Search Results (67)

Actinidia arguta is a dioecious plant, and the selection of superior male germplasm is crucial for ensuring effective pollination of female cultivars, maximizing their economic traits, and achieving high-quality yields. This study evaluated 30 male germplasms for pollen quantity, germination capacity, storage characteristics, and ultrastructural features. Results revealed significant variation in pollen germination rates (1.56–96.57%) among germplasms, with ‘Lvwang’, ‘TL20083’, and ‘TG06023’ performing best (all >90% germination). The storage characteristics study demonstrated that −80 °C is the optimal temperature for long-term pollen storage in A. arguta. Significant variations were observed in storage tolerance among different germplasms. Among them, Lvwang exhibited the best performance, maintaining a germination rate of 97.40% after 12 months of storage at −80 °C with no significant difference from the initial value, followed by TT07063. Pollen morphology was closely correlated with fertility. High-fertility pollen grains typically exhibited standard prolate or ultra-prolate shapes, featuring a tri-lobed polar view and an elliptical equatorial view, with neat germination furrows and clean surfaces. In contrast, low-fertility pollen grains frequently appeared shrunken and deformed, with widened germination furrows and visible exudates. Based on these findings, the following recommendations are proposed: ① Prioritize the use of germplasms with pollen germination rates >80% as pollinizers; ② Establish a rapid screening system based on pollen morphological characteristics. This study provides important scientific basis for both male germplasm selection and efficient cultivation practices in A. arguta (kiwiberry). Full article

This study evaluated the influence of different male date palm cultivars, distinguished by their chloroplast haplotypes, on pollen quality, pollination efficiency, metaxenia effects, and gene expression during fruit development. Chloroplast DNA analysis of 37 male trees revealed multiple haplotypes, from which cultivars B25, P8, C22, and B46 were selected for further investigation. Pollen viability varied significantly among cultivars, with P8 and B25 exhibiting the highest germination rates and pollen tube elongation, while C22 showed the lowest. These differences correlated with pollination success: P8 and B25 achieved fertilization rates near 99%, whereas C22 remained below 43%. Pollination outcomes also varied in fruit traits. Despite its low pollen performance, C22 induced the production of larger fruits at the Bleh (Kimri) stage, potentially due to compensatory physiological mechanisms. Phytochemical profiling revealed significant cultivar effects: fruits from B25-pollinated trees had with lower moisture and polyphenol content but the higher sugar levels and soluble solids, suggesting accelerated maturation. Ripening patterns confirmed this finding, with B25 promoting the earliest ripening and B46 causing the most delayed. Gene expression analysis supported these phenotypic differences. Fruits pollinated by P8, B25, and B46 exhibited elevated levels of cell-division-related transcripts, particularly the PdCD_1 gene (PDK_XM_008786146.4, a gene encoding a cell division control protein), which was most abundant in P8. In contrast, fruits from C22-pollinated trees had the lowest expression of growth-related genes, suggesting a shift toward cell expansion rather than division. Overall, the results show the critical role of male genotype in influencing fertilization outcomes and fruit development, offering valuable insights for targeted breeding strategies at enhancing date palm productivity and fruit quality. Full article

The undertaking of distant hybridization holds paramount significance for the innovation of tea germplasm resources and the cultivation of superior, specialized tea varieties. However, challenges manifest during the process of tea plant distant hybridization breeding, with reproductive barriers impeding the successful acquisition of hybrid progeny; the precise stages at which these barriers occur remain unclear. In this study, utilizing Camellia sinensis cv. Jinxuan as the maternal parent, as well as C. gymnogyna Chang and C. sinensis cv. Yinghong No.9 as the paternal parents, interspecific distant hybridization (DH) and intraspecific hybridization (IH) were conducted. The investigation involved the observation of pollen germination and pollen tube behavior on the stigma, the scrutiny of the developmental dynamics of the ovary post-hybridization, and the examination of the stages and reasons for reproductive disorders during tea tree distant hybridization. The findings indicate that both IH and DH exhibit pre-fertilization barriers. The pre-embryonic development of hybrids obtained from DH is normal, but there is a significant fruit drop during the stage of fruit development. The germination rate of mature seeds obtained from DH is low, and there are pronounced post-fertilization disorders, which are the primary reasons for the difficulty in achieving successful tea plant distant hybridization. An analysis of the genetic variation in phenotypes and chemical components in the progeny after distant hybridization revealed widespread variation and rich genetic diversity. The identification of progeny with a high amino acid and caffeine content holds promise for future production and breeding, providing valuable theoretical references for the selection of parents in the creation of low-caffeine-content tea germplasm resources. Full article

