Dataset describing the influence of preharvest gibberellic acid application on fruiting behavior, yield and fruit biochemical properties of rambutan (Nephelium lappaceum L.).

Rambutan (Nephelium lappaceum L.), an exotic non-climacteric tropical fruit in Bangladesh, has got wide acceptance to consumers as well as growers due to its attractive appearance, taste and nutrition, but the demerits of inadequate fruiting and yield as well as low edible properties at the farmers field requires to be addressed. Hence, an experiment was performed with gibberellic acid (GA3) and the obtained dataset demonstrates how GA3 application augmented the fruit set and retention, fruit yield and post-harvest biochemical properties of rambutan. Gibberellic acid was sprayed at seven various concentrations from 0 ppm (control) to 500 ppm at the mature panicles (inflorescence) during the pre-flowering and the early fruiting stages (three weeks after fruit set). The study was conducted in two sequential growing years (2020 and 2021) following a randomized complete block design (RCBD). Results revealed that 200-300 ppm doses had superiority over the lower (50-100 ppm) and higher (400-500 ppm) doses for promoting the fruit yield and quality. More specifically, fruit set and retention, fruit size and weight, pulp weight and thickness, pulp:peel ratio, edible portion and fruit yield as well as total soluble solids and total sugars contents in fruit were exhibited the best at 300 ppm being consonant with 200 ppm at majority cases, whereas GA3 doses from 200 ppm to 500 ppm performed similarly to enhance fruit physico-chemical qualities and shelf life of rambutan. Control treatment along with 50 ppm gibberellic acid dose demonstrated inferior results for yield and fruit quality promotion of rambutan. Thus, use of plant growth regulator at appropriate dose and time is imperative to rambutan improvement.

Exploring the impact of occupational factors on low back pain in ride-sharing motorbike drivers in Bangladesh: A comprehensive cross-sectional analysis.

Objective: Low back pain (LBP) is a major global public health issue, prevalent among various occupational groups worldwide. However, existing studies have predominantly focused on sedentary workers in developed nations, leaving a gap in understanding LBP prevalence and associated factors among occupational cohorts in low- and middle-income countries like Bangladesh. This study aimed to determine the prevalence and occupational factors contributing to LBP among ride-sharing motorbike drivers (RSMD) in Bangladesh. Methods: A cross-sectional study was conducted in Dhaka city from May 20 to August 08, 2023. Data were collected from Bangladeshi adult RSMD using a paper-based questionnaire developed by Eriksen et al. Chi-square or Fisher's Exact tests compared categorical variables with and without LBP, and multiple logistic regression analyses were performed with LBP as the dependent variable and various predictors to compute adjusted odds ratios with a 95% confidence interval. Results: The one-month prevalence of LBP was 58.8%. Regression analysis revealed elevated adjusted odds of experiencing LBP among participants with hypertension, those using multiple ride-sharing operators, commuter and older bike users, and non-users of riding kits. Additionally, increased adjusted odds of LBP were observed among participants of higher age, higher body mass index, and those covering longer distances per week. Conclusion: This study underscores a significantly higher prevalence of LBP among RSMD in Bangladesh, with occupational factors strongly predicting LBP. Implementing strategies such as regular physical exercise, weight reduction, using sports and newer motorbikes, and reducing working hours per week may help mitigate the prevalence of LBP within this cohort.

Dataset explaining the comparative seasonal crop load and harvest quality of guava upon pruning strategies.

