Different Stages Of Flowering Research Articles

Identification and Validation of New Reference Genes for Normalization of Gene Expression in Flower and Berry Developmental Stages of Interspecific Grape Hybrid V. vinifera (L.) × V. labrusca (L.)

Abstract In quantitative reverse transcription polymerase chain reaction (qRT-PCR), normalizing target gene expression using a reference gene is an indispensable step to control the variability of RNA extraction yield, RNA integrity, reverse transcription efficiency, and PCR amplification. In the present study, we identified candidate reference genes with stable expression during grapes’ flowering and berry development stages. Ten genes, including ACT, CYP5, RLI, TUB, UBC, UBC17, UBC60, UFD1, VAG, and ZNF with relatively stable expression, were selected based on RNAseq data generated earlier in grape hybrid ‘ARI 516’. The expression of these candidate genes was tested at different stages of flowering and grape berry development. Five different algorithms such as RefFinder, geNorm, NormFinder, BestKeeper, and the comparative ΔCq method were used to test the expression stability of candidate genes. A comprehensive ranking obtained by RefFinder showed that UBC17, RLI, and ZNF were the most stable reference genes during flower and berry development stages. UBC17, RLI, and ZNF were calibrators to normalize the expression of VvAGL11 as a target gene to validate the worthiness of identified reference genes. The result demonstrated that newly identified reference genes could be successfully used to normalize the expression of the target gene accurately. These reference genes will provide more choices for selecting appropriate reference genes to normalize gene expression in grapes.

Salicylic Acid Treatment and Its Effect on Seed Yield and Seed Molecular Composition of Pisum sativum under Abiotic Stress.

The reproductive stage of plant development has the most critical impact on yield. Flowering is highly sensitive to abiotic stress, and increasing temperatures and drought harm crop yields. Salicylic acid is a phytohormone that regulates flowering and promotes stress resilience in plants. However, the exact molecular mechanisms and the level of protection are far from understood and seem to be species-specific. Here, the effect of salicylic acid was tested in a field experiment with Pisum sativum exposed to heat stress. Salicylic acid was administered at two different stages of flowering, and its effect on the yield and composition of the harvested seeds was followed. Plants treated with salicylic acid produced larger seed pods, and a significant increase in dry weight was found for the plants with a delayed application of salicylic acid. The analyses of the seed proteome, lipidome, and metabolome did not show any negative impact of salicylic treatment on seed composition. Identified processes that could be responsible for the observed improvement in seed yields included an increase in polyamine biosynthesis, accumulation of storage lipids and lysophosphatidylcholines, a higher abundance of components of chromatin regulation, calmodulin-like protein, and threonine synthase, and indicated a decrease in sensitivity to abscisic acid signaling.

Cloning and Functional Identification of Gibberellin Receptor SvGID1s Gene of Salix viminalis.

Gibberellins (GAs) play a key role in the transition from vegetative growth to flowering and the GA receptor GID1 (GIBBERELLIN INSENSITIVE DWARF1) is the central part of GA-signaling. The differential expression of SvGID1 was found in the transcriptome sequencing in our previous study, which was further verified at different stages of flowering of Salix viminalis. In order to reveal the function GID1 of S. viminalis, two genes of SvGID1b and SvGID1c were cloned and transformed into Arabidopsis thaliana, respectively. The results showed that the full ORF length of SvGID1b and SvGID1c genes were both 1035bp, encoding 344 amino acids, which were typical globular proteins. The peptide chain contained more α-helix structure, and had 99% similarity with GID1b and GID1c amino acid sequences of Salix suchowensis. Phylogenetic analysis showed that SvGID1s had close genetic relationship with woody plants such as Populus alba and Populus tomentosa, and had far genetic relationship with rice. After overexpression in A. thaliana, the total gibberellin, active gibberellin content and the expression level of GA3ox1, the key gene for GA4 synthesis, were not significantly different from those in the wild-type, while the expression levels of FUL, SOC1 and FT, the key genes for flowering in plants, were increased, and the expression levels of FLC and GAI were decreased. The ectopic expression of SvGID1s increased the sensitivity of plants to gibberellin and enhanced gibberellin effect, caused early bolting, budding and flowering, led to higher plant, longer hypocotyl and other phenomena. The results provide a theoretical basis for clarifying the regulation of gibberellin on flower bud differentiation of flowering plants.

