This study investigated the effects of recurrent water deficit on drought tolerance traits in black pepper ( L.) 'Bragantina'. Plants were subjected to three cycles of water deficit followed by recovery periods. Water deficit reduced stomatal conductance, photosynthesis, transpiration, and water potential while increasing water-use efficiency. In addition, intercellular CO concentration, leaf temperature, root starch, and adaptive morphological characteristics in leaves and roots increased. Despite these adaptations, plants did not recover vegetative growth after rehydration. The primary tolerance mechanisms observed included increased abaxial epidermis thickness, stomatal density, fine roots, periderm thickness, and starch accumulation in roots. Although gas exchange and leaf water potential were restored, vegetative growth did not fully recover. This study highlights the response of black pepper to recurrent water stress and the underlying mechanisms of its drought tolerance.

Friv. is unique with its ability to survive desiccation to an air-dry state during periods of extreme drought and freezing temperatures. To understand its survival strategies, it is important to examine the protective mechanisms not only during desiccation but also during rehydration. We investigated the involvement of alternative cyclic electron pathways during the recovery of photosynthetic functions after freezing-induced desiccation. Using electron transport inhibitors, the role of PGR5-dependent and NDH-dependent PSI-cyclic electron flows and plastid terminal oxidase were assessed during rehydration of desiccated leaves. Recovery of PSII and PSI, the capacity of PSI-driven cyclic electron flow, the redox state of plastoquinone pool, and the intersystem electron pool were analyzed. Data showed that the effect of alternative flows is more pronounced in the first hours of rehydration. In addition, the NDH-dependent cyclic pathway played a more determining role in the recovery of PSI than in the recovery of PSII.

Climate change is one of the largest threats to grassland plant species, which can be modified by land management. Although climate change and land management are expected to separately and interactively influence plant demography, this has been rarely considered in climate change experiments. We used a large-scale experiment in central Germany to quantify the effects of grassland management, climate change, and their joint effect on the demography and population growth rate of 11 plant species all native to this temperate grassland ecosystem. We parameterized integral projection models with five years of demographic data to project population growth rate. We hypothesized that plant populations perform better in the ambient than in the future climate treatment that creates hotter and drier summer conditions. Further, we hypothesized that plant performance interactively responds to climate and land management in a species-specific manner based on the drought, mowing, and grazing tolerances as well as the flowering phenology of each species. Due to extreme drought events, over half of our study species went quasi extinct, which highlights how extreme climate events can influence long-term experimental results. We found no consistent support for our expectation that plants perform better in ambient compared with future climate conditions. However, several species showed interactive responses to the treatments, indicating that optimal management strategies for plant performance are expected to shift with climate change. Changes in population growth rates of these species across treatments were mostly due to changes in plant reproduction. Experiments combined with measuring plant demographic responses provide a way to isolate the effects of different drivers on the long-term persistence of species and to identify the demographic vital rates that are critical to manage in the future. Our study suggests that it will become increasingly difficult to maintain species with preferences for moister soil conditions, and that climate and land use can interactively alter demographic responses of the remaining grassland species.

Drought and salinity stress pose threats to agricultural production in drylands. Although breeding and genetic modification techniques have been employed to develop drought- and salt-tolerant crops, these methods are costly and risky. Hence, the potential application of endophytic fungi in dryland agriculture is being explored as a novel approach in improving plant tolerance to environmental stress. In this study, endophytic fungi with growth-promoting effects were isolated, characterized, and evaluated in terms of their ability to confer drought and stress tolerance to their host plants. Seventy-seven growth-promoting endophytic fungi belonging to 20 genera were isolated from barley roots; of these, strain T-2 elicited remarkable effects on plant growth parameters. Phylogenetic analysis revealed that strain T-2 belongs to genus Leptosphaeria, whose members are generally known as plant pathogens. Thus, Leptosphaeria sp. strain T-2 is a novel endophytic fungus that promotes plant growth. Moreover, it alleviated growth inhibition caused drought and salinity stress, as evidenced by the survival and maintained health of lettuce plants inoculated with strain T-2. The results of this study suggest that strain T-2 can be applied as a biofertilizer to improve agricultural production in drylands.

