The assessment of the degree and partitioning of genetic variation in crop populations and species is crucial to understand their adaptive evolution and provides vital knowledge to assist in the development of crops to combat food insecurity. Underutilised crops are understudied but are often drought-/heat-tolerant or nutritionally diverse; hence, as food security becomes more pressing, their investigations are increasing. Here, we focus on horsegram (Macrotyloma uniflorum (Lam.) Verdc.) and perennial horsegram (M. axillare (Meyer) Verdcourt), two closely related drought- and heat-tolerant underutilised legumes. Forty-two accessions were studied through phylogenetic and population genetic analysis and by measuring their seed and plant morphologies to assess genetic and morphological variation within and between the species. The species were distinct at the genetic level, with genetic diversity about 2.5 times greater in M. axillare than in M. uniflorum. Previously unsampled horsegram accessions from Africa were distinct from South Asia and therefore could contain novel genetic variation. Genetic variation suggested four clusters within perennial horsegram, which were largely structured by geography. Seed length is significantly greater in horsegram, and the two species differ in their dominant seed and stem colours, which could assist in-field identification. This work provides new insight into these species specifically and underutilised legumes more generally. Future investigations focused on identifying adaptive genetic variation are warranted to further reveal the potential of these crops in being optimized for promotion and commercialization, especially in countries which need more sustainable and reliable agricultural varieties to mitigate climate change.

Extreme events (e.g. severe drought) can hinder the establishment of saplings in tropical forest plantations. To assess the resistance and recovery of three commercially important Amazonian tree species under drought conditions and to identify their key functional strategies for drought response, we conducted a controlled drought experiment exposing saplings of Bertholletia excelsa, Dipteryx odorata, and Tachigali vulgaris to water deficit followed by recovery. Tachigali vulgaris (fast-growing species) was more vulnerable to drought, as 80% of the drought-treated plants died. Nevertheless, the individuals who survived demonstrated a rapid recovery of physiological performance following rewatering. Bertholletia excelsa and D. odorata (slow-growing species) were more resistant to drought stress, as evidenced by lack of mortality in these species. Drought-stressed plants had the lowest growth rates, more biomass allocated to roots and less leaf biomass. The greater biomass allocation to roots in B. excelsa and D. odorata, together with their more conservative functional traits compared to T. vulgaris, appears to play an important role in their lower sensitivity to drought. These species exhibited strategies consistent with drought avoidance. Our results highlight the specific strategies of these species under water-deficit conditions and can help guide decisions on species selection and plantation management for reforestation under climate change scenarios.

Seed and fruit set are processes determining yield in many crops. However, many growth models for horticultural crops do not explicitly incorporate these processes. The aim of this study was to develop a quantitative model to predict seed set, fruit set, and fruit mass based on the effects of temperature and duration of a period with high or low temperature on pollen number and pollen quality (viability and germination fraction). To develop the model, we conducted an experiment where fruiting dwarf tomato plants were grown at 18°C and exposed to 14°C for 4, 6, or 8 days, 30°C and 34°C for 1, 3, or 4 days, and a control treatment at 18°C continuously. Temperatures of 30°C and 34°C reduced pollen viability and germination, resulting in lower seed set and fruit mass. While fruit set remained unaffected at 30°C, both 14°C and 34°C led to reduced fruit set. At lower temperatures (14°C), our model predicted decreased yields due to a lower number of fruits in the truss, resulting from reduced fruit set and smaller fruit size compared to the reference temperature (18°C). At higher temperatures (30°C), our model predicted reduced fruit yield due to smaller individual fruit size, resulting from low seed set. Our research introduces a modelling framework that accounts for the influence of periods with high or low temperature on seed set, a process that is almost never considered in growth models for horticultural crops. This framework is crucial for developing strategies to optimize crop yield in response to temperature fluctuations.

Cytoplasmic male sterility (CMS) is a common biological phenomenon in chilli pepper hybrid production. Although several restorer-of-fertility (Rf) genes have been identified in pepper CMS lines, a regulatory network has yet to be constructed. Morphological characteristics of the sterile, maintainer, and restorer flower buds were studied at three different developmental stages. We conducted transcriptome analysis of the CMS/Rf system in pepper plants. Pentose and glucuronate interconversion pathways were particularly enriched in most comparison groups. In addition, differentially expressed genes among the different lines at flower bud stages 2 and 3 were generally enriched in amino sugar and nucleotide sugar metabolism pathways. In our study, the small auxin upregulated RNA (SAUR), A-ARR and GH3 genes in the plant hormone signal transduction pathway, Capana12g000348, CKX7 and cis-zeatin O-glucosyltransferase (CISZOG) genes in the zeatin biosynthesis pathway, and receptor-like protein kinase 2 (RLK2) in the germplasm development signal pathway showed gradual upregulation across developmental stages in the restorer line. However, expression of these genes was stable in the sterile and maintainer lines. qRT-PCR analysis showed that SAUR, A-ARR, GH3, Capana12g000348, CKX7, CISZOG, CRE1, AHP and TIR1 participate in CMS fertility regulation in chilli pepper. We constructed a regulatory network based on critical genes. Overall, our research provides a solid theoretical foundation for the development of CMS fertility studies on chilli pepper.

