Fruit Set Rate Research Articles

Study on the physiological mechanism and transcriptional regulatory network of early fruit development in Gleditsia sinensis Lam. (Fabaceae)

BackgroundGleditsia sinensis Lam. (Fabaceae) is a medicinal legume characterized by its spines and pods, which are rich in saponins, polysaccharides, and various specialized metabolites with potential medicinal and industrial applications. The low fruit set rate in artificially cultivated economic forests significantly impedes its development and utilization. A comprehensive understanding of the cellular events, physiological and biochemical processes, and molecular regulatory mechanisms underlying fruit initiation and early fruit development is essential for enhancing yield. However, such information for G. sinensis remains largely unexplored.ResultsIn this study, we identified that the early fruit development process in G. sinensis can be categorized into three distinct stages: pollination, the critical period of fertilization, and the initial fruit development followed by subsequent growth. The dynamic changes in non-structural carbohydrates and endogenous plant hormones within the ovary were found to play a significant role during fruit set and the early stages of fruit development. Additionally, the high activity of gibberellin, cytokinin, and sucrose-metabolizing enzymes in the ovary was conducive to early fruit development. Furthermore, we generated high-resolution spatiotemporal gene expression profiles in the ovary from the stage of efflorescence to early fruit development. Comparative transcriptomics and weighted gene co-expression network analysis revealed specific genes and gene modules predominant at distinct developmental stages, thereby highlighting unique genetic programming. Overall, we identified the potential regulatory network governing fruit initiation and subsequent development, as well as the sets of candidate genes involved, based on the aforementioned results.ConclusionsThe results offer a valuable reference and resource for the application of exogenous substances, such as hormones and sugars, during critical fruit development periods, and for the development of molecular tools aimed at improving yield.

Flower scent, pollinators, and effects of proximity between plants on fruit set of the rare, threatened, and endemic Daphne rodriguezii

AbstractThis study focuses on Daphne rodriguezii, a threatened plant species that is endemic to Menorca in the Balearic Islands of the Western Mediterranean. The main objective was to investigate the volatile organic compounds (VOCs) in the floral aroma, as well as the timing and chemical variations in scent production. The primary pollinators were identified, and the relationship between their behavior and the chemical profile of the floral scent was investigated. Furthermore, the impact of plant density on fruit set rates was evaluated to obtain valuable insights for conservation and habitat‐management initiatives. The findings reveal that D. rodriguezii emits a distinct sweet floral aroma that primarily consists of benzenoids and linalool derivatives. Scent emission occurs during the evening and night, coinciding with the activity period of moths (Autographa gamma), which were identified as the primary pollen vectors for this self‐incompatible species. The fruit set values exhibit a positive correlation with the proximity between plants. These results emphasize the importance of moths and plant proximity as crucial factors to consider in the conservation management of this species.

Competitive network of polyamines metabolic and ethylene biosynthesis pathways during gibberellin-induced parthenocarpic grape fruit setting

Polyamines (PAs) and ethylene are involved in the modulation of plant growth and development. However, their roles in fruit-set, especially in exogenous gibberellin (GA3)-induced grape parthenocarpic berries, and the related competitive action mode are poorly understood. For this, we, here performed their content determination, bioinformatics and expression pattern analysis of genes to identify the key ones in the competitive network of polyamines metabolic and ethylene biosynthesis (PMEB) pathways. The content of putrescine (Put) significantly increased; while 1-aminocyclopropanecarboxylic acid (ACC) sharply decreased during the fruit-set process of GA3-induced grape parthenocarpic seedless berries. Totally, twenty-five genes in PMEB pathways, including 20 polyamines metabolic (PM) genes and 5 ethylene biosynthesis (EB) ones were identified in grape, of which 8 PM and 2 EB genes possessed the motifs responsive to phytohormone GA. The expression levels of most PMEB genes kept changing during grape fruit-set generating a competitive action mode of GA3-mediated two metabolic fluxes toward PAs and ethylene synthesis. Exogenous GA3 might enhance grape fruit-set of parthenocarpic berries via up-regulation of VvSAMS4, VvSAMDC1/2, VvODC1, VvSPDS1, and VvPAO1 to promote PAs accumulation, whereby repressing the ethylene synthesis by down-regulation of VvACS1 and VvACO2. Our findings provide novel insights into GA3-mediated competitive inhibition of ethylene by PAs to promote the fruit-set of parthenocarpic berries in grape, which has important implications for molecular breeding of seedless grape with high fruit-setting rate.