In recent years, the increase in extreme climates, such as persistent high temperatures and drought, has adversely affected the growth and development of fast-growing trees. Melatonin (MT) plays an important role in plant responses to biotic and abiotic stresses, yet there is a lack of research on the specific role of limiting enzyme genes for MT biosynthesis in fast-growing woody plants. In this study, we investigated the function of PtoASMT, a key rate-limiting enzyme encoding gene for MT biosynthesis, which can be induced by drought, salt, and the phytohormones ABA, SA and JA. Our results show that: (1) PtoASMT was widely expressed in all tissues of poplar, but was highly expressed in petioles, moderately expressed in roots, stems, shoots and young leaves, exhibiting a typical diurnal expression rhythm in leaves, with the encoded protein localized on chloroplasts; (2) the content of MT was significantly promoted in overexpressing PtoASMT transgenic poplar plants, but there were no obvious differences in their growth and development; (3) overexpressing PtoASMT plants exhibited stronger drought tolerance, accumulating less reactive oxygen species (ROS) under drought stress relative to wild-type plants, whereas knockout PtoASMT plants were more sensitive and accumulated more ROS; (4) overexpressing PtoASMT plants were more resistant to fungi Dothiorella gregaria than WT plants, while knockout plants showed higher sensitivity; meanwhile, the expression of disease resistance-related genes (PRs and JAZ10) was significantly altered. We conclude that PtoASMT enhances the resistance of poplar to drought and Dothiorella gregaria by mediating MT biosynthesis in poplar. These findings contribute to a better understanding the role of ASMT gene in MT accumulation and stress resistance in poplar.

Native amine dehydrogenases (AmDHs) are rare and typically have narrow substrate specificity and low processivity. Therefore, they are often modified using protein engineering for industrial and pharmaceutical applications. This study presents identification and characterization of a novel native amine dehydrogenase (AmDH) encoding WD40 protein (All1750) from Anabaena PCC 7120. Heterologous expression of all1750 in E. coli enhanced its tolerance to abiotic stressors such as drought, cadmium, and NaCl, as evidenced by increase in gene expression (2-10-fold), spot assay results (3-4-fold) and decreased ROS generation (0.2-1.8-fold). Molecular docking analysis showed that All1750 has broad substrate binding activity, indicating its catalytic potential in amine oxidation. All1750 exhibited the appreciable enzymatic activity with acetophenone (0.8-1.0-fold increase), followed by 4-fluorophenyl acetone and 4-fluoropropiophenone. The Km values for acetophenone and 4-fluorophenyl acetone were 4.2-12.1-fold higher, suggesting a greater affinity of All1750 for these low-cost substrates compared to the expensive 4-fluoropropiophenone. Recombinant All1750 showed optimal enzyme activity at pH 8.0 and maintained thermo-stability at 70 °C with a half-life of approximately 3 h. Our findings provide valuable insights into the industrial application of the All1750 protein. This native AmDH from Anabaena can effectively utilize diverse cost-effective substrates, making it a promising biocatalyst for chiral amine biosynthesis.

The food demand to support the growing population worldwide is expected to increase up to 60 % by 2050. But, various abiotic stress including heat, drought, salinity, and heavy metal stress are becoming more prevalent due to global warming and seriously affecting the crop productivity. Nanotechnology has a great potential to solve this issue, as various nanoparticles (NPs) with their unique physical and chemical characteristics, have shown promising ability to enhance the stress tolerance and subsequently, improving the plant growth and development. Although NPs can be synthesized either via physically or chemically or biologically, application of biogenic NPs in agriculture are gaining strong attention due to their economic, environmental friendly, and sustainable benefits. The implementations of biogenic NPs have been reported to be enhancing both the quantitative and qualitative properties of crop production significantly by mitigating abiotic stress. Hence, this review paper critically discussed the application of biogenic NPs, synthesized using various biological methods i.e. bacteria, fungi, algae, and plant-based, in enhancing the abiotic stress resilience and crop production. Adverse effects of the major abiotic stresses on crops have also been highlighted in the paper. The paper also focused on the mechanistic insights of plant-NPs interactions, uptake, translocation and NPs-induced biochemical and molecular changes in plants to help mitigating the abiotic stress. The potential challenges and environmental implications of extensive use of biogenic NPs in agriculture compared to the chemogenic NPs has also been critically assessed. Future research direction is provided to delve into the potential of biogenic NPs as promising tools for mitigating abiotic stress, and improving plant growth and development for a sustainable agriculture via nanotechnology.

