Drought Stress Research Articles

Effects of Water, Fertilizer and Heat Coupling on Soil Hydrothermal Conditions and Yield and Quality of Annona squamosa

Seasonal drought and summer soil high-temperature stress in Southern China often lead to decreased yield and quality of Annona squamosa. It is important to explore reasonable and effective water and fertilizer management measures as well as cover measures to improve the soil hydrothermal conditions in orchards to realize the increase in yield and quality of Annona squamosa. This study involved a two-year (2022–2023) field experiment in Yun County, Lincang City, Yunnan Province, using three factors and a three-level orthogonal test, resulting in nine different experimental treatments for water, fertilizer and heat. The three irrigation levels were W1 (soil moisture content of 55% of field moisture capacity), W2 (soil moisture content of 75% of field moisture capacity) and W3 (soil moisture content of 85% of field moisture capacity). The three fertilizer levels were F1 (1666 kg·hm−2), F2 (2083 kg·hm−2) and F3 (2500 kg·hm−2), and the three cover methods were A1 (no cover), A2 (fresh grass cover) and A3 (straw cover). The effects of these treatments on soil hydrothermal conditions, growth indices and fruit yield and quality of Annona s1uamosa were systematically monitored and analyzed, and the relationships between these treatments and yield and quality was analyzed based on a Mantel test. The results showed that T5 (W2F2A3) had the highest average soil moisture content over two years, followed by T7 (W3F1A3). The T7 (W3F1A3) treatment effectively reduced soil temperature by 5 °C compared to T1 (W1F1A1). T5 (W2F2A3) had the highest average yield over two years, with an increase of 33.99% compared to T1 (W1F1A1). Additionally, T5 (W2F2A3) has the highest average soluble solids, soluble sugars and vitamin C content over two years, with increases of 28.13%, 13.36% and 4.86%, respectively, compared to T1 (W1F1A1). A Pearson correlation analysis showed that there was a significant correlation between Annona squamosa growth and soil moisture content and soil temperature, and the Mantel test showed that soil hydrothermal conditions had significant influence on the growth and yield. T5 (W2F2A3) has the highest comprehensive benefit in promoting growth, increasing yield and improving quality for the plant. The effects of different irrigation quantities, fertilizer amounts and different cover measures on the coupling interaction for soil hydrothermal status in the root zone, growth, yield and quality of Annona squamosa were investigated, providing reliable theoretical support for the scientific planting model of Annona squamosa in the low-heat river valley of Yunnan Province.

Enhancing growth and tolerance traits in pepper (Capsicum annuum L.) through water-saving irrigation practices

Due to their intensive cultivation, horticultural crops are particularly susceptible and vulnerable to the detrimental effects of drought stress, necessitating significant water inputs for optimal growth and yield. Accordingly, water-saving irrigation strategies, i.e., Partial Root zone Drying (PRD) and Regulated Deficit Irrigation (RDI) emerge as pivotal tools for bolstering the resilience of the horticultural sector. The current study aims to evaluate the impact of PRD and RDI strategies on pepper (Capsicum annuum L.) growth, and physio-biochemical attributes under semi-controlled greenhouse conditions. Research findings revealed pronounced enhancements in stem length under both irrigation strategies, with PRD exhibiting superior effects on shoot fresh and dry biomass (increases of 57.2% and 61.1%, respectively) compared to full irrigation. At the physiological level, PRD and RDI induced a significant reduction in stomatal conductance in pepper plants relative to full irrigation, while maintaining leaf water potential and relative water content. Biochemically, plants subjected to PRD and RDI methods exhibited significant accumulation of free proline, particularly pronounced with PRD (approximately 115.9% increase compared to full irrigation). Furthermore, Chl a and carotenoid concentration significantly increased under PRD, indicating sustained photosynthetic functionality. Comparatively, PRD appears as the more effective technique, offering the potential to conserve agricultural water about 50 without compromising growth parameters, while simultaneously enhancing tolerance traits in C. annuum. Nonetheless, further investigations on other traits across diverse soil types, climates, and cultivars under field conditions are imperative to ascertain the broader applicability of PRD and optimize its implementation.

