Cherry Fruit Development Research Articles

Genome-Wide Exploration of the Ethylene-Responsive Element-Binding Factor Gene Family in Sweet Cherry (Prunus avium L.): Preliminarily Unveiling Insights into Normal Development and Fruit Cracking

The ERF subfamily, a significant part of the APETALA2/ethylene-responsive element-binding factor (AP2/ERF) transcription family, plays a crucial role in plant growth, development, and stress responses. Despite its importance, research on this gene family in sweet cherry (Prunus avium L.) is limited. This study identified and analyzed the sweet cherry ERF subfamily in terms of classification, physicochemical properties, structural characteristics, chromosome distribution, gene replication and collinearity, Cis-acting elements, and potential protein interactions. Preliminary investigations of transcription during fruit cracking and normal development were also conducted. Fifty ERFs (PatiERF1~50) were identified, distributed unevenly across eight chromosomes and classified into ten groups with nineteen conserved motifs. Collinearity analysis with other plant species revealed homology, with the highest number of ERF orthologous genes found in apple (Malus domestica L.). Cis-acting elements, particularly abscisic acid response factor, were abundant in PatiERF promoters. Weighted gene co-expression network analysis (WGCNA) and quantitative real-time PCR (RT-qPCR) analysis indicated the involvement of PatiERFs in sweet cherry fruit development and cracking, and nine and four significant candidates related to these processes were speculated, respectively. Furthermore, four other classes of transcription factors (TFs), namely MYB, GRAS, BHLH, and BZIP, as well as 23 structure genes, were predicted to have co-expression and interaction relationships with PatiERFs during fruit development. This suggests their potential synergistic regulation with ERFs in the cherry fruit development process. Our study represents the first comprehensive genome-wide analysis of the ERF subfamily in sweet cherry, laying a crucial foundation for a deeper understanding of the molecular mechanisms correlated with fruit growth, development, and cracking mediated by ERF genes.

Molecular characterization and evolutionary relationships of DOFs in four cherry species and functional analysis in sweet cherry

The DOF (DNA binding with one finger) has multiple functions in plants. However, it has received little attention in the research field of cherries. In this study, the evolutionary relationship and molecular characterization of DOF in four cherry species were analyzed, revealing its expression pattern in sweet cherry. There are 23 members in Prunus avium cv. ‘Tieton’, 88 in Prunus cerasus, 53 in Cerasus × yedoensis, and 27 in Cerasus serrulata. Most of these genes are intron-less or non-intron, with a conserved C2-C2 domain. Due to heterozygosity and chromosomal ploidy, whole-genome duplication (WGD) events occur to varying degrees, and DOF genes are contracted during evolution. Furthermore, these genes are affected by purifying selection pressure. Under low-temperature treatment, the expression of PavDOF2 and PavDOF18 were significantly up-regulated, while that of PavDOF16 is significantly down-regulated. The expression of PavDOF9, PavDOF12, PavDOF14, PavDOF16, PavDOF17, PavDOF18, and PavDOF19 exhibits an increasing trend during flower development and varies during sweet cherry fruit development. PavDOF1, PavDOF8, PavDOF9, and PavDOF15 are localized in the nucleus but is not transcriptionally active. The findings systemically demonstrate the molecular characteristics of DOF in different cherry varieties, providing a basis for further research on the functions of these genes.

Organic acid metabolism in Chinese dwarf cherry [Cerasus humilis (Bge.) Sok.] is controlled by a complex gene regulatory network.

