Flower Abscission Research Articles

Genotypic variations in postfertility traits and yield components of mung bean (Vigna radiata (L.) R. Wilczek) germplasms in Chitwan, Nepal

Assessment of economic traits of germplasms, which are associated with genetic variation, is vital for mung improvement. Therefore, by wielding the randomized complete block design with 3 replications, a probe analysis using multiple trait stability indexing and analysis of variance with Duncan's test at p ≤ 0.05 is performed to compare the means of yield attributes. Moreover, simultaneous application of GA3 and NAA (50 mg/L each) was carried out at 30 DAS and at mid-flowering. Pondering not only factorial analysis but also correlation and path studies revealed that flower shedding before and 12 h after spraying is nearly detrimental to yield. In addition, yield/plant was positively (p < 0.001, r = 0.67–0.96) correlated with the harvesting index and test weight. 'Pratigya', demonstrating heightened sensitivity to environmental cues—unveils increased sensitivity—while 'VC3960A-88′ flourished with hormone-boosted pod formation. 'VC6368(46-40-3)' packed 11 pods/cluster, and 'CN95' thrived, excelling in abundant grains as well as clusters. Notably, 'VC6370-A′ topped yielder, whereas CN95 augmented an efficient harvest index of 0.48. Moreover, path analysis revealed that all postfertility traits are inherently associated with yield. By employing 17 % selection intensity, the MTSI unequivocally ascertained that not only 'VC6370A' but also 'CN95' are the ideal stable and prime performing genotypes for yield(3.04–2.8 tons/ha) as well as interactive traits, a marker for simultaneous selection, as well as improvement. The MTSI view of strengths and weaknesses harbingers that breeders need to focus on increasing the number of genotypes with the desired phenotypes—lower flower abscission, greater grain dimensions and pod setting, harvesting indices, and yields/ha.

Pattern of flower and fruit abscision and fruit growth of hass avocado under tropical conditions

Research elucidating abscission processes in fruits of Hass avocados has been conducted in production areas in the subtropics, but there are few studies under tropical climate conditions that can serve as a starting point to guide suitable management practices. In a seven-year-old commercial orchard of Hass avocados, grafted onto native rootstocks (Antillean rootstocks), 20 trees were evaluated. A weather station installed on-site monitored the climate of the location. The pattern of fruit growth and development, flower and fruit abscission, and yield variables were characterized. More than 145,000 and 270,000 flowers abscised per tree were recorded, with final fruit sets of 0.1 ± 0.009% and 0.19 ± 0.04% in the first and second crop years, respectively. Fruit growth followed a sigmoid curve with no differences in growing degree-days until the time of harvest. Additionally, the alternate bearing behavior of Hass avocado was confirmed with an average yield of 24.3 ± 4.5 kg/tree and 93.3 ± 9.5 kg/tree for the first and second crop years, respectively, finding an average alternate bearing index of 0.74 ± 0.06.

Navigating the shadows: SlCPK10 mediated flower abscission in tomatoes under low light.

Navigating the shadows: SlCPK10 mediated flower abscission in tomatoes under low light.

JOINTLESS Maintains Inflorescence Meristem Identity in Tomato.

JOINTLESS (J) was isolated in tomato (Solanum lycopersicum) from mutants lacking a flower pedicel abscission zone (AZ) and encodes a MADS-box protein of the SHORT VEGETATIVE PHASE/AGAMOUS-LIKE 24 subfamily. The loss of J function also causes the return to leaf initiation in the inflorescences, indicating a pivotal role in inflorescence meristem identity. Here, we compared jointless (j) mutants in different accessions that exhibit either an indeterminate shoot growth, producing regular sympodial segments, or a determinate shoot growth, due to the reduction of sympodial segments and causal mutation of the SELF-PRUNING (SP) gene. We observed that the inflorescence phenotype of j mutants is stronger in indeterminate (SP) accessions such as Ailsa Craig (AC), than in determinate (sp) ones, such as Heinz (Hz). Moreover, RNA-seq analysis revealed that the return to vegetative fate in j mutants is accompanied by expression of SP, which supports conversion of the inflorescence meristem to sympodial shoot meristem in j inflorescences. Other markers of vegetative meristems such as APETALA2c and branching genes such as BRANCHED 1 (BRC1a/b) were differentially expressed in the inflorescences of j(AC) mutant. We also found in the indeterminate AC accession that J represses homeotic genes of B- and C-classes and that its overexpression causes an oversized leafy calyx phenotype and has a dominant negative effect on AZ formation. A model is therefore proposed where J, by repressing shoot fate and influencing reproductive organ formation, acts as a key determinant of inflorescence meristems.