Impact of meteorological conditions on the biogenic volatile organic compound (BVOC) emission rate from eastern Mediterranean vegetation under drought

Abstract. A comprehensive characterization of drought's impact on biogenic volatile organic compound (BVOC) emissions is essential for understanding atmospheric chemistry under global climate change, with implications for both air quality and climate model simulation. Currently, the effects of drought on BVOC emissions are not well characterized. Our study aims to test (i) whether instantaneous changes in meteorological conditions can serve as a better proxy for drought-related changes in BVOC emissions compared to the absolute values of the meteorological parameters, as indicated by previous BVOC mixing-ratio measurements and (ii) the impact of a plant under drought stress receiving a small amount of precipitation on BVOC emission rate, and on the manner in which the emission rate is influenced by meteorological parameters. To address these objectives, we conducted our study during the warm and dry summer conditions of the eastern Mediterranean region, focusing on the impact of drought on BVOC emissions from natural vegetation. Specifically, we conducted branch-enclosure sampling measurements in Ramat Hanadiv Nature Park, under natural drought and after irrigation (equivalent to 5.5–7 mm precipitation) for six selected branches of Phillyrea latifolia, the highest BVOC emitter in this park, in September–October 2020. The samplings were followed by gas chromatography–mass spectrometry analysis for BVOC identification and flux quantification. The results corroborate the finding that instantaneous changes in meteorological parameters, particularly relative humidity (RH), offer the most accurate proxy for BVOC emission rates under drought compared to the absolute values of either temperature (T) or RH. However, after irrigation, the correlation of the detected BVOC emission rate with the instantaneous changes in RH became significantly more moderate or even reversed. Our findings highlight that under drought, the instantaneous changes in RH and to a lesser extent in T are the best proxy for the emission rate of monoterpenes (MTs) and sesquiterpenes (SQTs), whereas under moderate drought conditions, T or RH serves as the best proxy for MT and SQT emission rate, respectively. In addition, the detected emission rates of MTs and SQTs increased by 150 % and 545 %, respectively, after a small amount of irrigation.

Overexpression of the EuSIP5 Gene to Improve Drought Resistance in Tobacco

Soluble inorganic pyrophosphatase (s-PPase), a pyrophosphate hydrolase, is crucial for various physiological processes including plant growth and development, metabolic functions, and responses to abiotic stresses. However, research on s-PPase in woody plants is limited. To investigate the potential role of soluble inorganic pyrophosphatase in Eucommia ulmoides Oliver (E. ulmoides) in drought stress, the E. ulmoides soluble inorganic pyrophosphatase 5 (EuSIP5) cDNA sequence was amplified via RT-PCR. A bioinformatic analysis suggested that EuSIP5 may be an unstable amphipathic protein predominantly localized in the cytoplasm. In E. ulmoides, the highest expression of the EuSIP5 gene was detected in the leaves and pericarp of male plants from April to October, and in the leaves in July and September. Under drought conditions, the expression of EuSIP5 in E. ulmoides leaves was significantly greater than that in the control. An overexpression vector containing EuSIP5 was constructed and introduced into Nicotiana tabacum L. cv. Xanthi (N. tabacum L.). Compared with that in wild-type (WT) plants, wilting in N. tabacum L. EuSIP5-overexpressing (OE) plants was delayed by 4 days under drought stress. Additionally, the expression levels of the drought-related genes DET2, CYP85A1, P5CS, ERF1, F-box, and NCED1 were elevated in the leaves of transgenic N. tabacum L. Moreover, the activities of the protective enzymes peroxidase, superoxide dismutase, and catalase were significantly greater, whereas the malondialdehyde content was lower in the transgenic plants than in the WT plants. These findings suggest that the introduction of the EuSIP5 gene into N. tabacum L. enhances drought-related gene expression, increases antioxidant capacity, and reduces oxidative stress damage, thereby improving drought resistance.

