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1.
Warming of fruit during storage has been shown to decrease scald development, but the mechanisms involved in this effect are poorly understood. The effects of a single warming of 5 days at 20 °C after 2, 4, 6 and 8 weeks storage at 0 °C on development of superficial scald of ‘Fuji’ apples in relation to ethylene, a-farnesene and conjugated trienol (CTol) concentrations have been studied. Malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentrations, catalase (CAT) and peroxidase (POX) activities, total phenolic contents and total antioxidant activity were measured in order to assess the effects of the treatments on membrane damage and oxidant and antioxidant activity. Warming after 4 weeks storage reduced scald to the lowest level among all treatments. Warming greatly stimulated internal ethylene concentrations (IECs) and in turn, increased α-farnesene and CTol accumulation. Scald resistance, indicated by CAT and POX activities, total phenolic contents and total antioxidant activity, was higher in fruit in early than in late storage. The warming treatment after 4 weeks of storage resulted in higher concentrations of CTols and H2O2, as well as MDA, compared with the control fruit when kept at 20 °C after 6 and 12 weeks of storage, but lower than after 20 and 28 weeks. These results suggest that warming could inhibit scald development by modifying CTol accumulation as well as by affecting generation of accompanying active oxygen species (AOS), and reducing oxidative damage. These changes may cause a shift from a scald-sensitive metabolism to a resistant stage during storage.  相似文献   

2.
The effects of 1-methylcyclopropene (1-MCP) on ripening, superficial scald and concentrations of α-farnesene, conjugated trienols (CTols) and antioxidant enzyme activity of ‘KS6’ Asian pear (Pyrus serotina Rehd.) were studied. 1-MCP treated (2 μL L?1) or untreated control fruit were stored at 1 °C and 90–95% RH for up to 120 days. 1-MCP treated fruit were firmer than untreated fruit. Application of 1-MCP delayed skin color change. Scald appeared after shorter storage duration and was reduced, but not entirely controlled, with 1-MCP. Accumulation of α-farnesene and oxidation were slower in skin of 1-MCP treated fruit compared with controls. Catalase and peroxidase activities in untreated fruit either increased while activities decreased in 1-MCP treated fruit. Superoxide dismutase activity remained stable. The treatment of Asian pears with 1-MCP followed by cold storage maintained textural characteristics with less scald incidence.  相似文献   

3.
Postharvest 1-MCP can maintain fruit quality and inhibit development of superficial scald, a physiological storage disorder found in apple fruit, but the extent of the inhibition can vary by cultivar. In this study, we investigated whether multiple applications of 1-MCP, which are now permitted by a label modification of the commercial 1-MCP product, SmartFresh™, might improve scald control. ‘Cortland’ and ‘Delicious’ apples were untreated, treated on the day of harvest with the antioxidant inhibitor of scald, diphenylamine (DPA), or with 1 μL L−1 1-MCP at different intervals after harvest. Treatment times (days) were 1, 4, 7, 1 + 4, 4 + 7, 1 + 4 + 7, 7 + 14, 7 + 28, 7 + 42, and 7 + 84. Internal ethylene concentrations (IECs), flesh firmness, and accumulations of α-farnesene and conjugated trienols (CTols) were measured at harvest, at the time of treatment, and at intervals during air storage at 0.5 °C for up to 36 weeks. Scald was completely inhibited by DPA and all 1-MCP treatments in ‘Delicious’. However, effective control of scald in ‘Cortland’ was obtained with 1-MCP treatments within the first 4 days of harvest, either alone or in combination. Scald control with delayed 1-MCP treatments resulted in poorer scald control that was comparable to that obtained with DPA. IECs and α-farnesene accumulation were similar in untreated and DPA treated fruit, but inhibited by 1-MCP. However, differences among 1-MCP treatments became more evident with increasing storage periods. Inhibition of IECs and α-farnesene accumulation was greater in fruit treated on days 1, 4, 1 + 4, 4 + 7, 1 + 4 + 7, than on day 7 alone. A second application of 1-MCP on day 14 to fruit treated on day 7 increased inhibition of IECs, α-farnesene and CTol accumulations, but increasing delays before the second 1-MCP treatment resulted in progressively less inhibition of these factors. Similar effects of treatment on IECs, α-farnesene and CTol accumulations were found for both cultivars, even though no scald was detected in treated ‘Delicious’ apples. The results indicate that initial 1-MCP treatments should be applied to faster ripening cultivars such as ‘Cortland’ within a few days of harvest.  相似文献   

