Detection and Isolation of Preformed Antifungal Compounds from the Peel of Pyrus bretschneideri Rehd. cv. Pingguoli at Different Stages of Maturity

Ethanol‐dichloromethane crude extract from peel of pear (Pyrus bretschneideri Rehd. cv. Pingguoli) was separated by thin layer chromatographic plates and bioassayed with conidia of Alternaria alternata. The inhibition zones differed significantly in retention factor (R_f) at expanding stage, harvest time and after 100 days of cold storage. The compounds in the inhibition zones were isolated and identified with gas chromatography and mass spectroscopy. Palmitate methyl, oleic acid methyl, linolenic acid methyl and squalene were present at all stages. The concentration of these chemicals was the highest in expanding stage fruit peel and decreased rapidly with fruit development. It is suggested that these compounds may be the main antifungal compounds in the growing fruit. The phthalate alkyl esters occurred at relatively higher concentrations in pear peel at harvest and after 100 days of cold storage. Six phthalate alkyl esters were identified from peel of pear fruit after 100 days of cold storage. It is also supposed that these esters may be the antifungal compounds in postharvest pear.     

Plastid structure and carotenogenic gene expression in red- and white-fleshed loquat (Eriobotrya japonica) fruits

Loquat (Eriobotrya japonica Lindl.) can be sorted into red- and white-fleshed cultivars. The flesh of Luoyangqing (LYQ, red-fleshed) appears red-orange because of a high content of carotenoids while the flesh of Baisha (BS, white-fleshed) appears ivory white due to a lack of carotenoid accumulation. The carotenoid content in the peel and flesh of LYQ was approximately 68 μg g(-1) and 13 μg g(-1) fresh weight (FW), respectively, and for BS 19 μg g(-1) and 0.27 μg g(-1) FW. The mRNA levels of 15 carotenogenesis-related genes were analysed during fruit development and ripening. After the breaker stage (S4), the mRNA levels of phytoene synthase 1 (PSY1) and chromoplast-specific lycopene β-cyclase (CYCB) were higher in the peel, and CYCB and β-carotene hydroxylase (BCH) mRNAs were higher in the flesh of LYQ, compared with BS. Plastid morphogenesis during fruit ripening was also studied. The ultrastructure of plastids in the peel of BS changed less than in LYQ during fruit development. Two different chromoplast shapes were observed in the cells of LYQ peel and flesh at the fully ripe stage. Carotenoids were incorporated in the globules in chromoplasts of LYQ and BS peel but were in a crystalline form in the chromoplasts of LYQ flesh. However, no chromoplast structure was found in the cells of fully ripe BS fruit flesh. The mRNA level of plastid lipid-associated protein (PAP) in the peel and flesh of LYQ was over five times higher than in BS peel and flesh. In conclusion, the lower carotenoid content in BS fruit was associated with the lower mRNA levels of PSY1, CYCB, and BCH; however, the failure to develop normal chromoplasts in BS flesh is the most convincing explanation for the lack of carotenoid accumulation. The expression of PAP was well correlated with chromoplast numbers and carotenoid accumulation, suggesting its possible role in chromoplast biogenesis or interconversion of loquat fruit.     

Biochemical changes associated with the ripening of hot pepper fruit

Hot pepper ( Capsicum annuum L. cv. Chooraehong) fruit underwent a respiratory climacteric during ripening. However, the rate of ethylene production was low, reaching a maximum of approximately 0.7 μl kg⁻¹ h⁻¹ at the climacteric peak when the surface color was 30 to 40% red. Ripening was accompanied by a loss of galactose and arabinose residues from the cell wall. The content of uronic acid and cellulose in the wall changed only slightly during ripening. The average molecular weight of a cell wall hemicellulosic fraction shifted progressively toward a lower molecular weight during ripening. Total β-galactosidase (EC 3.2.1.23) activity increased 50-fold from the immature green to the red ripe stage. No polygalacturonase (EC 3.2.1.15) activity was detected at any stage of ripeness. Thus, the loss of galactose and arabinose residues from the cell wall, as well as the observed modification of hemicelluloses during ripening, seem to be unrelated to active polygalacturonase. Soluble polyuronide content remained relatively constant at approximately 60 μg (g fresh weight)⁻¹ as fruit ripended.     