The dataset explained the details on how pruning techniques significantly affected the seasonal variations on fruit availability and edible quality of guava (Psidium guajava L.) under fluctuating sub-tropical weather conditions. The present pruning data also directed a way of enhancing lean season (off-season) harvest without sacrificing the main season yield and fruit quality. In detail, the pruning strategies included branch removal of 0 cm, 15 cm, 30 cm and 45 cm from shoot-tip once a year during spring (early March), monsoon (early June) and autumn (early September) starting with spring pruning. Over two consecutive years (2019-2020 and 2020-2021), the pruning treatments were assigned in triplicates following a randomized Complete Block Design (RCBD) where the same plants received the same treatments during observation period. Data on crop load like number of fruits and fruit yield per plant and fruit biochemical traits namely total soluble solids, titratable acidity, total sugars, vitamin C and fruit specific gravity were recorded. To assess the seasonal variations, data collection was performed continuously and grouped at quarter intervals i.e., March-May, June-August, September-November and December-February of the year. Plants under pruning produced greater number of flowers and fruits for superior yield and quality compared to non-pruned plants. Irrespective of pruning techniques, June-August and September-November quarters had superior yield over others, whereas March-May harvests retained utmost fruit quality. Considering pruning time, plants reserved maximum harvestable fruits in June-August quarter under spring pruning followed by March-May quarter for autumn pruning compared to other combinations. Moreover, fruit biochemical attributes were examined the best at March-May harvests under autumn pruning. Alongside, June-August and September-November periods exhibited superiority for yield over others when plants were pruned at 30 cm level, but 45 cm pruning had best yield at March-May quarter. Whether, fruits had notable TSS, sugars, vitamin C and specific gravity obtained during March-May period from 45 cm pruning treatment. June-August was noted to produce inferior quality fruits in guava.

Biochemical analysis of the TPS-a subfamily in Medicago truncatula.

Terpenes are important mediators of plant chemical response to environmental cues. Here, we describe the genome-wide identification and biochemical characterization of TPS-a members in Medicago truncatula, a model legume crop. Genome mining identified thirty-nine full-length terpene synthases with a significant number predicted to produce monoterpenes and sesquiterpenes. Biochemical characterization of the TPS-a subfamily associated with sesquiterpene biosynthesis revealed such compounds, that exhibit substantial biological activity in other plants. Gene expression analysis using qPCR and the Medicago gene atlas illustrated distinct tissue and time-based variation in expression in leaves and roots. Together our work establishes the gene-to-metabolite relationships for sesquiterpene synthases in M. truncatula. Understanding the biosynthetic capacity is a foundational step to defining the ecological roles of this important family of compounds.

Assessment of Drought and Zinc Stress Tolerance of Novel Miscanthus Hybrids and Arundo donax Clones Using Physiological, Biochemical, and Morphological Traits.

High-yield potential perennial crops, such as Miscanthus spp. and Arundo donax are amongst the most promising sources of sustainable biomass for bioproducts and bioenergy. Although several studies assessed the agronomic performance of these species on diverse marginal lands, research to date on drought and zinc (Zn) resistance is scarce. Thus, the objective of this study was to investigate the drought and Zn stress tolerance of seven novel Miscanthus hybrids and seven Arundo clones originating from different parts of Italy. We subjected both species to severe drought (less than 30%), and Zn stress (400 mg/kg-1 of ZnSO4) separately, after one month of growth. All plants were harvested after 28 days of stress, and the relative drought and Zn stress tolerance were determined by using a set of morpho-physio-biochemical and biomass attributes in relation to stress tolerance indices (STI). Principal component analysis (PCA), hierarchical clustering analysis (HCA) and stress tolerance indices (STI) were performed for each morpho-physio-biochemical and biomass parameters and showed significant relative differences among the seven genotypes of both crops. Heatmaps of these indices showed how the different genotypes clustered into four groups. Considering PCA ranking value, Miscanthus hybrid GRC10 (8.11) and Arundo clone PC1 (11.34) had the highest-ranking value under both stresses indicating these hybrids and clones are the most tolerant to drought and Zn stress. In contrast, hybrid GRC3 (-3.33 lowest ranking value) and clone CT2 (-5.84) were found to be the most sensitive to both drought and Zn stress.

Demographic and Clinical Characteristics of Persons With Spinal Cord Injury in Bangladesh: Database for the International Spinal Cord Injury Community Survey 2023.

