Search Results

You are looking at 1 - 10 of 15 items for

  • Author or Editor: Yan Fu x
Clear All Modify Search
Authors: and

Loquat [Eriobotrya japonica (E. japonica)], a small genus of the subtribe Malinae that consists of ≈30 species, is an evergreen rosaceous fruit tree that is native to southeastern China, and some wild species that possess novel, favorable traits have excellent breeding potential. For example, Eriobotrya bengalensis blooms in late spring and ripens in early autumn in Guizhou Province, China, which prevents cold injury in winter by breeding spring-flowering cultivars using the special characters. Therefore, in the present study, the pollination treatments of cut-style pollination were evaluated that may promote successful distant hybridization in Eriobotrya japonica ‘Dawuxing’ × Eriobotrya deflexa and E. japonica ‘Dawuxing’ × E. bengalensis. The results indicated that the impairment of the pollen tube growth in the upper third of the style after pollen germination is an important factor leading to the failure of distant hybridization between the species tested in E. japonica, and that cut-style pollination can effectively overcome prefertilization barriers of the distant hybridization combination. Furthermore, the results of allele-specific polymerase chain reaction (AS-PCR) showed that S-genotypes, in accordance with the S-RNase heredity to separate the rule completely in offspring, should be both parents' S-RNase, and that the random 50 seedlings of Eb-2 and Ed-2 are true hybrids.

Open Access
Authors: , , and

Intron length polymorphisms were used to investigate relationships among eight Rhododendron L. species (R. catawbiense Michaux., R. minus Michaux., R. ponticum L., R. keiskei Miquel., R. arboreum Sm., R. dichroanthum Diels., ssp. scyphocalyx Cowan., R. maximum L. and R. dauricum L.) and two hybrid cultivars [i.e., R. `PJM' (R. minus var. minus × R. dauricum) and R. `Chionoides' (R. ponticum × unknown)]. A total of 27 of these markers were used to estimate phylogenetic relationships among the species and draw inferences about the parentage of the cultivars, which is partially unknown. In general the expressed sequence tag-polymerase chain reaction (EST-PCR) marker-based phylogenetic map of the eight species is congruent with the currently accepted morphology-based classification of these species at the subgenus as well as the section level. However, the constructed phylogenetic tree revealed that, at the subsection level, two species, R. arboreum (subsection Arborea Sleum.) and R. dichroanthum (subsection Neriiflora Sleum.), are grouped under the same “clade” (80% bootstrap score), suggesting that these species are more closely related than indicated in the current classification system that places them in separate subsections/clades. Moreover, our phylogenetic analysis of the three species belonging to section Ponticum G. Don. demonstrated a closer phylogenetic relationship between R. ponticum and R. maximum (bootstrap score of 74%) than between these species and R. catawbiense; such observation is consistent with a recent phylogenetic analysis of section Ponticum by Milne (2004) using the sequences of a chloroplast gene. Parentage analysis for the two cultivars confirmed the interspecific lineage of R. `PJM' and provided genetic support for the speculated R. ponticum and R. maximum parentage of R. `Chionoides'. Our results indicate that, in addition to their use in mapping studies, intron-flanking EST-based PCR markers are valuable tools for conducting phylogenetic and parentage analyses and/or gene flow studies.