Banana harvest maturity and fruit position on the quality of ripe fruit

There is an increasing market demand for smaller banana fruit. The way that this is being addressed involves harvesting some fruits on a bunch at a less advanced stage of maturity. Experiments were carried out to investigate the effect of age of fruit at harvest, position of the fruit on the bunch and different banana varieties on the speed of ripening and the quality of the ripe fruit at two different ripening temperatures after being exposed to exogenous ethylene. The maturity of bananas at harvest affected both the speed of ripening and the quality of the ripe fruit. Speed of ripening of fruit at 13°C was slower the more immature the fruit at harvest, but there was no effect on the speed of ripening of harvest maturity at a ripening temperature of 16°C. The effects of harvest maturity and position of the fruit on the bunch on peel colour and texture were significant but so small that they would be unlikely to affect the consumers' perception in a commercial situation. The higher soluble solids, flavour, sweetness and acceptability after ripening of the more mature fruit at harvest was sufficiently high that consumers could probably detect them.     

Effect of cold storage on larval and adult Anastrepha ludens (Diptera: Tephritidae) viability in commercially ripe, artificially infested Persea americana 'Hass'

Commercially ripe 'Hass' avocados, Persea americana Mill, artificially exposed to wild Anastrepha ludens (Loew) (Diptera: Tephritidae) females 24 h after harvest were placed in a cold storage facility to determine the effect of low temperature on larval survival and adult viability. Fruit were left for 3, 6, 9, and 12 d in a cold room at 5 degrees C followed by a 20-25-d period at ambient temperature to allow for larval development and pupation. Hass avocados and grapefruit, Citrus paradisi Macfadyen, maintained at ambient temperature served as controls. Overall, only 0.23% of the Hass avocados and 19.30% of the grapefruit were infested. The number of infested fruit increased with decreasing exposure time to cold. Puparia from cold-treated Hass avocados were significantly smaller than those stemming from cold-treated grapefruit. Hass avocados exposed for 12 d to 5 degrees C yielded no puparia, and those exposed for 6 and 9 d yielded 22 and two puparia, respectively, but no adults. Although Hass avocados exposed to cold temperature for 3 d yielded adults that reached sexual maturity (N = 16), females laid inviable eggs. Grapefruit exposed to cold for 12 d yielded normal-sized puparia (but no adults), whereas those exposed over 9 d yielded females able to lay viable eggs. We conclude that exposing fruit to cold storage after packing and during transport represents an effective risk-mitigating procedure in the highly improbable event that a gravid A. ludens female might lay eggs in a commercially ripe Hass avocado that had been left unprotected in a packinghouse.     

Insecticidal activity of Citrus aurantium fruit, leaf, and shoot extracts against adult olive fruit flies (Diptera: Tephritidae)

Solvent extracts of differing polarity from Citrus aurantium (L.) (Rutaceae) fruit, leaves, and shoots were evaluated for biological activity against adults of the olive fruit fly, Bactrocera oleae (Gmelin) (Diptera: Tephritidae). Using a petri dish residual exposure bioassay, we found that the petroleum ether extract from fruit alone showed insecticidal activity against the flies. The extract of the three fruit tissues (flavedo [peel], albedo, and flesh) indicated that bioactivity was limited to the flavedo, and this activity was significantly higher than that of the whole fruit extract. The most effective extract was obtained when fresh flavedo was used, whereas extracts of oven-dried flavedo were inactive. Fruit maturity also affected bioactivity; extracts of ripe fruit were more effective than those of unripe fruit. Our results suggest that C. aurantium flavedo contains secondary metabolites with insecticidal activity against B. oleae adults.     

Endogenous levels of polyamines and abscisic acid in pepper fruits during growth and ripening

The levels of polyamines (PA) and abscisic acid (ABA) in the pericarp of California variety pepper fruit ( Capsicum annuum L.) were analyzed during development and ripening. Putrescine level was 2.75 μmol g⁻¹ fresh weight 7 days after fruit set and fell during the exponential stage of growth to 1.05 μmol g⁻¹ fresh weight. During the second growth stage. PA and ABA levels remained stable and fell sharply at the beginning of maturation. The levels of spermidine and spermine decreased throughout fruit development and maturation from 0.61 to 0.05 and 0.31 to 0.02 μmol g⁻¹ fresh weight, respectively, but no changes were associated with the onset of maturation. ABA levels remained high (0.70-0.80 μg g⁻¹ fresh weight) during the stages of fruit growth and fell at the beginning of maturation to 0.12 μg g⁻¹ fresh weight, before rising again during the last stages of maturation and senescence. The decrease in putrescine and ABA levels and the subsequent increase in the latter may be responsible for controlling the processes of ripening in pepper fruit.     