Genome-Wide Analysis of Aquaporins Gene Family in Populus euphratica and Its Expression Patterns in Response to Drought, Salt Stress, and Phytohormones.

Aquaporins (AQPs) play an essential role in membrane water transport during plant responses to water stresses centered on conventional upstream signals. Phytohormones (PHs) regulate plant growth and yield, working with transcription factors to help plants withstand environmental challenges and regulate physiological and chemical processes. The AQP gene family is important, so researchers have studied its function and regulatory system in numerous species. Yet, there is a critical gap the understanding of many of their molecular features, thus our full knowledge of AQPs is far-off. In this study, we undertook a broad examination of the AQP family gene in Populus euphratica via bioinformatics tools and analyzed the expression patterns of certain members in response to drought, salt, and hormone stress. A total of 22 AQP genes were examined in P. euphratica, and were categorized into four main groups, including TIPs, PIPs, SIPs, and NIPs based on phylogenetic analysis. Comparable exon-intron gene structures were found by gene structure examination, and similarities in motif number and pattern within the same subgroup was determined by motif analysis. The PeuAQP gene family has numerous duplications, and there is a distinct disparity in how the members of the PeuAQP family react to post-translational modifications. Abiotic stress and hormone responses may be mediated by AQPs, as indicated by the abundance of stress response elements found in 22 AQP genes, as revealed by the promoter's cis-elements prediction. Expression pattern analysis reveals that selected six AQP genes from the PIP subgroup were all expressed in the leaves, stem, and roots with varying expression levels. Moreover, qRT-PCR analysis discovered that the majority of the selected AQP members were up- or down-regulated in response to hormone treatment and abiotic stress. Remarkably, PeuAQP14 and PeuAQP15 appeared to be highly responsive to drought stress and PeuAQP15 exhibited a high response to salt stress. The foliar application of the phytohormones (SA, IAA, GA3, MeJA, and ABA) were found to either activate or inhibit PeuAQP, suggesting that they may mitigate the effects of water shortage of poplar water stress. The present work enhances our knowledge of the practical roles of AQPs in stress reactions and offers fundamental information for the AQP genes in poplar species. It also highlights a direction for producing new varieties of poplar species with drought, salt, and hormone tolerance and holds substantial scientific and ecological importance, offering a potential contribution to the conservation of poplar species in arid regions.

Effect of Drought Stress on Yield Quality, Water Productivity and Profit Net of Potato Crop under surface and subsurface drip irrigation systems

Effect of Drought Stress on Yield Quality, Water Productivity and Profit Net of Potato Crop under surface and subsurface drip irrigation systems

Prohexadione calcium regulates wheat tolerance to drought stress by maintaining water balance and promoting antioxidant metabolism and photosynthesis

Prohexadione calcium regulates wheat tolerance to drought stress by maintaining water balance and promoting antioxidant metabolism and photosynthesis

Assessment of root foraging behaviour in Aralia elata subjected to drought stress under different light spectra

Drought may be more frequent in foreseen decades that will threat non-wood forest products (NWFP) in temperate forests. Plants cope with drought by increasing root foraging ability, which may be also impacted by exposure to light spectra (components of wavelengths in three colours of monochronic lights). In this study, three hybrid light spectra were provided by light-emitting diode (LED) in red (wavelength: 13.6% blue, 60.0% green, 26.4% red), green (2.9% blue, 84.6% green, 2.5% red), and blue (5.4% blue, 77.8% green, 16.9% red) lights for culturing potted Aralia elata seedlings in homogeneous (67.5 mg nitrogen [N] to both halves of pot) and heterogeneous (135 mg N to left half of pot) under drought and well-watered conditions. The red light spectrum was the unique illumination environment where height growth was promoted under well-watered condition and root biomass in fertilized patch was enhanced under drought. Compared to blue light spectrum, red light spectrum increased root foraging scale and precision and placement ratio. Red light spectrum also promoted aboveground biomass, but reduced root collar diameter. No interaction was detected between any pairs of factors among drought, light, and soil nutrient pattern. The heterogeneous pattern increased root to shoot biomass ratio with decreased shoot biomass and increased root foraging sensitivity and precision and fine root placement ratio. Drought enlarged the overall foraging scale with no effects on foraging sensitivity or precision. Overall, exposure to red light spectrum had the potential to promote fine root foraging behaviour under drought, but more trails deserve being tested in the future on a wider range of wavelengths.