Free access

MicroRNAs (miRNAs) related to phytohormone signal transduction and self-incompatibility may play an important role in the xenia effect. However, associated research in this area is still lacking in rabbiteye blueberry (Vaccinium ashei). In this study, we identified miRNAs, predicted their target genes, performed functional enrichment analysis of the target genes, and screened for miRNAs related to phytohormone signaling and self-incompatibility. A total of 491 miRNAs were identified, of which 27 and 67 known miRNAs as well as 274 and 416 new miRNAs were found in the rabbiteye blueberry cultivars Brightwell and Premier, respectively. Compared with ‘Premier’, 31 miRNAs were upregulated and 62 miRNAs were downregulated in ‘Brightwell’. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis indicated that the 4985 target genes predicted were involved in biosynthesis of amino acids, plant–pathogen interaction, and spliceosome pathways. A total of 10, one, one, five, two, five, and two candidate miRNAs related to auxin, cytokinin, gibberellin, abscisic acid, ethylene, brassinosteroid, and salicylic acid signaling, respectively, in rabbiteye blueberry pollen were identified. Further analysis indicated that novel_miR_49 was a candidate miRNA related to self-incompatibility, and their target gene was maker-VaccDscaff21-snap-gene-21.37. In addition, the KEGG enrichment analysis of the target genes of novel_miR_49 showed that they were involved in the ribosome, aminoacyl-tRNA biosynthesis, and glycosylphosphatidylinositol-anchor biosynthesis pathways. The results revealed that the microRNAs of rabbiteye blueberry pollen regulated to phytohormone signal transduction and self-incompatibility signal transduction based on related to auxin, cytokinin, gibberellin, abscisic acid, ethylene, brassinosteroid, and salicylic acid signaling. Results suggest that more research of the effects of miRNAs on regulation of hormone signal transduction and self-incompatibility is necessary for elucidating the molecular mechanism of the xenia effect.

Open Access

Application of sugar alcohol zinc (SA-Zn) spray to apple trees at certain developmental stages can improve fruit quality. Increasing the Zn concentration of fruit can improve nutritional content and promote human health. We conducted foliar application of SA-Zn to 13-year-old ‘Fuji’ apple trees at different developmental stages. The effects of SA-Zn application on Zn concentration, reducing sugar content, and carbohydrate metabolism-related enzyme activity in fruit were investigated. The foliar treatment increased Zn and reducing sugar concentrations significantly in mature fruit. Sorbitol dehydrogenase activity was higher in the fruit of trees treated before budbreak and 3 weeks after flowering compared with the control at the early fruit stage and was higher during fruit expansion in plants treated after termination of spring shoot growth. Mature fruit of trees treated during the fruit expansion stage showed higher sorbitol dehydrogenase activity than the control. Foliar SA-Zn treatment did not have a significant effect on sorbitol oxidase activity in apple fruit. Treatment before budbreak and at 3 weeks after flowering led to a significant increase in the activity of sucrose synthase and acid invertase at the early fruit stage. Treatment during the fruit expansion stage significantly increased the activity of acid invertase at maturity but had no effect on the activity of neutral invertase. Our results indicate that foliar SA-Zn application resulted in biofortification of Zn in apples, which led to higher activity of carbohydrate metabolism-related enzymes and accumulation of sugars.

Free access

After nearly a decade of development, the scale of blueberry (Vaccinium sp.) cultivation has increased, particularly in south China; however, this region is becoming increasingly challenged by temperature changes during the flowering phenophase. Understanding the effects of temperature on pollen germination and pollen tube growth in blueberry is thus important. Using the rabbiteye blueberry (V. ashei) ‘Brightwell’, different temperature treatments were carried out during open pollination and cross-pollination with the pollen from rabbiteye blueberry ‘Gardenblue’ in field, greenhouse, and controlled temperature experiments over two consecutive years. The differences in pollen germination, pollen tube dynamics, and ovule viability following different treatments were analyzed, and the critical temperatures were calculated using quadratic and modified bilinear equations to quantify the developmental responses to temperature. The results showed that the fruit set of the artificially pollinated plants inside the greenhouse was significantly higher than that outside the greenhouse. Furthermore, pollen germination and pollen tube growth gradually accelerated under the appropriate high-temperature range, resulting in reduced pollen tube travel time to the ovule. However, the percentage of the style traversed by the pollen tube did not increase at temperatures greater than 30 °C, and a high-temperature range could accelerate ovule degeneration. Therefore, impairment of pollen tube growth in the upper half of the style following pollen germination and ovule degeneration constituted important factors leading to reduced fruit setting under short periods of high temperature during the flowering phenophase in rabbiteye blueberry. This work advances our understanding of the effect of temperature on pollen germination, pollen tube growth, ovule longevity, and fruit setting in rabbiteye blueberry, and provides a foundation for continued cultivation and breeding enhancement. The findings propose that the tolerance of rabbiteye blueberry to a certain high-temperature range in the flowering phenophase should inform breeding strategies for temperature resistance and that temperature range is also an important indicator of suitable environments for cultivation to mitigate potential temperature stress.