Light recovery after maize harvesting promotes soybean flowering in a maize-soybean relay strip intercropping system.

Moving from sole cropping to intercropping is a transformative change in agriculture, contributing to yield. Soybeans adapt to light conditions in intercropping by adjusting the onset of reproduction and the inflorescence architecture to optimize reproductive success. Maize-soybean strip intercropping (MS), maize-soybean relay strip intercropping (IS), and sole soybean (SS) systems are typical soybean planting systems with significant differences in light environments during growth periods. To elucidate the effect of changes in the light environment on soybean flowering processes and provide a theoretical basis for selecting suitable varieties in various planting systems to improve yields, field experiments combining planting systems (IS, MS, and SS) and soybean varieties (GQ8, GX7, ND25, and NN996) were conducted in 2021 and 2022. Results showed that growth recovery in the IS resulted in a balance in the expression of TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) in the meristematic tissues of soybeans, which promoted the formation of new branches or flowers. IS prolonged the flowering time (2-7 days) and increased the number of forming flowers compared with SS (93.0 and 169%) and MS (67.3 and 103.3%) at the later soybean flowering stage. The higher carbon and nitrogen content in the middle and bottom canopies of soybean contributed to decreased flower abscission by 26.7 and 30.2%, respectively, compared with SS. Canopy light environment recovery promoted branch and flower formation and transformation of flowers into pods with lower flower-pod abscission, which contributed to elevating soybean yields in late-maturing and multibranching varieties (ND25) in IS.

The MYB transcription factor SmMYB113 directly regulates ethylene-dependent flower abscission in eggplant

Flower abscission is an important developmental process that can significantly reduce the yield of horticultural plants. We previously reported that SmMYB113 is a key transcription factor promoting anthocyanin biosynthesis and improve fruit quality. However, the overexpression of SmMYB113 in eggplant increased flower drop rate and reduced fruit yield. Here, we elucidate the regulatory mechanisms of SmMYB113 on flower abscission in eggplant. RNA-seq analysis indicated that the regulation of flower abscission by SmMYB113 was associated with altered expression of genes related to ethylene biosynthesis and signal transduction, including ethylene biosynthetic genes SmACS1, SmACS8 and SmACO4. Then, the ethylene content in flowers and the function of ethephon (ETH, which promotes fruit ripening) and 1-Methylcyclopropene (1-MCP, which acts as an ethylene perception inhibitor) were analyzed, which revealed that SmMYB113 directly regulates ethylene-dependent flower abscission. Yeast one-hybrid and dual-luciferase assays revealed that SmMYB113 could directly bind to the promoters of SmACS1, SmACS8, and SmACO4 to activate their expression. Through construction of a yeast two-hybrid (Y2H) screening library, the protein SmERF38 was found to interact with SmMYB113, and verified by Y2H, bimolecular fluorescence complementation (BiFC), and luciferase complementation assay. Furthermore, dual-luciferase assays showed that SmERF38 enhanced the role of SmMYB113 on the promoters of SmACS1. Our results provided new insight into the molecular mechanism of flower abscission in eggplant.

SlBEL11 regulates flavonoid biosynthesis, thus fine-tuning auxin efflux to prevent premature fruit drop in tomato.