The acidity of Chinese dwarf cherry [Cerasus humilis (Bge.) Sok.] fruits is a key factor affecting the sensory quality of fruits, and it undergoes great changes during development. The molecular mechanisms of these changes are still unclear. In this study, fruits of high-acid ‘Nongda4’ and low-acid ‘DS-1’ varieties of Chinese dwarf cherry were used to determine the acid content at different developmental stages. We used transcriptome profiles to identify key genes related to organic acid metabolism and construct their co-expression networks, and we studied the expression patterns of key genes in 36 Chinese dwarf cherry accessions. The titratable acid content of both ‘DS-1’ and ‘Nongda4’ fruits first increased and then decreased during fruit development; however, the titratable acid content of ‘DS-1’ fruits changed to a minor extent. The organic acid content of ‘Nongda4’ was significantly higher than that of ‘DS-1’. The organic acids in mature fruits were mainly malic acid and citric acid. Analysis of the differentially expressed genes related to organic acid metabolism revealed six key genes, including two MDH genes, one tDT gene, one ME gene, one PEPCK gene, and one VHA gene. Weighted gene co-expression network association analysis revealed four modules that were significantly correlated with organic acid content, and 10 key genes with high connectivity among these four modules were screened, including two PK genes, two MDH genes, two ME genes, one PEPCK gene, one VHA gene, one PEPC gene, and one tDT gene. According to the expression patterns of genes in different Chinese dwarf cherry accessions, seven genes were confirmed to represent key genes related to the regulation of organic acids during Chinese dwarf cherry fruit development. These results provide a foundation for further studies on the molecular mechanism of organic acid accumulation in Chinese dwarf cherry fruit.

Transcriptomic and Metabolomic Analysis of Quality Changes during Sweet Cherry Fruit Development and Mining of Related Genes.

Sweet cherries are economically important fruit trees, and their quality changes during development need to be determined. The mechanism of fruit quality changes in sweet cherries were determined by analyzing sweet cherry fruits at 12 developmental stages. The results showed that the soluble sugar, anthocyanin content, and hormones of sweet cherries all changed drastically during the color transition. Therefore, the fruits at the beginning of color conversion, at the end of color conversion, and at the ripening state were selected for the comprehensive analysis of their metabolome and transcriptome. Different sugars, such as D-glucose, sucrose, and trehalose, were identified in the metabolome. Dihydroquercetin, delphinidin-3-glucoside, cyanidin-3-rutincoside, and other flavonoid species were also identified. D-glucose and cyanidin-3-rutinoside were among the most important components of sweet cherry soluble sugars and anthocyanins, respectively. The transcriptional analysis identified key structural genes and nine transcription factors involved in the ABA, sugar, organic acid, and anthocyanin synthesis pathways, with the following specific regulatory patterns. NAC71, WRKY57, and WRKY3 regulate fruit sugar accumulation mainly by acting on INV, SPS, and SUS. MYC2 is involved in the synthesis of anthocyanin precursors by activating PAL and C4H, whereas TCP7 mainly regulates CHI and F3H. WRKY3, NAC71, and WRKY57 have important positive regulatory significance on anthocyanin accumulation, mainly by activating the expression of DFR, ANS, and 3GT.

Novel insights into the calcium action in cherry fruit development revealed by high-throughput mapping.

This work provides the first system-wide datasets concerning metabolic changes in calcium-treated fruits, which reveal that exogenously applied calcium may specifically reprogram sweet cherry development and ripening physiognomy. Calcium modulates a wide range of plant developmental processes; however, the regulation of fruit ripening by calcium remains largely uncharacterized. In this study, transcriptome, proteome and metabolome profiling was used to document the responses of sweet cherry fruit to external calcium application (0.5% CaCl2) at 15, 27 and 37days after full blossom. Endogenous calcium loading in fruit across development following external calcium feeding was accompanied by a reduction in respiration rate. Calcium treatment strongly impaired water-induced fruit cracking tested by two different assays, and this effect depended on the fruit size, water temperature and light/dark conditions. Substantial changes in the levels of numerous polar/non-polar primary and secondary metabolites, including malic acid, glucose, cysteine, epicatechin and neochlorogenic acid were noticed in fruits exposed to calcium. At the onset of ripening, we identified various calcium-affected genes, including those involved in ubiquitin and cysteine signaling, that had not been associated previously with calcium function in fruit biology. Calcium specifically increased the abundance of a significant number of proteins that classified as oxidoreductases, transferases, hydrolases, lyases, and ligases. The overview of temporal changes in gene expression and corresponding protein abundance provided by interlinked analysis revealed that oxidative phosphorylation, hypersensitive response, DNA repair, stomata closure, biosynthesis of secondary metabolites, and proton-pump activity were mainly affected by calcium. This report provides the fullest characterization of expression patterns in calcium-responsive genes, proteins and metabolites currently available in fruit ripening and will serve as a blueprint for future biological endeavors.