4.
‘Granny Smith’ apples are highly susceptible to superficial scald, a symptom of chilling injury. For many crops, low temperature storage results in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn leads to the generation of other dangerous reactive oxygen species (ROS). Application, prior to cold storage, of low oxygen (LO2, <0.5%) atmospheres, ethanol (<2% vapour) or 1-methylcyclopropene (1-MCP, 0.5 μL L−1) at 20 °C, was effective in reducing superficial scald in fruit following 24 weeks of cold storage. ROS levels were measured by confocal laser-scanning microscopy of apple peel treated with the fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate. In control fruit, ROS levels increased during cold storage and shelf-life and were very high after only 8 weeks, whereas in 1-MCP-, ethanol- and LO2-treated fruit, ROS levels remained low throughout storage. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase (MdCAT) was induced by LO2 treatment, whereas Mn superoxide dismutase (MdMnSOD) was induced by 1-MCP treatment. Polyphenol oxidase (MdPPO) gene expression levels were associated with scald symptom development and were highest in control fruit. Ethylene levels and expression of ethylene biosynthesis genes were correlated with α-farnesene levels and <alpha>-farnesene synthase (MdAFS) gene expression in the variously treated fruit. Accumulation of the α-farnesene oxidation product, 6-methyl-5-hepten-2-one (MHO), was highest in control fruit after 8 weeks, in accordance with ROS accumulation. The LO2 pretreatment mechanism might involve production of anaerobic metabolites, causing a delay in ethylene and α-farnesene biosynthesis and oxidation; this is different from the mechansism of action of 1-MCP, even though both consequently reduce ROS accumulation and scald symptoms.  相似文献   

5.
High-performance liquid chromatography–atmospheric pressure chemical ionization (APcI+)-time-of-flight mass spectrometry studies revealed that all-trans-β-carotene and the dibutyrates of all-trans-violaxanthin and 9-cis-violaxanthin were the main carotenoids in ‘Ataulfo’ and ‘Manila’ mango fruit mesocarp. The concentration of these carotenoids in the mesocarp was measured during fruit ripening and correlated with colorimetric changes of mesocarp and epidermis. The lowest and highest concentrations of all-trans-β-carotene, all-trans-violaxanthin and 9-cis-violaxanthin (as dibutyrates) during the ripening of ‘Manila’ mango were 0.25 × 10−3 to 35.57 × 10−3, 0.40 × 10−5 to 31.97 × 10−3 and 0 to 16.81 × 10−3 g kg−1 of fresh mesocarp, respectively. For ‘Ataulfo’ they were 2.55 × 10−3 to 39.72 × 10−3, 0.16 × 10−3 to 15.00 × 10−3 and 0.21 × 10−3 to 7.48 × 10−3 g kg−1 of fresh mesocarp, respectively. The concentration of these carotenoids increased in an exponential manner during fruit ripening in ‘Ataulfo’ and in an exponential or second-order polynomial manner in ‘Manila’. The highest correlation coefficients were obtained for the relationships between the mesocarp and epidermis a* and h° color values and the concentration of the evaluated carotenoids in both mango cultivars (R = 0.81–0.94). Equations to predict the concentration of the most important carotenoids in ‘Manila’ and ‘Ataulfo’ mango fruit on the basis of their mesocarp and epidermis color values were obtained.  相似文献   

6.
The effect of ethylene (2 μL L−1) on total and soft epicuticular wax content and wax morphology has been investigated in mature ‘Navelate’ (Citrus sinensis, L. Osbeck) oranges held under non-stressful environmental conditions (22 °C and constant high relative humidity (90–95% RH)). In addition, the objective of the study was to understand whether the ethylene-induced changes in epicuticular wax might participate in the beneficial effect of ethylene reducing non-chilling peel pitting, by modifying peel water, osmotic or turgor potential, or disease incidence caused by Penicillium digitatum (Pers.:Fr.) Sacc. Ethylene increased total and soft epicuticular wax content in ‘Navelate’ fruit and induced structural changes in surface wax that might be related to the formation of new waxes. Changes in epicuticular wax morphology, but not in its content, might be involved in the protective role of ethylene reducing non-chilling peel pitting, although the beneficial effect of the hormone is not related to water stress. Cell water and turgor potentials in freshly harvested fruit and fruit stored in air under non-stressful conditions suggest that water stress is not a limiting factor leading to the development of this physiological disorder. In addition, the results indicated that formation of new waxes in fruit treated with ethylene may partially cover stomata, cracks or areas lacking wax occurring in stored fruit and is likely to improve physical barriers to P. digitatum penetration.  相似文献   

