Abscisic Acid in Developing Zygotic Embryos of Theobroma cacao

Abscisic acid (ABA) levels were measured by enzyme-linked immunosorbent assay in developing zygotic embryos of Theobroma cacao. ABA was detected in all embryos tested, with a peak of ABA at levels of 1 to 3 micrograms per gram fresh weight during early maturation. This corresponded to embryos of 10 to 30% dry weight and to early stages of anthocyanin and lipid accumulation.     

Developmental profile of storage reserve accumulation in soybean somatic embryos

Soybean somatic embryos were developed as a model for investigating the developmental relationships of lipid biosynthesis and accumulation in this important crop. Batch cultures of embryos grown for 8 wk in liquid culture medium exhibited typical sigmoidal growth kinetics as they passed through characteristic globular, heart, torpedo, and cotyledon stages. Exponential growth occurred for the first 4 wk in culture with net growth terminating when total embryo fresh weight per culture flask reached a maximum of 4–4.5 g at 6 wk. This was followed by a slight decrease in embryo fresh weight (FW) and the onset of apparent tissue senescence as judged by yellowing and browning of embryos. On a FW basis, embryos accumulated up to 4% protein, 2.5% soluble sugars, 1.9% starch, and 1.5% lipid relatively early in development. Levels decreased to 0.8% protein, 0.5% soluble sugars, 0.03% starch, and 0.09% lipid at the end of the culture period. On a mass percent basis, lipid extracts were comprised of approximately 80–90% polar lipid early in embryo development. This shifted to 56% storage lipid (triacylglycerol) and 44% polar lipid after 4–5 wk in culture and then reverted back to 91% and 9% polar vs. storage lipid, respectively, by the end of the 8-wk culture period. On the average, polar and storage lipid fractions were comprised of 24% palmitic acid, 7% stearic acid, 8% oleic acid, 36% linoleic acid, and 26% linolenic acid. However, the amounts of linoleic and linolenic acids declined sharply during embryo senescence at the end of the culture period, with corresponding increases in the combined amounts of palmitic and stearic acids. This is the first report that documents the progress of storage reserve accumulation in soybean somatic embryos in relation to their continuous growth in liquid batch cultures.     

THE PHYSICAL AND CHEMICAL ENVIRONMENT OF THE DEVELOPING EMBRYO OF PINUS RESINOSA

The relationship between changes in soluble protein, hexose sugar, total lipid concentration, and osmotic potential occurring in gametophytic supernatant of Pinus resinosa Ait. during in vivo embryogenesis was measured. The effects of varying sucrose levels of culture medium on in vitro embryo and gametophyte development were examined. Increases in embryo volume, and fresh and dry weight of the female gametophyte during in vivo embryogenesis coincide with increasing levels of soluble protein, hexose sugar, and total lipid in the gametophytic supernatant. In contrast, osmotic potential of the supernatant increased only slightly between the zygote and proembryo stages of embryo development, and remained constant thereafter. Gametophytes plus embryos grown in vitro achieved dry weights approaching those of in ovulo gametophytes on media containing levels of sucrose up to 21%. Gametophytes on media with sucrose concentrations up to 21% also resembled normal in ovulo gametophytes in appearance. However, embryo development appeared to be suspended on treatment media containing from 9% to 21% sucrose, while embryos degenerated on media with constant sucrose levels of 3% and 6%. A treatment medium containing approximately 12% sucrose would provide an osmotic environment that duplicates that found in ovulo. While greater sucrose levels promoted more normal gametophyte development in Pinus resinosa, we failed to achieve complete development of the embryo in vitro. Conclusions and implications drawn from these results are discussed.     

Developmental stages and chemical composition in embryos of the cockroach, Diploptera punctata, with observations on the effect of diet

A developmental time-table has been established for the embryos of viviparous Diploptera punctata. The percentage of gestation time occupied by pre-dorsal closure stages is only 19 per cent compared to 40 or 50 per cent in non-viviparous species. The increase in wet weight of the embryos begins several days before dorsal closure and continues throughout gestation. The increase in dry weight, protein, carbohydrate, and uric acid does not begin until shortly after dorsal closure but thereafter parallels the increase in wet weight.The increase in oöcyte protein during vitellogenesis is tenfold, less than in oviparous or ovoviviparous species. But the increase in embryo protein during gestation is sixtyfold; this characterizes viviparity in D. punctata.Although total lipid increases during gestation, lipid as a percentage of wet weight decreases most rapidly before dorsal closure and less rapidly there-after. It is suggested that before dorsal closure lipid is the major energy source for development. After dorsal closure the embryos are able to drink through their mouths the fluid nutrient provided by the mother.The ultimate source of nutrients required by developing embryos is the maternal diet during gestation. Females starved from ecdysis do not produce young; females fed only sugar from ecdysis produce viable larvae but suffer loss in body weight. Embryos from such females, although normal in length, are deficient in protein.     

