Search Results (31)

Range limits are often hypothesized to arise from reduced reproductive success at distributional margins, yet direct tests integrating pollination and post-pollination processes remain uncommon. Whether reproductive failure constrains the distylous Gelsemium sempervirens at its western range edge in eastern Texas was investigated by quantifying flowering phenology, floral visitation, pollinator effectiveness, and seed fate over two flowering seasons. Flowering timing differed markedly between years due to freeze events, but flowering effort and morph synchrony remained high. Although multiple floral visitors were recorded, fruit set was overwhelmingly associated with the southeastern blueberry bee (Habropoda laboriosa), which dominated visitation and remained active throughout the flowering period. No evidence of autonomous self-pollination or breakdown of functional distyly was detected. Seed set in unattacked fruits was high and comparable to values reported from central-range populations. In contrast, post-pollination seed loss due to cryptic fruit herbivory substantially reduced seed survival, though herbivory patterns did not differ qualitatively from those documented elsewhere in the species’ range. Together, these results indicate that reproductive failure does not explain the abrupt western range limit of G. sempervirens and instead suggest that ecological transitions associated with the forest–prairie ecotone, rather than pollination or early seed development, may play a more important role in shaping the species’ distribution. Full article

Calanthe aristulifera is an endangered terrestrial orchid that has historically suffered from severe illegal poaching. However, little is understood regarding population dynamics for remaining C. aristulifera populations. This study presented the first record on the size, reproduction rate, and insect visitors of C. aristulifera populations on an oceanic island from 2021 to 2025, to identify threatening factors and provide conservation implications. Throughout the study period, complete absence of fruit set of C. aristulifera was found (natural fruit set ratio: 0%). This reflects the reproductive failure as an on-going threatening factor, regardless of the yearly variations in total number of C. aristulifera individuals (198–253) and flowering rate (62.2–87.4%). The known pollinators (Eucera nipponensis and Lasioglossum occidens) were undetected near C. aristulifera populations, which coincided with complete reproductive failure. Insects like Callipora lata, Episyrphus balteatus, and Bibio tenebrosus visited to C. aristulifera flowers, but direct field and photographic observations showed no pollinia removal by such insects. Overall results highlight that conservation programs should adopt management practices to attract effective pollinators to C. aristulifera populations. Ex situ conservation may also be an option to facilitate in vitro propagation experiments, and help the remaining C. aristulifera to avoid severe reproductive constraints. Full article

Magnolia crassipes is a valuable species in Magnolia sect. Michelia known for its unique purple flowers, but interspecific reproductive barriers limit its use in breeding. Using M. crassipes as the maternal parent, we performed 13 pollination combinations (one selfed control and crosses with 12 taxa spanning five sections). We assessed reproductive processes from pollen–stigma interaction to seed and seedling performance, and verified hybrids using SSR markers. Reproductive barriers are strongly associated with phylogenetic distance, shifting from pollen-adhesion failure in crosses with donors from distant-section, to abnormal pollen-tube guidance in cross with M. denudata, and to fruit initiation in crosses with pollen donors from sect. Michelia. Among these Michelia-donor crosses, prezygotic barrier strength varied among combinations, as reflected by differences in stigma germination and ovule entry rates, which strongly influenced the potential for fruit set success. Postzygotic barriers further reduced reproductive success via seed abortion (peaking at 83.8%). However, all germinated hybrids exhibited normal early growth. Notably, backcrossing with the F1 hybrid M. ‘Danxia’ significantly improved reproductive compatibility (seed abortion rate 6.3% and germination rate 100%). This study clarifies the key barriers in M. crassipes hybridization and provides a basis and practical strategies for its genetic utilization. Full article