Auxin regulates flower and fruit abscission, but how developmental signals mediate auxin transport in abscission remains unclear. Here, we reveal the role of the transcription factor BEL1-LIKE HOMEODOMAIN11 (SlBEL11) in regulating auxin transport during abscission in tomato (Solanum lycopersicum). SlBEL11 is highly expressed in the fruit abscission zone, and its expression increases during fruit development. Knockdown of SlBEL11 expression by RNA interference (RNAi) caused premature fruit drop at the breaker (Br) and 3 d post-breaker (Br+3) stages of fruit development. Transcriptome and metabolome analysis of SlBEL11-RNAi lines revealed impaired flavonoid biosynthesis and decreased levels of most flavonoids, especially quercetin, which functions as an auxin transport inhibitor. This suggested that SlBEL11 prevents premature fruit abscission by modulating auxin efflux from fruits, which is crucial for the formation of an auxin response gradient. Indeed, quercetin treatment suppressed premature fruit drop in SlBEL11-RNAi plants. DNA affinity purification sequencing (DAP-seq) analysis indicated that SlBEL11 induced expression of the transcription factor gene SlMYB111 by directly binding to its promoter. Chromatin immunoprecipitation-quantitative polymerase chain reaction and electrophoretic mobility shift assay showed that S. lycopersicum MYELOBLASTOSIS VIRAL ONCOGENE HOMOLOG111 (SlMYB111) induces the expression of the core flavonoid biosynthesis genes SlCHS1, SlCHI, SlF3H, and SlFLS by directly binding to their promoters. Our findings suggest that the SlBEL11-SlMYB111 module modulates flavonoid biosynthesis to fine-tune auxin efflux from fruits and thus maintain an auxin response gradient in the pedicel, thereby preventing premature fruit drop.

Inadequate Pollination Is a Key Factor Determining Low Fruit-to-Flower Ratios in Avocado

Avocado is an evergreen tree that exhibits protogynous dichogamy and displays a massive flower production, characterized by a high abscission of unfertilized flowers and developing fruitlets, ultimately leading to a low final fruit set. A common practice to improve avocado pollination involves introducing honey bee (Apis mellifera L.) hives during the flowering season. To evaluate the extent of inadequate pollination in avocado, the effect of different beehive densities on the percentage of flowers receiving pollen during the female flower stage was examined for seven years in an experimental orchard located in Southern Spain. A total of 17,288 flowers were observed under the microscope for this purpose. Additionally, pollen deposition was evaluated in five “Hass” avocado commercial orchards under different management strategies situated in the Malaga province (3960 flowers). The results obtained reveal that the percentage of flowers with pollen at the end of the female stage ranged from 2.85 (0.13% fruits retained at the end of June) in orchards without honey bee hives to 4.34 (0.11% fruits retained) in orchards in which 10 beehives per ha were placed. This percentage increased significantly to 13.79 after introducing 24 honey beehives per ha (0.21% fruits retained). Furthermore, the percentage of pollinated flowers in the commercial orchards remained below 15% even in those orchards in which pollen donors and honey bee hives were present. Thus, insufficient pollination could be considered as a primary limiting factor in avocado production under Mediterranean climates. Enhancing pollinator diversity and increasing their numbers could be a viable strategy to improve the percentage of avocado flowers receiving pollen during the female stage.

1-MCP microbubbles reduce chlorophyll degradation and maintain the quality of Dendrobium cv. Burana Jade orchid flowers

The effect of 1-methylcycloprepene microbubbles (1-MCP-MBs) on reducing chlorophyll degradation, prolonging vase life and maintaining the quality of Dendrobium cv. ‘Burana Jade’ inflorescences was investigated. The inflorescences were immersed in 50 ppm 1-MCP-MBs or tap water (control) for 5 min and then held at 23 ± 1 °C for 12 days. The 1-MCP-MB-treated inflorescences exhibited increased water uptake and significantly higher fresh weight than the controls. The results also showed that 1-MCP-MBs remarkably delayed bud opening and flower abscission, accompanied by suppression of ethylene production and a lower respiration rate than that of controls. Additionally, the treatment maintained the green color (hue angle value was comparable to initial storage day) of the inflorescences by delaying chlorophyll degradation related to inhibition of chlorophyllase and Mg-dechelatase activities. 1-MCP-MBs prolonged the vase life of Dendrobium cv. ‘Burana Jade’ up to 12 days, which was 2-fold longer than that of the control (approximately 5 days only). The results suggest that 1-MCP-MBs have the potential to be another alternative to conventional methods (fumigation) in prolonging vase life and maintaining the quality of Dendrobium orchids with the advantage of a shorter treatment time.

Transcriptome and Metabolome Jointly Revealed the Regulation and Pathway of Flower and Pod Abscission Caused by Shading in Soybean (Glycine max L.)