Ultrastructural changes in wheat embryos during a “presowing drought hardening” treatment

Summary Changes in the ultrastructure of the shoot apex of wheat embryos were studied during a reputed drought hardening treatment consisting of 48 hours of hydration followed by dehydration to air dry weight and during a subsequent second hydration for 48 hours. In the initial dry state lipid droplets are closely packed against the cell walls and the mitochondria and plastids have little internal structure. During the first hydration the lipid droplets are reduced in number and disperse while the mitochondria and plastids assume a normal appearance. The nucleus does not change appreciably. Under the conditions used in this work dehydration to air dry weight is not lethal to the embryos although notable changes in cellular structure occur: 1. Massive condensation of the normally loosely organized chromatin, 2. some loss of internal mitochondrial structure, 3. specific association of short elements of rough ER with vacuoles and lipid droplets, and 4. formation of fibrillar elements in the cytoplasm. In some respects then, embryos dehydrated after a 48 hour soaking have a very different structure to that of embryos that have dried during maturation of the seed. Since these changes are, in the case of viable embryos, reversible upon rehydration they cannot be linked, as such, to any long term drought hardening effect of the treatment. It is suggested that some changes, particularly the condensation of chromatin, may indicate a protective response to water stress. The kind of information needed to sustain this suggestion is discussed.This project is supported by grants from the Rural Credits Development Fund and the Australian Research Grants Committee.     

Composition, Degradation and Utilization of Endosperm During Germination in the Oil Palm (Elaeis guineensis Jacq.)

The insoluble carbohydrate and lipid fractions, and -D-galactosidase,ß-D-mannosidase and isocitrate lyase activities werestudied in the various tissues of oil palm (Elaeis guineensisJacq.) kernels prior to and during germination. In ungerminatedkernels insoluble carbohydrate and lipid constituted 36 and47% of endosperm dry weight respectively. During germinationthe thick endosperm cell walls became markedly thinner, concurrentwith a significant decrease in the percentage of insoluble carbohydrateand an increase in -galactosidase and ß-mannosidaseactivity in both degraded and residual endosperm. The proportionof lipid in degraded endosperm also increased significantly.The insoluble carbohydrate appears to be a galactomannan locatedin the secondary walls of the endosperm. No galactomannan wasdetected in oil palm embryos or haustoria. Isocitrate lyasewas present in, and confined to, tissues of the haustorium ofgerminating kernels. The enzyme was not active in endospermat any stage of germination, nor was it active in embryos beforeor at the end of imbibition. The results suggest that galactomannan is the second largestcomponent of oil palm endosperm and that it is utilized morerapidly than lipid during the early stages of germination. Thefact that isocitrate lyase activity is confined to the haustoriumsuggests that in Elaeis gluconeogenesis, the conversion of triglycerideto carbohydrate, takes place entirely within the cotyledon ofthe seed. Elaeis guineensis, galactomannan, galactosidase, germination, isocitrate lyase, mannosidase, oil palm     

Lipids in yolks and neonates of the viviparous lizard Niveoscincus metallicus

Niveoscincus metallicus is a small viviparous skink which provides a substantial amount of yolk to each of its developing embryos although some organic nutrients are also transferred across the placentae. The total amount of lipid present in the yolk of N. metallicus (37% of dry weight) is very much higher than that in the newborns (19% of dry weight), confirming that the yolk is utilised as an energy source during gestation. Triacylglycerols (TAG), which are storage compounds, are the major lipid resource available to the embryos and are present in relatively large amounts in the yolk of N. metallicus. Polar lipids (PL), which form the structural components of membranes, and sterols (ST), which are involved in the synthesis of hormones and vitamins, are also present in the yolk. The proportions of each of these lipid classes differs markedly between yolks and newborns. This may reflect variations in the role played by each lipid class in the provision of nutrients to, and development of, embryos.     