Diptera‐dominated generalist pollination systems in Eurya japonica and Eurya emarginata (Pentaphylacaceae)

AbstractWe investigated the flower visitors and floral traits of two dioecious shrub species Eurya japonica Thunb. (Pentaphylacaceae) and Eurya emarginata (Thunb.) Makino in temperate Kochi and subtropical Okinawa in Japan during the cool seasons. We demonstrated that the two Eurya species could be pollinated by a wide spectrum of flower visitors—mainly Diptera. The main pollinators were probably Chironomidae and Empididae for E. japonica in Kochi and Calliphoridae and Syrphidae for the remaining species–site combinations (i.e., E. emarginata in Kochi, E. japonica in Okinawa, and E. emarginata in Okinawa). We demonstrated that several dominant families of Dipteran visitors have the ability to pollinate the two Eurya species. Interestingly, floral traits (corolla diameter and nectar concentration) could not explain the difference in the assemblages. These results indicate that floral traits are not specifically adapted to their local pollinators. The fruit set rate was significantly lower for naturally pollinated flowers than for hand‐pollinated flowers, indicating pollen limitation in both Eurya species. However, there was no apparent difference in the number of seeds per fruit between naturally pollinated and hand‐pollinated flowers.

Effects of NH4 +-N: NO3 --N ratio on growth, nutrient uptake and production of blueberry (Vaccinium spp.) under soilless culture.

Blueberry (Vaccinium corymbosum) is a small pulp shrub, which prefers to grow on a soilless culture. For soilless culture, nutritional management remains typically vital for blueberry production. However, the effect of different nutritional treatments on blueberry growth and production is largely unknown. This study was designed to investigate to formulate a specific nutritional treatment for blueberry. The results showed that NH4 +-N: NO3 --N ratios significantly affected the growth, nutrient uptake, physiological characteristics, and flowering, as well as the fruiting characteristics of blueberry plants. The number of shoots and top projection area was increased considerably by 25:75 treatment. In contrast, 50:50 treatment promotes plant height, shoot length, and stem thickness, increasing chlorophyll contents, photosynthetic capacity, and P, Ca, and Mg in leaves. In contrast, 50:50 treatment promotes the flowering fruiting rate and prolongs the blueberry flowering period. The maximum soluble sugar contents were noted in 25:75, while maximum starch contents were reported in the 50:50 treatment. The treatments 100:0 and 75:25 promote early flowering and accelerate fruit set. Notably, NH4 +-N: NO3 --N ratios; 50:50 treatment significantly encourages plant growth, nutrient uptake, chlorophyll contents, photosynthetic capacity, and fruit setting rate in blueberry plants. These findings suggested that NH4 +-N: NO3 --N ratios 50:50 is the most appropriate treatment that significantly promotes vegetative growth and enhances production in blueberry plants. This study provides valuable information for improved blueberry production under a controlled environment.

Vegetative traits, floral biology, and mutualistic interactions in the tropical mountain shrub Ribes ciliatum (Grossulariaceae)