Florivory is the consumption or damage of flowers by herbivorous animals. It can directly affect plant fitness by damaging reproductive organs or indirectly by negatively influencing flower attractiveness to pollinators. We investigated florivory in field bindweed Convolvulus arvensis L. (Convolvulaceae) by combining data from natural surveys, experimental damage, and laboratory experiments on flower preferences of florivores. Surveys showed that flowers suffer damage from predators, including Leptophyes albovittata Kollar (Orthoptera: Tettigoniidae), which causes partial corolla damage, and from unknown predators that cause holes in the corolla. Experimentally damaged flowers had significantly lower reproductive success (number of seeds and proportion of total reproductive failure) than intact flowers. However, laboratory experiments with naïve bumblebees Bombus terrestris L. (Hymenoptera: Apidae) failed to detect a preference for undamaged flowers. This may be because B. terrestris is not a frequent pollinator of C. arvensis at our field sites, and naïve foragers, lacking prior experience, had not learned to associate corolla damage with reduced floral rewards. Our research shows that florivory negatively impacts C. arvensis reproductive success by altering pollinator behavior through reduced flower attractiveness. Full article

Distant hybridization between bread wheat (Triticum aestivum L.) and wild Aegilops species is a valuable approach to take to broaden genetic diversity, but it is frequently impeded by reproductive barriers. This study evaluated crossability, pollen tube dynamics, meiotic behavior, somatic chromosome numbers, and pollen fertility in twelve Kazakh wheat cultivars crossed with Ae. triaristata Willd., Ae. cylindrica Host, Ae. triuncialis L., and Ae. squarrosa L. under field-based controlled pollination. Hybridization success varied significantly among combinations, with Ae. triaristata showing the highest compatibility (26.0% in Bezostaya 1 × Ae. triaristata), while Ae. squarrosa produced the lowest seed set. In compatible crosses, pollen tubes reached the ovary within 20–30 min, whereas delayed elongation (>60 min) was associated with fertilization failure. Meiotic analysis revealed incomplete homologous pairing (3–7 bivalents per PMC) and high abnormality rates (>90%). Somatic chromosome counts (2n) of selected F₁ hybrids confirmed extensive aneuploidy and partial chromosome elimination. Pollen fertility was generally below 20%. These results identify Ae. triaristata as a promising donor species for pre-breeding in Kazakhstan and underscores the importance of integrating classical cytology with molecular approaches to overcome hybridization barriers. Full article

Cold stress can inhibit the growth of cucurbits, disrupt pollination and fertilization, induce fruit deformities, reduce plant resistance, and increase susceptibility to diseases, ultimately resulting in yield reduction, quality deterioration, or even complete crop failure. This review focuses on the main cucurbits, such as melon, cucumber, and watermelon, systematically expounding the roles of plant hormones, signaling molecules, soluble sugars, key regulatory factors, molecular mechanisms, and network interactions in their response to cold stress. Furthermore, it highlights future research directions and application potential. By analyzing existing challenges and prospective advancements in this field, the review aims to provide a comprehensive reference for facilitating genetic improvement in cold tolerance. Full article

Honeybees (Apis mellifera) are indispensable pollinators vital to global biodiversity, ecosystem stability, and agricultural productivity, and they promote over 35% of food crops and 75% of flowering plants. Yet, they are in unprecedented decline, partly as a result of neonicotinoid pesticide use elsewhere. These effects on honey bee health are synthesized in this paper through molecular, physiological, and behavioral data showing that sublethal effects of neonicotinoids impair honey bee health. As neurotoxic insecticides that target nicotinic acetylcholine receptors (nAChRs), these insecticides interfere with neurotransmission and underlie cognitive impairment, immune suppression, and oxidative stress. Developmental toxicity is manifested in larvae as retarded growth, reduced feeding, and increased death; queen and drone reproduction are impaired, lowering colony viability. As a result, adult bees have shortened lives and erratic foraging, are further disoriented, and experience impaired navigation, communication, and resource collection. Together, these effects cascade to reduced brood care, thermoregulatory failure, and heretofore unrecognized increased susceptibility to pathogens, increasing the probability of colony collapse at the colony level. Contaminants such as pesticides may cause pollinator exposure and, in turn, may cause their population to be undermined if they are not mitigated; therefore, urgent mitigation strategies, including integrated pest management (IPM), regulatory reforms, and adoption of biopesticides, are needed to mitigate pollinator exposure. The focus of this review lies in the ecological necessity of restructuring how agriculture is managed to simultaneously meet food security and the conservation of honeybee health, the linchpin of global ecosystems. Full article