Organic,inorganic, and caloric composition of eggs,pentaculae, and adults of the brooding sea cucumber Cucumaria curata cowles (Echinodermata: Holothuroidea)

Levels (percentage composition) of water, ash, carbohydrate, lipid, protein, and calories were determined for eggs, pentaculae, and adults of the sea cucumber Cucumaria curata Cowles. Component contents (μg/individual) were calculated for eggs and pentaculae. During the 28 days of development to hatching, the large yolky eggs gain water and ash, the total dry weight increasing from 169 to 190 μg/egg during embryogenesis. There were no statistically significant changes in lipid, protein, and caloric contents during embryogenesis, but carbohydrate decreased by 0.82 μg/egg.The decrease in carbohydrate is sufficient to account for estimated embryonic energy requirements. Based on the utilization of carbohydrate, embryos of C. curata show a nutritional pattern similar to that of the planktonic embryos of sea urchins and different from that of embryos developing from terrestrial eggs, freshwater eggs, and planktonic and demersal marine eggs.Although broods varied widely in egg number and mean egg dry weight, C. curata gives eggs which contain a constant proportion of organic components.Levels of ash, water, and protein in the adults exceeded those in the pentacula, and lipid comprises a much smaller proportion of the adult body than it did of the pentacula.     

Nitrogen distribution and excretion during embryonic post-yolk sac development inZoarces viviparus

In the viviparous teleostZoarces viviparus (L.) embryonic post-yolk sac development in the ovary is characterized by significant increases in dry weight and nitrogen per embryo, thus indicating an extensive matrotrophic relationship. In the ovarian fluid surrounding the embryos during their intraovarian development, sources of nitrogen were shown to derive from amino acids, urea, ammonia and various cellular components. The level of urea in the ovarian fluid increased significantly from 3.68±0.25 mol urea-N·ml^-1 during early post-yolk sac embryonic development to 6.14±0.44 in late development. The corresponding level of ammonia-N in the ovarian fluid increased from 0.25 to 0.45 mol·ml^-1. An estimation of embryonic nitrogen loss was made by measuring urea and ammonia-N excretion in vitro by post-yolk sac embryos or larvae (i.e. seawater-acclimated embryos). Urea-N constituted an average of 65% of the total nitrogen excreted by the embryos into the ambient medium during a 5-h time-course compared to only 35% in the larvae. Urea-N was excreted at maximum rates during the first hour of the experiment, 0.54±0.09 mol N·g^-1·h^-1 by embryos and 0.35±0.02 by larvae, and then declined to lower levels in both embryos and larvae. A decline after 1 h was also observed for excretion rates of ammonia. In conclusion, the capacity for urea excretion by post-yolk sac embryos ofZ. viviparus may be of adaptive significance for their prolonged stay in ovario. The capacity for excretion of urea seems to decrease after acclimation to sea water.Abbreviations aa amino acid(s) - bm body mass - dw dry weight - NPS ninhydrin-positive substances - sw sea water - ww wet weight     

Sugarbeet leaf disc culture: an improved procedure for inducing morphogenesis

In preparation for gene transfer experiments we investigated factors that might affect the production of shoots and somatic embryos from the wound callus of cultured sugarbeet leaf discs. A complex interaction was found between the leaf disc plating density, the disc culture medium, the source-shoot culture medium and the frequency of disc transfer to fresh medium. The most productive protocol utilized: source shoots maintained on MS medium containing 0.25 mg 1^-1 BA; multiple leaf discs (ten 4-mm discs/plate) plated onto an enriched modification of MS medium (RV) containing 1.0 mg 1^-1 BA and solidified with 0.3% Gelrite (not permitted to dry during hardening); and transfer of the discs to fresh medium every two weeks during the first month. This standard protocol produced more callus per plate and higher rates of morphogenesis per unit dry weight of callus than did the one-step method of Saunders and Doley. Water availability considerations were found to be critical to obtaining high morphogenic rates. Root induction frequency and quality was superior on shoots transplanted to MS medium containing 1 mg 1^-1 NAA as the sole growth regulator compared to IAA at the same concentration.Abbreviations BA N⁶-benzyladenine - IAA indole-3-acetic acid - NAA -naphthaleneacetic acid     