We report data on morphological variation and behavior of the recently described watersnake Helicops boitata, previously known strictly from the holotype. Our data come from five new specimens fortuitously found in a private area near the type locality, in the Brazilian Pantanal wetlands. The expanded sample revealed polymorphism in at least two scalation features previously assumed as diagnostic of the species (i.e., undivided condition of the cloacal plate and nasal scales) and confirmed the uniqueness of the ventral color pattern, as well as the divided condition of the foremost ventral shields. In addition, three individuals collected alive also exhibited the same harmless behavior reported to the holotype, a rather unusual feature among snakes of the genus Helicops. Other new behavioral observations include mostly nocturnal activity (in contrast with the previous data) and the ability to dig galleries in the soft substrate when attempting to escape. The finding of five individuals very close to each other suggest aggregations in habitats prone to retain humidity in the dry season of the Pantanal. Low abundance rates and possible habitat restrictions might render Helicops boitata particularly susceptible to seasonal fire episodes that consume large extensions of the wetlands, including temporarily dry flooding fields in which aquatic reptiles find refuge during the seasonal droughts.

Root depth is a major determinant of plant performance during drought and a key trait for strategies to improve soil carbon sequestration to mitigate climate change. While the model Arabidopsis thaliana offers numerous advantages for studies of root system architecture and root depth, its small and fragile roots severely limit the use of the methods and techniques currently available for such studies in soils. To overcome this, we have developed ClearDepth, a conceptually simple, non-destructive, sensitive, and low-cost method to estimate the root depth of Arabidopsis in relatively small pots that are amenable to mid- and large-scale studies. In our method, the root system develops naturally inside of the soil, without considerable space constraints. The ClearDepth parameter wall root shallowness (WRS) quantifies the shallowness of the root system by measuring the depth of roots that reach the transparent walls of clear pots. We show that WRS is a robust and sensitive parameter that distinguishes deep root systems from shallower ones while also capturing relatively smaller differences in root depth caused by the influence of an environmental factor. In addition, we leveraged ClearDepth to study the relation between lateral root angles measured in non-soil systems and root depth in soil. We found that Arabidopsis genotypes characterized by steep lateral roots in transparent growth media produce deeper root systems in the ClearDepth pots. Finally, we show that ClearDepth can also be used to study root depth in crop species like rice.

Dissecting the drought resistance (DR) mechanism and designing drought-resistant rice varieties are promising strategies to address the challenge of climate change. Here, we selected a typical drought-avoidant (DA) variety IRAT109 and drought-tolerant (DT) variety Hanhui15 as the parents to develop a stable recombinant inbred line (RIL) population (F, 1,262 lines). The de novo assembled genomes of both parents were released. Through re-sequencing of the RIL population, a set of 1,189,216 reliable SNPs were obtained and used for constructing a dense genetic map. Using both aboveground and underground phenomic platforms and multimodal cameras, we captured 139,040 image-based traits (i-traits) of whole plant's phenotypes in response to drought stress throughout entire rice growth period and identified 32,586 drought-responsive quantitative trait loci (QTLs) including 2,097 unique QTLs. The QTLs related to panicle i-traits occurred on the middle of chromosome 8 over 600 times, while the QTLs related to leaf i-traits on the 5' end of chromosome 3 over 800 times, indicating potential effect of these QTLs on plant phenotypes. We chose three candidate genes (OsMADS50, OsGhd8, OsSAUR11) related to leaf, panicle, and root traits respectively and verified their functions in resisting drought. Gene OsMADS50 was found to negatively regulate DR by modulating leaf dehydration, grain size, and root downward growth. Furthermore, a total of 18 and 21 composite QTLs significantly related to grain weight and plant biomass were screened from 597 lines in RIL population under drought conditions in field experiments, and composite QTL region was highly overlapped (76.9%) with known DR gene region. Based on three candidate DR genes, we proposed the haplotype design suitable for different environments and breeding objectives. This study provides a valuable reference for multi-modal and time-series phenomic analyses, deciphers the genetic mechanism of DA and DT rice varieties, and offers a molecular navigation map for breeding DR variety.