Kasugamycin (KSM) is easily affected by photolysis, acid–base destruction, and oxidative decomposition in the natural environment, leading to its poor durability and low effective utilization rate, which affects its control effect on plant bacterial diseases. Nanomaterials modified with environment-responsive agents enable the control of the release of pesticides through intelligently responding to external stimuli, thereby improving efficacy and reducing environmental impact. In this study, a pH-responsive controlled release system was constructed using zeolitic imidazolate frameworks (ZIF-93) for the sustained and targeted delivery of KSM. The synthesized KSM@ZIF-93 exhibited a diameter of 63.93 ± 11.19 nm with a drug loading capacity of 20.0%. Under acidic conditions mimicking bacterial infection sites, the Schiff base bonds and coordination bonds in ZIF-93 dissociated, triggering the simultaneous release of KSM and Zn²⁺, achieving a synergistic antibacterial effect. Light stability experiments revealed a 34.81% reduction in UV-induced degradation of KSM when encapsulated in ZIF-93. In vitro antimicrobial assays demonstrated that KSM@ZIF-93 completely inhibited Erwinia amylovora at 200 mg/L and had better antibacterial activity and persistence than KSM and ZIF-93. The field experiment and safety evaluation showed that the control effect of KSM@ZIF-93 on pear fire blight at the concentration of 200 mg/L was (75.19 ± 3.63)% and had no toxic effect on pollen germination. This pH-responsive system not only enhances the stability and bioavailability of KSM but also provides a targeted and environmentally compatible strategy for managing bacterial infections during the flowering period of pear trees. Full article

Daylily (Hemerocallis spp.) are perennial herbaceous flowers with high ornamental and medicinal value. Currently, the breeding of new daylily cultivars was mainly achieved through hybrid breeding, but issues such as self-incompatibility, hybridization barriers, and asynchronous reproductive phenology severely hinder the breeding process. Understanding pollen viability was essential for daylily breeding and cultivar improvement. In this study, we systematically investigated the effects of pollen viability determination methods, collection time, medium combinations, culture temperature and storage conditions on the pollen germination characteristics of daylily, using five daylily cultivars introduced in the Zhanjiang region of China as materials. Comparing the Iodine-potassium iodide (I₂-KI) staining and Acetocarmine staining, the results of 2,3,5-Triphenyltetrazolium Chloride (TTC) staining showed a significant positive correlation (p < 0.05) with the in vitro germination rate, which is suitable for the rapid detection of daylily pollen vigor. The daylily variation of pollen vigor was significant in different cultivars, and most cultivars had the highest vigor at 9:00–12:00 a.m., which was suitable for artificial pollination. The in vitro germination experiment showed that sucrose concentration was the key factor for daylily pollen germination and pollen tube growth, and the optimal medium for pollen in vitro germination was 50 g/L⁻¹ sucrose + 0.1 g/L⁻¹ H₃BO₃ + 0.06 g/L⁻¹ KNO₃ + 0.2 g/L⁻¹ Ca(NO₃)₂. The temperature experiment showed that the optimum temperature for pollen germination was 24.1–26.7 °C, and the optimum range for pollen tube growth was 24.1–25.7 °C, and the high temperature significantly inhibited the elongation rate of pollen tube. Storage experiments showed that low temperature (−40 °C) combined with drying treatment could significantly prolong pollen life, and the “Water Dragon” variety still maintained 41.29% vigor after 60 days of dry storage. This study provides theoretical basis and technical support for the introduction and domestication of daylily in South China, hybridization and garden application. Full article

