Back

Environmental and Experimental Botany

Elsevier BV

Preprints posted in the last 30 days, ranked by how well they match Environmental and Experimental Botany's content profile, based on 11 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

1
Enhanced photosynthetic efficiency and ROS modulation promote cold stress tolerance of indica rice

Roy, V.; Parveen, R.; Dasgupta, P.; Chaudhuri, S.

2026-05-03 plant biology 10.64898/2026.04.30.721858 medRxiv
Top 0.1%
6.3%
Show abstract

Indica rice, being a tropical crop, is highly sensitive to cold temperature. Cold stress affects vegetative growth, photosynthetic efficiency, along with reproductive features. Genetic resource screening in diverse landraces is an approach for identifying cold-tolerant traits. Here, we have characterised a boro germplasm, CB1, with an efficient germination rate and growth vigour when treated at chilling temperatures. CB1 seedlings show a higher survival rate compared to IR36 when subjected to prolonged chilling stress. Biochemical analyses indicated efficient ROS modulation, higher chlorophyll content, enhanced photosystem II efficiency and unique stomatal traits, leading to higher relative water content in CB1 plants during stress and recovery. Transcriptome analysis supported upregulation of chlorophyll biosynthesis, photosystem, & light harvesting complex and ROS scavenger genes in CB1 seedlings. Interestingly, high D1 protein turnover in CB1 promotes damage-repair of PSII for efficient photosynthesis. Furthermore, key transcription factors for stomatal development and expression of photosynthetic genes were upregulated in CB1 during stress recovery. Notably, higher expression of OsGLK1 and enrichment of GLK1 targets were observed in CB1 plants during chilling stress and recovery. Taken together, our results suggested that CB1 plants exhibit cold tolerance by modulating photosynthesis efficiency and stomatal behavior for better adaptability and survival against chilling temperature. HIGHLIGHTSThe efficient photosynthetic recovery, active ROS scavenging system and maintenance of water content through regulating stomatal traits, enhance the survival of indica germplasm CB1 against chilling stress.

2
AP2/ERF transcription factor RAP2.6 regulates early flowering in Arabidopsis thaliana by altering S-nitrosothiol levels and cytokinin responses

Das, A. K.; Mostofa, M. G.; Lee, D.-S.; Yun, B.-W.

2026-05-16 plant biology 10.64898/2026.05.13.725052 medRxiv
Top 0.1%
6.2%
Show abstract

RAP2.6, an AP2/ERF transcription factor (TF), regulates plant stress responses; however, its role in floral transition remains unexplored. Here, we evaluated RAP2.6s role in flowering and the associated transcriptional changes in Arabidopsis thaliana under long-day conditions. RAP2.6-overexpressing line showed early flowering with fewer rosette leaves, whereas rap2.6-1 mutant flowered later, had more rosette leaves, and higher expression of the floral repressor FLOWERING LOCUS C (FLC). Early flowering in the overexpressing line was accompanied by transcriptional activation of the floral integrators GIGANTEA (GI), FLOWERING LOCUS T (FT), and COSTANS (CO), potentially through RAP2.6 interaction with GCC/DRE cis-regulatory elements. RAP2.6-mediated floral transition depended on nitric oxide (NO), with flowering time largely varying based on NO bioactivity. RAP2.6 was found to be a downstream regulator of Arabidopsis S-NITROSOGLUTATHIONE REDUCTASE 1 (GSNOR1) in controlling S-nitrosothiol (SNO) levels, flowering time, and silique formation. The NITRIC OXIDE-ASSOCIATED 1 (NOA1)-dependent reduction in NO levels abolished early flowering in 35S::RAP2.6 plants without affecting silique formation. Furthermore, enhanced cytokinin sensitivity and upregulation of cytokinin biosynthetic genes suggest cytokinin involvement in RAP2.6-mediated flowering. Together, these findings highlight the crucial role of RAP2.6 in regulating flowering time by integrating redox and hormonal signaling to coordinate reproductive development in A. thaliana.

3
Transcriptomic Insights into Drought Tolerance Enhancement in Bread Wheat Induced by a Microalgae-based Biostimulant

Arvanitidou, C.; Ramos-Gonzalez, M.; Garcia-Gomez, M. E.; Garcia-Gonzalez, M.; Romero-Campero, F. J.

