential activity of photosystem II (PS II) (F_v/F₀), and maximal photochemical efficiency of PS II (F_v/F_m) values were highest at 60 % of full irradiance and lowest at 15 % of the full irradiance. The malondialdehyde (MDA) content in 15 % and 100 % of the full irradiance were higher than under the other irradiances. During the treatment, catalase, peroxidase, and superoxide dismutase activities firstly increased and then declined under 15 % and 100 % of the full irradiance and were steadily low under 60 % of the full irradiance, indicating a low production of reactive oxygen species. Therefore, C. japonica thrived best under 60 % of the full irradiance.

Maize crops are sensitive to NaCl stress, which is one of the most harmful abiotic stresses affecting agricultural productivity. To gain further insights into the differential metabolic responses to NaCl stress, we employed metabolomics and physiological approaches to understand the response of salt-tolerant (PH6WC) and sensitive (PH4CV) cultivars of maize. Salt stress caused a significant reduction in root growth, lower root numbers, softened roots, leaf etiolation, inhibition of leaf formation, and decreased shoot height and stem width in both the tolerant and sensitive genotypes compared with the control. These morphological characteristics increased with the progression of the NaCl concentration, however, they were less prominent in the salt-tolerant genotype. Evans blue staining demonstrated that NaCl-induced root cell death, and the root cells of 'PH4CV' were almost completely dead following 9 d of exposure to 100 mM NaCl. Under treatment with 100 mM NaCl, 79 compounds in the roots of 'PH4CV' were identified as being significant metabolites, and 85 compounds were identified as being significant metabolites in the roots of 'PH6WC'. The NaCl-induced changes in the metabolomes of these two maize cultivars indicate that 80 root-based compounds were different between NaCl-treated plants and controls. Among these metabolites, 30 were found in both maize cultivars when responding to NaCl stress. These compounds were associated with the metabolism of some basic compounds such as cis-9-palmitoleic acid, L-pyroglutamic acid, galactinol, deoxyadenosine, and adenine. The changing abundance of the 30 metabolites was not completely consistent in 'PH4CV' and 'PH6WC'. Glucose metabolism was exclusively induced by NaCl in the 'PH4CV' maize seedlings whereas nucleic acid metabolism was more significant in the 'PH6WC' maize seedlings in response to NaCl stress. Overall, 'PH6WC' and 'PH4CV' responded differently to NaCl stress, and this information is helpful in understanding how maize seedlings respond to this type of abiotic stress.

In view of the ecological, social, and economic importance of Myracrodruon urundeuva Allemão, the objective of this study was to investigate the strategies of this species under drought during its initial phase of development. Two-month-old plants were cultivated under continuous irrigation or no irrigation for 20 d. After this period, the water-stressed plants were rehydrated for 20 d. Physiological, biochemical, and anatomical variables were evaluated on 20^th and 40^th day. Water deficit (25 and 85 % leaf relative content) caused senescence followed by leaf abscission. Growth in height was negatively affected by water deficit (37 % reduction). A decrease in the thickness of the mesophyll was accompanied by a decrease of the total chlorophyll content. Water deficit affected saccharide metabolism and altered cellular component dynamics. Enzyme activities were higher during the rehydration period than during the water stress. There was no increase in lipid peroxidation in plants subjected to water deficit. A reduction in the stomatal opening during water stress was a strategy of reducing water loss through transpiration.

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.

Nitrogen and sulfur are major elements influencing plant growth and production of secondary metabolites. They interact to each other, but little is known about it in Isatis indigotica Fort. plants. In this study, 15 different treatments representing all possible combinations of 3 N treatments (N1, N2, and N3, corresponding to 5, 15, and 25 mM N, respectively) and five S treatments (S0, S1, S2, S3, and S4, corresponding to 0.00, 1.25, 2.50, 5.00 and 7.50 mM S, respectively) were used, and plant growth, indigo and indirubin yields, and expressions of genes encoding enzymes involved in N and S metabolisms were measured. The results show that the highest dry biomass was observed in N2S2 treatment. Moreover, net photosynthetic rate in the N2S2 treatment was significantly higher than under other treatments (except for N3S2 treatment). A low nitrogen concentration (5 mM) was beneficial to the accumulation of alkaloids, and the N1S1 and N2S2 treatments resulted in the highest yields of indigo and indirubin, respectively. Additionally, the yields of indigo and indirubin were positively correlated with the expression of APS reductase and glutamine synthetase genes, respectively.