Allelopathic activity of water-soluble and volatile secretions of Crocus sativus L. (Iridaceae) flowers in the Northern Black Sea region

The introduction of new crops to agrophytocenoses, to which Crocus sativus belongs, should be preceded by research into their ecological safety and place in crop rotation. When harvesting raw materials for obtaining saffron, up to 90% of by-products remain, which during decomposition can have a negative effect on the soil and indirectly on the plants that are grown after saffron. Therefore, the aim of the research was to study the allelopathic activity of water-soluble and volatile secretions of Crocus sativus flowers in the agroclimatic conditions of the Northern Black Sea region. The research was conducted in 2021 according to the generally accepted methodology, freshly picked flowers were used, from which individual elements were extracted, and flowers of different stages of flowering. The following research methods were used: field, laboratory, computational and statistical. The results of the research established that the water-soluble secretions of Crocus sativus flowers and their parts stimulate the energy of germination and inhibit the growth of one-day seedlings of Lactuca sativum. Water-soluble secretions of Crocus sativus flowers have a negative allelopathic effect. The index of allelopathic activity under the action of water-soluble secretions of flowers ranges from -0.26 for a flower with all parts to -0.01 for petals. The highest stimulating effect of volatile secretions on the growth of Lactuca sativum roots and the allelopathic activity index value is characteristic of the flower that has just bloomed and the stamens, and the lowest - for the pistils. The allelopathic activity of the volatile secretions of Crocus sativus flower parts is set at the level of 6.4 (pistil) and 28.8% (stamens). Substances that inhibit the germination of Lactuca sativum roots are found mainly in the stamens. It was determined that the volatile secretions of Crocus sativus flower parts reduce the energy of seed germination of the test plant. The practical value of the research is that the results of the research can be used when determining the place of the crop in crop rotation and the duration of its cultivation in one field

Proteolytic activity, identification and expression profile of a KDEL-CysEP gene in common lilac flowers depending on the flowering conditions

In a temperate zone, common lilac blooms in May, and the whole flowering process lasts ca. 3 weeks. The flowering process starts in July of the previous year, during winter flower buds are in the state of deep dormancy, and their activity starts again in the spring of the next year. Forcing is a method, that may induce flowering in plants, independently of the natural blooming period. The temperatures required to start blooming in lilac during standard forcing method in November are ca. 37°C. This method is rapid, but gives panicles of poor quality. The alternative is forcing at 15°C, but in November plants forced by this method require 49 days to bloom as compared to 23 days for the standard 37°C. Anyway, the main advantage of this method is a very good quality of flowers and long vase life. In this study we investigated the cysteine protease activity and its expression profile at different stages of flowering (flower bud whitening and swelling, open flowers, wilted flowers) for lilac flowers (Syringa vulgaris L.) blooming under three different conditions: natural conditions in May and forcing in a greenhouse in November at 37°C (standard forcing) or at 15°C (alternative forcing). The gene expression did not correlate with the cysteine endoprotease activity. Alternative forcing method at 15°C affected the flowering process delaying senescence, presumably due to the low cysteine protease activity.

Determining Phenological Patterns Associated with the Onset of Senescence in a Wheat MAGIC Mapping Population.

The appropriate timing of developmental transitions is critical for adapting many crops to their local climatic conditions. Therefore, understanding the genetic basis of different aspects of phenology could be useful in highlighting mechanisms underpinning adaptation, with implications in breeding for climate change. For bread wheat (Triticum aestivum), the transition from vegetative to reproductive growth, the start and rate of leaf senescence and the relative timing of different stages of flowering and grain filling all contribute to plant performance. In this study we screened under Smart house conditions a large, multi-founder “NIAB elite MAGIC” wheat population, to evaluate the genetic elements that influence the timing of developmental stages in European elite varieties. This panel of recombinant inbred lines was derived from eight parents that are or recently have been grown commercially in the UK and Northern Europe. We undertook a detailed temporal phenotypic analysis under Smart house conditions of the population and its parents, to try to identify known or novel Quantitative Trait Loci associated with variation in the timing of key phenological stages in senescence. This analysis resulted in the detection of QTL interactions with novel traits such the time between “half of ear emergence above flag leaf ligule” and the onset of senescence at the flag leaf as well as traits associated with plant morphology such as stem height. In addition, strong correlations between several traits and the onset of senescence of the flag leaf were identified. This work establishes the value of systematically phenotyping genetically unstructured populations to reveal the genetic architecture underlying morphological variation in commercial wheat.