SUPERMAN Targets PHRAGMOPLAST ORIENTING KINESIN to Negatively Regulate Leaf Cell Division in Poplar

ABSTRACTPlant organs achieve their specific size and shape through the coordination of cell division and cell expansion, processes that are profoundly influenced by environmental cues. Cytokinesis during cell division depends on the position of the cytokinetic wall, but how this process responses to environment fluctuations remains underexplored. Here, we investigated a regulatory module involving C2H2‐type zinc finger protein (C2H2‐ZFP) in leaf morphology during drought stress. A total of 123 C2H2‐ZFP members were identified through a comparative genome survey in Populus alba × P. glandulosa ‘84K’. Among them, PagSUPa, an orthologous gene of Arabidopsis SUPERMAN, was selected due to its responsiveness to drought stress and was further confirmed to play a role in leaf development. Phenotypic characterization and cellular analysis revealed that PagSUPa fine‐tunes the duration of cell proliferation in the adaxial epidermis, thereby influencing leaf morphology by modulating leaf adaxial‐abaxial polarity. Additionally, we found that PagSUPa directly suppresses the expression of PHRAGMOPLAST ORIENTING KINESIN1 (PagPOK1) and PagPOK2, genes encoding proteins involved in phragmoplast orientation and position, which results in impaired cytokinesis and cell wall organization. This study provides novel insights into the regulatory network governed by the SUP gene during leaf development, specifically in relation to cell division.

Pearl millet phenology assessment: An integration of field, a review, and in silico approach

AbstractPearl millet [Pennisetum glaucum (L.) R.Br.] is an essential subsistence cereal for food security in dryland farming systems of the semiarid tropics (e.g., in sub‐Saharan Africa) and has improved tolerance to drought, heat, and salinity stress compared to other domesticated cereals. Assessing the variation on phenology is critical toward devising effective adaptative management strategies for crop adaptation to current and future climate change. In this context, pearl millet presents a vast genetic diversity, exhibiting sensitivity to temperature and photoperiod. Hence, this study aims to describe the genotypic variability in the phenological responses of pearl millet to temperature and photoperiod, particularly affecting leaf number with implications on the overall total time to flowering. The dataset encompassed 21 publications from seven countries, with experiments conducted from 1965 to 2023, including three field studies from the United States. Broad variability has been reported for phyllochron values ranging from 45 to 111°Cd leaf−1, with a mean value of 67°Cd leaf−1. Thermal time to panicle initiation ranged from 340 to 594°C, but no response to photoperiod duration was found due to the nature of dataset. Maximum number of leaves per shoot ranged from 11 to 25, showing response (1.55–2.15 leaf h−1) to photoperiod due to variations in thermal time to flowering (from 875 to 1346°Cd). Thermal time to flowering increased ca. 323°Cd h−1 under day durations longer than 13.3 h, below which basic vegetative phase duration was close to 1033°Cd. Based on the Agricultural Production Systems sIMulator simulations, different combinations of the above responses (in silico cultivars) generated a great range of times to flowering (44–120 days) for locations in Senegal, Brazil, India, and United States. The findings of this study can help breeders to explore the phenological genetic variability of pearl millet and provide inputs for crop growth models to evaluate future in silico scenarios.