Northward expansion of economically essential plants is a vital strategy for enhancing agricultural productivity; however, it often results in reduced yields. This study systematically assessed the impact of translocating the high-value oilseed species Camellia hainanica from its native tropical habitat Sanya to the temperate cultivation area of Changsha, focusing on its reproductive processes, including flowering, pollination, and fruit development. Our findings revealed a 45-day delay in anthesis at the transplanted location, which was associated with notably lower average daily temperatures (7.89 °C in Changsha compared to 24.63 °C in Sanya) during the anthesis period. While floral longevity, stigma receptivity, and pollen viability remained comparable between sites, anther dehiscence was markedly delayed by three days after transplanting. Crucially, pollinator visitation during peak flowering plummeted by 92% compared to the levels in Sanya, and a 57% reduction in pollen deposition on stigmas occurred. Consequently, natural fruit sets in Changsha collapsed to 0%, significantly lower than those in Sanya, despite artificial cross-pollination achieving an 11% fruit set rate. These results and the pollination deficit coefficient (D = 1.00) all demonstrate that severe pollination deficits are the key limitation causing reproductive failure in northward-expanded C. hainanica orchards. Addressing these yield constraints necessitates targeted breeding for earlier flowering genotypes and implementing pollination management strategies. Full article

Paeonia ludlowii is a threatened and valuable germplasm in the cultivated tree peony gene pool, with distinctive traits such as tall stature, pure yellow flowers, and scarlet foliage in autumn. However, the crossability barrier limits gene transfer from P. ludlowii to cultivated tree peony. Therefore, our study investigated the reasons for the lack of crossability between P. ludlowii and Paeonia ostii ‘Fengdan’. Distant cross pollination (DH) resulted in the formation of many calloses at the ends of the pollen tubes, which grew non-polar, twisted, entangled, and often stopped in the style. Pollen tubes elongated the fastest in self-pollination (CK), and pollen tubes elongated faster and fewer pollen tube abnormalities were observed in stigmas treated with KCl solution before pollination (KH) than in DH. During pollen–pistil interactions, the absence of stigma exudates, high levels of H₂O₂, O₂⁻, MDA, ^•OH, ABA, and MeJA, and lower levels of BR and GA₃ may negatively affect pollen germination and pollen tube elongation in the pistil of P. ostii ‘Fengdan’. Pollen tubes in CK and KH penetrated the ovule into the embryo sac at 24 h after pollination, whereas only a few pollen tubes in DH penetrated the ovule at 36 h after pollination. Pre-embryo abnormalities and the inhibition of free nuclear endosperm division resulted in embryo abortion in most of the fruits of DH and many fruits of KH, which occurred between 10 and 20 days after pollination, whereas embryos in CK developed well. Early embryo abortion and endosperm abortion in most of the fruits of DH and KH led to seed abortion. Seed abortion in KH and DH was mainly due to an insufficient supply of auxins and gibberellins and lower content of soluble protein and soluble sugars. The cross failure between P. ludlowii and P. ostii ‘Fengdan’ is mostly caused by a pre-fertilization barrier. KH treatment can effectively promote pollen tube growth and facilitate normal development of hybrid embryos. These findings provide new insights into overcoming the interspecific hybridization barrier between cultivated tree peony varieties and wild species. Full article