Multiple-population QTL mapping of maturity and fruit-quality traits reveals LG4 region as a breeding target in sweet cherry (Prunus avium L.)

Sweet cherry maturity date and fruit quality are relevant traits for its marketability, transport, and consumer acceptance. In this work, sweet cherry fruit development time, maturity date, and commercial fruit-quality traits (size, weight, firmness, soluble solid content, and titratable acidity) were investigated to improve the knowledge of their genetic control, and to identify alleles of breeding interest. Six sweet cherry populations segregating for these traits were used for QTL analyses. These populations descend from cross- and self-pollinations of local Spanish sweet cherries ‘Ambrunés’ and ‘Cristobalina’, and breed cultivars (‘Brooks’, ‘Lambert’, or ‘Vic’). The six populations (n = 411), previously genotyped with RosBREED Cherry 6 K SNP array, were phenotyped for 2 years. QTL analyses were conducted using a multifamily approach implemented by FlexQTL™. Fruit development time, soluble solid content, and titratable acidity QTLs are first reported in sweet cherry in this work. Significant QTLs were detected for all the traits. Eighteen were more stable as they were detected for 2 years. Of these, nine are first reported in this work. The major QTLs for fruit development time, maturity date, firmness, and soluble solid content were identified on the same narrow region of linkage group 4. These traits also showed significant positive correlation (long fruit development time associated with late maturity, high firmness, and high SSC). NAC transcription factor genes identified on this LG4 region may be candidate genes for the regulation of these traits in sweet cherry, as previously described in syntenic regions of other Rosaceae species. Haplotypes of breeding interest on this LG4 genomic region were identified and will be useful for sweet cherry breeding from this and related plant material.

Proteomic and metabolic analysis reveals novel sweet cherry fruit development regulatory points influenced by girdling

Despite the application of girdling technique for several centuries, its impact on the metabolic shifts that underly fruit biology remains fragmentary. To characterize the influence of girdling on sweet cherry (Prunus avium L.) fruit development and ripening, second-year-old shoots of the cultivars ‘Lapins’ and ‘Skeena’ were girdled before full blossom. Fruit characteristics were evaluated across six developmental stages (S), from green-small fruit (stage S1) to full ripe stage (stage S6). In both cultivars, girdling significantly altered the fruit ripening physiognomy. Time course fruit metabolomic along with proteomic approaches unraveled common and cultivar-specific responses to girdling. Notably, several primary and secondary metabolites, such as soluble sugars (glucose, trehalose), alcohol (mannitol), phenolic compounds (rutin, naringenin-7-O-glucoside), including anthocyanins (cyanidin-3-O-rutinoside, cyanidin-3-O-galactoside, cyanidin-3.5-O-diglucoside) were accumulated by girdling, while various amino acids (glycine, threonine, asparagine) were decreased in both cultivars. Proteins predominantly associated with ribosome, DNA repair and recombination, chromosome, membrane trafficking, RNA transport, oxidative phosphorylation, and redox homeostasis were depressed in fruits of both girdled cultivars. This study provides the first system-wide datasets concerning metabolomic and proteomic changes in girdled fruits, which reveal that shoot girdling may induce long-term changes in sweet cherry metabolism.