Metabolism of carbohydrate and lipid reserves in germinated cotton seeds

Utilization of reserve lipid and carbohydrates during germination (0–12 h) and postgerminative growth (12–48 h) was studied in cotton (Gossypium hirsutum L.) seedlings. Raffinose and stachyose were utilized during the germination period and early growth; mobilization was associated with -galactosidase (EC 3.2.1.22) activity. Results from pulse-chase experiments with [³H]raffinose supplied exogenously to 4-h soaked seeds indicated that raffinose-derived catabolites contributed to the coincident increase in cotyledon sucrose and starch, and to the small increase in axis dry weight. Starch appears to be an alternative sink for end products of hydrolysis of reserve carbohydrates prior to the onset of rapid axis growth and cotyledon expansion. Mobilization of neutral lipid commenced at about 16 h after soaking, concomitant with development of key glyoxylate-cycle and other gluconeogenesis-related enzyme activities. Axis dry weight increased three-fold between 24 and 48 h. Results from pulse-chase (3 h, 16 h) experiments in which [2-¹⁴C]acetate was supplied to cotyledons of intact 22-h-old seedlings showed that acetate-derived metabolites were not transported exclusively to the axes, but were partitioned between axes and cotyledons. Only 27% of total incorporated radioactivity was recovered in axes following the chase, 18% was evolved as CO₂, and the rest was recovered in water-soluble substances (20%) and polymers (31%) within the cotyledons. Of the polymers, 55% of the activity was in polysaccharides (Starch, pectic substances, hemicellulose, cellulose), 25% in protein, and 20% in unidentified neutral and acidic compounds. Considering these data, the amount of lipid mobilized, and various routes by which supplied [2-¹⁴C]acetate could be metabolized, it appears that lipidderived compounds contribute only 25–40% of axis dry-weight gain. Lipid-derived substances retained in the cotyledons likely are utilized for expansion and differentiation of the cotyledons into photosynthetic organs.     

Toxicity of antibiotics on zygotic embryos of white spruce (Picea glauca) cultured in vitro

The toxicity of kanamycin, hygromycin B, geneticin, methotrexate and cefotaxime on zygotic embryos ofPicea glauca was studied. Embryos placed on bud induction medium produced approximately 20 adventitious buds per embryo under control conditions. Addition of antibiotics reduced the number of bud-forming embryos. Using the percentage of embryos with buds as an indication of antibiotic toxicity, two-day-old explants were found to be more sensitive than nine-day-old. Kanamycin toxicity was enhanced by cefotaxime and this effect increased with increases in concentration of either antibiotic. Although no morphological difference was observed after 21 days, embryos growing on medium containing 20 g ml^–1 kanamycin showed a decrease of 73% in dry weight and 23% in protein content per embryo when compared to control embryos. Similarly, a decrease of 38% in dry weight and 40% in protein content per embryo was found in embryos on medium containing 300 g ml^–1 cefotaxime.Abbreviations BA 6 benzyl-aminopurine - EDTA ethylenediamine-tetraacetic acid - PVP 10 polyvinylpyrrolidone (MW 10,000) - Tris-HCl Tris [hydroxymethyl] amino hydrochloride NRCC No. 30262     

The microspore-derived embryo ofBrassica napus L. as a tool for studying embryo-specific lipid biogenesis and regulation of oil quality

Summary A time-course study of lipid accumulation in microspore-derived embryos and developing zygotic embryos of rapeseed (Brassica napus L. ssp.oleifera) is presented. Rapid storage fat (triacylglycerol) biosynthesis was induced in microspore-derived embryos of oilseed rape (cv Topas) when the embryos were transferred from standing cultures (10 ml) to fresh medium (75 ml) and shake cultured. Triacylglycerols accumulated, after a lag period of 7 days, at a linear rate of approximately twice that of the developing zygotic embryo. The fatty acid composition of triacylglycerols in microspore-derived embryos closely parallelled that of the developing zygotic embryos. In the microspore-derived embryos, the amount of phosphatidylcholine, the major substrate for the production of polyunsaturated fatty acids in oilseeds, remained constant during the linear phase of triacylglycerol production, whereas it increased steadily in the zygotic embryos. The fatty acid composition of individual cotyledons from microspore embryos shake cultured for 15 days was compared with that of individual mature seeds. Relative amounts of the major fatty acids, i.e. palmitic, oleic and linoleic acids, were essentially the same, whereas the microspore-derived embryos had about 35% less stearic acid and 35% more linolenic acid than the mature seeds. Variation in the amounts of oleic, linoleic and linolenic acids between seeds was similar to that found between cotyledons of microspore-derived embryos, whereas variation in palmitic and stearic acid levels was significantly lower between microsporederived cotyledons than between the seeds. The results indicate that microspore-derived embryos from shake cultures should be convenient for use in studying the regulation of oil biosynthesis and for rapidly screening for oil quality in genetically altered rapeseed.     