Plant species in tropical mountain ecosystems experience significant environmental variation across short spatial distances. These systems offer an opportunity to assess geographic variation in plant traits in relation to biotic and abiotic environments. We examined plant vegetative and reproductive traits in the shrub R. ciliatum across two native conifer forests in central Mexico. We measured plant height, number of branches, leaf size, flower production, floral morphology, floral longevity, and plant reproductive success in R. ciliatum populations found in fir forests (3100 m) and Hartweg's pine forests (subalpine habitat, 3700 m). We also quantified the level of pollinator dependence, pollinator visitation rates, and fruit consumption rates by frugivorous birds in both populations. Plants were shorter and had smaller leaves in the subalpine forest than in the fir forest. Floral longevity decreased in the subalpine forest, but flower production, flower size, and fruit weight remained similar across populations. Fruit set and pollinator visitation rates were higher in the subalpine forest; however, seed weight and fruit consumption rates did not differ between sites. Hummingbirds and bumblebees were the primary pollinators of R. ciliatum, and the bird Ptiliogonys cinereus was the most important fruit consumer at both sites. Fruit set was entirely dependent on pollinators. Reduced plant size in the subalpine forest coincides with a general pattern associated with high mountain environments. In contrast, reproductive characters had a closer relationship to the pollination environment. The absence of variation in flower size and shape was consistent with the similarity in the composition of the pollinator community. Meanwhile, compared to lower-elevation forests, the subalpine forest exhibited shorter-lived flowers and increased fruit set, associated with higher pollinator visitation rates. Ribes ciliatum is a key resource for pollinators and frugivores at a time of year when few other floral resources are available in these high-elevation mountain forests.

Effects of Pollen Germination and Pollen Tube Growth under Different Temperature Stresses in Mango (Mangifera indica L.) by Metabolome.

The dramatic temperature fluctuations spurred by global warming and the accompanying extreme weather events inhibit mango growth and threaten mango productivity. Particularly, mango flowering is highly sensitive to temperature changes. The mango fruit setting rate was significantly positively correlated with pollen activity, and pollen activity was regulated by different metabolites. In this study, the in vitro pollen of two mango varieties ('Renong No.1' and 'Jinhuang'), in which sensitivity to temperature differed significantly, were subjected to different temperature stresses (15 °C, 25 °C and 35 °C), and their metabolomics were analyzed. The present results showed that 775 differential metabolites were screened by liquid chromatography-mass spectrometry and divided into 12 categories. The two varieties had significant differences in metabolite expression under different temperature stresses and the effect of low temperature on 'Renong No.1' mainly focused on amino acid metabolism, while the effect on 'Jinhuang' was mainly related to glycolysis. However, under the 35 °C temperature stress, 'Renong No.1' responded by redistributing riboflavin and betaine in vivo and the most obvious metabolic pathway of 'Jinhuang' enrichment was pyrimidine metabolism, which had undergone complex main body formation and extensive regulatory processes. The changes of metabolites of different varieties under low temperature and high temperature stress were different. Among them, flavonoids or flavonoid derivatives were included in class A (216 metabolites), C (163 metabolites) and D (233 metabolites) metabolites, indicating that flavonoid metabolites had an obvious regulatory effect on mango pollen metabolism under different temperature stress. The present results provide valuable information for reproductive biology studies and breeding in mango, in particular, the selection and breeding of the most suitable varieties for different production areas.

Phenological, Morphological and Pomological Characteristics of ‘Samsun Güzeli’ Pear Genotype on BA29 Rootstock

Türkiye has many local pear cultivars; some of them do not have much production and propagation potential due to their low quality and undesirable vegetative and generative characteristics. However, those that are superior in terms of fruit quality and yield characteristics have found a place for themselves in both local and national markets. In this respect, the ‘Samsun Güzeli’ genotype, which is an important local cultivar, is an ideal cultivar with many features and has a high potential to spread its cultivation all over Türkiye and other countries. ‘Samsun Güzeli’ is an autumn genotype, can easily meet the high demand in local and international markets due to its attractive color, smooth fruit shape and high quality. Despite all these valuable features, this cultivar is still not well known in Türkiye. There is a great need to disseminate cultivation and research on this subject. This study mainly aimed to reveal the phenological, morphological and pomological characteristics of the ‘Samsun Güzeli’ local pear genotype grafted on BA29, a commercially traded rootstock in 2021-2022. The results showed that the ‘Samsun Güzeli’ pear genotype completed its phenological cycle in 255 days in 2021 and 228 days in 2022 in Samsun climatic conditions. Fruit set rate of the genotype was 12.05% and the average yield was 17306.23 kg ha-1. It was also determined that the morphological characteristics averages were as the following; rootstock diameter 76.71 mm, trunk diameter 61.97 mm, trunk cross-sectional area 34.06 cm2, tree height 253.12 cm, canopy volume 0.96 m3, annual shoot length 37.19 cm and leaf area 11.74 cm2. Averages values of pomological and chemical properties recorded as the following; fruit weight 114.60 g, fruit volume 109.90 ml, soluble solid content (SSC) 13.16%, acidity 0.33%, and pH 4.37. In the sensory evaluations, the highest scores were obtained by juiciness (6.32) in the year 2022 while scores of overall visual quality were lowest in both years. In conclusion, it can be said that the ‘Samsun Güzeli’ genotype performs adequately in terms of fruit yield and quality on the standard dwarf rootstock and conducting new studies might be beneficial to disseminate the genotype.