Main regulatory pathways, key genes and microRNAs involved in flower formation and development of moso bamboo (Phyllostachys edulis).

SummaryMoso bamboo is characterized by infrequent sexual reproduction and erratic flowering habit; however, the molecular biology of flower formation and development is not well studied in this species. We studied the molecular regulation mechanisms of moso bamboo development and flowering by selecting three key regulatory pathways: plant–pathogen interaction, plant hormone signal transduction and protein processing in endoplasmic reticulum at different stages of flowering in moso bamboo. We selected PheDof1, PheMADS14 and six microRNAs involved in the three pathways through KEGG pathway and cluster analysis. Subcellular localization, transcriptional activation, Western blotting, in situ hybridization and qRT‐PCR were used to further investigate the expression patterns and regulatory roles of pivotal genes at different flower development stages. Differential expression patterns showed that PheDof1, PheMADS14 and six miRNAs may play vital regulatory roles in flower development and floral transition in moso bamboo. Our research paves way for further studies on metabolic regulatory networks and provides insight into the molecular regulation mechanisms of moso bamboo flowering and senescence.

Flowering conditions affect flower longevity in Syringa vulgaris and cause changes in protein content, protease activity and expression of a KDEL-CysEP gene

Forcing is a method that is usually used to induce flowering in plants, independent of the natural blooming period. The temperatures required to start blooming in lilac in November are ca. 37°C causing degeneration of flowers. Forcing at 15 °C in November requires 49 days to bloom as compared to 23 days for the standard 37 °C, but gives panicles of much better quality than those forced by standard method (37 °C). In this study, we have investigated the protein content, total protease activity, and cysteine protease activity at different stages of flowering (flower bud whitening and swelling, open flowers, wilted flowers) for lilac flowers (Syringa vulgaris L., fam. Oleaceae) blooming under three different conditions: natural conditions in May and forcing in a greenhouse in November at 37 °C (standard forcing) or at 15 °C (alternative forcing). The protein content was relatively constant during flowering for each of the three sets of conditions. Flowers from 15 °C had a significantly lower total protease and cysteine endoprotease activity than flowers from 37 °C at all stages. Flowers from plants blooming in May had a very time-specific cysteine protease activity, which was dramatically higher for the open flower stage than for the other stages. The partial coding sequence for a KDEL-CysEP was isolated, and its expression was determined by qRT-PCR. The gene expression did not correlate with the cysteine endoprotease activity especially in May natural flowering and November alternative forcing at 15 °C. Alternative forcing method at 15 °C affected the flowering process delaying senescence, presumably due to the low cysteine protease activity.

RNA-Seq analysis reveals genetic bases of the flowering process in oriental hybrid lily cv. Sorbonne

Flowering is a critical step in plant reproduction. Oriental lily (Lilium) characterized by showy flowers is increasingly used; however, the blossom period is an important limiting factor influencing the value of lily. Improving the flowering of lily by molecular breeding technology has limitless applications, but the mechanism of the regulation of lily flowering remains to be studied. Transcriptomes providing comprehensive sequence profiling data of transcription variation during flowering process in Oriental hybrids lily Sorbonne were assembled from RNA-Seq data. Approximately 124.16 million 90 bp paired-end clean reads were assembled into 66 327 unigenes and compared with the UniProt databases. There are 30 254 unigenes that have significant hits to the sequences in the UniProt database, 60 738, 16 601, and 12 494 unigenes have similarity to the GO, KEGG, and COG databases, respectively. By analyzing dynamic changes in the transcriptome of lily flowering based on our RNA sequencing (RNA-Seq) data, some genes involved in floral induction were found, which revealed the complicated flower regulation network at the transcriptome level during lily flowering. Moreover, 12 DEGs related to flowering including LoLFY, LoMAF, LoFT, LoAG, LoCBF, LoAGL6a, LoSOC1, LoSEP1, LoNAC1, LoAPX, LoARF10, and LoICE were identified with real-time quantitative RT-PCR analysis. The results suggested that the flower of Oriental lily possessed a high proportion of flowering genes active at different stages of flowering. According to the results of the present study, we predicted that they would play an important role during flowering process; these data provided the foundation for future studies of metabolism during flowering of Oriental lily.