2026-05-18 plant biology 10.64898/2026.05.18.725825 medRxiv
Top 0.1%
6.1%
Show abstract

Bread wheat (Triticum aestivum) is a staple food crucial for global caloric intake and food security. The current climate emergency demands the development of sustainable agricultural practices, particularly in the context of drought-induced yield reductions in bread wheat. Microalgae-based biostimulants have emerged as promising tools to enhance crop tolerance to drought stress while concurrently mitigating atmospheric CO2 accumulation. This study characterizes the transcriptomic responses to the foliar application of the microalgae-based biostimulant LRMTM in drought-stressed and fully irrigated wheat plants unveiling its mode of action. Drought stress at the tillering stage significantly altered gene expression activating key pathways related to phosphate starvation response (PSR), inositol phosphate signaling, and tocopherol biosynthesis. The application of the microalgae-based biostimulant LRMTM in drought-stressed plants further enhanced the expression of drought-responsive genes, particularly those involved in PSR and carbon fixation. Specific responses to LRMTM treatment in drought-stressed plants were also found related to abscisic acid (ABA) signaling activating genes involved in stomata closure, which plays a critical role in drought tolerance. In fully irrigated plants, LRMTM treatment was also beneficial modulating circadian rhythms, shade avoidance and attenuating stress responses. Phenotypic analysis showed that LRMTM-treated plants exhibited enhanced drought tolerance, increased height and spike length even under fully irrigated conditions. These results indicate that the microalgae-based biostimulant LRMTM not only enhances wheat response to drought but also promotes growth and productivity in both stressed and non-stressed conditions which could contribute to the development of sustainable agriculture in the face of the current climate challenges.

4
The lack of peroxisomal Glycolate Oxidases 1 and 2 influences mitochondrial electron transport chain and its redox state under control and cadmium stress

Collado-Arenal, A. M.; Rodriguez-Serrano, M.; Pelaez-Vico, M. A.; Terron-Camero, L. C.; Perez-Gordillo, F. L.; Ranea-Robles, P.; Lopez, L. C.; Sandalio, L.; Romero-Puertas, M. C.

2026-05-08 plant biology 10.64898/2026.05.06.723131 medRxiv
Top 0.1%
4.9%
Show abstract

The production of reactive oxygen species (ROS) in response to cadmium (Cd) has been extensively studied, demonstrating that they play a key role in the plants response to this heavy metal. While the role of enzymes like RBOHs has been thoroughly studied, the function of other ROS-producing enzymes, such as peroxisomal glycolate oxidase (GOX), remains largely overlooked. Peroxisomal GOX is a core metabolic enzyme of the photorespiratory pathway occurring in chloroplasts, mitochondria and peroxisomes. Using Arabidopsis (Arabidopsis thaliana) mutants lacking the main peroxisomal GOX genes, GOX1 (gox1-1) and GOX2 (gox2-1) we explored their function in plant response to Cd. Although photosynthetic capacity appears to be affected to the same extent in both mutants under control and Cd stress conditions, GOX2 seems to play a greater role in ROS production in response to the metal. Transcriptomic analyses on WT and gox2-1 pointed to the mitochondrial electron transport chain (mETC) as a target of Cd stress. We further investigated the individual GOX1 and GOX2 functions in mETC regulation and redox state. Although oxidative ratio of mitochondria was higher in both mutants, it was more pronounced in the absence of GOX1. Furthermore, the mETC is affected in both mutants but the regulation of its components differs in each mutant. These results point out the different functions of the two photorespiratory GOX isoforms in Arabidopsis, leading to a better understanding of the photorespiratory pathway.

5
Transient uncoupling of the Suc-Tre6P-SnRK1 nexus during salt stress associates with biphasic metabolic reprogramming and root plasticity

Barbieri, G.; Parola, R.; Feil, R.; Rodriguez, M. S.

2026-05-12 plant biology 10.64898/2026.05.08.723798 medRxiv
Top 0.2%
3.4%
Show abstract

Soil salinization threatens global agriculture reducing yields, yet the metabolic signals controlling salt-sensitive root plasticity in alfalfa remain unclear. We hypothesize that salinity transiently uncouples the sucrose-trehalose-6-P (Tre6P)- Sucrose non-fermenting kinase 1 (SnRK1) nexus, aligning with a biphasic root metabolic response and altered root architecture. Alfalfa seedlings were grown in a hydroponic system and exposed to 200 mM NaCl, with root samples collected from 1 h to 7 d. While primary root growth and biomass remained unchanged, lateral root development was enhanced under salinity. Early response (1 h-1 d) was characterized by reduced carbon metabolites, low Tre6P, increased malondialdehyde, and SnRK1 activation, with a decline in glycolytic and TCA intermediates. During this phase, sucrose was negatively correlated with both Tre6P and SnRK1. Late response (3-7 d) showed a SnRK1 reactivation, Tre6P recovery, and osmoprotectant accumulation, including increased antioxidant capacity (+75% at 3dpt), proline (+178%), and sucrose (+18%) and starch depletion (-57%) at 7dpt respect to control. These metabolic changes coincided with the enhanced lateral root emergence. These findings indicate a two-phase response: early metabolic downscaling with transient Suc-Tre6P-SnRK1 disruption, followed by recovery with Tre6P restoration, SnRK1 reactivation, osmoprotection, and sustained root plasticity under salinity. HighlightSalinity triggers a temporary metabolic shift in alfalfa roots: plants first conserve energy, then adapt to stress, maintaining lateral root growth and flexible root architecture.