Onion (Allium cepa L.) plants produce umbellate inflorescences that bear dozens of hermaphrodite flowers. Outcrossing is encouraged by a strong protandrous dichogamy. Honeybees are reported as the most suitable pollinator for this crop due to their efficiency in pollen transfer. However, bee activity does not always guarantee pollination success and an adequate seed set. This work aimed to analyze the developmental changes of the pistil along the flower lifespan to determine the reasons for common failures in the onion seed set. Studies were carried out in two productive seasons, in a male sterile line and a fertile line, using two different pollination procedures. The results showed that the stigma papillae did not fully develop until 4 days after anthesis (DAA), reducing the stigma receptivity to only 4 days. The style did not reach its maximum length until 8 DAA, when ovule fertility was achieved. Eight days were needed for the pollen tube to grow, reach, and fertilize the ovules. The results were consistent over two consecutive years. The short period of stigmatic receptivity and strong protandrous dichogamy limit the duration of the effective pollination period and could explain the poor cropping performance in obtaining seeds from some onion hybrid lines. Full article

Backcrossing between Sikitita and its male parent Arbequina, offers the possibility to check the suitability of different self-incompatibility models proposed for olive. To determine Sikitita’s response to self- and cross-pollination treatments, including pollination with its father Arbequina, we compared the parameters following pollen–pistil interaction, the resulting initial and final fruit set, and the paternity of the seeds produced under different crosses. The results showed that Sikitita behaves as a self-incompatible cultivar due to the inhibition of pollen tube growth in the pistil of self-pollinated flowers. This incompatibility reaction led to a significant reduction of self-fertilization and fruit set. Seed paternity analyses confirmed the self-incompatibility response of Sikitita. A similar incompatibility response was observed in Sikitita flowers when hand-pollinated with pollen of Arbequina and Koroneiki. On the contrary, cross-pollination with Arbosana gave excellent results, with analyses showing that pollen of Arbosana is largely preferred by Sikitita to father its seeds more than the pollen of other cultivars presented in the orchard. The backcross failure of Sikitita with Arbequina pollen suggests that the self-incompatibility system in olives is not of the gametophytic type. In contrast, pollination tests fit features of previously reported sporophytic self-incompatibility systems. However, some amendments are proposed, among them the incompatibility groups for Sikitita and Koroneiki. Full article

Ovule abortion significantly contributes to a reduction in chestnut yield. Therefore, an examination of the mechanisms underlying ovule abortion is crucial for increasing chestnut yield. In our previous study, we conducted a comprehensive multiomic analysis of fertile and abortive ovules and found that ACS genes in chestnuts (CmACS) play a crucial role in ovule development. Therefore, to further study the function of ACS genes, a total of seven CmACS members were identified, their gene structures, conserved structural domains, evolutionary trees, chromosomal localization, and promoter cis-acting elements were analyzed, and their subcellular localization was predicted and verified. The spatiotemporal specificity of the expression of the seven CmACS genes was confirmed via qRT–PCR analysis. Notably, CmACS7 was exclusively expressed in the floral organs, and its expression peaked during fertilization and decreased after fertilization. The ACC levels remained consistently greater in fertile ovules than in abortive ovules. The ACSase activity of CmACS7 was identified using the genetic transformation of chestnut healing tissue. Micro Solanum lycopersicum plants overexpressing CmACS7 had a significantly greater rate of seed failure than did wild-type plants. Our results suggest that ovule fertilization activates CmACS7 and increases ACC levels, whereas an overexpression of CmACS7 leads to an increase in ACC content in the ovule prior to fertilization, which can lead to abortion. In conclusion, the present study demonstrated that chestnut ovule abortion is caused by poor fertilization and not by nutritional competition. Optimization of the pollination and fertilization of female flowers is essential for increasing chestnut yield and reducing ovule abortion. Full article

Apples exhibit S-RNase-mediated self-incompatibility and typically require cross-pollination in nature. ‘Hanfu’ is a cultivar that produces abundant fruit after self-pollination, although it also shows a high rate of seed abortion afterwards, which greatly reduces fruit quality. In this study, we investigated the ovule development process and the mechanism of ovule abortion in apples after self-pollination. Using a DIC microscope and biomicroscope, we found that the abortion of apple ovules occurs before embryo formation and results from the failure of sperm–egg fusion. Further, we used laser-assisted microdissection (LAM) cutting and sperm and egg cell sequencing at different periods after pollination to obtain the genes related to ovule abortion. The top 40 differentially expressed genes (DEGs) were further verified, and the results were consistent with switching the mechanism at the 5′ end of the RNA transcript (SMART-seq). Through this study, we can preliminarily clarify the mechanism of ovule abortion in self-pollinated apple fruits and provide a gene reserve for further study and improvement of ‘Hanfu’ apple fruit quality. Full article