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.

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.

We investigated the effects of 0.025 or 0.05 mM methyl jasmonate (MeJA) on the growth characteristics, antioxidant enzyme activities, non-enzymatic antioxidant content, and carbon and nitrogen metabolizing enzyme activities in Glycyrrhiza uralensis exposed to 100 mM NaCl. Results showed that salt stress decreased the stem length and lateral root number and the treatment with 0.025 or 0.05 mM MeJA increased the root length of salt-stressed G. uralensis seedlings but decreased root diameter, stem length, and stem diameter. MeJA application modulated oxidative stress in salt-stressed G. uralensis seedlings. It decreased the catalase activity but enhanced peroxidase activity and ascorbate content. However, treatment with 0.05 mM MeJA significantly increased the malondialdehyde content of salt-stressed seedlings. Salt stress inhibited carbon and nitrogen metabolism. The application of MeJA enhanced the activities of sucrose synthase, and sucrose phosphate synthase, and nitrate reductase in salt-stressed seedlings.

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.

Using in vitro culture, we determined the effect of photoperiod during growth of Chenopodium rubrum mother plants on vegetative and reproductive development of offspring. Photoperiod during flowering induction of mother plants (the first 6 d after the germination) has the key influence on seed germination and offspring growth, while offspring flowering and seed maturation is determined by photoperiod their mothers experienced during, and shortly after, flowering induction. The mechanism can be through changes in seed protein pattern which we found dependent on photoperiod experienced by mother plants.

This study aimed to evaluate the effect of putrescine priming on the initial growth, chlorophyll fluorescence, primary metabolites accumulation, and antioxidant enzyme activities in two maize hybrids with contrasting drought tolerances. Seeds of Zea mays L. hybrids DKB 390 (drought tolerant) and BRS 1030 (drought sensitive) were primed with putrescine (10 or 100 µM). Paper rolls moistened with distilled water or mannitol (-0.6 MPa) were maintened at 30°C for 7 d. The growth parameters were higher in the DKB hybrid than in the BRS hybrid. Putrescine priming (10 µM) promoted the root growth of BRS at levels similar to those of DKB and improved photochemical and non-photochemical quenching and maximum quantum efficiency of BRS seedlings. Higher levels of reducing sugars were found in DKB seedlings when compared to BRS in both roots and leaves, especially with 100 µM putrescine. Total soluble sugar and starch were lower in the maize roots under water deficit and with 10 µM putrescine for both hybrids. BRS seedlings showed higher starch content in the leaves in the control and 10 µM putrescine treatments. Superoxide dismutase was activated in BRS plants by the priming, especially in the roots, but this effect was not observed for catalase, ascorbate, or guaiacol peroxidase, although the DKB seedlings presented much higher guaiacol peroxidade activity than BRS seedlings in both the roots and shoots. In conclusion, putrescine priming (10 M) improved the morphological and biochemical responses of the drought sensitive maize hybrid BRS.