Urbanization often negatively impacts pollinator abundance and richness; however, its effects on different pollination components and plant reproductive success are highly variable. Previous research efforts have also shown geographic and taxonomical bias, with non-insect-pollinated plant species in tropical cities underrepresented in the literature. Although bats represent the most persistent mammal group in urban ecosystems, studies addressing the effect of urbanization on chiropterophilous plants are scarce. Here, we addressed the impacts of urbanization on flowering phenology, pollination, and reproductive success in the chiropterophilous tree Ceiba pentandra (L.) Gaertn. (Malvaceae) in two major tropical cities of the Yucatan Peninsula. We found that urbanization has led to an earlier flowering phenology; however, no effect of urbanization was detected in the two pollination components evaluated: pollinator visitation rate and pollen deposition. Finally, the effects of urbanization on the reproductive success of C. pentandra were mixed. While marginally negative effects of urbanization were found in fruit set, positive effects were found in seed germination. These findings suggest that urban pollinators can provide similar levels of pollination services and thus lead to comparable reproductive success for C. pentandra in forests and cities. Full article

N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) and N-phenyl-1,2,3-thidiazole-5ylurea (TDZ) are plant growth regulators used for seedless treatment in grape. In this study, the flowers of ‘Shine Muscat’ (Vitis labruscana Bailey × V. vinifera L.) were treated with 3, 5, and 10 mg/L CPPU and TDZ one week before flowering. The results showed that both CPPU and TDZ treatments reduced the pollen germination rate and caused abnormal stamen and pollen grain phenotypes, resembling the male sterility observed in ‘Y_14’ (a novel grapevine germplasm derived from the self-progeny of ‘Shine Muscat’). Using RNA-seq technology, the stamens of flowers treated with 10 mg/L CPPU (CPPU_10), 10 mg/L TDZ (TDZ_10), and the control (CK) were analyzed. A total of 520 and 722 differentially expressed genes (DEGs) were identified in CPPU and TDZ treatments, respectively. GO and KEGG analyses revealed that the common pathways leading to pollen abortion in both treatments were primarily associated with hydrolase activity (acting on glycosyl bonds), phenylpropanoid biosynthesis, pentose and glucuronate interconversions, and ABC transporters. By comparing the DEGs across the three groups (Y_14 vs. SM, CPPU_10 vs. CK, TDZ_10 vs. CK), 16 DEGs exhibited similar expression patterns. Further tissue-specific expression analysis identified nine genes that were highly expressed in stamens and shared the same expression pattern in sterile lines. These findings provide a foundation for further studies on the impact of CPPU and TDZ treatments on grape stamen fertility. Full article

Successful pollination and fertilization are crucial for grain setting in cereals. Wheat is an allohexaploid autogamous species. Due to its evolutionary history, the genetic diversity of current bread wheat (Triticum aestivum) cultivars is limited. Introducing favorable alleles from related wild and cultivated wheat species is a promising breeding strategy for resolving this issue. However, wide hybridization between bread wheat and its relatives is hampered by the presence of suppressor genes and difficulties in crossing. Optimized methods for observing pollen tubes are essential for understanding the mechanism of crossability between wheat and its relatives. Here, we improved the crossing procedure between bread wheat and rye (Secale cereale) and established an optimized protocol for visualizing pollen tube behavior. Crossing via detached spike culture significantly enhanced crossing efficiency and phenotypic stability. A combination of canonical aniline blue staining and optimized clearing and sectioning allowed us to visualize pollen tube behavior. The proportion of rye pollen tubes reaching the micropyle was lower than that for pollen tubes germinated on the stigmatic hair, explaining why the hybrid seed-setting rate was approximately 75% instead of 100%. This method sheds light on wide hybridization through deeper visualization of the insides of pistils. Full article

All 32 Brazilian species of Parodia Speg (Cactaceae) occurring in Rio Grande do Sul State are considered threatened, according to the IUCN criteria. Until 2021, Parodia rechensis (CR) was known by only two small populations. However, a new population with over 400 individuals was discovered in 2021, prompting the study of its reproductive biology as a way to promote its conservation. Anthesis, breeding system, and natural pollination were studied in the field. The breeding system was studied by applying controlled pollination treatments to plants excluded from pollinators (bagged). Germination features were studied at the Seed Bank of the Porto Alegre Botanical Garden under controlled temperatures (20, 25, and 30 °C). The anthesis is diurnal and lasts for up to four days. The flowers offer pollen as the sole resource to the pollinators. The study species is unable to set fruit and seed without the agency of pollinators and has self-incompatible (unable to set fruit and seeds when pollinated with pollen of the same individual) characteristics that can considerably restrict its reproduction. Native bees of Halictidae and Apidae (Hymenoptera) are the main pollinators, with a smaller contribution of Melyridae (Coleoptera) and Syrphidae (Diptera). Natural fruit set is moderate (≤64%, per individual), but the species presents vegetative growth, producing several branches from the mother plant. Seeds showed the optimum germination rate at 20 °C and an inhibition of 75% in germinability at 30 °C. Our findings suggest the need to manage the species’ habitat to guarantee the permanency of the plants and healthy populations of pollinators as well. Our findings raise concerns about the germination and establishment of new individuals in the context of rising temperatures caused by climate change. Suggestions for the possible management of the extant populations are made. Full article