Flowers and pod abscission significantly reduces soybean yield. This study aims to identify the main signaling pathways and key candidate genes in soybean leaves that affect flower and pod abscission under shade conditions. This information will be useful for the localization and cloning of genes related to abscission. Two soybean cultivars with different abscission rates (Liaodou 32 and Shennongdou 28) were used in this experiment. The soybean leaves were subjected to 50% shading treatment and the transcriptome and metabolome was sequenced during the light-sensitive period. The effects of weak light at different growth stages on the metabolic pathways of soybean leaves and organ abscission were investigated by analyzing plant phenotype and physiological changes. The results showed that both two cultivars triggered the same molecular mechanism and similar metabolite accumulation mode by shading, but the regulations of the two cultivars were different. The key candidate genes identified for soybean flower and pod abscission caused by shading were DIV, MYB06, MYB44, MY1R1, MYBS3, WRKY6, WRK53, WRK70, WRK40, DOF14, CDF3, CDF2, GATA5, DREB3 and ERF3; the differentially expressed genes that caused the variation between the cultivars were SRM1, MYB16, WRK24, COL16, MYB61 and TRB1. The main metabolic pathways involved in soybean flower and pod abscission caused by shading were secondary metabolite biosynthesis pathway, metabolic pathway, cofactor biosynthesis pathway, phenylpropanoid biosynthesis pathway, flavonoid biosynthesis pathway, fatty acid biosynthesis pathway and amino acid biosynthesis pathway; the DEMs that caused the differences among the cultivars were carbon metabolism, glutathione metabolism, biotin metabolism, nucleotide metabolism, purine metabolism, plant hormone signaling, flavone and flavonol biosynthesis, lysine degradation, arginine and proline metabolism, amino sugars and nucleotide sugars metabolism, etc. In conclusion, shading treatment in the light-sensitive period of soybean changed the physiological response and gene expression level of leaves, inhibited carbohydrate metabolism and transport and biosynthesis of secondary metabolites, and thereby leading to increased competition and hormonal disruption, which promoted the abscission of soybean flowers/pods and reduced grain yield.

Abscisic acid- and ethylene-induced abscission of yellow lupine flowers is mediated by jasmonates

The appropriate timing of organ abscission determines plant growth, development, reproductive success, and yield in relation to crop species. Among these, yellow lupine is an example of a crop species that loses many fully developed flowers, which limits the formation of pods with high-protein seeds and affects its economic value. Lupine flower abscission, similarly to the separation of other organs, depends on a complex regulatory network functioning in the cells of the abscission zone (AZ). In the present study, genetic, biochemical, and cellular methods were used to highlight the complexity of the interactions among strong hormonal stimulators of abscission, including abscisic acid (ABA), ethylene, and jasmonates (JAs) precisely in the AZ cells, with all results supporting that the JA-related pathway has an important role in the phytohormonal cross-talk leading to flower abscission in yellow lupine. Based on obtained results, we conclude that ABA and ET have positive influence on JAs biosynthesis and signaling pathway in time-dependent manner. Both phytohormones changes lipoxygenase (LOX) gene expression, affects LOX protein abundance, and JA accumulation in AZ cells. We have also shown that the signaling pathway of JA is highly sensitive to ABA and ET, given the accumulation of COI1 receptor and MYC2 transcription factor in response to these phytohormones. The results presented provide novel information about the JAs-dependent separation of organs and provide insight and details about the phytohormone-related mechanisms of lupine flower abscission.

Studying the Effect of Dense Planting on the Mechanism of Flower Abscission in Soybean through Combined Transcriptome-Metabolome Analysis

A high pod abscission rate in soybean plants results in a significant decrease in the yield per plant. Under dense planting conditions, dense tolerant soybean cultivars had a relatively low rate of pod abscission, thereby facilitating higher yield. In this experiment, two planting densities were used to analyze the differentially expressed genes and metabolites between the abscised and non-abscised flowers of two soybean cultivars on the basis of transcriptomic and metabolomic techniques. The flower abscission rate of LD32 was significantly lower than that of SND28. Both cultivars were enriched in the photosynthesis, sugar, and starch metabolism; MAPK signaling; and phenylalanine metabolism pathways at different planting densities. However, under dense planting, the trend of differential gene changes in the density-tolerant CV LD32 was opposite to that of the conventional CV SND28. The results of the joint analysis indicated that the co-regulation of cytokinin dehydrogenase 6 (CKX6) and cis-zeatin riboside monophosphate (CZRM) in the zeatin biosynthesis pathway of LD32 under dense planting conditions was the main factor for the relatively low rate of pod abscission under dense planting conditions.