Bioactive Compounds of Fruit Parts of Three Eugenia uniflora Biotypes in Four Ripening Stages

Variability of secondary metabolites in edible (peel and pulp) and inedible (seeds) parts of three pitanga varieties, red, red-orange and purple, was investigated during the maturation process. Hydrolysable tannins, anthocyanins, and flavonoids were quantified by HPLC/DAD and carotenoids by absorbance. Peel/pulp showed greater complexity of constituents (carotenoids, anthocyanins, flavonoids, and hydrolysable tannins), while only tannins were identified in seeds, but in quantities of 10 to 100 times greater. The red-orange variety showed the highest levels of phenolic compounds in seeds and peel/pulp, except anthocyanins. The analysis of the principal response curves showed that the pitanga biotype has greater influence on metabolite variation than ripening stages. During peel/pulp maturation, a reduction in the levels of flavonoids and tannins contrasted with an increase in carotenoids and cyanidin-3-O-glucoside in all varieties, whereas in the seeds oenothein B, the major tannin, increased up to 1.32 g/100 g fresh weight. Such marked differences between fruit parts demonstrate that the seeds in stages E3 and E4 are a source of hydrolysable tannins, compounds known for their antitumor activity, while peel/pulp of all varieties in the ripe stage provide natural antioxidants, such as carotenoids and flavonoids. Lastly, the purple biotype can be a rich source of the cyanidin-3-O-glucoside pigment a potent bioactive compound.     

Role of Antifungal Gallotannins,Resorcinols and Chitinases in the Constitutive Defence of Immature Mango (Mangifera indica L.) against Colletotrichum gloeosporioides

Conidia of Colletotrichum gloeosporioides germinate and form infection hyphae on inoculated, immature mango but remain quiescent until fruit ripening. Antifungal resorcinols have previously been implicated for quiescence of C. gloesoporioides and Alternaria alternata on mango. This study revealed the presence of a mixture of several gallotannins with glycosidic linkages, including 1,2,3,4,6‐penta‐O‐galloyl‐β‐D‐glucopyranose, with significant antifungal activity in the unripe mango fruit peel. Gallotannin antifungal activity was greater in a cultivar resistant (295.8 mm² inhibition) to anthracnose than in a susceptible (148.4 mm² inhibition) cultivar. In both, the activity decreased with ripening but the decrease was 10% less in the resistant cultivar. Three recorcinols, 5‐pentadecylresorcinol, 5‐(12‐cis‐heptadecenyl)resorcinol, AR 21 and another resorcinol derivative were present in the unripe fruit peel and all declined during ripening, more significantly the 5‐(12‐cis‐heptadecenyl)resorcinol and AR 21. Mango latex, when drained out, separates into an oily and aqueous phase. The aqueous phase showed significant chitinase activity and the ability to digest conidia of C. gloeosporioides. The oily phase has previously been reported to contain resorcinols. Draining fruits of latex soon after harvest resulted in greater incidence and severity of anthracnose at ripe stage. Chitinase activity was less in the peel of fruits from which latex was drained. The evidence suggests that the resistance of unripe mango to C. gloeosporioides is because of an elaborate constitutive defence system comprising antifungal resorcinols, gallotannins and chitinases.     

不同成熟度菠萝贮藏特性的差异

随着菠萝果皮由绿转黄,果肉硬度及可溶性固形物含量降低,可溶性糖醛酸含量增加,多聚半乳糖醛酸酶(PG)活性持续升高,而果胶脂酶(PE)活性在过熟期达到高峰并开始下降。研究表明,同一菠萝不同部位果肉硬度、PG活性及可溶性糖醛酸含量差异较大。     

Non-invasive photoacoustic spectroscopic determination of relative endogenous nitric oxide and ethylene content stoichiometry during the ripening of strawberries Fragaria anannasa (Duch.) and avocados Persea americana (Mill.)

Employing non-invasive photoacoustic spectrometry, emissions of nitric oxide (NO) and ethylene in post-harvest strawberries and avocados were monitored. A clear-cut stoichiometric relationship was found between the two gases: unripe fruit manifesting high NO and low ethylene levels-the converse in ripe fruit. Findings are discussed in the light of putative control of ethylene-promoted fruit senescence by endogenous NO.     

Isolation of defense-related genes differentially expressed in the resistance interaction between pepper fruits and the anthracnose fungus Colletotrichum gloeosporioides

Unripe mature green fruits of pepper (Capsicum annuum) are susceptible to Colletotrichum gloeosporioides, whereas ripe red fruits are not. We established this pepper-C. gloeosporioides interaction as a model system to study the fungal resistance that develops during ripening of nonclimacteric fruit. Histochemical examination of transverse sections suggested that fungal invasion 24 h after inoculation (HAI) and colonization 48 HAI are critical events that differentiate between resistant and susceptible interactions. Based on this observation, we used messenger RNA differential display to isolate defense-related genes differentially expressed at 24 and 48 HAI. RNA gel blot analysis showed that six out of eighty cloned cDNAs were differentially expressed after infection of ripe fruit. The proteins encoded by these six clones, ddP1, ddP3, ddP4, ddP6, ddP13, and ddP47, showed significant homology to aldehyde dehydrogenase, P23 protein, NP24 protein, cytochrome P450 protein, esterase, and MADS-box protein, respectively, and may be involved in the resistance of ripe fruit to C. gloeosporioides infection.     