Free access

Plants growing in salt-affected soils may have retarded growth and inhibited or altered metabolic processes. This study aims at investigating the impact of subsurface soil salinity on root growth and metabolic processes in perennial ryegrass (Lolium perenne). The seeds of perennial ryegrass (cv. Quick Start II) were planted in polyvinyl chloride (PVC) tubes (10 cm diameter × 42 cm long) for 2 months. The experiment consisted of three treatments: 1) control, 40 cm filled with sand–peat mixture (7 sand : 3 peat wt/wt); 2) T20, a 20-cm-deep layer of saline soil covered with a 20-cm-deep layer of sand–peat mixture; and 3) T30, a 30-cm-deep layer of saline soil covered with a 10-cm-deep layer of sand–peat mixture. Our study showed that soil salinity at the subsurface inhibited the growth of perennial ryegrass roots. Compared with the control, the root activity in saline soil layer decreased, whereas it remained high in the mixture-soil zone. The content of amino acids in the roots obtained from the surface soil (0–10 cm) in T30 was greater than that in both the T20 and the control regimes. The content of soluble sugars in the roots went up with the decrease of the depth of sand–peat mixture. The increased root activity and free amino acids content in the roots sampled from the upper soil layers coupled with the increased soluble sugars in the roots subjected to soil salinity stress in the bottom soil layer represents some adaptive responses and regulative mechanisms in perennial ryegrass.

Free access

The xenia effect refers to the phenomenon whereby the pollen genotype directly affects seed and fruit development during the period from fertilization to seed germination, which leads to different characteristics in phenotypic traits. The xenia effect can create differences in the endosperm and embryo formed after double fertilization and can also alter various fruit parameters, such as the fruit-ripening period; the fruit shape, size, and color; the flavor quality, such as sugars and acids; as well as the nutrient quality, such as anthocyanins. The xenia effect manifests in various ways, playing an important role in increasing the yield of fruit trees, improving fruit appearance and internal quality, as well as in directional breeding. Compared with other pomology research areas, our understanding of the xenia effect is still in its infancy. Currently, xenia is classified into two types: xenia and metaxenia. In the former, the direct effects of the pollen genotype are exhibited in the syngamous parts of the ovules; that is, the embryo and endosperm only. In the latter, the effects of the pollen genotype are demonstrated in structures other than the embryo and endosperm; that is, in tissues derived wholly from the mother plant material, in seed parts such as the nucellus and testa, as well as in the carpels and accessory tissues. However, the current classification has various shortcomings. In the present study, we propose a novel classification based on whether the appearance of xenia results from the tissue formed by double fertilization. Three xenia types are proposed: double-fertilization xenia, non–double-fertilization xenia, and combined xenia. The new classification has great theoretical and practical significance for future studies on the xenia effect and its mechanisms and also provides a more effective, broader application of xenia in improving the yield and quality of fruit trees.