Monitoring of plant and airborne inoculum of Sclerotinia sclerotiorum in spring oilseed rape using real‐time PCR

Sclerotinia stem rot of spring oilseed rape (Brassica napus) is caused by Sclerotinia sclerotiorum. In Sweden, the disease leads to severe crop damage that varies from year to year. A real‐time PCR assay was developed and used to determine the incidence of S. sclerotiorum DNA on petals and leaves of spring oilseed rape as well as in air samples, with the aim of finding tools to improve precision in disease risk assessment. Five field experiments were conducted from 2008 to 2010 to detect and study pathogen development. Assessments of stem rot showed significant differences between experimental sites. The real‐time PCR assay proved fast and sensitive and the relationship between percentage of infected petals determined using a conventional agar test and the PCR assay was linear (R2 > 0·76). There were significant differences in S. sclerotiorum incidence at different stages of flowering. The incidence of S. sclerotiorum DNA on the leaves varied (0–100%), with significantly higher incidence on leaves at lower levels. In one field experiment, S. sclerotiorum DNA was not detected on petals during flowering, whereas the pathogen was detected on leaves, with a corresponding stem rot incidence of 7%. The amount of S. sclerotiorum DNA in sampled air revealed that spore release did not coincide with flowering on that experimental site. Thus, using a real‐time PCR assay to determine the incidence of S. sclerotiorum on oilseed rape leaves, rather than on petals, could potentially improve disease risk assessment.

RNA-Seq Analysis Reveals Genetic Bases of the Flowering Process in Oriental Hybrid Lily cv. Sorbonne

Flowering is a critical step in plant reproduction. Oriental lily (Lilium) characterized by showy flowers is increasingly used; however, the blossom period is an important limiting factor influencing the value of lily. Improving the flowering of lily by molecular breeding technology has limitless applications, but the mechanism of the regulation of lily flowering remains to be studied. Transcriptomes providing comprehensive sequence profiling data of transcription variation during flowering process in Oriental hybrids lily Sorbonne were assembled from RNA Seq data. Approximately 124.16 million 90 bp paired end clean reads were assembled into 66 327 unigenes and compared with the UniProt databases. There are 30 254 unigenes that have significant hits to the sequences in the UniProt database, 60 738, 16 601, and 12 494 unigenes have sim ilarity to the GO, KEGG, and COG databases, respectively. By analyzing dynamic changes in the transcrip tome of lily flowering based on our RNA sequencing (RNA Seq) data, some genes involved in floral induc tion were found, which revealed the complicated flower regulation network at the transcriptome level during lily flowering. Moreover, 12 DEGs related to flowering including LoLFY, LoMAF, LoFT, LoAG, LoCBF, LoAGL6a, LoSOC1, LoSEP1, LoNAC1, LoAPX, LoARF10, and LoICE were identified with real time quan titative RT PCR analysis. The results suggested that the flower of Oriental lily possessed a high proportion of flowering genes active at different stages of flowering. According to the results of the present study, we pre dicted that they would play an important role during flowering process; these data provided the foundation for future studies of metabolism during flowering of Oriental lily.

Gibberellin metabolism in Vitis vinifera L. during bloom and fruit-set: functional characterization and evolution of grapevine gibberellin oxidases.