The study aims to explore the demographic and clinical characteristics of persons with spinal cord injury (SCI) in Bangladesh. A total of 3035 persons with SCI spanning from 2018 to 2022 were included in this cross-sectional study. Information about demographic and clinical variables was obtained from the medical records and verified through telephone calls to ensure accuracy and consistency. Approximately half (48.30%) of the study participants were located in Dhaka Division. The average age of persons with SCI was 38.3 years, with a standard deviation of 15.9 years, and the largest proportion (33.4%) fell within the age range of 18-30 years. Males outnumbered females by nearly 2.5 times. In the study, 59.6% had suffered traumatic injuries, whereas 40.4% had SCI attributable to disease-related causes; 58.1% were diagnosed with tetraplegia and 40.1% with paraplegia. Fall from height (42.1%) and road traffic trauma (27%) were the most common causes of traumatic injuries. Degenerative myelopathy (41.1%) was the most frequent cause of non-traumatic SCI, followed by tumors (27.7%) and tuberculosis (TB; 14.8%). Both traumatic (58.3%) and degenerative (56.7%) causes of SCI commonly affected the cervical spine, whereas TB (24.4%) and tumors (47.5%) had a higher incidence of affecting the dorsal spine. In the absence of a registry or national database for patients with SCI in Bangladesh, this study would serve as representative data for future studies.

Analgesic and Sedative-Hypnotic Potentiality of Crude Methanolic Extract of Gomphandra tetrandra (Wall.) Sleumer Leaves.

Objectives: Gomphandra tetrandra (Wall.) Sleumer (leaves) belonging to the family Stemonuraceae was investigated for preliminary phytochemical screening and evaluating their pharmacological activities in various pharmacological models. Materials and Methods: The crude methanolic extract was screened with different chemical reagents for the qualitative detection of different phytochemical groups. The peripheral analgesic function was determined using the acetic acid-induced writhing procedure and sedative-hypnotic behaviors were assessed using hole-board, open field, and hole-cross tests using different doses of the extract (200 mg/kg and 400 mg/kg body weight). Results: Phytochemical screening revealed that methanolic extract of G. tetranda leaves contains steroids, gums, mucilages, phytosterols, carbohydrates, and flavonoids. The crude methanolic extract at 200 mg/kg and 400 mg/kg doses showed statistically significant activity in acetic acid-induced writhing inhibition test with 60% (p<0.01) and 76.47% (p<0.01) inhibition, respectively, compared to control. The extract also had dose-dependent substantial (p<0.01) sedative-hypnotic activities compared with diazepam in the hole-board, open field, and hole-cross tests. Conclusion: It may be assumed that the methanolic leaf extract of G. tetrandra possesses a strong possibility of having analgesic and sedative-hypnotic activity due to the presence of bioactive compounds in its leaves. Moreover, observed results have opened a new era of in-depth research to discover the possible mechanism of analgesic and sedative-hypnotic activity.

Influence of the Degree of Hydrolysis on Functional Properties and Antioxidant Activity of Enzymatic Soybean Protein Hydrolysates.

Soybean protein hydrolysates were prepared using two proteolytic enzymes (Alcalase and Protamex) and the degree of hydrolysis (DH) and their functional and antioxidant properties were evaluated. The highest DH value was 20%, with a yield of 19.77% and protein content of 51.64%. The total amino acid content was more than 41% for all protein hydrolysates. The protein hydrolysates from Protamex at pH 2.0 had excellent solubility, emulsifying activity, and foaming capacity, at 83.83%, 95.03 m2/g, and 93.84%, respectively. The water-holding capacity was 4.52 g/g for Alcalase, and the oil-holding capacity was 4.91 g/g for Protamex. The antioxidant activity (62.07%), as measured by the samples' reaction with DPPH (2,2-diphenyl-1-picrylhydrazyl) and the reducing power (0.27) were the strongest for Protamex. An ABTS activity rate of 70.21% was recorded for Alcalase. These findings indicated a strong potential for the utilization of soybean protein hydrolysates to improve the functional properties and antioxidant activity of soybeans as well as their nutritional values.