Targeted Metabolites and Transcriptome Analysis Uncover the Putative Role of Auxin in Floral Sex Determination in Litchi chinensis Sonn.

Litchi exhibits a large number of flowers, many flowering batches, and an inconsistent ratio of male and female flowers, frequently leading to a low fruit-setting rate. Floral sexual differentiation is a crucial phase in perennial trees to ensure optimal fruit production. However, the mechanism behind floral differentiation remains unclear. The objective of the study was to identify the role of auxin in floral differentiation at the transcriptional level. The results showed that the ratio of female flowers treated with naphthalene acetic acid (NAA) was significantly lower than that of the control stage (M0/F0). The levels of endogenous auxin and auxin metabolites were measured in male and female flowers at different stages of development. It was found that the levels of IAA, IAA-Glu, IAA-Asp, and IAA-Ala were significantly higher in male flowers compared to female flowers. Next-generation sequencing and modeling were employed to perform an in-depth transcriptome analysis on all flower buds in litchi 'Feizixiao' cultivars (Litchi chinensis Sonn.). Plant hormones were found to exert a significant impact on the litchi flowering process and flower proliferation. Specifically, a majority of differentially expressed genes (DEGs) related to the auxin pathway were noticeably increased during male flower bud differentiation. The current findings will enhance our comprehension of the process and control mechanism of litchi floral sexual differentiation. It also offers a theoretical foundation for implementing strategies to regulate flowering and enhance fruit production in litchi cultivation.

Study on the Effect of Foliar Fertilizers on the Growth and Yield of V108 Heat-Tolerant Cucumber Variety

This study evaluates the efficacy of various foliar fertilizers on the growth and yield of the heat-tolerant cucumber variety TV108. The experimental design included six different foliar fertilizers and a control, with applications made weekly at a concentration of 1 mL per liter of water. Results showed that all foliar treatments significantly enhanced plant height compared to the control. Among these, Treatment T4 (ATONIK foliar fertilizer) demonstrated the most pronounced effect, achieving a main stem height of 216.57 cm by the 70th day, which was significantly higher than other treatments and the control. Treatment T4 also excelled in increasing stem diameter, with a final measurement of 1.48 cm, and in promoting both male and female flower formation. The fruit set rate was highest in Treatment T4, reaching 28.67% on day 56 and maintaining at 8.67% by day 70. This treatment also proved most effective in reducing the incidence of key diseases and pests, including powdery mildew, white mold, green worms, and yellow beetles. Regarding yield, Treatment T4 produced the highest individual fruit yield (2.32 kg/plant), actual yield (33.8 tons/ha), and theoretical yield (84.91 tons/ha). Additionally, it enhanced fruit quality, as indicated by the largest fruit length (15.22 cm), diameter (4.13 cm), and the highest Brix value (3.50%). These results substantiate that Treatment T4 is the most effective foliar fertilizer for enhancing both growth and quality of heat-tolerant cucumbers under experimental conditions.

Elucidating the Role of SlBBX31 in Plant Growth and Heat-Stress Resistance in Tomato.