7.
Edible composite coatings based on hydroxypropyl methylcellulose (HPMC), hydrophobic components (beeswax and shellac), and food preservatives with antifungal properties were evaluated on ‘Valencia’ oranges during long-term cold storage. Selected food preservatives included potassium sorbate (PS), sodium benzoate (SB), sodium propionate (SP), and their mixtures. Intact oranges or oranges artificially inoculated with Penicillium digitatum or Penicillium italicum were coated and stored up to 60 d at 5 °C followed by 7 d of shelf-life at 20 °C. Some antifungal HPMC–lipid coatings significantly reduced incidence and severity of both green (GM) and blue (BM) molds on inoculated and cold-stored oranges, and PS + SP-based coating was the most effective. In general, the coatings controlled GM better than BM. After 30 and 60 d at 5 °C plus 7 d at 20 °C, fruit weight loss, rind firmness, internal gas concentrations, ethanol and acetaldehyde contents of the juice, sensory flavor, off-flavor, and fruit appearance were not adversely affected by application of the antifungal coatings, which showed promise as potential substitutes for citrus commercial waxes. However, further studies should follow to improve some coating physical characteristics in order to provide better water loss control and higher gloss on coated oranges.  相似文献   

8.
Standard quality parameters, consumer acceptability, emission of volatile compounds and ethylene production of ‘Mondial Gala®’ apples (Malus × domestica Borkh.) were determined in relation to storage atmosphere, storage period and shelf-life period. Fruit were harvested at the commercial date and stored in AIR (21 kPa O2:0.03 kPa CO2) or under three different controlled atmospheres (CAs): LO (2 kPa O2:2 kPa CO2), ULO1 (1 kPa O2:1 kPa CO2), or ULO2 (1 kPa O2:2 kPa CO2). Fruit samples were analysed after 12 and 26 weeks of storage plus 1 or 7 d at 20 °C.Apples stored in CA maintained better standard quality parameters than AIR-stored fruit. The volatile compounds that contributed most to the characteristic aroma of ‘Mondial Gala®’ apples after storage were butyl, hexyl and 2-methylbutyl acetate, hexyl propanoate, ethyl butanoate, ethyl hexanoate, ethyl, butyl and hexyl 2-methylbutanoate. Data obtained from fruit analysis were subjected to principal component analysis (PCA). The apples most accepted by consumers showed the highest emission of ethyl 2-methylbutanoate, ethyl hexanoate, tert-butyl propanoate and ethyl acetate, in addition to the highest titratable acidity and firmness values.  相似文献   

9.
低温与1-MCP处理对明水梨果实黑皮病的抑制效应   总被引：1，自引：0，他引：1  
研究了低温（4±1）℃与1-甲基环丙烯（1-MCP）处理对明水梨果实黑皮病发生的抑制效应及其作用机理。研究结果表明,低温与1-MCP均显著地抑制梨果实黑皮病的发生,低温结合1-MCP处理能够完全抑制果实黑皮病的发生。低温与1-MCP也抑制α-法尼烯和共轭三烯含量的增加,抑制程度越明显,果实黑皮指数越低,表明α-法尼烯和共轭三烯的形成是梨果实黑皮病发生的主要原因。  相似文献   

10.
A manually operated high-pressure hot-water washing system consisting of a boiler, hot-water mixing tank, contact loop, heat exchanger, spray mixing tank, high-pressure hot-water washing manifold, low-pressure fresh water rinse manifold, and pressure pump was constructed and installed in a packingline. The system developed 20–50 °C washing water at pressures up to 980 kPa. ‘d’Anjou’ pears (Pyrus communis L.), shortly after harvest, and after storage for 3 and 4 months in regular air (RA) or for 4, 7 and 8 months in controlled atmosphere (CA) at −1 °C were washed through the packingline with different wetting agents (0.1% Silwet, 0.01 and 0.1% Defoamer, and water), water pressures (regular and high-pressure (210–980 kPa)), water temperatures (control (tap water, 4–22 °C), 40 °C, and 50 °C), and brushes (soft and firm), respectively. The effect of the washing conditions on fruit quality was investigated after 1 month of storage at −1 °C to simulate shipping condition, and then again after 1 week at 20 °C to simulate marketing condition. Hot-water caused severe heat scald. When nozzle temperature was 50 °C, the incidence of heat scald increased to over 50% for the fruit stored in RA for 3 months. Combined with hot-water, 540 kPa high-pressure washing increased the incidence of friction discoloration. There were lower incidences of friction discoloration and heat scald for fruit stored in CA for 7 months, in comparison to that in RA for 3 months. However, those fruit did not ripen properly as indicated by a high extractable juice content. Fruit washed at harvest had minor incidences of friction discoloration regardless of different brushes, water pressures, and wetting agents. Fruit washed after storages in either 4 months RA or 4 or 8 months CA suffered a high incidence of friction discoloration including scuffing symptoms and pressure marking. The firm brushes caused a higher incidence of friction discoloration mainly because of scuffing symptoms. However, no differences were found between different water pressures and wetting agents with respect to friction discoloration. Fruit stored for 4 months RA suffered 26–28% friction discoloration in comparison to 16–18% in CA stored fruit with firm brush washing. Extended CA storage increased friction discoloration even with soft brush washing. The results suggest that a washing system with high-pressure spray, <30 °C warm water, wetting agent Defoamer and rotating soft brushes were significantly effective in removing surface pests and decay control without causing internal or external damage of fruit.  相似文献   