Geomagnetic Field (GMF)-Dependent Modulation of Iron-Sulfur Interplay in Arabidopsis thaliana.

The geomagnetic field (GMF) is an environmental factor affecting the mineral nutrient uptake of plants and a contributing factor for efficient iron (Fe) uptake in Arabidopsis seedlings. Understanding the mechanisms underlining the impact of the environment on nutrient homeostasis in plants requires disentangling the complex interactions occurring among nutrients. In this study we investigated the effect of GMF on the interplay between iron (Fe) and sulfur (S) by exposing Arabidopsis thaliana plants grown under single or combined Fe and S deficiency, to near-null magnetic field (NNMF) conditions. Mineral analysis was performed by ICP-MS and capillary electrophoresis, whereas the expression of several genes involved in Fe and S metabolism and transport was assayed by qRT-PCR. The results show that NNMF differentially affects (i) the expression of some Fe- and S-responsive genes and (ii) the concentration of metals in plants, when compared with GMF. In particular, we observed that Cu content alteration in plant roots depends on the simultaneous variation of nutrient availability (Fe and S) and MF intensity (GMF and NNMF). Under S deficiency, NNMF-exposed plants displayed variations of Cu uptake, as revealed by the expression of the SPL7 and miR408 genes, indicating that S availability is an important factor in maintaining Cu homeostasis under different MF intensities. Overall, our work suggests that the alteration of metal homeostasis induced by Fe and/or S deficiency in reduced GMF conditions impacts the ability of plants to grow and develop.

Effect of Magnetopriming on Photosynthetic Performance of Plants.

Magnetopriming has emerged as a promising seed-priming method, improving seed vigor, plant performance and productivity under both normal and stressed conditions. Various recent reports have demonstrated that improved photosynthesis can lead to higher biomass accumulation and overall crop yield. The major focus of the present review is magnetopriming-based, improved growth parameters, which ultimately favor increased photosynthetic performance. The plants originating from magnetoprimed seeds showed increased plant height, leaf area, fresh weight, thick midrib and minor veins. Similarly, chlorophyll and carotenoid contents, efficiency of PSII, quantum yield of electron transport, stomatal conductance, and activities of carbonic anhydrase (CA), Rubisco and PEP-carboxylase enzymes are enhanced with magnetopriming of the seeds. In addition, a higher fluorescence yield at the J-I-P phase in polyphasic chlorophyll a fluorescence (OJIP) transient curves was observed in plants originating from magnetoprimed seeds. Here, we have presented an overview of available studies supporting the magnetopriming-based improvement of various parameters determining the photosynthetic performance of crop plants, which consequently increases crop yield. Additionally, we suggest the need for more in-depth molecular analysis in the future to shed light upon hidden regulatory mechanisms involved in magnetopriming-based, improved photosynthetic performance.

Extracellular Fragmented Self-DNA Is Involved in Plant Responses to Biotic Stress.