Thiourea Supplementation Improves Drought Stress Response of Ridge‐Sown and Mulch‐Applied Rainfed Maize (Zea mays L.) via Improved Leaf Source to Grain Sink Dynamics

ABSTRACTIn regions of South Asia where rainfed maize is grown, effective crop management during drought is essential for maximising yield. A variety of water‐conserving planting practices are used, and more recently, techniques such as foliar supplementation to maintain nutrients during drought have also shown promise. However, specific combinations of these approaches are often untested for optimality. Here, we explore the effects of two maize planting practices (ridge sowing and mulching) to conserve water, in combination with foliar thiourea. Drought stress response of crop was assessed at two experimental sites (L‐I and L‐II), through split‐plot design (main plots: flat sowing + mulch, flat sowing, ridge sowing + mulch [RS + M] and ridge sowing; sub‐plots: unsprayed, water spray, 500 ppm thiourea and 1000 ppm thiourea). Plant performance was assessed via dry matter accumulation, grain growth rate, stomatal parameters, grain yield, stover yield and nitrogen uptake. Rainfall breaks induced three dry spells during the pre‐anthesis and grain‐filling period. RS + M showed maximum drought tolerance by enhancing rainwater and nutrient use (N uptake [88.1 and 115.1 kg ha−1]) and recorded significantly higher periodic dry matter accumulation (149.2 and 156.8 g) along with higher 1000‐grain weight (181.0 and 196.6 g), grain‐filling duration (36.3 and 34.9 days) and leaf health parameters over the flat‐sown treatments. Furthermore, foliar supplementation of thiourea at 1000 ppm caused improved leaf health, likely through activation of a source to sink response (transfer of energy and materials from leaves to other plant organs) that alleviated moisture stress. Ultimately, the combination of RS + M and 1000 ppm thiourea led to the highest grain yields (32.1 and 39.5 qha−1).

Exacerbated Tree Growth Decline of an Old Platycladus orientalis Forest after Rapid Warming at the Northern Edge of the Taihang Mountain of China

Old trees are irreplaceable conservation resources with numerous ecological and socio-cultural values. While many forests have experienced significant declines under recent climate warming, the risk of growth declines in old trees remains unknown. Here, we tackle this problem by dendrochronological studies of 30 old trees in a Platycladus orientalis forest at the northern boundary of the Taihang Mountain of China. We examined annual growth trajectories of trees at individual level and discovered four severe growth decline events over the last 150 years, including the periods of 1894–1899, 1913–1919, 1964–1967 and 2004–2018. The most recent growth decline event lasted for 15-year and involced 50% to 75% of the old trees. This decline was unprecedented in both its extent and duration. Furthermore, the growth–climate relationship of these old trees has changed since 1990. Before 1990, tree growth was significantly correlated with minimum winter; after 1990, tree growth became significantly correlated with the self-calibrating Palmer Drought Index. These results suggest that warming-induced droughts after 1990 could be the primary driver of the recent growth decline. If climate warming continues and drought stresses intensify, the old trees may face an increased risk of growth decline and even mortality.

Enhancing Plant Stress Tolerance: The Role of LcWRKY40 Gene in Drought and Alkaline Salt Resistance in Tobacco and Yeast.

Leymus chinensis, a halophytic perennial grass belonging to the Poaceae family, thrives in saline-alkali grasslands and harbors a rich repository of resistance-related genetic resources. This study focused on deciphering the stress-responsive mechanisms of L. chinensis by conducting transcriptomic sequencing under NaHCO3 stress, which resulted in the annotation of a segment corresponding to the 51WRKY gene. The alkali-induced gene LcWRKY40 (QIG37591) was identified by phylogenetic analysis. Real-time quantitative PCR analysis was performed on L. chinensis plants subjected to PEG6000 and alkaline salt (NaHCO3) stress, and the results indicated that the LcWRKY40 gene was upregulated in both the leaves and roots. The localization of the LcWRKY40 protein was confirmed by the use of green fluorescent protein (GFP) fusion technology in transformed rice protoplast cells. The GAL4-driven transformation of the LcWRKY40 gene in INVScI yeast cells, which exhibited enhanced tolerance upon overexpression of the LcWRKY40 gene under mannitol and alkaline salt (NaHCO3) stress conditions. Under drought stress using mannitol, the fresh weight of Nicotiana tabacum overexpressing the LcWRKY40 gene was significantly higher than that of wild-type(WT) tobacco. Through drought and salt alkali stress, we found that overexpressed tobacco at different stages always outperformed the wild type in terms of fresh weight, SOD, MDA, and Fv/Fm. This study provides preliminary insights into the involvement of the LcWRKY40 gene in responding to drought and alkaline salt stresses, highlighting its role in enhancing plant resistance to drought and saline-alkaline conditions. These findings lay the foundation for future molecular breeding strategies aimed at improving grass resistance from different aspects.