Gibberellins (GAs) are involved in the regulation of flowering and fruit-set in grapes (Vitis vinifera L.), but the molecular mechanisms behind this process are mostly unknown. In this work, the family of grapevine GA oxidases involved in the biosynthesis and deactivation of GAs was characterized. Six putative GA 20-oxidase (GA20ox), three GA 3-oxidase (GA3ox), and eight GA 2-oxidase (GA2ox) proteins, the latter further divided into five C19-GA 2ox and three C20-GA2ox proteins, were identified. Phylogenetic analyses suggest a common origin of the GA3ox and C19-GA2ox groups and challenge previous evolutionary models. In vitro analysis revealed that all GA3ox and GA20ox enzymes prefer substrates of the non-13-hydroxylation pathway. In addition, ectopic expression of GA2ox genes in Arabidopsis thaliana confirmed the activity of their encoded proteins in vivo. The results show that bioactive GA1 accumulates in opening grapevine flowers, whereas at later developmental stages only GA4 is detected in the setting fruit. By studying the expression pattern of the grapevine GA oxidase genes in different organs, and at different stages of flowering and fruit-set, it is proposed that the pool of bioactive GAs is controlled by a fine regulation of the abundance and localization of GA oxidase transcripts.

Entomofauna of Oil Palm Tree Inflorescences at La Mé Experimental Station (Côte d’Ivoire)

Pollination of oil palm tree is mainly entomophilous. The inflorescences of this plant lodge many insects. The identification and quantification of these insects have proven ability to hold their pollination. The entomofauna of female and male inflorescenc es was inventoried and quantified at La ME, a station of CNRA, the National Center of Agronomic Research of CUte d'Ivoire (West Africa) for a period of 2 years. The insects of the male inflorescences were listed at the beginning, the full and the end of an thesis on 1536spikeletsof 384 male inflorescences. For the insects of female inflorescences, 96 inflorescences were covered with a muslin sheath. The insects arriving on these inflorescences were captured in 2 days corresponding to anthesis length, durin g 10 minutes per hour, from 6 am to 6 pm. Species Elaeidobiussp., Microporumsp., Prosoestussp.and Athetaburgeoniwere common and regular present regardless of inflorescence type. Species Gabrius sp., Thrips sp., Anthocoridesp., Lithargussp.and thebees (Nomia sp.and Apismellifera)were rarely observed in female inflorescences.Elaeidobiuskamerunicus and Prosoestus sp.were more abundant on the female than on the male inflorescences. The higher level of insects was observed in full anthesis onmale inflorescences whereas among female inflorescences it was noted at the first day of flowering. Knowledge of the insect fauna of oil palm inflorescences according to different stages of flowering allows better management of pollination.

Essential Oil Composition of the Inflorescence of Artemisia capillaris Thunb. Collected at Different Stages of Flowering from Kumaon Region of Western Himalaya

The essential oils obtained from Artemisia capillaris at different stages of flowering were analyzed by GC and GC/MS. The main components of this oil were capillene, γ-terpinene, eugenol, limonene, p-cymene, myrcene and α-pinene. Capillene (40.1%), α-pinene (2.4%) and p-cymene (2.5%) were higher in the oil obtained from plants collected during full bloom stage, while γ-terpinene (24.6%) and eugenol (15.0%) were the main components of the oil from the seed setting stage. Characteristic of the oil was the presence of the rarely occurring compounds like capillene and norcapillene.

Flower Development and Senescence-Related Changes in Agapanthus africanus (Aliaceae)

In this study it was determined that fresh weight changes, peroxidase activity, soluble protein and anthocyanin content and the changes in the membrane permeability in four different stages of flowering ( developing flower buds, anthesis, mature flowers, senescing flowers) of Agapanthus africanus. It was seen that fresh weight amount in mature flowers stage is the highest when it was compared with senescing flowers. It was found a negative correlation between decrease of anthocyanin content and increase of membrane permeability in senescing flower stage because of losing of semi-permeability in membranes during senescence.

Variations in the components of Osmanthus fragrans Lour. essential oil at different stages of flowering

A headspace solid-phase microextraction (HS-SPME) method was used to extract the essential oil of Osmanthus fragrans Lour., which was then analysed by gas chromatography–mass spectrometry (GC–MS) at four different stages of flowering. The primary chemical components of the essential oil extracted from O. fragrans were linalool and its oxide, α-ionone, β-ionone, nerol, γ-decalactone, 9,12,15-octadecatrienoic acid, and hexadecanoic acid, most of which were at their highest concentrations in extracts obtained from flowers at the initial flowering stage. HS-SPME using a PDMS/DVB fibre is a simple, rapid, and solvent-free method for the extraction of volatile compounds emitted from living O. fragrans. HS-SPME with GC–MS can be used to determine the aromatic maturity in O. fragrans, to decide the optimal harvest date. The initial flowering stage was the best time to harvest O. fragrans.