Open Access

Berry fruits produced by Vaccinium (Ericaceae) plants are small but have a signature flavor and have become increasingly popular in the 21st century. However, self-incompatibility (SI) results in a relatively low fruit-set ratio and reduced fruit quality in Vaccinium. In this study, using Vaccinium ashei (V. ashei) styles after cross-pollination (CP) and self-pollination (SP) as material, transcriptomics and gene expression analyses were performed using high-throughput RNA sequencing and quantitative real-time polymerase chain reaction (qRT-PCR). Subsequently, evolutionary analysis and conserved sequences analysis of candidate genes were conducted. Among the 135,324 unigenes, 30,863 were shown to be differentially expressed, and eight randomly selected differentially expressed genes were expressed in the styles at 96 hours after SP and CP. The transcriptomics and qRT-PCR results were significantly correlated, which confirmed the reliability of the differentially expressed genes obtained in our study. Compared with SP96, six differentially expressed ribonuclease T2 family genes were obtained in CP96, which were considered candidates for S-RNase. Additionally, the spatiotemporal and organizational expression trends of six candidates for S-RNase were confirmed by qRT-PCR, and the evolutionary and conservative sequence analysis indicated six candidate S-RNases with the typical S-RNase structure. The spatiotemporal and organizational expression results and evolutionary and conservative sequence analyses of the six candidate S-RNases suggest that SI in V. ashei is likely an S-RNase-mediated gametophytic one. This finding suggests the involvement of novel, previously undiscovered components involved in the V. ashei SI system. These findings help elucidate the molecular mechanisms of SI in rabbiteye blueberry and may also benefit breeding, production, and genomics research in V. ashei and other Vaccinium species.

Open Access

This research was initiated to determine the response of apple (Malus ×domestica) fruit quality to sprays of zinc sulfate (ZnSO4) and sugar alcohol zinc. Two apple cultivars Fuji and Gala were evaluated, the leaf zinc (Zn) concentration of which were about 14.3 mg·kg−1 dry weight without Zn deficiency symptoms. The trees were sprayed with ZnSO4 and sugar alcohol zinc separately during four different developmental stages: 2 weeks before budbreak (P1), 3 weeks after bloom (P2), the termination of spring shoot growth (P3), and 4 weeks before harvest (P4). The fruit was harvested at maturity and analyzed for fruit quality and fruit Zn concentration. Zinc sprays during the four different developmental stages increased Zn concentration of peeled and washed fruit at harvest, without phytotoxicity. The treatments at stages P2 and P4 increased average fruit weight of ‘Gala’ and ‘Fuji’, respectively. The treatments at stages P1 and P4 increased the fruit firmness of ‘Gala’, while the treatments at stages P1 and P2 increased the fruit firmness of ‘Fuji’. The treatments at stages P1, P2, and P4 increased the soluble sugar and vitamin C of ‘Gala’ fruit, while the treatments at all the stages increased the soluble sugar and vitamin C of ‘Fuji’. And the effects of sugar alcohol zinc were equal and more pronounced than those of ZnSO4. Thus, Zn sprays at critical periods can improve fruit quality of apple trees, which show no Zn deficiency symptoms with leaf Zn concentration less than 15 mg·kg−1 dry weight.

Full access

The characteristics of litchi pollen have drawn increasing attention in recent years. Previous studies indicated that there are significant differences in the quantity and viability of litchi pollen grains among different varieties and flowering stages. Moreover, the same variety may show a different quantity of pollen grains and viability in different years. There is still a lack of systematic studies on the change of pollen germination rate and pollen amount in different varieties and at different flowering stages. In this study, the changes in the germination rate of pollen at different development stages were studied. It was primarily revealed that the pollen germination rate already approached its peak upon the filament extends fully, but the anther does not dehisce the developmental stage. In 2009 and 2010, the viability and number of pollen grains per anther were investigated in 65 litchi cultivars, and a difference was observed among cultivars. The pollen germination rate ranged between 20.14% (‘Wuchali’) and 54.69% (‘Donlongmili’). The number of pollen grains per anther ranged between 1555 (‘Zhongshanzhuangyuanhong’) and 7455 (‘Houye’). Sixty-five litchi cultivars were classified into six clusters based on the pollen quantity and germination rate. Most litchi cultivars can produce large amounts of viable and compatible pollen grains during the flowering period. Thus, our results indicate that the pollen amount and germination rate might not be the only factors restricting the successful pollination of litchi.

Free access