Rhododendron resources are abundant in China, and hybridization breeding technology is the primary method for cultivating Rhododendron varieties. In order to optimize the utilization of wild Rhododendron resources for distant hybridization, this study took three horticultural varieties of Rhododendron subgenus Tsutsusi and the Rhododendron decorum Franch. of the subgenus Hymenanthes as the research objects, and the cross-compatibility between subgenera was analyzed from the aspects of pollen tube growth and ovary and seed development. At the same time, the statistics of ovary swelling rate and fruit bearing rate, numbers of capsule seeds, 1000 seed weight of hybrid seeds, germination rate, green seedling rate, and other indexes were analyzed to comprehensively evaluate hybrid fertility. The results showed that there was obvious pre-fertilization and post-fertilization barriers existing in the hybridization of Rhododendron × hybridum hort. and R. decorum. During the growth of pollen tubes, a large amount of callus appeared, which led to the entanglement, distortion, and abnormal development of the pollen tubes; only part of the pollen tubes entered into the ovary or ovule. The pre-fertilization barriers can be overcome by early pollination and delayed pollination. According to the observation of the ovary paraffin section, 45 d after pollination, the seed was shriveled and developed abnormally. The comprehensive evaluation of hybrid fertility showed that ‘Sima’ × R. decorum was fertile, ‘Yin Taohong’ × R. decorum was a weakly fertile, and ‘Little Taohong’ × R. decorum was sterile. This study provided a scientific basis for intergeneric hybridization breeding between the subgenus Tsutsusi and the subgenus Hymenanthes. Full article

Pear trees must be artificially pollinated to ensure yield, and the efficiency of pollination and the quality of pollen germination affect the size, shape, taste, and nutritional value of the fruit. Detecting the pollen germination vigor of pear trees is important to improve the efficiency of artificial pollination and consequently the fruiting rate of pear trees. To overcome the limitations of traditional manual detection methods, such as low efficiency and accuracy and high cost, and to meet the requirements of screening high-quality pollen to promote the yield and production of fruit trees, we proposed a detection method for pear pollen germination vigor named YOLOv8-Pearpollen, an improved version of YOLOv8-n. A pear pollen germination dataset was constructed, and the image was enhanced using Blend Alpha to improve the robustness of the data. A combination of knowledge distillation and model pruning was used to reduce the complexity of the model and the difficulty of deployment in hardware facilities while ensuring that the model achieved or approached the detection effect of a large-volume model that can adapt to the actual requirements of agricultural production. Various ablation tests on knowledge distillation and model pruning were conducted to obtain a high-quality lightweighting method suitable for this model. Test results showed that the mAP of YOLOv8-Pearpollen reached 96.7%. The Params, FLOPs, and weights were only 1.5 M, 4.0 G, and 3.1 MB, respectively, and the detection speed was 147.1 FPS. A high degree of lightweighting and superior detection accuracy were simultaneously achieved. Full article

The increasing use of photoselective nets (PNs) raises the question of their influence on pollen traits. We aimed to evaluate the effect of PNs (yellow, pearl, and grey) on the pollen of ‘Matua’ and ‘Tomuri’ Actinidia deliciosa cultivars. The pollen size and the exine were studied with a light microscopy and a scanning electron microscopy, and the fertility was analysed by a viability assay and in vitro germination. The total soluble proteins (TSPs) and sugars (TSSs) were quantified by colorimetric assays. The molecular structure of the pollen grain’s wall was analysed by a Raman spectroscopy. The pollen from the plants under the PNs had a larger width and area and a lower germination rate. No significant changes were observed in the exine’s microperforations. The TSP and TSS contents were influenced by the cultivar and PNs (particularly the pearl PN). The Raman spectra of the pollen from the plants grown under the nets presented some bands that significantly shifted from their original position, indicating differences in the vibration modes of the molecules, but no overall changes at their structural or organisation level were found. Our study showed that the PNs could influence several pollen traits, with the pearl PN inducing greater modifications. Our results also support the idea that cultivars affect the outcome of some characteristics. Full article