Effect of shading nets on environmental conditions and fruit abscission in quince (Cydonia oblonga L.)

The quince tree has been cultivated since ancient times in the province of Isfahan in Iran. Flower and fruit drop is one of the most important problems in the cultivation of quince in Iran. In this study, the role of shading nets as a protective factor in quince orchard was investigated to adjust climatic factors and reduce flower and fruit drop. A 20-year-old quince orchard was equipped with shading net system, and another part was compared as a control plot without shading net system in 2021 and 2022. The color of shading net and the percentage of shading were 30% green, 50% green and 50% white. According to the results, flowers opened five days later under the shading nets than outdoors. Percent fruit set, leaf length and width, number of fruits, and yield were significantly higher under the shade net than outdoors. Green 30% had the highest chlorophyll fluorescence index. The fruit set percentage and yield inside the shading nets were more than twice that outside. Total soluble solids and the abscission percentage in the control plot were more than the plot under nets. According to meteorological data, the temperature inside the shade netting was only 0.33–0.67 °Celsius lower than outside, but the radiation intensity outside the nets (30,362.44 lx) was more than two and a half times the amount of radiation under the shading nets (11,876.02 Lux). According to the obtained results, it is recommended to use the shade nets in quince orchards, where happened abscission of flowers and fruits leads to a decrease in yield. The green shade net color of 30 and 50% is recommended for orchards due to the higher chlorophyll fluorescence index, fruit set percentage, number of fruits, and yield.

Review on organic foliar application – A nutritional boost to pulse productivity

India is the world’s top producer and consumer of pulses. The area under pulse crop is increasing continuously but productivity is decreasing over years. Reduced production is caused by a lack of care, an uneven fertilizer application and the emergence of physiological problems, particularly inefficient assimilate partitioning, poor pod development, excessive flower abscission due to the nutrient stress. Foliar nutrition is an efficient way of supplementing the available plant nutrients when they lack in the soil. Organic fertilizers are mainly used to stimulate growth by providing proper nutrients at the right dose and proper stage of the crop growth. Liquid organic manures are the source of macronutrients, necessary micronutrients, required amino acids, growth promoting factors and certain beneficial microorganisms. There is an opportunity for increasing pulse yield and quality by raising soil fertility and productivity by increased ability of conservation of soil organic carbon and soil moisture.

Genetic analysis of heat tolerance in hot pepper: insights from comprehensive phenotyping and QTL mapping.

High temperatures present a formidable challenge to the cultivation of hot pepper, profoundly impacting not only vegetative growth but also leading to flower and fruit abscission, thereby causing a significant reduction in yield. To unravel the intricate genetic mechanisms governing heat tolerance in hot pepper, an F2 population was developed through the crossing of two distinct genotypes exhibiting contrasting heat tolerance characteristics: DLS-161-1 (heat tolerant) and DChBL-240 (heat susceptible). The F2 population, along with the parental lines, was subjected to comprehensive phenotyping encompassing diverse morphological, physiological, and biochemical heat-related traits under high temperature conditions (with maximum temperature ranging from 31 to 46.5°C and minimum temperature from 15.4 to 30.5°C). Leveraging the Illumina Nova Seq-6000 platform, Double digest restriction-site associated DNA sequencing (ddRAD-seq) was employed to generate 67.215 Gb data, with subsequent alignment of 218.93 million processed reads against the reference genome of Capsicum annuum. Subsequent variant calling and ordering resulted in 5806 polymorphic SNP markers grouped into 12 LGs. Further QTL analysis identified 64 QTLs with LOD values ranging from 2.517 to 11.170 and explained phenotypic variance ranging from 4.05 to 19.39%. Among them, 21 QTLs, explaining more than 10% phenotypic variance, were identified as major QTLs controlling 9 morphological, 3 physiological, and 2 biochemical traits. Interestingly, several QTLs governing distinct parameters were found to be colocalized, suggesting either a profound correlation between the QTLs regulating these traits or their significant genomic proximity. In addition to the QTLs, we also identified 368380 SSR loci within the identified QTL regions, dinucleotides being the most abundant type (211,381). These findings provide valuable insights into the genetics of heat tolerance in hot peppers. The identified QTLs and SSR markers offer opportunities to develop heat-tolerant varieties, ensuring better crop performance under high-temperature conditions.