11.
‘Blanquilla’ pears processed as fresh-cut products are highly sensitive to browning and softening. Common postharvest methods, such as the use of antibrowning compounds and/or modified atmosphere packaging, fail to preserve ‘Blanquilla’ pear slices long enough to be marketable. However, treatment with 1-MCP before cutting and peeling considerably improved their textural properties (9.2 N vs. 1.1 N with and without 1-MCP treatment, respectively) and color (a* values of 1 vs. 5 after 15 d at 4 °C, for slices pear treated with 1-MCP and without treatment, respectively). These positive changes were closely related to a decrease in respiratory activity determined on whole pears after 3 months of storage in air at 0 ± 1 °C and 95% R.H. (0.40 ± 0.05 mmol CO2 kg−1 h−1 vs. 0.77 ± 0.04 mmol CO2 kg−1 h−1 with and without 1-MCP treatment, respectively) and ethylene production (1.18 ± 0.36 nmol C2H4 kg−1 h−1 vs. 5.751 ± 1.12 nmol C2H4 kg−1 h−1 for samples treated with and without 1-MCP, respectively). The use of 1-MCP allows fresh-cut ‘Blanquilla’ pears to be sold up to about 5 d after processing. Treatment with 1-MCP could be a viable alternative to common technologies for extending the shelf-life of ‘Blanquilla’ pears as a fresh-cut product.  相似文献   

12.
A set of near-isogenic lines (NILs) of melon (Cucumis melo L.) was used to test the relationship between the climacteric pattern and postharvest disorders at harvest and after 30 days at 8 °C. The NILs contained different chromosome introgressions in the linkage group III from the non-climacteric exotic Korean accession PI 161375 transferred into the genetic background of the non-climacteric Spanish cultivar ‘Piel de Sapo’ (PS). A quantitative trait locus (QTL) in this linkage group induced climacteric behavior in eight NILs accompanied by a peak of ethylene production and fruit dehiscence to different degrees. The cultivar ‘Nicolás’ and one NIL showed a non-climacteric pattern of respiration rate and ethylene production. The climacteric NILs were used to test the relationship between this pattern and postharvest disorders. The reference climacteric lines ‘Fado’ and ‘Védrantais’ were more sensitive to CI and associated Cladosporium rot than the NILs or PS. In general, a more intense climacteric behavior was accompanied by fruit dehiscence, and higher total losses and greater skin scald after storage, than in PS. A higher incidence of chilling injury (CI) in the climacteric NILs was found compared with the non-climacteric ones, although with exceptions (one NIL for CI in the form of scald; the same NIL and one more for pitting). The climacteric onset and netting scald were not related, and CI in the form of skin spots was only found in climacteric NILs and was positively correlated with the maximum peak of ethylene production. Some climacteric NILs did not follow the rule of a higher susceptibility to other disorders and decay after storage compared with PS, such as for example in fruit over-ripening (detected externally or internally), Cladosporium rot at the peduncle and Alternaria rot. Mealiness was independent of climacteric behavior. Three climacteric NILs obtained better flavor scores after storage than PS, although the maximum peak of ethylene production was positively correlated with off-flavor. Genotypic correlation between disorder data and the physiological data of climacteric fruit revealed positive (flavor index) or negative postharvest consequences (skin injuries, rots or off-flavors). At least one QTL can be assigned to most of the quality traits analyzed.  相似文献   