Determination of Critical Crop Water Stress Index of Tea under Drought Stress Based on the Intercellular CO2 Concentration

Climatic changes have caused seasonal drought to occur frequently in tea fields of low-mountain and hill regions over the past decades. This leads to huge losses in the quality and yields of famous tea, which restricts the economic development of the tea industry. It is crucial to implement suitable irrigation scheduling. The crop water stress index (CWSI) is the main index to assess the water status of the crop. When the crop suffers irreversible drought stress, its critical water status cannot be easily evaluated using the CWSI. The change from stomatal limitations (SLs) to non-stomatal limitations (NSLs) of photosynthesis is vital for accurately recognizing crop drought stress. Thus, the objective of this research is to determine the critical crop water stress index of tea based on intercellular CO2 concentration (Ci) dynamic responses to drought stress. During two sensitive periods of water stress (famous tea harvest season and summer drought season, which are from March to April and July to August, respectively), the dynamic changes in the CWSI in tea were calculated and analyzed based on the CWSI theoretical model. The upper and lower baselines were determined on a daily basis and during a certain period. A critical value of the CWSI represents irreversible drought damage. This was determined by the characteristic response of the Ci of tea leaves during extreme drought stress. The results showed the following: (1) during the famous tea harvest season and summer drought season, the daily variation in CWSI was similar. During a certain period, the former maintained a stable fluctuation, while the latter increased in fluctuation. (2) The Ci showed a trend of fluctuating downward to a low point and then upward during extreme drought stress. After reaching the low point, it quickly increased in the former and stabilized for a day in the latter. When the Ci reached the low point, the upper benchmark of this critical point was 13.9 μmol·mol−1, the lower benchmark was 3.4, and the CWSI was 0.27. This critical CWSI could be used as an irrigation threshold point to ensure normal production for tea fields.

Genome-Wide Identification and Characterization of MYB Transcription Factors in Sudan Grass under Drought Stress.

Sudan grass (Sorghum sudanense S.) is a warm-season annual grass with high yield, rich nutritional value, good regeneration, and tolerance to biotic and abiotic stresses. However, prolonged drought affects the yield and quality of Sudan grass. As one of the largest families of multifunctional transcription factors in plants, MYB is widely involved in regulating plant growth and development, hormonal signaling, and stress responses at the gene transcription level. However, the regulatory role of MYB genes has not been well characterized in Sudan grass under abiotic stress. In this study, 113 MYB genes were identified in the Sudan grass genome and categorized into three groups by phylogenetic analysis. The promoter regions of SsMYB genes contain different cis-regulatory elements, which are involved in developmental, hormonal, and stress responses, and may be closely related to their diverse regulatory functions. In addition, collinearity analysis showed that the expansion of the SsMYB gene family occurred mainly through segmental duplications. Under drought conditions, SsMYB genes showed diverse expression patterns, which varied at different time points. Interaction networks of 74 SsMYB genes were predicted based on motif binding sites, expression correlations, and protein interactions. Heterologous expression showed that SsMYB8, SsMYB15, and SsMYB64 all significantly enhanced the drought tolerance of yeast cells. Meanwhile, the subcellular localization of all three genes is in the nucleus. Overall, this study provides new insights into the evolution and function of MYB genes and provides valuable candidate genes for breeding efforts in Sudan grass.