Comparative transcriptome analysis reveals the molecular regulation underlying the adaptive mechanism of cherry (Cerasus pseudocerasus Lindl.) to shelter covering

BackgroundRain-shelter covering is widely applied during cherry fruit development in subtropical monsoon climates with the aim of decreasing the dropping and cracking of fruit caused by excessive rainfall. Under rain-shelter covering, the characteristics of the leaves and fruit of the cherry plant may adapt to the changes in the microclimate. However, the molecular mechanism underlying such adaptation remains unclear, although clarifying it may be helpful for improving the yield and quality of cherry under rain-shelter covering.ResultsTo better understand the regulation and adaptive mechanism of cherry under rain-shelter covering, 38,621 and 3584 differentially expressed genes were identified with a combination of Illumina HiSeq and single-molecule real-time sequencing in leaves and fruits, respectively, at three developmental stages. Among these, key genes, such as those encoding photosynthetic-antenna proteins (Lhca and Lhcb) and photosynthetic electron transporters (PsbP, PsbR, PsbY, and PetF), were up-regulated following the application of rain-shelter covering, leading to increased efficiency of light utilization. The mRNA levels of genes involved in carbon fixation, namely, rbcL and rbcS, were clearly increased compared with those under shelter-free conditions, resulting in improved CO2 utilization. Furthermore, the transcription levels of genes involved in chlorophyll (hemA, hemN, and chlH) and carotenoid synthesis (crtB, PDS, crtISO, and lcyB) in the sheltered leaves peaked earlier than those in the unsheltered leaves, thereby promoting organic matter accumulation in leaves. Remarkably, the expression levels of key genes involved in the metabolic pathways of phenylpropanoid (PAL, C4H, and 4CL) and flavonoid (CHS, CHI, F3’H, DFR, and ANS) in the sheltered fruits were also up-regulated earlier than of those in the unsheltered fruits, conducive to an increase in anthocyanin content in the fruits.ConclusionsAccording to the physiological indicators and transcriptional expression levels of the related genes, the adaptive regulation mechanism of cherry plants was systematically revealed. These findings can help understand the effect of rain-shelter covering on Chinese cherry cultivation in rainy regions.

Current Season Photoassimilate Distribution in Sweet Cherry

Sweet cherry (Prunus avium) tree canopies comprise three types of leaf populations: fruiting spur (FS), nonfruiting spur (NFS), and extension shoot (ES) leaves. The contribution of each leaf population as sources of photoassimilate synthesis and distribution for sweet cherry fruit development has not been described previously. To determine how carbon fixed by different leaf populations is distributed to reproductive and vegetative sinks during fruit development, fruiting branches of 7-year-old ‘Ulster’ sweet cherry trees grown on ‘Gisela®6’ (Gi6) (Prunus cerasus × Prunus canescens) rootstock at Michigan State University’s Clarksville Research Center (Clarksville, MI) were exposed to 13CO2 labeling on five dates in 2003 [25, 40, 44, 56, and 75 days after full bloom (DAFB), which occurred on 30 Apr.], comprising the period from late Stage I (SI) to late Stage III (SIII) of fruit development. Forty-eight hours after labeling, whole branches were removed and separated into different organs for 13C analysis by gas chromatography–mass spectrometry (GC-MS). The organs analyzed included: FS leaves, NFS leaves, ES leaves, fruit, and wood + bark from the segment of the branch corresponding to each leaf population. Relative distribution of C from each leaf population source to each sink varied during fruit development. Overall, the proportion of 13C recovered in the fruit was highest for the FS leaf population (which included fruit exposure to 13CO2), followed by the NFS leaves, then ES leaves. From SI to SIII, ≈60% of the 13C recovered in the FS portion of the branch was found in the fruit, except during the exponential growth of fruit in mid-SIII (56 DAFB) when this proportion was nearly 80%. About 30% of the 13C fixed by NFS leaves was found in the fruit during Stage II (SII) (40 DAFB) and early (44 DAFB) and late (75 DAFB) SIII, with higher proportions at SI (45% at 25 DAFB) and mid-SIII (70%). About 25% of the 13C fixed by ES leaves was found in the fruit during SI, SII, and late SIII, with a lower proportion (17%) at early SIII when shoot growth was exponential, and a higher proportion (nearly 60%) at mid-SIII. The proportion of 13C fixed and translocated to ES growth was minimal from FS and NFS leaves throughout the sampling dates, but that by the ES leaves was significant, peaking at early SIII. The results illustrate the dynamics of C contribution from each leaf population between vegetative and reproductive sinks during growth in sweet cherry orchards, which provides useful physiological information for canopy pruning and crop load regulation.