Heat stress inhibits plant growth and productivity. Among the main regulators, B-box zinc-finger (BBX) proteins are well-known for their contribution to plant photomorphogenesis and responses to abiotic stress. Our research pinpoints that SlBBX31, a BBX protein harboring a conserved B-box domain, serves as a suppressor of plant growth and heat tolerance in tomato (Solanum lycopersicum L.). Overexpressing (OE) SlBBX31 in tomato exhibited yellowing leaves due to notable reduction in chlorophyll content and net photosynthetic rate (Pn). Furthermore, the pollen viability of OE lines obviously decreased and fruit bearing was delayed. This not only affected the fruit setting rate and the number of plump seeds but also influenced the size of the fruit. These results indicate that SlBBX31 may be involved in the growth process of tomato, specifically in terms of photosynthesis, flowering, and the fruiting process. Conversely, under heat-stress treatment, SlBBX31 knockout (KO) plants displayed superior heat tolerance, evidenced by their improved membrane stability, heightened antioxidant enzyme activities, and reduced accumulation of reactive oxygen species (ROS). Further transcriptome analysis between OE lines and KO lines under heat stress revealed the impact of SlBBX31 on the expression of genes linked to photosynthesis, heat-stress signaling, ROS scavenging, and hormone regulation. These findings underscore the essential role of SlBBX31 in regulating tomato growth and heat-stress resistance and will provide valuable insights for improving heat-tolerant tomato varieties.

A new approach for artificial pollination in walnut trees: AirPoll

Pollination is the first step in the plant's fruit development. Therefore, fruit setting does not occur without pollination. Some problems encountered in natural pollination cause pollination not to be achieved as desired and cause significant losses in yield and fruit quality. Artificial pollination applications with drones are the best way to solve these problems. In this study, the AirPoll artificial pollination machine, which performs artificial pollination through the air using drone technology, was developed and the operating success of the machine was tested in walnut gardens. In the experiment gardens, female flowers on 18 branches of 5 trees each in the artificially pollinated area with a drone and in the control area were marked with colored strings. Control trees were selected from a distance that would not be possible to transport pollen with a drone. As a result of the study carried out in 2020 and 2021, the average fruit setting rate in trees pollinated by drone was determined as 94.61%. In control trees, 32.33% fruit setting was achieved. Thus, it was determined that the productivity increase in artificial pollination with AirPoll was 62.28%. In addition, in the study, Computational Fluid Dynamics (CFD) simulation analysis was performed using ANSYS Fluent 2024 R1 software to predict the downward air flow and pollen distribution in the walnut tree crown. The analysis was carried out in 680 iterations using drone propellers at a rotation speed of 4500 rpm, 4 m/s airflow and a k-w viscous model. In the analysis, it was observed that the pollen was distributed homogeneously with the determined height and the created artificial pollination environment. Based on the results obtained from the simulations, a convergence criterion of 5e−3 for continuity and 1e−6 for speed, k, w was determined. Considering all the results, the ease of use of the developed AirPoll artificial pollination machine and the successful results obtained in field trials reveal the effectiveness of the AirPoll artificial pollination machine.

Honeybee (Apis mellifera L.) pollination enhances the yield and flavor quality of kiwifruit.

Pollination is essential for achieving high yields and enhancing the quality of kiwifruit cultivation, both of which significantly influence growers' interests and consumers' preferences. However, compared to studies on yield, there are fewer studies exploring the impact of pollination methods on the flavor of kiwifruit Actinidia chinensis Planchon. This study examined the effects of bee (Apis mellifera L.) pollination and artificial pollination on the yield and flavor of kiwifruit in the main producing areas of China. Compared with those pollinated artificially, bee-pollinated kiwifruit exhibited a greater fruit set rate, heavier fruit weight, and greater number of seeds. Notably, the number of seeds was positively correlated with fruit weight in bee-pollinated kiwifruit, whereas no such correlation was detected in artificially pollinated fruit. Bee pollination not only enhanced the yield but also improved the flavor of kiwifruit. Specifically, bee-pollinated kiwifruit contained higher levels of sucrose and lower concentrations of glucose and fructose, while the acid content was less affected by pollination methods. Furthermore, significant differences were observed in the volatile organic compound (VOC) levels in kiwifruit subjected to different pollination treatments, with bee-pollinated fruit exhibiting a superior flavor. Our findings provide new insights into the beneficial role of bee pollination in enhancing kiwifruit yield and quality, underscoring the crucial importance of bees in kiwifruit pollination.