Essential oil composition of four Hypericum species from Iran

L., is used as a valuable medicinal plant for nervous exhaustion, depression, and seasonal affective disorders [3]. This genus contains a wide range of different natural product classes, including naphthodianthrones (e.g., hypericin), prenylated phloroglucinols (e.g., hyperforin), xanthones, flavonoids, biflavonoids, tannins, proanthocyanidins, and phenolic acids [4]. Hypericum helianthemoides (Spach) Boiss., H. hirtellum (Spach) Boiss., H. scabrum L., and H. dogonbadanicum Assadi. are four Hypericum species whose oils have been subjected to analysis in this article. H. dogonbadanicum, the only member of the section Campylusporus in Iran, is a narrow endemic plant confined to mountainous regions NE of Gachsaran city, SW of Iran; the other three species belong to the Hirtella section and are distributed W and NW of Iran [2]. Here we report on the chemical composition of these four species, two of which, Hypericum helianthemoides and H. hirtellum, have not been subjected to any previous phytochemical analysis. Data on the constituents of the four Hypericum oils are shown in Table 1. According to Table 1, monoterpenes are the major constituents of H. scabrum (Fars, Doshman Ziari, 2005; 73.7%) and H. dogonbadanicum (Kohkilooyeh, Gachsaran, 2006; 59.4%), while the major compounds in H. helianthemoides (Fars, Hesami, Roshan Kuh, 2005) and H. hirtellum (Fars, Neyriz, 2006) are sesquiterpenes with 74.1% and 53.0% of the total oils, respectively. The first major compound of H. scabrum and H. dogonbadanicum is α-pinene, which is a major and characteristic constituent of many Hypericum species like H. perforatum [5], H. forrestii [6], H. perfoliatum [7], H. triquetrifolium [8], H. hircinum [9], H. hyssopifolium, and H. heterophyllum [10]. In three previous works on H. scabrum oil, α-pinene was also shown to be the first major compound and in two of them, like ours, α-pinene constituted more than 40% of the total oil [11, 12]. However, in the other report α-pinene only comprised 11.2% of the total oil [13]. Comparison of the other constituents of these reports and ours show that the other major compounds are completely different from each other, which could be attributed to different localities where the plant materials were collected. The major constituents of H. dogonbadanicum oils of our work and previous work [14] were the same but differ in order and percentage. α-Pinene (34.7%), β-pinene (32.1%), limonene (12.1%), and camphene (6.6%) were the first four major compounds of previous work that were the first (12.8%), third (4.7%), second (8.2%), and sixth (3.9%) majors of ours. Major compound percentages in our work were totally less than the previous work. Because of the very limited distribution range of this species, locality could not be an important factor in this difference. Our plant material was collected before bud blooming; different stages of flowering may resulted in different chemical compositions of these two oils. Two first major compounds of H. helianthemoides and H. hirtellum are the same; β-caryophyllene (23.3%, 14.1%) and spathulenol (17.4%, 12.3%) with respective percentage. β-Caryophyllene was also among the major constituents of H. perforatum [5], H. triquetrifolium [8], H. bupleuroides [15], H. carinatum [16], H. maculatum [17], H. foliosum [18], and H. brasiliense [19]; and spathulenol was one of the main compounds of H. perforatum [5], H. hissopifolium [20] and H. linarioides [21]. α-Pinene is also the fourth and third major compounds of H. helianthemoides (6.7%) and H. hirtellum (9.8%), respectively. The third major constituent of H. helianthemoides is 14-hydroxy-9-epi-(E)-carophyllene, with the caryophyllene skeleton. Compounds with this skeleton comprise 47.9% of H. helianthemoides total oil. Nonane was a characteristic constituent of H. perfoliatum [7], H. triquetrifolium [8], H. hircium [9], H. scabrum [11], H. caprifoliatum [16], H. foiosum [18], and H. richeri [22] oils, the amount of which was not considerable in the four Hypericum oils of our work.