6
Effects of leaf removal on photosynthetic activity, fruit yield, and quality of micro-dwarf tomatoes

Usenko, D.; Giladi, C.; Ziv, C.; Helman, D.

2026-05-13 plant biology 10.64898/2026.05.10.724098 medRxiv
Top 0.2%
3.2%
Show abstract

Micro-dwarf tomato cultivars are increasingly considered for urban and controlled-environment agriculture due to their compact architecture and suitability for high-density planting. However, optimal canopy management strategies for these cultivars remain poorly defined. In this study, we evaluated the effects of different leaf removal intensities on leaf-level physiological performance, fruit yield, and fruit quality in three micro-dwarf tomato cultivars (Mohammed, Hahms Gelbe Topftomate, and Red Robin) grown under contrasting seasonal light conditions. Plants were subjected to low (15%), moderate (30%), or severe (90%) leaf removal, and leaf-level gas exchange was measured across canopy layers, along with yield and fruit quality assessments. Severe leaf removal (90%) increased carbon assimilation, transpiration, and stomatal conductance in middle and lower canopy leaves by up to approximately twofold compared with control plants, indicating improved light availability at the leaf level. However, these physiological enhancements did not consistently translate into higher yield, reflecting reduced whole-plant source capacity under excessive leaf removal. Low to moderate leaf removal (15-30%) generally increased or maintained yield and fruit number, whereas severe leaf removal reduced yield in Hahms Gelbe and Red Robin, particularly under low seasonal radiation. In contrast, Mohammed exhibited yield increases of up to 220% under low leaf removal and maintained increased yield even under severe leaf removal under high-light conditions. Fruit quality was largely unaffected by leaf removal, except for total soluble solids, which declined by approximately 12% under severe leaf removal across cultivars, consistent with sugar dilution under source limitation. Overall, these results demonstrate that optimal leaf removal in micro-dwarf tomatoes requires balancing improved canopy light distribution with maintenance of sufficient leaf area for carbon assimilation. Leaf removal thresholds are strongly cultivar- and light-dependent, emphasizing the need for cultivar-specific canopy management strategies in compact tomato systems and controlled-environment agriculture.

7
The PSI-NDH supercomplex prevents chilling-induced PSI photoinhibition

Takeuchi, K.; Harimoto, S.; Ifuku, K.

2026-05-13 plant biology 10.64898/2026.05.11.724080 medRxiv
Top 0.2%
3.1%
Show abstract

Chilling stress induces photosystem I (PSI) photoinhibition in chilling-sensitive cucumber, in which insufficient activity of the chloroplast NADH dehydrogenase-like complex (NDH) leads to PSI over-reduction and damage. However, it is not yet clear whether these findings can be generalized to other species or what the molecular mechanism underlying impaired NDH function is. In this study, we first examined whether NDH is essential for PSI protection under chilling stress using an NDH-deficient rice mutant. Compared with wild-type plants, the NDH-deficient mutant exhibited enhanced PSI over-reduction and pronounced PSI photoinhibition under chilling stress. In contrast, rice plants expressing flavodiiron protein (FLV), which functions as an alternative electron acceptor downstream of PSI, did not exhibit PSI photoinhibition under chilling stress, demonstrating that electron sink capacity of NDH is important for PSI protection under chilling stress. Furthermore, analysis of the factors responsible for NDH dysfunction under chilling stress in cucumber revealed that chilling stress destabilizes the PSI-NDH supercomplex, leading to NDH monomerization and a consequent loss of NDH activity. This NDH monomerization is likely attributable to chilling-induced damage to the light-harvesting complex Lhca, which mediates the association between PSI and NDH. Together, these results indicate that NDH is essential for protecting PSI from photoinhibition under chilling stress in both rice and cucumber, and that chilling-induced destabilization of the PSI-NDH supercomplex represents a key molecular mechanism underlying PSI over-reduction and photoinhibition.

8
Herbivory-induced alterations in cytosolic proteins of pigeon pea (Cajanus cajan) leaves

S, A.; Kalita, P. J.; Meshram, S. K.; Das, A.; Patil, R. I.; Das, S.; Jaba, J.; Das, D.; Acharjee, S.