柑橘果实的光合特性、产物运输及分配在糖分积累中的作用

测定了温州蜜柑 (CitrusunshiuMarc .cv .Miyagawawase)果实发育进程中干鲜重、果皮光合速率和叶绿素含量的变化 ,并用14 CO2 示踪技术研究了果皮和叶同化生成的光合产物在果实内的运输分配特性。结果表明 :果皮光合速率与叶绿素含量有关 ,随着叶绿素含量的下降 ,果实光合速率也快速下降。在果实完熟之前 ,即使是当果皮积累的干重超过汁囊时 ,叶同化产物仍主要分配到汁囊中 ;而在完熟阶段 ,果皮光合速率接近零 ,果皮成了叶同化产物的主要库。果皮的同化产物 ,主要保留在果皮中 ,输入到汁囊的比率随果实发育而下降 ,但高峰时也有 12 %输入汁囊。与对照相比 ,果实遮光处理后降低了果皮与汁囊的干重和含糖量。上述结果表明果皮光合产物主要用于果皮自身的发育并能减少对叶光合产物的依赖 ,同时也能部分增加汁囊糖的积累     

Latency of Infection in Unripe Avocados by Colletotrichum gloeosporioides is Not Due to Inadequate Enzyme Potential

Colletotrichum gloeosporioides produced exo-pectin lyase and protease in a) liquid cultures with incorporated washed cell wall material from unripe or ripe avocado and b) autoclaved immature fruit. The activity of exo-pectin lyase and protease produced in liquid cultures incorporating washed cell walls from immature fruits was almost the same as when washed cell walls from ripe fruits were incorporated. Ripe fruit tissue rotted by the fungus contained exo-pectin lyase, endo-polygalacturonase (endo-PG) and protease. The endo-PG was found to be endogenous to avocado fruit, and had a pH optimum of 5.5. The pH optima of exo-pectin lyase and protease were 8.5 and 7.5 respectively in all three enzyme preparations. All these enzyme preparations completely macerated avocado fruit tissue discs in vitro in less than 3 h of incubation but not potato tuber discs. Neither immature nor ripe fruit contained substances, proteinaceous or otherwise, which could inhibit the exo-pectin lyase or protease activity of these preparations. The results indicated that C. gloeosporioides possesses sufficient enzyme potential to invade cell walls of unripe fruit and that the fruit tissue does not have a mechanism to inactivate such enzymes.     

Comparative analysis of some biochemical parameters of argan pulp morphotypes (<Emphasis Type="Italic">Argania spinosa</Emphasis> (L) Skeels) during maturity and according to the continentality in Essaouira region (Morocco)

Argania spinosa (L.) Skeels is an endemic forest tree for Morocco. The phytochemical compounds evaluation of four different morphotypes of their fruit pulps was investigated. The total content of sugar, protein and phenolic compounds were monitored during three different stages of maturation in the semi-continental (Mejji) and littoral regions (R’zwa). Total sugars, proteins, phenolics increased up to the ripe stage of all argan fruit morphotypes in the two regions. Spherical shape had higher sugar and protein content than other morphotypes. A significant difference (p < 0.05), was demonstrated by Pearson’s test, between the different morphotypes at three stages studied for all the phytochemicals compounds. Likewise, ANOVA test established that the variation of this compounds was influenced by the stage of maturation and/or region of development and/or their interaction according to fruit shape. Results from this study revealed that the increase of these parameters level take place for the most part during the last stages of maturity which synchronize with fruit softening. Furthermore, our results showed information about the richness of argan fruit pulp in carbohydrates compounds and secondary metabolites as the possibility of their contribution in nutritive forage value especially at ripe stage.     