Fruiting Characteristics and Molecular-Assisted Identification of Korla Fragrant Pear Bud Mutation Materials

Korla fragrant pear is a high-quality local pear variety native to Xinjiang, China. Currently, the low fruit-setting rate and low calyx shedding rate problems in Korla fragrant pears have been highlighted, which seriously affect the fruit yield and quality. It is of great significance to research the fruiting characteristics and molecular-assisted identification of Korla fragrant pear bud mutation materials for enriching the germplasm resources of Korla fragrant pear. In this research, a natural pollination group (YB) of Korla fragrant pear bud mutation materials and a natural pollination group (CK) of Korla fragrant pears were established. On the fruiting characteristics, the fruit-setting rate and calyx-removal rate of the two groups were investigated. In terms of fruit quality, the fruit shape index, fruit specific gravity, soluble solids content, sugar:acid ratio, soluble sugar content, and other indicators were measured. For the anatomical structure of the calyx tube, the detachment cells were observed. The formation time of the two groups of detached cells was compared. In the GBS simplified genome sequencing, a phylogenetic tree was constructed based on the obtained SNP sites. A principal component analysis, population genetic structure analysis, and genetic diversity index analysis were carried out. In the aspect of SSR molecular marker identification, the SSR types were counted. Polyacrylamide gel electrophoresis was performed. The results demonstrate the following: (1) the fruit-setting rate (30.87%) and calyx-removal rate (68.11%) in the YB group were significantly higher than those in the CK group (19.37%) and the calyx-removal rate (55.18%). (2) There was no significant difference in fruit quality indexes, such as average fruit weight (127.10–130.00 g) and soluble sugar content (9.47–9.56%) between the two groups. (3) Abscission-layer cells were observed at 2, 4, 6, 8, and 10 h after calyx tube discoloration in the YB group and at 48, 72, and 96 h after calyx tube discoloration in the CK group. (4) The genetic background of the YB group and the CK group was similar at the GBS level, but there were differences at the DNA level. This research finally shows that Korla fragrant pear bud mutation material is a good germplasm resource. This germplasm resource can promote the structural optimization of Korla fragrant pear varieties and the healthy development of the industry.

Comparative Proteomic Analysis of Floral Buds before and after Opening in Walnut (Juglans regia L.).

The walnut (Juglans regia L.) is a typical and an economically important tree species for nut production with heterodichogamy. The absence of female and male flowering periods seriously affects both the pollination and fruit setting rates of walnuts, thereby affecting the yield and quality. Therefore, studying the characteristics and processes of flower bud differentiation helps in gaining a deeper understanding of the regularity of the mechanism of heterodichogamy in walnuts. In this study, a total of 3540 proteins were detected in walnut and 885 unique differentially expressed proteins (DEPs) were identified using the isobaric tags for the relative and absolute quantitation (iTRAQ)-labeling method. Among all DEPs, 12 common proteins were detected in all four of the obtained contrasts. GO and KEGG analyses of 12 common DEPs showed that their functions are distributed in the cytoplasm metabolic pathways, photosynthesis, glyoxylate and dicarboxylate metabolism, and the biosynthesis of secondary metabolites, which are involved in energy production and conversion, synthesis, and the breakdown of proteomes. In addition, a function analysis was performed, whereby the DEPs were classified as involved in photosynthesis, morphogenesis, metabolism, or the stress response. A total of eight proteins were identified as associated with the morphogenesis of stamen development, such as stamen-specific protein FIL1-like (XP_018830780.1), putative leucine-rich repeat receptor-like serine/threonine-protein kinase At2g24130 (XP_018822513.1), cytochrome P450 704B1-like isoform X2 (XP_018845266.1), ervatamin-B-like (XP_018824181.1), probable glucan endo-1,3-beta-glucosidase A6 (XP_018844051.1), pathogenesis-related protein 5-like (XP_018835774.1), GDSL esterase/lipase At5g22810-like (XP_018833146.1), and fatty acyl-CoA reductase 2 (XP_018848853.1). Our results predict several crucial proteins and deepen the understanding of the biochemical mechanism that regulates the formation of male and female flower buds in walnuts.