2026-05-08 plant biology 10.64898/2026.05.07.723431 medRxiv
Top 0.3%
2.1%
Show abstract

Insect herbivory triggers cytosolic proteome reprogramming by activating defense pathways and modulating key metabolic processes. We found that simulated herbivory in pigeon pea (Cajanus cajan) induced reactive oxygen species (ROS) production and molecular alterations within 12 hours (h) of post treatment. We compared the leaf proteome profiles of two cultivated genotypes, ICPL 332 (moderately resistant) and ICPL 87 (susceptible), using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) coupled with mass spectrometry (MS). More than 220 protein spots were detected in ICPL 332 and over 200 in ICPL 87. Comparative analysis revealed 75 differentially accumulated proteins (DAPs), of which 40 were consistently reproducible across biological replicates. These included 11 unique to ICPL 87, 9 unique to ICPL 332, and 10 common to both genotypes. Among the shared DAPs, ICPL 332 showed five upregulated and five downregulated, whereas ICPL 87 exhibited only two upregulated and eight downregulated. Functional categorization grouped DAPs into primary metabolism, stress response, and growth and development. Proteins related to primary metabolism were largely downregulated in both genotypes, while stress-associated proteins exhibited substantial downregulation in ICPL 87 compared to ICPL 332. Overall, the results demonstrate proteomic adjustments underlying defense responses in pigeon pea genotypes.

9
OsGGCT1 provides tolerance to Fusarium oxysporum in Arabidopsis thaliana by upregulating γ-glutamyl cycle

Chaudhary, D.; Viashnav, R.; Giri, B.; Joshi, D. N. C.

2026-05-18 plant biology 10.64898/2026.05.15.725392 medRxiv
Top 0.3%
2.1%
Show abstract

{gamma}-Glutamyl cyclotransferases (GGCTs) belongs to class of cytosolic enzymes that are responsible for glutathione (GSH) degradation under stress conditions. They regulate GSH homeostasis through the {gamma}-glutamyl cycle which is responsible for maintaining the synthesis of GSH as well as its breakdown, enabling recycling of its constituent amino acids. Although GGCTs have been implicated in enhancing heavy metal (HMs) tolerance in plants, their role in biotic stress remains largely unexplored. Previously, OsGGCT1 was identified as a gene strongly upregulated in Fusarium stress. In this study, the GGCT1 homolog from Oryza sativa japonica was characterized for its role in conferring tolerance to Fusarium oxysporum (F.O.). Similar to abiotic factors, biotic stresses significantly impact crop yield and productivity. The rhizosphere harbors diverse microbial communities, including harmful pathogens such as F. oxysporum. Fusarium causes wilt disease in a variety of plant species, such as: tomato, legumes, rice, and Arabidopsis thaliana. Our results demonstrate that overexpression of OsGGCT1 enhanced tolerance to F. oxysporum in A. thaliana, primarily by reducing fungal spore accumulation. Transgenic plants showed elevated expression of OsGGCT1 along with AtGSH1 and AtGSH2, reduced levels of reactive oxygen species (ROS), improved growth and photosynthetic performance and enhanced activities of the antioxidant enzymes. OsGGCT1 serves as a key component in maintaining GSH homeostasis by supporting glutamate (Glu) regeneration necessary for sustained GSH biosynthesis. Overall, these findings identify OsGGCT1 as an important constituent of the GSH-mediated detoxification pathway against Fusarium oxysporum and provide valuable molecular insights for developing Fusarium-tolerant rice varieties with reduced fungal accumulation.

10
Characterization of Rhizosphere Oxidation Associated with Root Development in Rice Using Planar Oxygen Optodes

Kawai, T.; Teramoto, S.; Ma, X.; Fukushima, D.; Hmwe, K. K.; Kimani, S. M.; Tokida, T.; Uga, Y.

2026-05-18 plant biology 10.64898/2026.05.14.725292 medRxiv
Top 0.3%
1.8%
Show abstract

Rhizosphere oxidation is a key adaptive mechanism in reductive soil environments, in which oxygen released from roots alters rhizosphere redox conditions and regulates biogeochemical processes. Rice plants possess an internal oxygen transport system, and radial oxygen loss (ROL) from roots is closely associated with root development. However, the spatial patterns of ROL in soil and their relationships with root traits remain poorly characterized. In this study, we developed a multimodal imaging system that integrates planar oxygen optodes with X-ray computed tomography to simultaneously visualize rhizosphere oxidation and root development in rice. Daily time-course tracking of individual crown roots revealed dynamic changes in the spatial distribution and magnitude of rhizosphere oxygen in relation to root elongation and aging. Root thickness was positively correlated with dissolved oxygen levels near root tips. Genotypic comparisons further identified a cultivar with reduced rhizosphere oxidation despite possessing thicker roots among the tested genotypes, thereby indicating the involvement of additional physiological processes. Overall, these findings demonstrate that rhizosphere oxidation is regulated by root growth stage and thickness and dynamically modulated during root development.