Lespedeza davurica (Laxm.) is a leguminous plant with significant ecological benefits, but its embryonic development mechanism remains unclear. We investigated the flower bud differentiation, megaspore and microspore formation, gametophyte development, and embryo and endosperm development in L. davurica. Our aim was to elucidate the relationship between the external morphology and internal development processes of male and female floral organs during growth, as well as the reproductive factors influencing fruiting. The results indicated that although the pistil develops later than the stamen during flower bud differentiation, both organs mature synchronously before flowering. L. davurica pollen exhibits three germination grooves, a reticulate outer wall, and papillary structures on the anther surface. In vivo pollination experiments revealed abnormal spiral growth of L. davurica pollen tubes within the style and the occurrence of callus plugs, which may reduce the seed setting rate. The anther wall development follows the dicotyledonous type, with tetrads formed through microspore meiosis exhibiting both left–right symmetry and tetrahedral arrangements. L. davurica has a single ovule, and the embryo sac develops in the monosporic polygonum type. After dormancy, the zygote undergoes multiple divisions, progressing through spherical, heart-shaped, and torpedo-shaped embryo stages, culminating in a mature embryo. A mature seed comprises cotyledons, hypocotyl, embryo, radicle, and seed coat. Phylogenetic tree analysis reveals a close genetic relationship between L. davurica and other leguminous plants from the genera Lespedeza and Medicago. This study provides valuable insights into the regulation of flowering and hybrid breeding in leguminous plants and offers a new perspective on the development of floral organs and seed setting rates. Full article

Most banana improvement programs are restricted to using a sub-set of edible landraces for sexual hybridization as the majority are female sterile. This results from an array of factors that work in tandem and lead to sterility. Use of pollen germination media (PGM) during pollination significantly increases seed set, but it is a very small fraction compared to the potential seed set. This research therefore explored early pollination (a day before anthesis), evening pollination, saline treatment, plant growth regulators (PGRs) treatment, and ovule culture as potential techniques for overcoming sterility in bananas. Early and evening pollinations did not increase seed set because of immature flowers and a mismatch of male and female flower opening, respectively (t-prob. = 0.735 and 0.884). Immersion of bunches in a saline solution before pollination and ovule culture also did not overcome pollination barriers. Auxin antagonists (TIBA and salicylic acid) increased seed set, though their respective increases were not statistically significant (t-prob. = 0.123 and 0.164, respectively). The use of auxin antagonists shows great potential for overcoming pollination barriers in bananas. However, application rates and time of application have to be optimized and used holistically with other promising techniques, such as use of PGM. Full article

Pollen, the male gametophyte of seed plants, is extremely sensitive to UV light, which may prevent fertilization. As a result, strategies to improve plant resistance to solar ultraviolet (UV) radiation are required. The tardigrade damage suppressor protein (Dsup) is a putative DNA-binding protein that enables tardigrades to tolerate harsh environmental conditions, including UV radiation, and was therefore considered as a candidate for reducing the effects of UV exposure on pollen. Tobacco pollen was genetically engineered to express Dsup and then exposed to UV-B radiation to determine the effectiveness of the protein in increasing pollen resistance. To establish the preventive role of Dsup against UV-B stress, we carried out extensive investigations into pollen viability, germination rate, pollen tube length, male germ unit position, callose plug development, marker protein content, and antioxidant capacity. The results indicated that UV-B stress has a significant negative impact on both pollen grain and pollen tube growth. However, Dsup expression increased the antioxidant levels and reversed some of the UV-B-induced changes to pollen, restoring the proper distance between the tip and the last callose plug formed, as well as pollen tube length, tubulin, and HSP70 levels. Therefore, the expression of heterologous Dsup in pollen may provide the plant male gametophyte with enhanced responses to UV-B stress and protection against harmful environmental radiation. Full article