Evidence for the accumulation of peroxidized lipids in membranes of senescing cotyledons

Fluorescent products of lipid peroxidation accumulate with age in microsomal membranes from senescing cotyledons of Phaseolus vulgaris. The temporal pattern of accumulation is closely correlated with a rise in the lipid phase transition temperature reflecting the formation of gel phase lipid. Increased levels of fluorescent peroxidation products are also detectable in total lipid extracts of senescent cotyledons. Lipoxygenase activity increases with advancing age by about 3-fold on a fresh weight basis and 4-fold on a dry weight basis indicating that the tissue acquires elevated levels of lipid hydroperoxides. As well, levels of glutathione and superoxide dismutase activity decline on a dry weight basis as the cotyledons age, rendering the tissue more susceptible to oxidative damage. Catalase activity rises initially and then declines during senescence, but peroxidase activity rises steeply. Thus, apart from this increase in peroxidase, which would scavenge H₂O₂ only if appropriate cosubstrates were available, the defense mechanisms for coping with activated oxygen species (O₂⁻, H₂O₂, OH) are less effective in the older tissue. The observations support the contention that formation of gel phase lipid in senescing membranes is attributable to lipid peroxidation and suggest that the reactions of lipid peroxidation are utilized by the cotyledons to mediate deteriorative changes accompanying the mobilization and transport of metabolites from the storage tissue to the developing embryo.     

Major differences in isoforms of starch-branching enzyme between developing embryos of round- and wrinkled-seeded peas (Pisum sativum L.)

In order to determine whether round-and wrinkled-seeded peas (Pisum sativum L.) differ in the activity and properties of starch-branching enzyme (1,4--D-glucan, 1,4--D-glucan-6-glycosyl transferase; EC 2.4.1.18) in their developing embryos, essentially isogenic lines of peas, differing only at the r (rugosus) locus that confers the round (RR, Rr) or wrinkled (rr) phenotype, were studied. Activity of the enzyme rises rapidly from an early stage of development in embryos of round peas, but only at later stages in embryos of wrinkled peas. The purified enzyme from mature embryos of round peas can be resolved into two isoforms that differ in molecular weight and in their ability to branch amylose. The purified enzyme from mature embryos of wrinkled peas is a single protein with the same molecular weight and branching properties as one of the isoforms from embryos of round peas. The difference in activity of starch-branching enzyme between embryos of round and wrinkled peas is likely to be due to the absence from embryos of wrinkled peas of one of the isoforms occurring in embryos of round peas.Abbreviations DEAE diethylaminoethyl - FW fresh weight - kDa kilodalton - SDS sodium dodecyl sulfate     

Differential,temporal and spatial expression of genes involved in storage oil and oleosin accumulation in developing rapeseed embryos: implications for the role of oleosins and the mechanisms of oil-body formation

The temporal and spatial expression of oleosin and ₉-stearoyl-ACP desaturase genes and their products has been examined in developing embryos of rapeseed, Brassica napus L. var. Topas. Expression of oleosin and stearate desaturase genes was measured by in situ hybridisation at five different stages of development ranging from the torpedo stage to a mature-desiccating embryo. The temporal pattern of gene expression varied dramatically between the two classes of gene. Stearate desaturase gene expression was relatively high, even at the torpedo stage, whereas oleosin gene expression was barely detectable at this stage. By the stage of maximum embryo fresh weight, stearate desaturase gene expression had declined considerably while oleosin gene expression was at its height.In contrast to their differential temporal expression, the in situ labelling of both classes of embryo-specific gene showed similar, relatively uniform patterns of spatial expression throughout the embryo sections. Immunogold labelling of ultra-thin sections from radicle tissue with anti-oleosin antibodies showed similar patterns to sections from cotyledon tissue. However, whereas at least three oleosin isoforms were detectable on western blots of homogenates from cotyledons, only one isoform was found in radicles. This suggests that some of the oleosin isoforms may be expressed differentially in the various types of embryo tissue. The differential timing of stearate desaturase and oleosin gene expression was mirrored by similar differences in the timing of the accumulation of their ultimate products, i.e. storage oil and oleosin proteins. Oil-body fractions prepared from young (2.5 mg) embryos contained very little oleosin protein, as examined by SDS-PAGE and western blotting, whereas identically prepared fractions from dry seeds contained over 10% (w/w) oleosin. Dehydration of oil bodies from young embryos resulted in their breakdown and coalescence into large clumps of oil which could not be re-emulsified, even after rehydration. In contrast, the oleosin-rich oil bodies from mature embryos were stable to dehydration and subsequent rehydration. It is suggested that, in developing rapeseed embryos, the accumulation of storage oil and oleosins is not concomitant but that the eventual deposition of oleosins onto the surfaces of storage oil bodies is essential for their stability during seed desiccation.Abbreviations ABA abscisic acid - ACP acyl carrier protein - GLC gas-liquid chromatography - PBS phosphate-buffered saline     