11
Iron availability regulates PIN-mediated auxin transport and distribution to modulate root gravitropic growth in Arabidopsis

Fang, Y.; Kong, M.; Peng, Y.; Tan, S.

2026-05-22 plant biology 10.64898/2026.05.20.726447 medRxiv
Top 0.4%
1.7%
Show abstract

Iron (Fe) is an essential micronutrient for plant growth, and the hormone auxin is a key regulator of developmental processes, including root gravitropism. Here, we investigated the molecular mechanisms underlying the crosstalk between iron nutrition and auxin-mediated root growth in Arabidopsis thaliana. Phenotypic analysis revealed that iron deficiency strongly shaped root system architecture and root gravitropism, and these phenotypes were exacerbated in the iron uptake mutant irt1-1. Genetic analysis revealed that iron deficiency did not aggravate the gravitropic defect of the pin2 mutant, eir1-4, suggesting that iron availability modulates root gravitropism through a PIN2-dependent pathway. Further transcriptomic analysis confirmed that iron deficiency significantly altered the expression of numerous genes related to the auxin pathway, providing molecular evidence for the observed physiological connection. Collectively, this study revealed that iron availability regulates root gravitropic growth by modulating PIN-mediated auxin transport and distribution, providing insights into how plants integrate nutritional cues with developmental programs. Graphical abstract A brief descriptionIron modulates auxin transport and root tip distribution by regulating PIN2 protein, thereby mediating root gravitropism in Arabidopsis. Public summaryO_LIIron nutrition specifically regulates root gravitropism and architecture in Arabidopsis. C_LIO_LIIron deficiency disrupts local auxin homeostasis in root tips and impairs asymmetric distribution in response to gravity. C_LIO_LIIron deficiency stress significantly reduces the abundance of PIN2 protein in root tip cells and disrupts its polar localization pattern on the plasma membrane, thereby precisely modulating polar auxin transport by interfering with the vesicle trafficking and recycling efficiency of PIN2. C_LIO_LIRNA-seq results showed that iron deficiency induced differential expression of multiple auxin-related genes, indicating that iron nutrition affects root development through the auxin pathway. C_LI

12
Cytokinin-mediated repression of jacalin lectins reinforces root immunity

George, A. P.; Koolath, V.; Das, K. K.; Das, A.; Haque, S.; Karuvanthodi, I. T.; Ambatipudi, K.; Satbhai, S. B.; Ramireddy, E.

2026-05-18 plant biology 10.64898/2026.05.15.725414 medRxiv
Top 0.4%
1.7%
Show abstract

The root cap is essential for perceiving environmental cues surrounding the root. However, the molecular mechanisms underlying root cap-mediated immunity and how it defends against invading pathogens remain largely unresolved. Our results indicate that cytokinin plays a major role in regulating soil-borne pathogen such as Ralstonia pseudosolanacearum load around the root and root cap. As Ralstonia populations increase, cytokinin signalling is activated and represses the expression of its downstream signalling targets such as root cap-specific proteins JAL10 and JAL20, to impart the tolerance against the Ralstonia. The functional analysis jacalin-associated lectin family proteins JAL10 and JAL20, revealed that loss-of-function leads to enhance tolerance to Ralstonia whereas gain-of-function leads to susceptibility compared to Col-0. Our Glycoproteomic and metabolomic analyses indicate that JAL10 and JAL20 act as negative regulators of cell wall remodelling and likely to promotes cell wall thickening, thereby enhancing resistance to soil-borne infections. The knockdown of ortholog of JAL protein in Tomato also revealed its conserved function in imparting tolerance to Ralstonia pseudosolanacearum. Further we also show downregulation of JALs by other soil-borne pathogen infection, suggesting that cytokinin might protecting the vulnerable areas of root tip regions by regulating the expression of root cap-specific JALs and thereby fortifying the cell wall.

13
Identification of Potential Regulatory Non-Coding RNAs in Lotus Japonicus Symbiosis

Budnick, A.; Utley, D.; Blahovska, Z.; Radutoiu, S.; Sederoff, H.