Dynamic temporal transcriptome analysis reveals grape VlMYB59-VlCKX4 regulatory module controls fruit set.

Fruit set is a key stage in determining yield potential and guaranteeing quality formation and regulation. N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) has been widely applied in grape production, the most iconic of which is the promotion of grape fruit set. However, current studies still lack the molecular mechanism of CPPU-induced grape fruit set. Here, the dynamic, high-resolution stage-specific transcriptome profiles were generated based on two different treatments and five developmental periods during fruit set in 'Kyoho' grape (Vitis vinifera L. × V. labrusca L.). Pairwise comparison and functional category analysis showed that phytohormone action cytokinin was significantly enriched during the CPPU-induced grape fruit set, but not the natural one. Value differentially expressed gene (VDEG) was a newly proposed analysis strategy for mining genes related to the grape fruit set. Notably, the cytokinin metabolic process was significantly enriched among up-regulated VDEGs. Of importance, a key VDEG VlCKX4 related to the cytokinin metabolic process was identified as related to the grape fruit set. Overexpression of VlCKX4 gene promoted the Arabidopsis plants that produce more and heavier siliques. The transcription factor VlMYB59 directly bound to the promoter of VlCKX4 and activated its expression. Moreover, overexpression of VlMYB59 gene also promoted the Arabidopsis fruit set. Overall, VlMYB59 responded to CPPU treatment and directly activated the expression of VlCKX4, thus promoting the fruit set. A regulatory pathway of the VlMYB59-VlCKX4 module in the fruit set was uncovered, which provides important insights into the molecular mechanisms of the fruit set and good genetic resources for high fruit set rate breeding.

Seed quality and germination performance increase with cross-pollination in members of subtribe Orchidinae (Orchidaceae)

Abstract Over half of angiosperms have self-incompatibility systems to avoid self-pollination and inbreeding depression. Many members of Orchidaceae are self-compatible, but they may be prone to negative consequences of self-pollination. We investigated the effects of both within-flower (autogamy) and within-plant (geitonogamy) self-pollination, and cross-pollination on fruit set, seed quality, and germination rates in 11 related orchid taxa of subtribe Orchidinae. We hand-pollinated flowers and measured fruit set to estimate pre- and postzygotic barriers. We collected morphometric data on embryos and seeds and calculated the percentage of seeds with embryos and seed viability. We then calculated inbreeding depression values for each treatment for each taxon. Ten taxa produced fruits when self-pollinated, but germination rates and seed size increased with cross-pollination. Higher seed viability was correlated with larger embryos/seeds. However, geitonogamous pollination generally resulted in the lowest seed quality compared with autogamy and cross-pollination, with high values of inbreeding depression being detected. Only seven of the 11 taxa (Anacamptis papilionacea, Himantoglossum adriaticum, Ophrys apifera, Ophrys bertolonii, Orchis patens subsp. brevicornis, Orchis provincialis, and Serapias vomeracea) were confirmed as self-compatible. These results show that cross-pollination improves overall seed quality, and that the assessment of self-compatibility in orchids should be based on postfruiting stages.