The present work aimed to evaluate the effect of heat stress on common bean (Phaseolus vulgaris L.) genotypes during the reproductive phase as a function of the inoculation of plants with Bacillus subtilis. The treatments were established by inoculating two strains of B. subtilis (AP-3 and AP-12) and a control. The plants were subjected to heat stress when they reached the reproductive stage, with an increase in temperature to 28/33°C. The duration of the stress period was ten days. Flowering, biochemical, and gene expression evaluations were performed. There was the interaction of B. subtilis AP-3 with the bean cultivar IAC-Imperador, reducing flower abortion, promoting the formation of new flower buds, and increasing the content of proline and guaiacol peroxidase activity in plant tissues. However, there was a reduction of transcription of genes encoding the 1-carboxylic acid-1aminocyclopropane oxidase and ethylene response factors and an increase of the Δ¹-pyrroline-5-carboxylate synthetase1 gene. These results suggest that B. subtilis may modulate some metabolic pathways in response to high-temperature stress during the reproductive phase of the common bean. This also confirms that Bacillus strains represent a useful option to moderate abiotic stresses.

The influence of nitrogen deprivation on leaf development and the biomechanics of leaf growth were studied using maize (Zea mays L.) seedlings grown under low irradiance. Although the nitrogen deprivation had no significant effect on photosynthesis, the leaf length, the leaf area, and the total assimilation area of plants decreased. The mature size of the epidermal cells was not altered, while the cells of nitrogen-deprived plants reached their final length closer to the leaf base than the epidermal cells of control plants. Decreases in the length of the growing zone (from 50 to 30 mm) and in the maximum value of relative elemental growth rate (from 0.08 to 0.06 mm mm^-1 h^-1) were observed in the nitrogen deprived plants. The maximal value of growth velocity in the control treatment was higher along the elongation zone, except for the basal 20 mm, where there was no significant difference between the control and the N-deprived plants. The net deposition rates of water and dry matter were also affected by nitrogen deprivation: the values of these features decreased and the spatial position of the maximum of the deposition rates shifted towards the leaf base.

Ripe wild-type Malay apple (Syzygium malaccense) cv. Saraek fruit epidermis is red, whereas a mutant has a white skin. Wild-type and mutant fruit were used as a fruit model to study the regulation and gene expression patterns of anthocyanin biosynthesis and a myeloblastosis (MYB) transcription factor during growth and development. Fruit size, color, anthocyanin composition, and the expression of genes involved in anthocyanin biosyntheses were determined during fruit growth and ripening. Wild-type ripe fruit had a greater diameter and fruit mass than the mutant. The total anthocyanin content was approximately nine-fold higher in wild-type red fruit than in mutant white fruit. The major anthocyanin in the fruit skin of the wild-type was cyanidin-3-O-glucoside with minor amounts of pelargonidin-3-O-glucoside, peonidin-3-O-glucoside, and cyanidin-3,5-O-diglucoside. No anthocyanin was found in mutant fruit. The accumulation of cyanidin-3-O-glucoside during fruit growth and ripening was correlated with red color development and activities of phenylalanine ammonia lyase (PAL) and UDP-glucose:flavonoid-3-O-glucosyltransferase (UFGT). We cloned fragments and characterized seven genes involved in anthocyanin biosynthesis pathway namely phenylalanine ammonia lyase (SmPAL), chalcone synthase (SmCHS), chalcone isomerase (SmCHI), flavanone-3-hydroxylase (SmF3H), dihydroflavonol 4-reductase (SmDFR), leucoanthocyanidin dioxygenase (SmLDOX), and UDP glucose-flavonoid-3-O-glucosyl transferase (SmUFGT), as well as a MYB transcription factor (SmMYB). The expressions of all the genes were determined by semi-quantitative reverse transcription (RT)-PCR and quantitative real-time RT-PCR. The skin of wild-type fruit contained transcripts of all above mentioned genes, whereas the mutant fruit showed no SmUFGT and SmMYB expressions, which correlated with the absence of anthocyanin accumulation during fruit growth and ripening. These results suggest that lack of anthocyanin biosynthesis in mutant fruit may be via the regulation of UFGT and MYB transcription factor expressions.

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.