Differences in reproductive function between terminal and lateral flowers in the capitulum of Albizia julibrissin (Fabaceae) based on female fertility, ovule number, and pistil and polyad size

AbstractThe division of labor between florets responsible for reproduction and special functions occurs widely in condensed inflorescences. The capitulum of Albizia julibrissin consists of approximately 10–20 lateral flowers and usually one nectar‐secreting terminal flower; the two flower types are morphologically distinct, but the differences in reproductive function have not been revealed. To determine the differences in reproductive function between terminal and lateral flowers, we compared the ratio of terminal and lateral flowers at the flowering and young pod stages. Additionally, ovule number, stigma size, polyad size, and the ratio of flower abscission were compared between the two flower types. Significant differences were detected only in female fertility between the two flower types. At the flowering stage, 6.8% of flowers were terminal flowers, whereas at the young pod stage, all young fruits were obtained from lateral flowers. At the final stage of blooming, based on the generalized linear model analysis, the ratio of surviving terminal flowers was lower than that of the lateral flowers in a capitulum. These results suggest that the terminal flowers of A. julibrissin had female sterility or, at least, female fertility was lower than in lateral flowers. Therefore, it is necessary to reexamine some previous studies that assumed A. julibrissin to be andromonoecious with hermaphroditic terminal flowers and male lateral flowers. Further comparisons of the quality of ovules and polyads are necessary to clarify whether there is a division of labor between the terminal and lateral flowers in A. julibrissin.

Involvement of IDA-HAE Module in Natural Development of Tomato Flower Abscission.

The unwanted detachment of organs such as flowers, leaves, and fruits from the main body of a plant (abscission) has significant effects on agricultural practice. Both timely and precise regulation of organ abscission from a plant is crucial as it influences the agricultural yield. The tomato (Solanum lycopersicum) has become a model system for research on organ abscission. Here, we characterized four tomato natural abscission variants named jointless (j), functionally impaired jointless (fij), functionally impaired jointless like (fij like), and normal joint (NJ), based on their cellular features within the flower abscission zones (AZ). Using eight INFLORESCENCE DEFICIENT IN ABSCISSION (SlIDA) genes and eight HAESA genes (SlHAE) identified in the genome sequence of tomato, we analyzed the pattern of gene expression during flower abscission. The AZ-specific expression for three tomato abscission polygalacturonases (SlTAPGs) in the development of flower AZ, and the progression of abscission validated our natural abscission system. Compared to that of j, fij, and fij like variants, the AZ-specific expression for SlIDA, SlIDL2, SlIDL3, SlIDL4, and SlIDL5 in the NJ largely corelated and increased with the process of abscission. Of eight SlHAE genes examined, the expression for SlHSL6 and SlHSL7 were found to be AZ-specific and increased as abscission progressed in the NJ variant. Unlike the result of gene expression obtained from natural abscission system, an in silico analysis of transcriptional binding sites uncovered that SlIDA genes (SlIDA, SlIDL6, and SlIDL7) are predominantly under the control of environmental stress, while most of the SlHSL genes are affiliated with the broader context in developmental processes and stress responses. Our result presents the potential bimodal transcriptional regulation of the tomato IDA-HAE module associated with flower abscission in tomatoes.

Comprehensive analyses of the proteome and ubiquitome revealed mechanism of high temperature accelerating petal abscission in tree peony