A growing body of evidence indicates that extracellular fragmented self-DNA (eDNA), by acting as a signaling molecule, triggers inhibitory effects on conspecific plants and functions as a damage-associated molecular pattern (DAMP). To evaluate early and late events in DAMP-dependent responses to eDNA, we extracted, fragmented, and applied the tomato (Solanum lycopersicum) eDNA to tomato leaves. Non-sonicated, intact self-DNA (intact DNA) was used as control. Early event analyses included the evaluation of plasma transmembrane potentials (Vm), cytosolic calcium variations (Ca2+ cy t), the activity and subcellular localization of both voltage-gated and ligand-gated rectified K+ channels, and the reactive oxygen species (ROS) subcellular localization and quantification. Late events included RNA-Seq transcriptomic analysis and qPCR validation of gene expression of tomato leaves exposed to tomato eDNA. Application of eDNA induced a concentration-dependent Vm depolarization which was correlated to an increase in (Ca2+)cyt; this event was associated to the opening of K+ channels, with particular action on ligand-gated rectified K+ channels. Both eDNA-dependent (Ca2+)cyt and K+ increases were correlated to ROS production. In contrast, application of intact DNA produced no effects. The plant response to eDNA was the modulation of the expression of genes involved in plant-biotic interactions including pathogenesis-related proteins (PRPs), calcium-dependent protein kinases (CPK1), heat shock transcription factors (Hsf), heat shock proteins (Hsp), receptor-like kinases (RLKs), and ethylene-responsive factors (ERFs). Several genes involved in calcium signaling, ROS scavenging and ion homeostasis were also modulated by application of eDNA. Shared elements among the transcriptional response to eDNA and to biotic stress indicate that eDNA might be a common DAMP that triggers plant responses to pathogens and herbivores, particularly to those that intensive plant cell disruption or cell death. Our results suggest the intriguing hypothesis that some of the plant reactions to pathogens and herbivores might be due to DNA degradation, especially when associated to the plant cell disruption. Fragmented DNA would then become an important and powerful elicitor able to trigger early and late responses to biotic stress.

Exposure to (Z)-11-hexadecenal [(Z)-11-16:Ald] increases Brassica nigra susceptibility to subsequent herbivory.

It is well established that plants emit, detect and respond to volatile organic compounds; however, knowledge on the ability of plants to detect and respond to volatiles emitted by non-plant organisms is limited. Recent studies indicated that plants detect insect-emitted volatiles that induce defence responses; however, the mechanisms underlying this detection and defence priming is unknown. Therefore, we explored if exposure to a main component of Plutella xylostella female sex pheromone namely (Z)-11-hexadecenal [(Z)-11-16:Ald] induced detectable early and late stage defence-related plant responses in Brassica nigra. Exposure to biologically relevant levels of vapourised (Z)-11-16:Ald released from a loaded septum induced a change in volatile emissions of receiver plants after herbivore attack and increased the leaf area consumed by P. xylostella larvae. Further experiments examining the effects of the (Z)-11-16:Ald on several stages of plant defence-related responses showed that exposure to 100 ppm of (Z)-11-16:Ald in liquid state induced depolarisation of the transmembrane potential (Vm), an increase in cytosolic calcium concentration [Ca2+]cyt, production of H2O2 and an increase in expression of reactive oxygen species (ROS)-mediated genes and ROS-scavenging enzyme activity. The results suggest that exposure to volatile (Z)-11-16:Ald increases the susceptibility of B. nigra to subsequent herbivory. This unexpected finding, suggest alternative ecological effects of detecting insect pheromone to those reported earlier. Experiments conducted in vitro showed that high doses of (Z)-11-16:Ald induced defence-related responses, but further experiments should assess how specific the response is to this particular aldehyde.

The Geomagnetic Field (GMF) Modulates Nutrient Status and Lipid Metabolism during Arabidopsis thaliana Plant Development.

The Geomagnetic field (GMF) is a typical component of our planet. Plant perception of the GMF implies that any magnetic field (MF) variation would induce possible metabolic changes. In this work was we assessed the role of the GMF on Arabidopsis thaliana Col0 mineral nutrition and lipid metabolism during plant development. We reduced the local GMF (about 40 µT) to Near Null Magnetic Field (NNMF, about 30 nT) to evaluate the effects of GMF on Arabidopsis in a time-course (from rosette to seed-set) experiment by studying the lipid content (fatty acids, FA; and surface alkanes, SA) and mineral nutrients. The expression of selected genes involved in lipid metabolism was assessed by Real-Time PCR (qPCR). A progressive increase of SA with carbon numbers between 21 and 28 was found in plants exposed to NNMF from bolting to flowering developmental stages, whereas the content of some FA significantly (p < 0.05) increased in rosette, bolting and seed-set developmental stages. Variations in SA composition were correlated to the differential expression of several Arabidopsis 3-ketoacyl-CoAsynthase (KCS) genes, including KCS1, KCS5, KCS6, KCS8, and KCS12, a lipid transfer protein (LTPG1) and a lipase (LIP1). Ionomic analysis showed a significant variation in some micronutrients (Fe, Co, Mn and Ni) and macronutrients (Mg, K and Ca) during plant development of plants exposed to NNMF. The results of this work show that A. thaliana responds to variations of the GMF which are perceived as is typical of abiotic stress responses.

