Abstract Hybridization is a key mechanism in the adaptive evolution of weeds and invasive species. The evolutionary success of hybrids may be shaped by selection on functional traits, interacting with maternal genotype and ecological context. We performed experimental hybridization and common garden field experiments to assess phenotypic variation on functional traits, and the strength and direction of linear and quadratic selection acting on them, in bidirectional crop–weed hybrids and their parents of Raphanus sativus, across two contrasting environments: agrestal (agricultural) and ruderal (human-disturbed uncultivated area), over two years. Bidirectional hybrids exhibited overall greater values for size-related traits than their parents, with similar flowering time and no significant effects of cross direction. Selection acted on multiple functional traits through both linear and quadratic components, with broadly similar patterns across environments and cross types, although selection tended to be slightly stronger in hybrids than in weeds. Intraspecific crop–weed hybridization, regardless of cross direction, can increase weediness in weedy radish by enhancing plant size, thereby increasing competitive ability and potential interference with crops. Our findings highlight how hybridization and selection shape plant evolution, influencing the potential introgression of crop alleles into wild or weedy gene pools. Understanding the hybridization process and the mechanisms that control it is crucial for managing the evolutionary outcomes of crop-weed hybridization.

Influences of climate change on light availability are often overlooked; yet, understory species may experience shifts in irradiance as rising temperatures influence phenology and community composition. Light management is crucial for seedling success, and a whole-plant approach can help elucidate consequences of light on plant performance. Rhododendron minus is an evergreen shrub native to the Southeast United States that grows from rock outcrops to the understory. We conducted two experiments to unravel influences of light on plant function: (i) a manipulative greenhouse experiment on seedlings from a sun-exposed provenance examining pigments, plant architecture, and biomass patterns under shade, ambient, and supplemental light and (ii) a common garden experiment comparing pigments of mature plants from six provenances differing in latitude, elevation, climate, and solar radiation. We used multispectral imaging to estimate anthocyanin through the normalized difference anthocyanin index (NDAI) and chlorophyll through the normalized difference vegetation index (NDVI). Supplemental light seedlings had significantly higher NDAI than shade and ambient seedlings, but there was no significant treatment effect on NDVI or total biomass. Supplemental light seedlings also exhibited leaf movements that reduced projected surface area over time. This work highlights the importance of anthocyanins and plant architecture in allowing seedlings to maintain similar performance across light environments. In our common garden experiment, plants from northern, colder provenances had higher NDAI compared to warmer, southern provenances. We suggest that interactions between temperature and irradiance likely drive intraspecific variation in NDAI across the range, indicating that climate change could influence future pigment evolution.

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.

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.

Climate change is intensifying droughts across the globe, challenging species to adapt to novel conditions. While plant physiological and phenological responses to drought are well-documented, less is known about how water scarcity affects the evolution of selfing across species ranges. According to the selfing syndrome hypothesis, in environments where selfing confers a fitness advantage, selection should favour floral traits associated with increased selfing relative to outcrossing. We used a field experiment near the northern range edge of the scarlet monkeyflower (Mimulus cardinalis) to test this hypothesis both spatially (among leading-edge, central, and trailing-edge populations), and temporally (between cohorts separated by a period of historic drought). Although populations from different range positions showed genetic differentiation in some floral traits, these differences did not consistently support predictions of the selfing syndrome hypothesis. Contrary to the predictions of reduced investment in floral rewards and increased selfing ability at range edges, the sugar content of nectar was greater and autogamous seed set was smaller in leading-edge than central populations, herkogamy tended to be greater in trailing-edge populations relative to leading-edge and central ones, and nectar volume did not vary predictably among regions. There was no support for the evolution of selfing syndrome from the predrought ancestors to the postdrought descendants. Instead, in leading-edge populations, descendants evolved greater sugar content relative to ancestors, and there were no other differences between ancestors and descendants in any other trait or region. Overall, these findings suggest that mating system evolution in M. cardinalis likely reflects a complex interplay of regional factors including range position, historical adaptation, and local environmental variability, rather than simple stress-induced shifts towards selfing.

Gene-editing tools enable precise, targeted genome modifications, providing new approach for the rapid and sustainable improvement of tea plant (Camellia sinensis (L.) Kuntze). Developing such an approach is especially important due to the perennial nature and complex genetics of the tea plant, which make traditional breeding slow and inefficient. To validate a gene editing protocol in the elite local tea cultivar Kolkhida three candidate genes were selected. Two guide RNAs (gRNAs) were designed for each gene, and corresponding constructs for targeted genome modification in tea were generated. Successful modifications of the target sequences in cv. Kolkhida tea protoplasts were achieved for all three target genes. The high mutagenic efficiency of the selected gRNAs was observed for two out of three genes, including induction of precise deletions between target motifs. gRNAs were delivered in protoplasts via co-transfection technique, and combined gRNA activity was observed when transfection efficiency exceeded 28%. The genome modification method for tea protoplasts established in this study can serve as a screening protocol to evaluate the in vivo efficiency of different genome editing approaches in the tea plant.