Tree peony (Paeonia suffruticosa Andrews) is a well-known ornamental plant with high economic value, but the short fluorescence is a key obstacle to its ornamental value and industry development. High temperature accelerates flower senescence and abscission, but the associated mechanisms are poorly understood. In this study, the tandem mass tag (TMT) proteome and label-free quantitative ubiquitome from tree peony cut flowers treated with 20 °C for 0 h (RT0), 20 °C or 28 °C for 60 h (RT60 or HT60) were examined based on morphological observation, respectively. Totally, 6970 proteins and 1545 lysine ubiquitinated (Kub) sites in 844 proteins were identified. Hydrophilic residues (such as glutamate and aspartate) neighboring the Kub sites were in preference, and 36.01% of the Kub sites were located on the protein surface. The differentially expressed proteins (DEPs) and Kub-DEPs in HT60 vs RT60 were mainly enriched in ribosomal protein, protein biosynthesis, secondary metabolites biosynthesis, flavonoid metabolism, carbohydrate catabolism, and auxin biosynthesis and signaling revealed by GO and KEGG analysis, accompanying the increase of endogenous abscisic acid (ABA) accumulation and decrease of endogenous indoleacetic acid (IAA) level. Additionally, the expression patterns of six enzymes (SAMS, ACO, YUC, CHS, ANS and PFK) putatively with Kub modifications were analyzed by proteome and real-time quantitative RT-PCR. The cell-free degradation assays showed PsSAMS and PsACO proteins could be degraded via the 26 S proteasome system in tree peony flowers. Finally, a working model was proposed for the acceleration of flower senescence and abscission by high temperature. In summary, all results contributed to understanding the mechanism of flower senescence induced by high temperature and prolonging fluorescence in tree peony.

Transcriptome and targeted hormone metabolome reveal the molecular mechanisms of flower abscission in camellia.

Camellia is among the most ornamentally valuable flowers and plants worldwide. Flower abscission typically causes significant financial losses by the horticultural landscape. Previous research has revealed that phytohormones, transcription factors, and other genes involved in floral development regulate the maintenance and mortality of flowers. In this study, for the first time, the transcriptomes and targeted hormone metabolomics of three developmental stages of the receptacles of two distinct camellia strains (CF: abscission strain, CHF: nonabscission strain) were analyzed to determine their roles in regulating blossom abscission in camellia. ABA content was shown to be considerably upregulated throughout all phases of CF development, as were the genes implicated in the ABA production pathway and their downstream counterparts. Highly expressed genes in CF were involved in galactose metabolism, phenylpropanoid biosynthesis, amino and nucleotide sugar metabolism, pentose and glucuronate interconversions, and MAPK. Among others, highly expressed genes in CHF are associated with fructose and mannose metabolism, alpha-linolenic acid metabolism, biosynthesis of secondary metabolites, starch and sucrose metabolism, and cutin, suberin, and wax biosynthesis. A vast variety of stress response-related pathways and redox-related activities were also shown to be active in CHF. In contrast, CF dramatically activated pathways associated with lignin production, keratinogenesis, cell wall biogenesis, and ABA response. A comparative transcriptomic study of the CF and CHF pathways revealed that the downstream response pathways of hormones, including CTK, BR, IAA, ethylene, and GA, were very active in CF, indicating a significant amount of signal transduction and transcriptional regulation by CF. In addition, members of the transcription factor family, such as MYB, bHLH, MADS, and WD40, may regulate flower abscission. A comparative transcriptome analysis of two distinct strains of camellia receptacles elucidates the molecular processes and regulatory characteristics of flower abscission and provides direction for the targeted improvement and breeding of camellia.

Flower Thinning Improves Fruit Quality and Oil Composition in Camellia oleifera Abel

Camellia oleifera is a woody oil tree with overlapping flower bud differentiation and fruit maturation. Therefore, mechanical harvesting of fruits leads to flower abscission. The present study investigated the effects of flower number per tree on fruit growth, yield, nutrient accumulation, and oil fatty acid composition in C. oleifera. Here, we set different flower numbers per tree by thinning flowers. Heavy flower thinning (T2 and T3) significantly reduced fruit yield and the proportion of palmitic, palmitoleic, linoleic, and linolenic acid in fatty acids compared with other treatments. However, heavy thinning favored an increase in fruit size and weight, seed and dry kernel rate of fresh fruit, soluble protein and oil accumulation in seeds, and the proportion of oleic acid and stearic acid in fatty acids, and it had no significant effect on oil yield per tree compared with light thinning (T1) and control (T0). T2 and T3 decreased soluble sugar content in the kernels at the later stage of fruit development (260–320 days after full bloom (DAFB)) in contrast to the rapid fruit growth period (200–230 DAFB). As the crop load decreased, fruit ABA content increased continuously during 260–320 DAFB, while fruit IAA content increased during 260–300 DAFB and then decreased during 310–320 DAFB. These data suggest that the abscission of a few flowers during mechanical harvesting will not affect fruit production efficiency in C. oleifera.