Functional Identification and Regulatory Active Site Screening of the DfDXS Gene of Dryopteris fragrans.

Dryopteris fragrans (L.) Schott has anti-inflammatory and antioxidant properties, and terpenoids are important components of its active constituents. The methyl-D-erythritol 4-phosphate (MEP) pathway is one of the major pathways for the synthesis of terpene precursors in plants, and 1-deoxy-D-xylulose-5-phosphate synthase (DXS) is the first rate-limiting enzyme in this pathway. DXS has been shown to be associated with increased stress tolerance in plants. In this experiment, two DXS genes were extracted from the D. fragrans transcriptome and named DfDXS1 and DfDXS2. Based on phylogenetic tree and conserved motif analyses, DXS was shown to be highly conserved evolutionarily and its localization to chloroplasts was determined by subcellular localization. Prokaryotic expression results showed that the number and growth status of recombinant colonies were better than the control under 400 mM NaCl salt stress and 800 mM mannitol-simulated drought stress. In addition, the DfDXS1 and DfDXS2 transgenic tobacco plants showed improved resistance to drought and salt stress. DfDXS1 and DfDXS2 responded strongly to methyl jasmonate (MeJA) and PEG-mimicked drought stress following exogenous hormone and abiotic stress treatments of D. fragrans. The transcriptional active sites were investigated by dual luciferase and GUS staining assays, and the results showed that the STRE element (AGGGG), the ABRE element (ACGTGGC), and the MYC element (CATTTG) were the important transcriptional active sites in the promoters of the two DXS genes, which were closely associated with hormone response and abiotic stress. These results suggest that the DfDXS gene of D. fragrans plays an important role in hormone signaling and response to stress. This study provides a reference for analyzing the molecular mechanisms of stress tolerance in D. fragrans.

Genome-wide investigation of caffeic acid O-methyltransferases and expression analysis under different abiotic stresses and anthracnose infection in pepper (Capsicum annuum L.)

ABSTRACT The caffeic acid O-methyl transferases (COMTs) facilitate the biosynthesis of lignin and play important roles in many processes, including growth, development and response to stresses. Pepper (Capsicum annuum L.) is a major horticultural crop with significant nutritional and medicinal values. Nevertheless, a comprehensive assessment of the COMT genes in pepper and their involvement in drought, salt tolerance and anthracnose resistance remains unestablished. In the present study, 80 pepper COMT genes were identified and classified into four major groups based on domain structure and phylogenetics. Additionally, the sequence analysis, gene structures, and duplication events were analysed. The genes were unevenly distributed across 10 chromosomes, and 10 pairs of tandem and 13 pairs of segmental duplicated genes were detected in the COMT gene family. Examination of cis-acting regulatory elements detected the presence of phytohormone-specific, stress-receptive and light responsive elements in the pepper COMT promoters. Moreover, qRT-PCR analysis revealed significant upregulated expression of CanCOMT48 to drought stress, CanCOMT14 to salinity stress and CanCOMT18 to anthracnose infection by Colletotrichum truncatum, suggesting their important functions in different stresses. Our results provide significant insights into the expression and probable function of selective COMTs which could be used as potential candidate genes for pepper tolerance breeding.

Silicon Modifies Photosynthesis Efficiency and hsp Gene Expression in European Beech (Fagus sylvatica) Seedlings Exposed to Drought Stress.