Leaf trichomes in plants act as the first line of physical defence against herbivory, in addition to many other reported functions. Although trichomes have been found to vary intraspecifically and can be induced by herbivory, their interactive effects under additional factors, such as plant age and abaxial vs. adaxial leaf surfaces, are less understood. Here, using five common tomato varieties, we explored the effects of these factors and their interactions on trichome type and density. We quantified the densities of Type VI glandular trichomes, non-glandular trichomes, and total trichomes on abaxial and adaxial leaf surfaces, and total leaf trichomes with and without herbivory by Spodoptera exigua at both vegetative and reproductive stages. Further, we also tested whether the time taken to initiate feeding by S. exigua larvae could be influenced by the number of trichomes on the adaxial and abaxial surfaces. The results showed that there is significant variation in trichome density among varieties and leaf surfaces. Also, there were differences in herbivory-induced trichome production, with variable responses across varieties and growth stages. Bioassay results showed that insects took longer to initiate feeding on the abaxial leaf surface than on the adaxial surface, potentially due to the higher density of non-glandular trichomes on the abaxial side. Collectively, we report that the regulation and development of trichomes on the leaf surface of tomatoes is governed by multiple factors, with potential consequences for herbivore feeding, suggesting how physical defences play a significant role in insect–plant interactions.

Soil nutrient heterogeneity has generally been shown to benefit alien plants more than native ones. However, whether drought, an important aspect of climate change, alters these effects remains an open question. We used a greenhouse experiment with two alien and two native herbaceous plants. Plants were grown either alone or in a mixture (one alien plant and one native plant) in homogeneous and heterogeneous soils, with or without drought. We found that shoot mass of the native plant Alternanthera sessilis and the alien plant Celosia argentea were 27.4% and 76.6% lower in heterogeneous soils than homogenous soils, respectively, indicating a negative effect of soil nutrient heterogeneity. However, these negative effects were eliminated when the plants were grown alone in drought conditions. In contrast, soil nutrient heterogeneity, drought, and competition had little effect on the growth of the native plant Achyranthes bidentata and the alien plant Amaranthus retroflexus. These results suggest that plant species differ in their growth responses to complex environmental changes. These results may have implications for understanding plant invasion outcomes in heterogeneous environments under global climate changes.

Drought stress can affect the growth of soybean seedlings because soybeans require a large amount of water for growth and development. However, the storage and redistribution of water in the soil are related to the soil’s texture. This experiment used the soybean varieties hefeng46 and heinong84, and studied the effects of four moisture conditions on the content of membrane lipid peroxides, the activities of enzymes and non-enzymatic antioxidants the content, and also the key enzymes of carbon and nitrogen metabolism in soybean seedlings under loamy sand and sandy loam soil conditions. The results suggested that as the duration of drought increased, in loamy sand, under serious drought (SD), the contents of malondialdehyde and proline, as well as the activities of superoxide dismutase and glutamine synthetase, in hefeng46 and heinong84 were significantly increased by 160% and 146%, 1431% and 1924%, 167% and 282%, and 64% and 69%, respectively, compared to the normal water (CK). However, in sandy loam, the hydrolytic direction activity of sucrose synthase in intermediate drought treated hefeng46 and heinong84 was significantly increased by 1247% and 169% compared to the CK, and the content of reduced glutathione was dramatically raised. In contrast, the synthetic direction activity of sucrose synthase in SD treated hefeng46 and heinong84 was significantly decreased by 69% and 70% compared to the CK. The combined results indicated that under drought stress, soybean in sandy loam soil exhibited stronger drought resistance.

Nectaries are specialized nectar-producing structures. Nectar traits affect animal behaviour and ecological and evolutionary processes, such as pollination and biotic defence. Previously, we found that there are differences in the characteristics of nuptial nectar (NN) and extranuptial nectar (ENN) and in the types of animals that visit each nectary in Amphilophium mansoanum (Bignoniaceae) flowers. We now hypothesize that nectar traits reflect the anatomical, histochemical, and subcellular characteristics of each nectary type. Using routine light microscopy, scanning electron microscopy, and transmission electron microscopy methods, we studied NN and ENN, respectively in young flower buds, pre-anthesis buds, and first- and second-day flowers. NN was a prominent annular disk; whereas, ENN was a concave, patelliform trichome. Only ENN contained alkaloids, while both nectaries contained starch grains, lipid droplets, proteins, terpenes, and phenolic compounds. Both nectaries showed subcellular organization consistent with hydrophilic and lipophilic secretion, the latter being predominant in second-day flowers. In NN, the subnectary parenchyma had phloem and amyloplasts until pre-anthesis. Starch grains decreased and tracheary elements were seen in newly opened flowers. ENN are not vascularized, with vascular bundles from the calyx approaching the base of the nectary. Starch grains were scarce and very small in the ENN secretory head cells. Fibrillary proteins were found only in NN and periplastidial reticulum was observed only in ENN. In NN, nectar secretion begins shortly before anthesis, being released through the raised stomata and the reticulate cuticle. In ENN, secretion extends from the young flower bud stage to senescent flowers, accumulating in small subcuticular spaces and being continuously released through the intact cuticle. Temporal differences in NN and ENN production, as well as in the structural characteristics and nectar release mechanisms between NN and ENN, may explain the differences in nectar characteristics of A. mansoanum.