2026-05-21 plant biology 10.64898/2026.05.19.726297 medRxiv
Top 0.4%
1.6%
Show abstract

O_LISymbiosis between legumes and rhizobia is beneficial on nutrient-poor soils, as it enables the fixation of atmospheric N2. To establish this symbiosis, gene expression in both the host plant and the symbiont has to be regulated. To understand the underlying RNA-mediated regulation of host gene expression, we designed experiments to identify competing endogenous networks involving circular RNA, microRNA, and linear transcripts during symbiosis, using wt and symbiosis-deficient Lotus japonicus mutants with the rhizobium Mesorhizobium loti (M. loti). C_LIO_LICircRNA, miRNA, and linear transcripts were identified from Lotus japonicus wildtype and CCamK mutant (ccamk-13; snf-1) seedlings without inoculation or with M. loti inoculation using deep short-read sequencing with rRNA-depletion and random primers. C_LIO_LIDifferentially expressed miRNAs showed negative correlations to predicted target genes and may regulate symbiotic processes. The symbiosis essential iron-sensor LjnsRING/BRUTUS expresses a circRNA which was upregulated in symbiotic treatments. This circRNA may act as a target mimic and contribute to nodule longevity. CircRNAs are predicted to act predominantly as trans-regulatory molecules with similar frequencies in Arabidopsis thaliania, Oryza sativa, and Lotus japonicus. C_LIO_LIWe identified novel miRNAs, long noncoding RNAs, and circRNAs, and nominated several as potential new regulatory non-coding RNAs that may act as target mimics to stabilize genes and support symbiosis. C_LI SummarySymbiosis between Lotus japonicus and Mesorhizobium loti involves treatment-specific regulation of competing endogenous RNA networks involving circular RNA, miRNA, and linear transcripts.

14
Simulated Microgravity Induces Cultivar-Specific Changes Affecting Salmonella enterica Ingression Independent of Stomatal Physiology

Wiest, T. A.; Bais, H.

2026-05-15 plant biology 10.64898/2026.05.13.724889 medRxiv
Top 0.4%
1.5%
Show abstract

Advances in NASAs astrobiology program have demonstrated the feasibility of cultivating plants in space and in analog extraterrestrial habitats. In addition to abiotic stressors, plants grown in terrestrial and space-like environments are challenged by both phytopathogens and opportunistic human pathogens, with implications for plant productivity and human health. The persistence of human-associated pathogens in spacecraft and space stations raises significant concerns regarding food safety. The molecular, biochemical, and signaling mechanisms governing stomatal development and function under microgravity remain poorly understood. We employed an experimental system incorporating human pathogen Salmonella enterica and lettuce microgreens exposed to simulated microgravity through two-dimensional clinorotation to investigate plant innate immunity and stomatal development and function. We further evaluated four lettuce cultivars to determine whether genetic variation impacts these factors under simulated microgravity conditions. Our findings indicate that simulated microgravity significantly influences stomatal development and function, as evidenced by an increase in stomatal density and variable changes to stomatal aperture. Notably, cultivar-dependent variation in stomatal traits and responses to Salmonella enterica was observed under microgravity conditions. Although increased stomatal density was hypothesized to enhance pathogen ingression, internalization was more strongly predicted by cultivar selection and simulated microgravity; simulated microgravity increased ingression, with red pigmented cultivars having less pathogen than green cultivars. These results suggest that targeted selection of cultivars with favorable physiological traits may improve food safety and the viability of crop production systems in space environments. They also suggest that development and function of stomata may change in spaceflight conditions.

15
Water beneath the pavement: assessing the benefits of passive irrigation for urban Lophostemon confertus trees in western Sydney

Siclari, D.; Tjoelker, M. G.; Perera, C.; Pfautsch, S.; Rymer, P. D.; Marchin, R. M.

2026-05-03 plant biology 10.64898/2026.04.29.721794 medRxiv
Top 0.5%
1.0%
Show abstract

Urban environments typically experience higher temperatures than surrounding natural landscapes, making urban vegetation crucial for cooling local areas and improving the health of city residents. Impervious urban surfaces limit the absorption and retention of precipitation, potentially limiting tree water access and threatening long-term survival. Here, we measured tree physiology and growth of Lophostemon confertus (Queensland brush box) trees to investigate how a passive irrigation system that stores stormwater affected the performance of young, establishing trees in a hot and dry suburb of western Sydney, Australia. During the 2024-2025 austral summer, three years after planting, the local climate was periodically hot and dry, with a total of 16 days above 35 {degrees}C. Irrigated L. confertus trees had higher water availability (i.e., higher predawn leaf water potential,{Psi} pre), lower water stress (i.e., higher midday leaf water potential,{Psi} mid, more frequently above turgor loss point), greater stomatal conductance (gs) on hot and dry summer days, and reduced leaf temperatures (Tleaf), compared to control trees. No significant differences in growth rates were observed between irrigated and control trees during the first three establishment years, but irrigated trees had greater crown survival during the hot, dry summer. Our results suggest passive irrigation may mitigate periods of short-term heat and drought stress in urban trees by increasing water access to support transpiration that prevents leaves from overheating, improving tree health. Higher tree transpiration may lead to greater ecosystem services by increasing cooling benefits, contributing to mitigation of urban heat island effects.