Estrogenic and antiestrogenic properties of clomiphene citrate in laboratory mice

The estrogen agonistic and antagonistic properties of clomiphene citrate were investigated in the mice. Clomiphene citrate was tested at various doses of 0.1, 1.0, 10 and 100 μg for three consecutive days in immature and mature bilaterally ovariectomized mice. Clomiphene citrate showed uterotrophic activity in both immature and ovariectomized conditions. The lower doses of 0.1 and 1.0 μg were ineffective to show any uterotrophic stimulation. Clomiphene citrate at 10 μg dose produced 305.56% increase in uterine weight i.e., 27.70 ± 0.24 vs 6.83 ± 0.06 in immature and 182.27% i.e., 42.68 ± 1.12 vs 15.12 ± 0.57 in ovariectomized mice. Clomiphene citrate at 100 μg dose showed significant uterotrophic effect e.g., 435.57% i.e., 36.58 ±0.34 vs 6.83 ± 0.06 in immature and 586% i.e., 103.80 ± 0.60 in ovariectomized mice. When clomiphene citrate was administered in combination with 0.32 μg of estradiol 17-β it caused significant antagonistic effect (decrease in uterine weight) at 10 and 100 μg respectively. Clomiphene citrate at 10 μg dose produced 32% i.e., 28.93 ± 0.43 vs 38.04 ± 2.68 in immature and 35% i.e., 59.64±1.44 vs 83.34 ±0.25 in ovariectomized mice respectively. Histological observation clearly showed that clomiphene citrate at 10 and 100 μg doses did not cause any differential hypertrophy of the epithelial layer. Similar doses in combination with estradiol produced significant antagonistic effect on uterine weight and luminal epithelial cell height.     

Isolation and characterization of a new antifungal metabolite ofTrichoderma reesei

A mycelial extract ofTrichoderma reesei (P-12) was separated into four fractions by high performance liquid chromatography (HPLC). Out of these, two were found to exhibit antifungal activity when tested against plant pathogenic fungi. The level of antifungal compounds was higher in media containing glucose as the carbon source as compared to one containing cellulose. The synthesis of these antifungal compounds started after 3 days of inoculation at 30°C and continued upto 8 days. No further increase was recorded beyond this period.     

Cell wall-degrading enzymes and pectin solubility and depolymerization in immature and ripe watermelon (Citrullus lanatus) fruit in response to exogenous ethylene

Watermelon fruit have been shown to be extremely sensitive to exogenous ethylene, exhibiting acute symptoms of whole-fruit softening and placental-tissue water-soaking following short periods of exposure to the gas. This study addressed the firmness, specific activities of cell wall hydrolases, and solubility and molecular mass properties of polyuronides in placental tissue in response to treatment of intact fruit with ethylene. Watermelon fruit were harvested at the immature and full-ripe stages and exposed to 50 µl l⁻¹ ethylene for 6 days at 20°C. The firmness of placental tissue from ethylene-treated ripe and immature fruit decreased nearly 80% during 6 days of ethylene exposure, whereas the firmness of placental tissue from fruit maintained in air remained relatively constant up to day 3 and then decreased slightly (12%) during the following 3 days of storage. Although ethylene treatment in some cases influenced the levels of extractable placental-tissue polygalacturonase (EC 3.2.1.15), pectinmethylesterase (EC 3.2.1.11), and α -(EC 3.2.1.22) and β -galactosidase (EC 3.2.1.23) specific activities, these effects were not observed for fruit of both developmental stages and appeared not to be directly involved in the water–soaking syndrome. Symptoms of water-soaking were accompanied by increases in the levels of water- and CDTA ( trans -1,2-cyclohexanediamine- N,N,N',N' -tetraacetic acid)-soluble polyuronides and significant molecular mass downshifts in polyuronides in both immature and ripe watermelon fruit. Polyuronide depolymerization in ethylene-treated ripe fruit was extensive. The parallel trends of enzyme changes in ethylene- compared with air-treated fruit indicate that extractable enzyme levels are not associated with development of the water-soaking disorder. The potential involvement of membrane dysfunction in the water-soaking phenomenon is discussed.     

Mitochondrial enzymes in mango fruit during ripening

Mitochondria isolated from immature (developing), mature (unripe), and ripe mango pulp actively oxidized the intermediates of the Krebs cycle. The oxidation of citrate, oxoglutarate, succinate and malate by both unripe and ripe fruit mitochondria was several fold greater than that by mitochondria from immature fruit. The levels of malic dehydrogenase and succinic dehydrogenase increased with the onset of ripening, whereas the level of citrate synthase increased several fold on maturation but decreased six-fold on ripening. Isocitrate dehydrogenase and malic enzyme were very high in the immature fruit but after a sudden decrease in the matured fruit showed a considerable rise thereafter. The ratio of the activities of isocitrate lyase to isocitrate dehydrogenase is considerably higher in the immature fruit and greatest in the unripe (mature) fruit. This, together with a higher concentration of glyoxylate at these stages, indicate the operation of the glyoxylate bypass. Oxidized and reduced forms of pyridine nucleotides were estimated.