Transcriptional regulation of PaPYLs, PaPP2Cs and PaSnRK2s during sweet cherry fruit development and in response to abscisic acid and auxin at onset of fruit ripening

To further understand the basis of abscisic acid (ABA) signal transduction in regulating sweet cherry fruit development and ripening, and also the interaction between ABA and indole acetic acid (IAA) at the onset of fruit ripening, full-length or partial cDNA of three PaPYLs (ABA receptor), six PaPP2Cs (type 2C protein phosphatase) and six PaSnRK2s (subfamily 2 of SNF1-related kinases) were identified from sweet cherry. Multiple alignments and phylogeny analyses showed that most of the functional residues or domains were well conserved within each gene family; all PaPP2Cs belonged to the group A PP2C; PaSnRK2.4 and PaSnRK2.5 belonged to subclass III of SnRK2. PaPYL2/3, PaPP2C3/4/6 and PaSnRK2.4 were highly expressed at the early stages of fruit development. Moreover, PaPYL2, PaPP2C3/4, PaSnRK2.4 also had a high expression level at the onset of fruit ripening. Exogenous ABA treatment at 28 days after full bloom decreased the IAA level and promoted fruit ripening by increasing anthocyanin and soluble solids content. However, although IAA treatment induced the ABA accumulation, it delayed the onset of fruit ripening. Most of the PaPYLs and PaSnRK2s didn’t strongly respond to ABA and IAA treatments at 28 days after full bloom, while expressions of PaPP2C3, PaPP2C5 and PaPP2C6 were significantly induced by exogenous ABA and PaPYL1 was significantly induced by exogenous IAA.

Respiratory activity of ‘Chelan’, ‘Bing’ and ‘Selah’ sweet cherries in relation to fruit traits at green, white-pink, red and mahogany ripening stages

Sweet cherry fruit development is subjectively sub-divided into four stages on the basis of exocarp color, which includes green, white-pink, red and mahogany stages. ‘Chelan’, ‘Bing’ and ‘Selah’, representing early-, mid- and late-season cultivars, respectively, and three different abscission-responses, were selected to explore the relationships between respiratory activity, fruit quality attributes, and pedicel-fruit retention force (PFRF) at the four developmental stages. Respiratory rate was higher in the early ripening cultivar (‘Chelan’) than in the mid- or late ripening cultivars at maturity. However, the cultivars showed similar respiration patterns with a rapid decline of respiration at the green stage followed by a gradual decline, irrespective of abscission behavior or ripening date. A small respiratory peak was observed from the end of the green stage to the beginning of the white-pink stage. Firmness and pedicel retention force (the force required to break the stem and to separate the stem from the fruit) were positively correlated at all stages of fruit development; however, these attributes were negatively correlated with fruit size, particularly at the white-pink and mahogany stages. Also, both firmness and pedicel retention force were greatest at the transition of green and white-pink stages. Fruit respiration rate increased as PFRF increased and decreased as fruit weight, size, soluble solids content (SSC) and titratable acidity (TA) increased in all three cultivars.

Identification of putative candidate genes involved in cuticle formation in Prunus avium (sweet cherry) fruit.