Background: Climate change is leading to severe and long-term droughts in European forest ecosystems. can have profound effects on various physiological processes, including photosynthesis, gene expression patterns, and nutrient uptake at the developmental stage of young trees. Objectives: Our study aimed to test the hypothesis that the application of silica (SiO2) influences photosynthetic efficiency and gene expression in 1- to 2-year-old Fagus sylvatica (L.) seedlings. Additionally, we aimed to assess whether silicon application positively influences the structural properties of leaves and roots. To determine whether the plant physiological responses are genotype-specific, seedlings of four geographically different provenances were subjected to a one-year evaluation under greenhouse conditions. Methods: We used the Kruskal-Wallis test followed by Wilcoxon's test to evaluate the differences in silicon content and ANOVA followed by Tukey's test to evaluate the physiological responses of seedlings depending on treatment and provenance. Results: Our results showed a significantly higher Si content in the roots compared with the leaves, regardless of provenance and treatment. The most significant differences in photosynthetic performance were found in trees exposed to Si treatment, but the physiological responses were generally nuanced and provenance-dependent. Expression of hsp70 and hsp90 was also increased in leaf tissues of all provenances. These results provide practical insights that Si can improve the overall health and resilience of beech seedlings in nursery and forest ecosystems, with possible differences in the beneficial role of silicon application arising from the large differences in wild populations of forest tree species.

Integrated miRNA and mRNA Transcriptome Analysis Reveals Regulatory Mechanisms in the Response of Winter Brassica rapa to Drought Stress.

Drought is a major abiotic stress factor that reduces agricultural productivity. Understanding the molecular regulatory network of drought response in winter rape is of great significance for molecular Brassica rapa. In order to comprehensively analyze the network expression of DEGs and DEMIs in winter rape under drought stress, in this study we used Longyou 7 as the experimental material to identify DEGs and DEMIs related to drought stress by transcriptome and miRNA sequencing. A total of 14-15 key differential mRNA genes related to drought stress and biological stress were screened out under different treatments in the three groups. and 32 differential miRNAs were identified through targeted regulatory relationships, and the mRNA expression of 20 target genes was negatively regulated by the targeting regulatory relationship. It is mainly enriched in starch and sucrose metabolism, carbon metabolism and other pathways. Among them, gra-MIR8731-p3_2ss13GA18GA regulated the expression of multiple mRNAs in the three treatments. miRNA is mainly involved in the drought resistance of Chinese cabbage winter rape by regulating the expression of target genes, such as starch and sucrose metabolism, amino acid biosynthesis, and carbon metabolism. These miRNAs and their target genes play an indispensable role in winter rapeseed drought stress tolerance regulation.

Integrating remotely sensed imagery in a forest gap model to study North American boreal forests in a changing world

Abstract Boreal forests of Alaska and Western Canada are experiencing rapid climate change characterized by higher temperatures, more extreme droughts, and changing disturbance regimes, resulting in forest mortality and composition changes. Mechanistic models are increasingly important for predicting future forest trends as the region experiences novel environmental change. Previously, many process-based models have generated starting conditions by ‘spinning up’ to equilibrium. However, setting appropriate initial conditions remains a persistent challenge in using mechanistic forest models, where stochastic events and latent parameters governing tree establishment have long-lasting impacts on simulation outcomes. Recent advances in remote sensing analysis provide information that can help address this issue. We updated an individual-based gap model, the University of Virginia Forest Model Enhanced (UVAFME), to include initial conditions derived from aerial and satellite imagery at two locations. Following these updates, material legacies (e.g., trees, seed banks, soil organic layer) allowed new forest types to persist in UVAFME simulations, landscape-level forest heterogeneity increased, and forest-wide biomass estimates increased. At both study sites, initialization from remotely sensed data had a strong impact on forest cover and volume. Climate change impacts were simulated decades earlier than when the model was ‘spun up'. In Alaska’s Tanana Valley State Forest, warmer climate scenarios drove deciduous expansion, increased drought stress, and resulted in a 28% decrease in overall biomass by 2100 between historical and high emissions climate scenarios. At a lowland site in Northern British Columbia, lodgepole pine (Pinus contorta) remained dominant and became more productive with exogenous climate forcing as temperature, nutrient, and flooding limitations decreased. These case studies demonstrate a new framework for forest modeling and emphasize the advantages of integrating remotely sensed data with mechanistic models, thereby laying groundwork for future research that explores near-term impacts of non-stationary ecological change.