Efficiency of Antioxidants on Physiological Traits and Growth Curve of Date Palm Fruit Cultivars Barhi and Zamli

The study aimed to investigate the impact of variety factor on the physiological characteristics and growth curve of date palm fruits in a private orchard in the Hartha district of Al-Masheeb, north of Basrah province. Two date palm varieties, Barhi and Zamli, were selected and antioxidants tocopherol and Glutathione were used at three concentrations (0, 75, 150 mg/L) for each. The interaction between these factors was studied in terms of physiological characteristics and growth curves. Results showed no significant differences between the varieties' physiological characteristics, but the spray treatments had a significant effect on the percentage of fruit set. The Glutathione spraying treatment had the highest rate of fruit set (86.60%), while the comparison treatment had the lowest drop rate (77.55%). The interaction treatments also had significant differences in drop rate and non-set fruit percentages. The Zamli variety showed the highest growth curve of physical traits (6 and 12 weeks after pollination), while antioxidant spray treatments had significant differences in the rate of physical characteristics. The interaction had a significant effect on the studied characteristics during the two growth periods

Effects of Actinomycete Act12 on Soil Microbial Community Structure and Plant Traits of Ziziphus jujuba Mill.

Biocontrol agents play a crucial role in agricultural production by reducing the use of pesticides and chemical fertilizers, controlling pests and diseases, and enhancing crop yield and quality. While extensive research has focused on the growth-promoting and yield-increasing effects of biocontrol agents on herbaceous plants, their impact on woody crops such as trees and shrubs has not been reported. This study investigates the effects of the actinomycete strain Act12, applied via root drenching and foliar spraying, on the flowering and fruit set rates, leaf physiology and enzyme activity, and fruit characteristics and yield of the jujube tree (Ziziphus jujuba Mill.). Additionally, this study analyzes the physicochemical properties of the soil and the diversity and community structure of its microorganisms. The results indicate that treatment with Act12 significantly altered the α and β diversity of soil microorganisms and enhanced the interaction networks among them. This led to increased levels of available nitrogen, phosphorus, and potassium in the soil, significantly improving nutrient availability. Consequently, there was an improvement in the number of flower buds and fruits, as well as an increase in the longitudinal diameter and individual fruit weight of the jujube. These effects significantly enhanced the yield and total sugar content of the winter jujube. Given these findings, Act12 can be considered an effective microbial agent for enhancing the yield and quality of winter jujube when applied to the soil.

Microscopic observation and transcriptome analysis provide insights into mechanisms of hybrid incompatibility in Rhododendron

Hybridization across species has been widely utilized to improve agriculturally important traits in Rhododendron. These interspecific hybridizations are often inhibited by reproductive barriers at the prezygotic and postzygotic stages. Thus, in order to character the barriers and reveal the underlying regulation mechanism of interspecific hybrid incompatibility in Rhododendron, we compared the pollen germination and pollen tube growth, fruit growth, seed number and germination rate between intraspecific (Rhododendron ‘XXL’ × R. ‘XXL’) and interspecific (R. ‘XXL’ × R. delavayi) hybridizations. After pollination, the pollen germination rate and pollen tube growth rate of interspecific hybridization (Inter) were always higher than that of intraspecific hybridization (Intra) during the whole observation period. Conversely, the fruits and ovules of Intra grew faster than that of Inter after 20 DAP. The ratio of shrunken embryos of Inter was 73.27 ± 10.19 %, which was significantly higher than that of Intra with 28.41 ± 8.33 % at 40 DAP. Moreover, the fruit setting rate, the average number of seeds per fruit and seed germination rate of Intra were significantly higher than that of Inter at 150 DAP. These results indicated that the barriers of interspecific incompatibility between R. ‘XXL’ × R. delavayi could be mainly ascribed to post-fertilization isolation. Consequently, RNA-Seq analysis on ovaries at three developmental stages from two hybridizations indicated that plant hormone signal transduction, flavonoid biosynthesis, MAPK signaling pathway and plant-pathogen interaction pathways might play important roles in regulation of hybrid incompatibility between R. ‘XXL’ × R. delavayi. The results can provide a basis for the study of the hybrid incompatibility mechanism of Rhododendron, and provide useful information for the breeding and conservation of genetic resources of Rhododendron.