16
RAP2.3 is required for MYB51 and SIGMA3 expression during the response of Arabidopsis thaliana to multifactorial stress combination

Sinha, R.; Pelaez-Vico, M. A.; Mohanty, D.; Pascual, L. S.; I Zandalinas, S.; Lyu, Z.; Bereimipour, A.; Azad, R.; Joshi, T.; Mittler, R.

2026-05-19 plant biology 10.64898/2026.05.18.725943 medRxiv
Top 0.6%
0.9%
Show abstract

In nature, plants are subjected to multiple environmental stress factors simultaneously or sequentially. Recent studies revealed that when three or more stress factors impact a plant simultaneously (termed multifactorial stress combination; MFSC), plant survival declines, even if the intensity of each individual stress involved in the MFSC is low. We previously identified RAP2.3 as a key transcription factor (TF) required for Arabidopsis thaliana survival, specifically under a MFSC of salt+excess light+heat stress (i.e., S+EL+HS). Here we report that RAP2.3 is required for the expression of SIGMA3, a nuclear-encoded factor that directs plastid RNA polymerase to specific plastid promoters, and MYB51, a key stress response TF involved in glucosinolate metabolism and oxidative stress responses, specifically during a MFSC of S+EL+HS. Like rap2.3 mutants, myb51 and sig3 mutants display significantly low survival rate specifically under the MFSC of S+EL+HS. Based on MYB51 gene regulatory network analysis and characterization of jasmonic acid (JA) mutants, we further reveal that suppression of JA signaling could play an important role in promoting plant survival under conditions of S+EL+HS. Our findings uncover an additional layer of the response of plants to MFSC, as well as identify potential targets for breeding crops with enhanced tolerance to climate change.

17
Acellular starch domains in the endosperm of wheat and oat

KOSINA, R.; Tomaszewska, P.; Kochmanski, L.

2026-05-13 plant biology 10.64898/2026.05.12.724639 medRxiv
Top 0.6%
0.9%
Show abstract

The transformation of the free nuclear syncytium into cellular endosperm tissue with starch and protein accumulation is a well-established phenomenon, at least in the fruits of cereals of the Triticeae tribe. The present article demonstrates that there is considerable diversity inherent in this type of caryopsis morphogenesis. By examining various taxa (species, varieties, and cultivars) of wheat, oats, and some wild grasses, this research reveals significant deviations in endosperm morphogenesis from the typical state. A new developmental pattern of endosperm was identified, characterized by several distinctive features such as incomplete cellularization of the syncytium and starch accumulation within the acellular endosperm domains and the endosperm cavity. A large number of plastids were observed in the syncytium stage, which served as the basis for the later amyloplast stage. The acellular endosperm domains and the cavity domain exhibited connections at specific discontinuities in the modified aleurone layer surrounding the cavity. The peripheral parts of the caryopsis received fewer assimilates necessary for starch synthesis, which was attributed to their increased distance from the transfer system and a likely reduction in the efficiency of assimilate transport through the apoplast in these areas. The starch cavity volume constituted a few percent of the overall caryopsis volume, which could serve as a foundation for potential breeding improvements to enhance starch yields across different varieties.

18
Alternative polyadenylation and the sex-specific gene expression program in hemp

Shivakumar, A.; Hunt, A. G.; Chakrabarti, M.

2026-05-17 plant biology 10.64898/2026.05.13.725035 medRxiv
Top 0.6%
0.8%
Show abstract

Hemp (Cannabis sativa) produces a wide array of medicinally significant compounds, including cannabidiol (CBD). These compounds are predominantly synthesized in female hemp inflorescences. The proposed research utilizes next-generation sequencing-based transcriptome analysis using a 3{square}-end-directed approach to identify differentially expressed genes between male and female hemp plants at the early vegetative stage. 886 differentially expressed genes (DEGs) were identified, a majority of which were upregulated in males compared to females. We hypothesized that alternative RNA processing contributes to sex-specific gene expression. To this end, 932 genes were identified that exhibited significant changes in poly(A) site usage when comparing males and females. These genes were much more likely to be differentially expressed, supportive of this hypothesis. Males tend to have longer 3 UTRs with canonical motifs found in the Near-Upstream Elements (NUE), compared to the shorter 3 UTRs in females, which have A-rich motifs near the cleavage site. This suggests that polyadenylation remodels hemp mRNAs with distal poly(A) sites being preferred in males. To further investigate when this sex-specific gene expression program is established, RNA was isolated from plants at various developmental stages, such as developing seeds, four-day-old seedlings, and different developmental stages up to four weeks after sowing. Diagnostic male-specific genes were analyzed using RT/PCR. The results indicate that sex-specific gene expression is not evident in seeds but rather is set during or after germination. SignificanceO_LIHemp males tend to have longer 3 UTRs with canonical motifs found in the Near-Upstream Elements (NUE), compared to the shorter 3 UTRs in females, which have A-rich motifs near the cleavage site. C_LIO_LIThe sex-specific gene expression program is not yet established in mature seed but is set in the time between germination and 4 days of growth. C_LI