The prevalence of psychiatric disorders among 3-4 year olds in an urban sample in Bangladesh.

Preschool period is the most important stage of life when major development occurs that lays the foundation of later life. Nearly similar ranges of psychiatric disorders start during preschool age and they continue to childhood and adolescence. Early intervention can reduce risks of adverse psychosocial outcome and longitudinal continuity of disorders. Detailed assessment of psychiatric disorders among this population is increasingly of high importance. Present study was aimed to determine the prevalence of psychiatric disorders among 3-4 year olds and to find out possible baseline correlates. This was a quantitative, cross-sectional and descriptive study carried out from March to May 2018 in 160 random urban community samples of Dhaka city. Of these, 86 were boys and 74 were girls. Household Questionnaire and validated parent version of Bangla Strengths and Difficulties Questionnaire (SDQ) for screening psychopathology had been applied to the consented parents or caregivers of the respondents. Mean age of the subjects was 3.63 ± 0.49 years. Overall, predictive prevalence of psychiatric disorder was 11.9 %. Among them, 4.4 % was emotional disorder, 5.6 % was conduct disorder and 1.9 % was hyperactivity. Prevalence of predictive psychiatric disorders was roughly similar in 3 and 4 years age. Girls had an excess of emotional disorder and boys had more behavioral disorder. Comorbidity was found at a higher rate with significant overlapping among the broad types of psychiatric disorders. This study supports the other findings of psychiatric disorders among the preschool children that would ultimately help in applying suitable screening procedures and subsequent management of psychiatric conditions.

The Geomagnetic Field Is a Contributing Factor for an Efficient Iron Uptake in Arabidopsis thaliana.

The Earth's magnetic field, defined as the geomagnetic field (GMF), is an unavoidable environmental factor for all living organisms. Variation in the GMF intensity was found to affect the content of some nutrients and their associated channels and transporters in Arabidopsis thaliana. In this work, we observed that reduction of the GMF to near null magnetic field (NNMF) affects the accumulation of metals in plant tissues, mainly iron (Fe) and zinc (Zn) content, while the content of others metals such as copper (Cu) and manganese (Mn) is not affected. Accordingly, Fe uptake genes were induced in the roots of NNMF-exposed plants and the root Fe reductase activity was affected by transferring GMF-exposed plant to NNMF condition. Under Fe deficiency, NNMF-exposed plants displayed a limitation in the activation of Fe-deficiency induced genes. Such an effect was associated with the strong accumulation of Zn and Cu observed under NNMF conditions. Overall, our results provide evidence on the important role of the GMF on the iron uptake efficiency of plants.

Landmark-based morphometric and meristic variations of freshwater garfish, Xenentodon cancila from four natural stocks of South-Western Bangladesh.