The arrest of embryogenesis at gastrula stage in the diapausing silkwormBombyx mori is related to the synthesis of protein P61

Summary Two-dimensional protein gels are used to assess systematically changes in protein synthesis in diapausing and non-diapausing early embryos ofBombyx mori throughout natural breakage of diapause by chilling and after artificial prevention of diapause by HCl+ heat-shock treatment. A set of proteins, the heat-shock protein (hsp) 70 family previously described, was synthesized in diapausing and non-diapausing development at the early germ-anlage stage; by contrast, protein 61 (P61; 61 kDa) was synthesized only in the diapausing gastrula stage. The synthesis of P61 decreased during days at 5°C. Thereafter, we observed the synthesis of the hsp 70 family at 5°C. After the artificial prevention of diapause, P61 synthesis was not induced at the gastrula stage, whereas the hsp 70 family was enhanced in the 6 h following the preventive treatment. P61 was only synthesized after treatments were ineffective in preventing diapause and in inducing hsp 70. Thus, P61 can be described as a diapause arrest-associated protein.     

Protein and lipid content of the rotifer Brachionus plicatilis during variable growth and feeding condition

Rotifers (Brachionus plicatilis) grown atdifferent growth rate ( = 0.05–0.39 d^–1)were analyzed for protein, lipid, fatty acids, aminoacids and free amino acids, and values are expressedin terms of individuals and dry weight. Increase ingrowth rate is equivalent with increased food rationof the individual rotifer, which responded by higheregg ratio. The protein content per individualrotifer increased by 60–80% when the growth rate increased, whereas the protein content per dryweight showed a slight, although insignificant,increase (p > 0.05). The lipid content perindividual was constant, whereas lipid per dryweight decreased when the growth rate increased. Theratio DHA/EPA decreased when the growth ratesincreased. The amino acids profile in percent oftotal amino acids showed low variation betweencultures maintained at different growth rates,whereas the values expressed in terms of amino acidper individual showed higher variation. The range ofvariation for free amino acids was more pronouncedthan for total amino acids.Short-term food enrichment of poorly fed rotifers( = 0.05 d^–1) with balanced protein richdiet resulted in increased protein and lipid contentper rotifer. The protein content per dry weightshowed only minor changes whereas lipid per dryweight increased. Contrary, short term enrichmentwith a lipid rich diet resulted in increased lipidcontent per individual rotifer and per dry weight,whereas the protein content per individual remainedconstant and the protein content per dry weightshowed a slight decrease.Our experiments show that the amount of protein, wasquite variable in rotifers, and that feeding andgrowth condition were decisive factors affecting it.The range of variation was large enough to be animportant factor during first feeding of marinelarvae, and should therefore be considered infeeding larvae.     

Increased oxidative stress,lipid peroxidation and protein degradation trigger senescence in <Emphasis Type="Italic">Iris versicolor</Emphasis> L. flowers

Dynamics in various physiological and biochemical aspects were studied during various stages (I—tight bud stage to VI—senescent stage) of flower development in Iris versicolor. Floral diameter, fresh & dry mass and water content increased during flower opening and decreased towards senescence. Senescence was found to be related to the increased lipid peroxidation which was reflected in the decreased membrane stability index towards senescence. This increase in the lipid peroxidation was probably initiated by increased lipoxygenase activity which shot up just prior to the increase in lipid peroxidation. Soluble protein content showed a marginal decrease towards senescence with a corresponding increase in specific protease activity. Sugar fractions and α-amino acids showed a significant decrease towards senescence. Superoxide dismutase and ascorbate peroxidase activity increased as the flowers opened and thereafter a significant decrease was registered towards senescence. Catalase activity improved as the flower matures, but decreased prior to flower opening through senescence. The protein patterns from the tepal tissues resolved through electrophoresis showed a consistency in proteins upto the flower opening but a marginal decrease was registered in both high and low molecular weight proteins towards senescence. However, a protein of molecular weight 76.5 kDa showed up during senescent stages which may have a role in flower senescence.