Our research intended to appraise the performance of two different Pseudomonas strains on Zea mays L. (cv. B73) under drought stress and non-stress conditions. Plants were inoculated with P. putida KT2440 (Pp) and P. fluorescens (Pf1) followed by sampling at 0, 3^rd, and 6^th day after imposition of drought stress (DAS). Both strains demonstrated significant improvement in root length, protein content, chlorophyll content, and root and shoot fresh masses as compared to un-inoculated drought stressed plants. Real-time quantitative PCR analysis revealed that drought stress responsive genes, i.e., the cold-related dehydrin 410 gene, WRKY18, and major facilitator superfamily were significantly down-regulated by Pf1 and Pp inoculation under drought stress condition on 6 DAS. Similarly, the down-regulated transcript abundance of lipoxygenase genes in inoculated plants on 6 DAS showed the role of Pf1 and Pp in scavenging reactive oxygen species under drought stress conditions. Among the selected jasmonic acid pathway responsive genes, maize protease inhibitor and 12-oxo-phytodienoatereductase 7 (OPR7) also revealed a potential role of these rhizobacteria under drought stress conditions. Seed inoculation of both strains significantly down-regulated the expression of OPR7 gene under stress conditions. Our results advocate the complex growth promotion effects of both selected rhizobacterial strains and amelioration of the drought by modulating the expression of drought stress responsive genes.

The reverse transcription quantitative real-time PCR (RT-qPCR) is becoming increasingly important for gene expression studies. However, the accuracy and reliability of RT-qPCR depend on normalizing expression to reference genes. In this study, ten candidate reference genes, including cyclophilin (CYP), elongation factor 1b (EF1b), α-tubulin (TUA5), β-tubulin (TUB4), ubiquitin10R (UBQ10R), 60S ribosomal RNA (60S), alcohol dehydrogenase (ADH3), metalloprotease (MTP), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and actin (ACT2) were evaluated for the stability of expression in three tissues of two peanut cultivars [Zhonghua 2(ZH₂) and 99-1507] under Al stress by four statistical algorithms (geNorm, NormFinder, BestKeeper, and RefFinder). The results suggested that the top-ranked reference genes under Al-induced programmed cell death (PCD) in peanut were UBQ10R, EF1b and CYP, with the most suitable combination of reference genes being [UBQ10R+ACT2]. The UBQ10R exhibited the most stable expression in all samples, while TUB4 was the least stable gene. The relative expression of AhMC1 (the caspase-like protease family gene, which played a significant role in Al-induced PCD) showed that there was no significant difference with the best reference gene and the best gene combination in RT-qPCR normalization, but there was significant difference with the least stable gene TUB4 as reference gene. This is the first study to evaluate the stability of reference genes in peanut under Al-induced PCD, and the results will provide guidance to identify appropriate reference genes for further RT-qPCR analyses under Al stress in peanut.

In our previous study on geranium, we showed that increases in growth irradiance from sub-optimal to near-optimal could delay boron deficiency effects on photosynthesis. In this study, we further investigated the effects of growth irradiance on tolerance to B stress by growing geranium (Pelargonium × hortorum cv. Maverick White) under sub- to supra-optimal B concentrations (4.5, 45, and 450 μM) and under three irradiances of 100, 300, or 500 μmol m^-2 s^-1 PAR for 30 d. In general, at low and medium irradiances, sub- and supra-optimal B availability decreased root and shoot dry masses, but at high irradiance, the B stress was prevented. Net photosynthetic rate decreased by the supra-optimal B concentration at the high irradiance only suggesting B-related photoinhibition. Tissue B content and root specific B uptake only modestly decreased by the low B treatment, but increased greatly by the high B availability, and the higher irradiance decreased the tissue B content and the root B uptake only at the low and medium B supplies. Interestingly, the increases in irradiance decreased the content and uptake of all other nutrients, except Fe uptake. Effects of the B stress on the content of other nutrients were variable, but the B stress often exacerbated decreases in nutrient content with the increasing irradiance which would be especially important under nutrient-limiting conditions. Hence, in this study, the B stress effects on growth were mitigated by the increases in growth irradiance, which offset negative effects on physiology, and the protective effects of irradiance were likely caused by its positive effects on plant carbon/energy status rather than on tissue B content or B uptake.