Embryo rescue (ER) techniques are among the oldest and most successful in vitro tissue culture protocols used with plant species. ER refers to a series of methods that promote the development of an immature or lethal embryo into a viable plant. Intraspecific, interspecific, or intergeneric crosses allow the introgression of important alleles of agricultural interest from wild species, such as resistance or tolerance to abiotic and biotic stresses or morphological traits in crops. However, pre-zygotic and post-zygotic reproductive barriers often present challenges in achieving successful hybridization. Pre-zygotic barriers manifest as incompatibility reactions that hinder pollen germination, pollen tube growth, or penetration into the ovule occurring in various tissues, such as the stigma, style, or ovary. To overcome these barriers, several strategies are employed, including cut-style or graft-on-style techniques, the utilization of mixed pollen from distinct species, placenta pollination, and in vitro ovule pollination. On the other hand, post-zygotic barriers act at different tissues and stages ranging from early embryo development to the subsequent growth and reproduction of the offspring. Many crosses among different genera result in embryo abortion due to the failure of endosperm development. In such cases, ER techniques are needed to rescue these hybrids. ER holds great promise for not only facilitating successful crosses but also for obtaining haploids, doubled haploids, and manipulating the ploidy levels for chromosome engineering by monosomic and disomic addition as well substitution lines. Furthermore, ER can be used to shorten the reproductive cycle and for the propagation of rare plants. Additionally, it has been repeatedly used to study the stages of embryonic development, especially in embryo-lethal mutants. The most widely used ER procedure is the culture of immature embryos taken and placed directly on culture media. In certain cases, the in vitro culture of ovule, ovaries or placentas enables the successful development of young embryos from the zygote stage to maturity. Full article

Peonies are significant ornamental plants that are primarily propagated through distant cross-breeding to create new varieties. However, hybrid failure is a critical issue that impedes the advancement of breeding. Numerous studies have demonstrated that endogenous hormones in the seed embryo constitute a significant factor in embryo failure. Nevertheless, it is still unknown how plant hormones control the development of peony embryos at the molecular level. In this study, we characterized the endogenous hormone levels in peony seeds of hybrid-aborted, hybrid-normal, and self-crossing normal after 26 days of pollination (DAP). Our findings show that the hybrid-aborted embryos had significantly higher amounts of ABA, IAA, and GA. In addition, the ratio of GA+IAA/ABA was lower than that of the hybrid-normal seeds and higher than that of the self-crossing normal seeds. To further investigate the mechanism of hormone control on peony embryo development, we conducted a transcriptome sequencing analysis of the three seed types. Results revealed that differentially expressed genes involved in phytohormone metabolism and signal transduction significantly enriched the aborted embryos. Furthermore, we examined the expression levels of six hormones in different seeds and used the Gene Common Expression Trend analysis to analyze genes highly correlated with phytohormone in the KEGG pathway. We used protein interaction networks to explore the interactions between proteins in the hormone pathway in aborted embryos. Then we identified key genes and transcription factors (TFs) such as Abscisic acid-insensitive 5 (ABI5), Auxin Response Factor 5 (ARF5), Gibberellin Insensitive Dwarf 1 (GID1), Arabidopsis Response Regulator4 (ARR4), Jasmonate-zim-domain protein 1 (JAZ1), Brassinazole-resistant 1 (BZR1), etc., whose functions require further investigation. Our findings establish a foundation for the metabolic regulation of peony hybrid embryo abortion via networks regulating phytohormone signaling. However, further research is needed to determine the exact mechanisms by which hormones regulate peony embryo development and to explore new methods for improving the success rate of hybridization. Full article