Comparison of Antioxidant and Free Radical Scavenging Activities of the Essential Oils from Flowers and Fruits of Otostegia persica Boiss

The aerial parts of the endemic plant of Otostegia persica Boiss. in two different stages of flowering and fruiting were hydro-distilled to extract oils in the yields of 0.3 and 0.15% (v/w), respectively. The oils were analyzed by GC and GC/MS. Twenty-eight and thirty-one components were identified, representing 97.59 and 94.61% of the oils, respectively. The main compounds of the essential oil flowers (EOFL) were alpha-pinene (17.21%), 1-octen,3-ol (13.44%) and cubenol (7.27%), whereas diisooctyl phthalate (45%) and hexadecanoic acid (11.07%) were the major constituents of the essential oil of the fruits (EOFR). The oils were screened for their possible antioxidant activities by two complementary test systems, namely DPPH free radical-scavenging and ammonium thiocyanate. In both tested systems, EOFL exerted greater antioxidant and radical scavenging activity. In the first case, EOFL exerted antioxidant activity with an IC50 19.8 +/- 1.8 microg mL(-1) almost similar to BHA and ascorbic acid (15.2 +/- 1.1 and 17.4 +/- 1.3), respectively. In the ammonium thiocyanate system, the inhibition rate of oxidation of linoleic acid for EOFL was estimated 93.5 +/- 2.8. The higher activity of this oil in comparison to EOFR may be attributed to its high content of monoterpenes, especially oxygenated ones in the oil of the flowers.

Evolution of endogenous gibberellins at different stages of flowering in relation to return bloom of cactus pear ( Opuntia ficus-indica L. Miller)

The effect of flower emasculation, flower injection with paclobutrazol and the complete removal of the spring flush of flowers and cladodes on the changes in GA 3 concentration at different stages of bloom in flowers and fertile cladodes of Opuntia ficus-indica has been determined. Throughout the bloom period, the concentration of GA 3 was higher in intact flowers and the cladode than in flowers emasculated or injected with paclobutrazol. With the onset of blooming, GA 3 started to accumulate both in the flower and in the fertile cladode, and the highest concentration was measured at full bloom in the flower and in the cladodes whose flowers were not removed. Flower emasculation or removal similarly affected GA 3 concentration at any stage of bloom. Until petal shedding GA 3 concentration was higher in the flowers than in the fertile cladodes. Consistent return bloom occurred only when the spring flush was removed before bloom. Fruit resulting from flowers emasculated or treated with paclobutrazol had a smaller size, percent flesh and seed content than fruits produced by untreated flowers.

Change in Panicle Susceptibility Associated with Flowering Rate of Spikelets in Bacterial Grain Rot of Rice Caused by Pseudomonas glumae.

Change in susceptibility of rice spikelets (cvs. Koshihikari, Koganebare and Asominori) to bacterial grain rot, caused by Pseudomonas glumae, with time was examined by spraying bacterial suspension to panicles at different stages of flowering. Percentage of diseased spikelets of these varieties was highest when they were inoculated on flowering day and remained high when they were inoculated within 3 days after flowering. The disease was very low when spikelets were inoculated 2 days before or 4 days after flowering, even though spikelets were incubated under high humidity (RH<95%) condition for 24hr after inoculation. These results indicate that susceptibility of rice spikelets changes with time during a short, critical period before and after flowering and that high humidity at this stage is crucial to the infection of spikelets. Analysis on the relationship between susceptibility of a whole panicle and the flowering rate of spikelets within a panicle showed that panicle susceptibility depends on the rate of flowering per day after heading. This correlation indicates that susceptibility of rice plants to the disease in the field may be estimated from the heading rate of panicle in the field and from the extent of susceptibility of each panicle per day. The relative value for cumulative susceptibility of rice plants (Tt) in the field on the day t after first heading was represented by the value for total susceptibility of all panicles on the day t which was calculated by daily heading rate of panicles on days 0 to t after first heading in the field and by the panicle susceptibility on each day after heading. The Tt value of rice plants increased similarly from heading time, which is defined as the day when more than 40% of panicles have headed, and then decreased 5 to 6 days after heading time. Tt was very low about 12 days after heading time, suggesting that rice plants in the field are susceptible to the disease during a short length of time, i.e., from the heading time to about 11 days after that.