19
Phosphorus-laden Mg/Fe Layered Double Hydroxide Dispersed on Douglas fir Biochar as a Controlled Release Fertilizer and its effect on the growth of bush beans (Phaseolus vurlagris).

Singh, T.; Rodrigo, P. M.; Folk, R. A.; Dhillon, J.; Varco, J. J.; Mlsna, T.

2026-05-23 plant biology 10.64898/2026.05.22.727001 medRxiv
Top 0.7%
0.8%
Show abstract

Many agricultural soils are deficient in key macronutrients needed for healthy plant development. Relying on highly water-soluble commercial fertilizers for long durations can be costly and environmentally harmful. This study investigates a phosphorus-loaded Mg/Fe layered double hydroxide (LDH) dispersed on Douglas fir biochar (Mg/Fe-LDH biochar) as a controlled-release fertilizer and evaluates its impact on bush bean (Phaseolus vulgaris L.) growth. Emphasizing sustainability, the work integrates controlled-release fertilizers, biochar, and LDH modification to enhance nutrient use efficiency and mitigate environmental runoff. Mg/Fe-LDH was directly synthesized on biochar via a co-precipitation approach, loaded the composite with phosphate by anion exchange, and characterized the material using elemental analysis, N2 Brunauer-Emmett-Teller (BET) determinations surface area analysis, and x-ray photoelectron spectroscopy to confirm successful LDH modification on Douglas fir biochar, and high surface area with accessible active sites. The synthesis yielded a stable P-Mg/Fe-LDH biochar with enhanced dispersibility and phosphate-buffering capacity, enabling controlled-release fertilization. In greenhouse experiments, bush beans grown with the P-Mg/Fe-LDH biochar exhibited improved growth metrics, including increased yield (beans fresh weight of 31.7 g), biomass (plant dry weight of 6.3 g), plant height (32.8 cm), and improved nutrient uptakes (1.88 mg (P) g-1) at 100.88 kg (P2O5) ha-1 compared with unfertilized controls and conventional P fertilizers, indicating efficient, controlled-release phosphate delivery and sustained nutrient availability. The results demonstrate that integrating LDH-modified biochar can enhance P uptake and plant growth while reducing leaching losses. Overall, this study highlights the strategic significance of combining biochar, layered double hydroxides, and controlled-release formulations to advance sustainable nutrient management and improve crop performance in agroecosystems. The findings offer a promising pathway for environmentally conscious fertilizer design and soil amendment strategies that align with global goals for resource efficiency and food security. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/727001v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@316444org.highwire.dtl.DTLVardef@adcd48org.highwire.dtl.DTLVardef@8068aforg.highwire.dtl.DTLVardef@58d623_HPS_FORMAT_FIGEXP M_FIG C_FIG

20
Genome sequence of the medicinal plant Urtica dioica reveals the genetic basis of the flavonoid metabolism

Wolff, K.; de Oliveira, J. A. V. S.; Fuerstenberg, L.; Hagedorn, M.; Garz, B.; Borchert, M.; Pucker, B.

2026-05-16 plant biology 10.64898/2026.05.15.725508 medRxiv
Top 0.7%
0.7%
Show abstract

BackgroundUrtica dioica, also known as stinging nettle, is a widespread plant that can indicate high nitrogen availability in the soil. It is probably best known for the pain caused by touching it. U. dioica is also recognized as a medicinal plant with reports claiming applicability against numerous diseases. ResultsA highly continuous genome sequence was constructed based on nanopore long read sequencing data. The total assembly size is 1.1 Gbp with an N50 of 40.7 Mbp. RNA-seq data and hints from other species were integrated to produce a high quality annotation of the protein encoding genes. This genomic resource enabled the identification of genes involved in the flavonoid biosynthesis. A particular focus was on anthocyanin biosynthesis genes as these are crucial for high light and nitrogen deprivation stress response, which is revealed by redding of the leaves. ConclusionThis genomic resource provides the basis for future studies unraveling the biosynthesis pathways underlying various medically important compounds produced by stinging nettles.