Pediocactus bradyi, a semi-globose cactus endemic to northern Arizona, displays a root-contraction mechanism to survive extreme drought: its roots contract, pulling the stem below ground during dry periods, re-emerging once rains return. To quantify how root contraction shapes population dynamics, we developed an integral projection model based on 31 years of demographic data from a P. bradyi population on the Navajo Nation Off-Reservation Trust Land. We explored two scenarios: one including root contraction and one excluding it. We found that, being ∼10% of the individuals and mostly confined to smaller individuals, root contraction did not have an effect on the long-term population growth [λ = 1.041 (1.039, 1.303) with contraction vs. λ = 1.044 (1.035, 1.289) without]. Also, we show that larger individuals have higher survival and reproductive rates, while growth declines beyond 35 mm in diameter. An elasticity analysis confirmed that survival and growth are the main vital rates affecting population growth, followed by root elongation after contraction. Thus, while root contraction may improve individual survival, elongation is in fact more important at the population level. Therefore, as with most cacti species, conservation efforts should focus on ensuring the survival of large individuals irrespective of their root contraction status.

Plants use chemicals to respond to their environments. Despite the impact of competition on plant productivity, few studies consider how plant–plant competition affects phytochemistry; most phytochemistry studies focus on plant–consumer interactions. It therefore remains unclear how plants chemically respond to changes in both competition and consumer pressure. We used 1H-NMR spectroscopy to characterize the phytochemistry (both primary and secondary metabolites) of a C4 grass (Andropogon gerardi) and a legume (Lespedeza capitata) in a field experiment. Both species were grown with intraspecific or interspecific neighbours (monoculture or 16-species polyculture) with or without a combined fungicide + insecticide treatment (consumers reduced vs. consumers present) in a factorial design. We measured species aboveground biomass, healthy plant cover (NDVI) and phytochemistry in the four treatments to determine whether plants alter their biomass, phytochemistry, or both in response to neighbours and herbivory. Phytochemistry of A. gerardi did not vary with neighbour identity or consumers, in contrast to A. gerardi biomass, which was higher under interspecific competition and when consumers were reduced. Phytochemistry of L. capitata was also unrelated to consumer reduction, though L. capitata had higher NDVI under reduced consumers. However, L. capitata had lower biomass and exhibited phytochemical signs of metabolic stress (lower sugars and higher amino acid production) when grown with interspecific neighbours. Theory and empirical work have focused on coevolution with consumers as driving phytochemical variation, but our results suggest that—at community scales—the competitive environment may be more important than consumer pressure in determining short-term phytochemical responses of some species.

Vessel scaling from tip to base in angiosperms has largely been studied based on vessel diameter. Here, we test if vessel anatomy and transport efficiency in a Fagus sylvatica L. sapling show axial scaling by maintaining a largely proportional ratio of lumen to end-wall resistivity to sap flow with tree height. Vessel diameter (D) of more than 50 000 vessels was measured based on wood sections, while mean vessel length (LV) was measured semi-automatically with a Pneumatron for 58 stem segments. Based on tip-to-base variation in D and LV, we estimated vessel lumen conductivity (KH) at the individual vessel level. We also estimated end-wall conductivity (KW) based on Darcy’s law, integrating pit membrane thickness (TPM) with scaling of D and total inter-vessel pit membrane area (AP) across the sapling. Axial variation in KW was evaluated against end-wall pressure difference (). In addition to a tip-to-base increase in D, we found an increase in LV and AP, illustrating basipetal vessel lengthening. These patterns were associated with proportional changes in KW and KH, which followed a 1:1 relationship with distance to the tip, each contributing to ∼ 50% of the whole-tree conductivity/resistivity. Our findings suggest that vessel dimensions and hydraulic functionality show axial scaling in angiosperm trees, suggesting that anatomy corresponds to the adjustment of hydraulic functionality with plant height. Proportional adjustment of KW and KH highlights the key role of vessel dimensions and inter-vessel pits in regulating transport efficiency and safety, potentially maintaining constant resistance per unit leaf area with height growth.