The cuticular membrane (CM) of Prunus avium (sweet cherry) and other fleshy fruit is under stress. Previous research indicates that the resultant strain promotes microscopic cuticular cracking. Microcracks impair the function of the CM as a barrier against pathogens and uncontrolled water loss/uptake. Stress and strain result from a cessation of CM deposition during early development, while the fruit surface continues to expand. The cessation of CM deposition, in turn, may be related to an early downregulation of CM-related genes. The aims of this study were to identify genes potentially involved in CM formation in sweet cherry fruit and to quantify their expression levels. Fruit growth and CM deposition were quantified weekly from anthesis to maturity and rates of CM deposition were calculated. Sequences of genes expressed in the sweet cherry fruit skin (exocarp) were generated using high-throughput sequencing of cDNA and de novo assembly and analysed using bioinformatics tools. Relative mRNA levels of selected genes were quantified in the exocarp and fruit flesh (mesocarp) weekly using reverse transcriptase-quantitative real-time PCR and compared with the calculated CM deposition rate over time. The rate of CM deposition peaked at 93 (±5) μg per fruit d(-1) about 19 d after anthesis. Based on sequence analyses, 18 genes were selected as potentially involved in CM formation. Selected sweet cherry genes shared up to 100 and 98 % similarity with the respective Prunus persica (peach) and Arabidopsis thaliana genes. Expression of 13 putative CM-related genes was restricted to the exocarp and correlated positively with the CM deposition rate. The results support the view that the cessation of CM deposition during early sweet cherry fruit development is accounted for by a downregulation of genes involved in CM deposition. Genes that merit further investigation include PaWINA, PaWINB, PaLipase, PaLTPG1, PaATT1, PaLCR, PaGPAT4/8, PaLACS2, PaLACS1 and PaCER1.

Cloning and expression analysis of cDNAs for ABA 8′-hydroxylase during sweet cherry fruit maturation and under stress conditions

Abscisic acid (ABA) plays a key role in various aspects of plant growth and development, including adaptation to environmental stress and fruit maturation in sweet cherry fruit. In higher plants, the level of ABA is determined by synthesis and catabolism. In order to gain insight into ABA synthesis and catabolism in sweet cherry fruit during maturation and under stress conditions, four cDNAs of PacCYP707A1 — PacCYP707A4 for 8′-hydroxylase, a key enzyme in the oxidative catabolism of ABA, and one cDNA of PacNCED1 for 9-cis-epoxycarotenoid dioxygenase, a key enzyme in the ABA biosynthetic pathway, were isolated from sweet cherry fruit ( Prunus avium L.). The timing and pattern of PacNCED1 expression was coincident with that of ABA accumulation, which was correlated to maturation of sweet cherry fruit. All four PacCYP707As were expressed at varying intensities throughout fruit development and appeared to play overlapping roles in ABA catabolism throughout sweet cherry fruit development. The application of ABA enhanced the expression of PacCYP707A1 — PacCYP707A3 as well as PacNCED1, but downregulated the PacCYP707A4 transcript level. Expressions of PacCYP707A1, PacCYP707A3 and PacNCED1 were strongly increased by water stress. No significant differences in PacCYP707A2 and PacCYP707A4 expression were observed between dehydrated and control fruits. The results suggest that endogenous ABA content is modulated by a dynamic balance between biosynthesis and catabolism, which are regulated by PacNCED1 and PacCYP707As transcripts, respectively, during fruit maturation and under stress conditions.

Effects of ethephon on the respiration and ethylene evolution of sweet cherry (Prunus avium L.) fruit at different development stages

Abstract The role of ethylene on sweet cherry ( Prunus avium L.) fruit respiration was studied at three stages of development. An ethylene-releasing compound, ethephon [(2-chloroethyl)phosphonic acid], was applied at concentrations from 10 to 1000 ppm to straw-, pink- and mahogany-colored fruits. Depending upon the ethephon concentration applied, rates of ethylene evolution as high 6 μl C 2 H 4 kg fruit −1 h −1 were detected. Ethylene evolution was undetectable from untreated, mature fruits. Fruit respiration rates declined at all stages, regardless of the rate of ethylene evolved. Ethephon did not affect the firmness of mature, mahogany-colored sweet cherry fruit. These results confirm that sweet cherry fruit are nonclimacteric because untreated fruit produced neither respiratory nor ethylene peaks near maturity. Respiration was not stimulated in the presence of exogenous ethylene during these later stages of sweet cherry fruit development, as it is in other nonclimacteric fruits.