OBJECTIVE: The morphometric and meristic variations of Xenentodon cancila was studied based on the landmark-based truss network system to assess their phenotypic variations among four different freshwater stocks, viz. Boluhorpur baor, Jhenaidah (BBJ) (n = 29); Bhairab River, Jashore (BRJ) (n = 34); Arial Khan River, Madaripur (AKRM) (n = 28), and Bohnni baor, Gopalganj (BBG) (n = 25) in Bangladesh. MATERIALS AND METHODS: Seven meristic characters were counted by using a needle. Eight morphometrics and 28 truss measurements were measured by using tpsDigV.2.1 software. In meristic characters, Kruskal-Wallis test was performed to determine any significant differences, whereas, in morphometrics and truss measurements, univariate statistics and discriminant function analyses were carried out by using SPSS 22 version. RESULTS: Significant differences were observed in four meristic characters among seven meristic characters in the Kruskal-Wallis test. In univariate statistics, only nine characters were observed significantly different among eight morphometrics and 28 truss measurements. The contribution of three discriminant function analyses (DFA), in which first DFA showed 49.2%, second DFA showed 33%, and third DFA showed 17.8% on behalf of both morphometric and truss measurements. In discriminant space, the four stocks were clearly separated. Two clusters were formed among four stocks, where BBG formed a single cluster, whereas BBJ and BRJ aggregately formed another cluster. Additionally, AKRM formed a sub-cluster with BBJ. CONCLUSION: The preliminary information generated from the current study would be beneficial for further genetic studies and in the assessment of ecological impacts on X. cancila stocks in Bangladesh.

Tetranins: new putative spider mite elicitors of host plant defense.

The two-spotted spider mite (Tetranychus urticae) is a plant-sucking arthropod herbivore that feeds on a wide array of cultivated plants. In contrast to the well-characterized classical chewing herbivore salivary elicitors that promote plant defense responses, little is known about sucking herbivores' elicitors. To characterize the sucking herbivore elicitors, we explored putative salivary gland proteins of spider mites by using an Agrobacterium-mediated transient expression system or protein infiltration in damaged bean leaves. Two candidate elicitors (designated as tetranin1 (Tet1) and tetranin2 (Tet2)) triggered early leaf responses (cytosolic calcium influx and membrane depolarization) and increased the transcript abundances of defense genes in the leaves, eventually resulting in reduced survivability of T. urticae on the host leaves as well as induction of indirect plant defenses by attracting predatory mites. Tet1 and/or Tet2 also induced jasmonate, salicylate and abscisic acid biosynthesis. Notably, Tet2-induced signaling cascades were also activated via the generation of reactive oxygen species. The signaling cascades of these two structurally dissimilar elicitors are mostly overlapping but partially distinct and thus they would coordinate the direct and indirect defense responses in host plants under spider mite attack in both shared and distinct manners.

Overexpression of geraniol synthase induces heat stress susceptibility in Nicotiana tabacum.

MAIN CONCLUSION: Transgenic tobacco plants overexpressing the monoterpene alcohol geraniol synthase exhibit hypersensitivity to thermal stress, possibly due to suppressed sugar metabolism and transcriptional regulation of genes involved in thermal stress tolerance. Monoterpene alcohols function in plant survival strategies, but they may cause self-toxicity to plants due to their hydrophobic and highly reactive properties. To explore the role of these compounds in plant stress responses, we assessed transgenic tobacco plants overexpressing the monoterpene alcohol geraniol synthase (GES plants). Growth, morphology and photosynthetic efficiency of GES plants were not significantly different from those of control plants (wild-type and GUS-transformed plants). While GES plants' direct defenses against herbivores or pathogens were similar to those of control plants, their indirect defense (i.e., attracting herbivore enemy Nesidiocoris tenuis) was stronger compared to that of control plants. However, GES plants were susceptible to cold stress and even more susceptible to extreme heat stress (50 °C), as shown by decreased levels of sugar metabolites, invertase activity and its products (Glc and Fru), and leaf starch granules. Moreover, GES plants showed decreased transcription levels of the WRKY33 transcription factor gene and an aquaporin gene (PIP2). The results of this study show that GES plants exhibit enhanced indirect defense ability against herbivores, but conversely, GES plants exhibit hypersensitivity to heat stress due to suppressed sugar metabolism and gene regulation for thermal stress tolerance.