Clonal reproduction is often considered advantageous in stressful environments. While considerable research has explored how clonality supports plant survival in wet and cold conditions, its role in arid and semi-arid conditions remains underexplored. To address this gap, this study examines the distribution and diversity of clonality as a key component of belowground growth form (BGF) along aridity gradients across SW and Central Asia using the species-rich Lamiaceae family as a model. Data were collected from 281 species with a variety of BGFs occurring in a broad range of habitats. Data on BGFs were collected primarily in the field, with additional data from herbarium records and digital databases. BGFs were categorized into hypogeogenous rhizomes, epigeogenous rhizomes, stolons, and non-clonal types. Species distribution data were obtained from regional floras and the Global Biodiversity Information Facility (GBIF) and analysed using precipitation-related bioclimatic variables. Clonal species of the Lamiaceae family, particularly those with hypogeogenous and epigeogenous rhizomes, were more prevalent in extreme environments, both water-limited and moisture-rich, highlighting their adaptation to stressful conditions. They thrived in arid habitats like deserts and semi-deserts as well as wet habitats such as forests or wetlands. Non-clonal species were concentrated in the centre of the gradient, dominating montane steppe shrublands where water availability was moderate and seasonally variable. Clonal plants are not avoiding arid environment. This is particularly noteworthy for species with hypogeogenous rhizomes that have been shown to prefer wet conditions in temperate regions. The exact mechanisms that permit their specialization to wet or dry conditions is to be further studied experimentally. These findings highlight how climate change may differentially affect species based on their BGFs.

Hybridization, polyploidization, and apomixis are evolutionary forces that obscure genetic differentiation and boost morphological variability. These processes have shaped the family Rosaceae, particularly the genus Crataegus, which includes both diploid and polyploid species reproducing sexually or via apomixis. In Central Europe, C. monogyna and C. laevigata are predominantly diploid sexuals, while C. rhipidophylla is mainly a polyploid apomict. These species hybridize to form C. × media, C. × macrocarpa, and C. × subsphaerica. Our aim was to assess how hybridization, apomixis, and polyploidy shape Crataegus diversity by integrating genetic, morphological, and cytological data. Leaves and fruits were collected from ten natural populations where all three species coexist and hybridize. Species identification was performed with novel nuclear microsatellites, marking the first genetic-based Crataegus taxonomy in Central Europe. Ploidy levels were estimated by flow cytometry (FCM), including seed screening to infer reproductive modes. A combined morphological analysis of leaves and fruits was used to distinguish parental species and evaluate hybrid variability. Genotyping identified distinct genetic clusters for parental species and their hybrids, with geographic structuring within C. laevigata and C. rhipidophylla. Morphological data clearly separated genetically defined parental species, although hybrids can be difficult to distinguish from parents due to a big overlap in morphology. FCM indicated that C. × media is predominantly a diploid sexual hybrid like its diploid parents, while other tri- or tetraploid hybrids with polyploid C. rhipidophylla as a parent are apomictic. Ploidy rather than hybridization dictates the mode of reproduction.

Salinity is one of the most devastating abiotic stresses limiting crop productivity. Here, the salinity tolerance level and physiological changes in Echinochloa frumentacea in saline and alkaline soils were estimated by studying root morphology, quantifying ions (Ca2+, K+, Na+, Ca2+/Na+, and K+/Na+) in roots, and measuring antioxidant enzyme activities, malondialdehyde (MDA), proline, and soluble sugar contents. Echinochloa frumentacea was tested against four neutral and alkaline salts, NaCl: Na2SO4:NaHCO3:Na2CO3 in different proportions at 60, 120, 180, 240, and 300 mmol L−1 concentrations. Echinochloa frumentacea was evaluated and compared with plant species, which are commonly cultivated in non-saline and alkaline soils i.e. Echinochola crusgalli, Avena sativa, Salicornia europaea, Medicago sativa, and Glycyrrhiza uralensis. The results revealed an increase in root length, diameter, absorption area, fresh, and dry weight at 120 mmol L−1. However, a gradual decrease in these parameters was observed at higher salt concentrations. In contrast, an increase in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities, and MDA and proline levels were observed with increasing salt concentration. The roots of E. frumentacea absorbed higher levels of ions than the other five forage plant species. Higher K+/Na+ and strong root structure in E. frumentacea indicate its better tolerance in saline soil than in alkaline soil. Our results demonstrate that E. frumentacea can tolerate up to 120 mmol L−1 salt in a saline–alkaline environment and is more suitable for growth in saline soil. In addition, the root system of E. frumentacea can be used to dechlorinate the chloride from soil and reduce its toxic effect on plants. It can also be used as a target species for selection and breeding programs to improve salt tolerance in future studies.