Cherry fruit development: The use of a microassay for studying indoleacetic acid oxidase

An improved procedure is described for extraction and assay of indoleacetic acid oxidase from seeds of sour cherry (Prunus cerasus L.). The extraction procedure was optimized for pH, buffer, polyvinylpolypyrrolidone (PVP) and tissue: buffer ratio. Greatest extraction efficiency was obtained at pH 4.0, 0.2 M acetate buffer, tissue: PVP ratio of 1:2.5 and tissue: buffer ratio of 50 ml per g of seed. The enzyme was assayed at 30°C using indoleacetic acid-1-14C as substrate and radioassaying the 14CO2 evolved. Mn2+ and 2,4-dichlorophenol enhanced enzyme activity but were not obligatory. A minimum substrate concentration of 60 μM was needed for quantitative evaluation. This assay was sensitive and reproducible, enzyme activity being demonstrated in as little as 0.8 mg of seed tissue with a coefficient of variation of 1 to 9%.

Cherry fruit development: Indoleacetic acid oxidase isoenzymes in the seed

Two anionic indoleacetic acid oxidase isoenzymes were separated by polyacrylamide gel electrophoresis from an acetate buffer (0.2 M, pH 4.0) extract of sour cherry (Prunus cerasus L. cv. Montmorency) seed. One isoenzyme migrated to Rf 0.25 (I1) and the other to Rf 0.78 (I2). Isoenzyme I, exhibited hyperbolic kinetics and was found during all three stages of fruit development with the highest levels during early stage II. The isoenzyme I2 showed sigmoidal kinetics and was found only during stages II and III of fruit growth with highest levels during stage III. The activities of both isoenzymes were markedly enhanced by addition of Mn2+ and 2,4‐dichloro‐phenol to the reaction mixture. Isoenzyme I, showed higher affinity for indoleacetic acid than isoenzyme I2. The significance of these isoenzymes in cherry fruit growth is discussed.

Cherry Fruit Development: Changes in Seed IAA Oxidase Activity

Abstract Indoleacetic acid (IAA) oxidase activity was measured in seeds of Prunus cerasus L. cv. Montmorency from full bloom to maturity. IAA oxidase activity reached a maximum at early Stage II of fruit development and decreased to trace levels during Stage III. The peak of IAA oxidase activity coincided with the time that the seed approached full size and endosperm was at a maximum volume and just prior to the rapid growth phase of the embryo. Inhibitors of IAA oxidase were coextracted (acetate buffer, 0.2 m, pH 4.0) with the enzyme. Low molecular weight compounds, which modified IAA oxidase activity, were separated from the enzyme extract with Sephadex G-25. The compounds from seeds of fruits in Stages I and III inhibited and from Stage II enhanced IAA oxidase activity. The possible role of IAA oxidase and the effectors in cherry fruit development are discussed.

Endogenous Plant Growth Substances in Developing Fruit of Prunus cerasus L. V. Changes in Inhibitor (ABA) Levels in the Seed and Pericarp1

Abstract Abscisic acid (ABA) was isolated from sour cherry (Prunus cerasus L. cv. Montmorency) fruit and identified by thin-layer and gas-liquid chromatography and combined gas chromatography-mass spectrometry. Inhibitor levels in the seed paralleled those in the pericarp and were, in general, directly related to growth rate of the fruit, higher levels being found during the initial rapid growth (Stage I) than during the retarded growth phase (Stage II). The level of the inhibitor increased in Stage III, then decreased in the final stages of maturity. The possible role of endogenous ABA in cherry fruit development is discussed.