13.
Seed starch content (SSC) greatly affects the taste, flavour and processing properties of soy foods. The objective in this study was to identify quantitative trait loci (QTL) for SSC in soybean. A total in 169 recombinant inbred lines (RILs) derived from a cross in ‘Williams 82’ and ‘PI 366121’ were grown for three consecutive years. The SSC of the RILs displayed continuous variation with transgressive segregation and hence amenable for QTL mapping. Nine significant QTL exhibiting 5.6–11.3% of the total phenotypic variation (PVE) were identified. The QTL qSTR06_2 showed highest PVE (9.1–11.3%) at LOD values of 4.25–5.39. No stable QTL over 3 years were identified, indicating strong environmental influence on SSC. The QTL qSTR11_1 and qSTR20_1 were found to colocalize with some of the previously reported QTL for sucrose content in soybean, implying the interrelationship between starch and sucrose biosynthesis. As the carbohydrate components may affect key constituents such as oil and protein in soybean seed, findings of the study may be useful in breeding soybeans with improved seed composition.  相似文献   

14.
This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in ‘Jonagold’ apple fruit using a multi-spectral vision system. Reflectance spectra of damaged and sound tissue were recorded using a visible/NIR spectrometer. Analysed defects consisted of scald, hail damage (with and without skin perforation), limb rubs, russets, scab tissue, frost damage, rot, visible flesh damage and recent bruises. Camera filter effects were approximated by summing the reflectances of all the wavelengths within the filter bandwidth. Combinations of three and four filters were tested and evaluated for discriminating damaged tissues from healthy ones. If a three-filter combination appeared sufficient to detect most of the damaged tissue, a four-filter combination should be considered for the complete sorting automation of this bicolour apple variety. A fourth filter was necessary to quantify the ratio between the blush and ground colours. Regarding recent bruise defects which represented the major difficulty, an image segmentation algorithm based on local contrast variations can enhance their detection.  相似文献   

15.
Summary A 0–4 scoring system to quantify scald (Rhynchosporium secalis) infection is suggested. Scores 1, 2, 3 and 4 allocated to represent 1/4, 1/2, 3/4 and 4/4 of the crop canopy scalded are easy to comprehend and intermediate scores e.g. 0.5, 1.5, 2.5 and 3.5 give it the breadth of a quantitative scale. Scores on a large number of lines showed a high degree of repeatability and were found to be highly correlated with the log transformed values of the actual leaf area damage. Although it was suggested that predictions of leaf area damage at scores 3–4 should be applied with caution, broad generalization of the scores in discriminating the amount of disease were shown to be soundly based and offered plant breeders a tool to standardize the evaluation of scald resistance in field plots on a large scale with this quick and reliable scoring system.  相似文献   

16.
We measured the effects of increased daytime temperature during 2- (2007/08) or 3-week periods (2008/09) on the yield and yield components of irrigated Shiraz vines in the Barossa Valley of Australia. A simple and inexpensive open system was used to elevate temperature during a single phenological window, either bracketing budburst (E-L stage 4), shortly after flowering (E-L stage 23), bracketing pea size (E-L stage 31), around veraison (E-L stage 35) or shortly before harvest (E-L stage 38). Two important features of the heating systems were tracking of diurnal temperature dynamics, and maintaining relative humidity, hence avoiding the interaction between temperature and vapour pressure deficit. Minimum temperature was unchanged.Compared to controls, maximum ambient temperature was increased between 1.8 and 4.1 °C in treated plots but canopy temperature of treated vines only increased by 0.9–1.1 °C. Elevation of bunch temperature was 2.3–3.2 °C. Increasing temperature around budburst transiently accelerated development in comparison to controls; no phenological changes were detected for other timings of treatment. Yield averaged 4.3 kg vine−1 in 2007–08 and 6.1 kg vine−1 in 2008–09. In both seasons and for all timings of treatment, increasing temperature did not affect yield or its components; lack of yield response did not result, therefore, from compensatory mechanisms, e.g. heavier berries compensating for fewer fruit. The dynamics of berry growth and total soluble solids were largely unaffected by temperature. Under our experimental conditions, the capacity of irrigated Shiraz canopies to partially buffer a 2–4 °C increase in maximum ambient temperature may have been important for the maintenance of yield, and berry growth and sugar accumulation.  相似文献   

17.
There is a need to develop alternative harvest indexes for black skinned plums. The aim of this research was to analyze and compare the most commonly used indexes for deciding the harvest date for Japanese plum, and evaluate the effectiveness of new approaches for studying maturation. The ripening process was monitored on-tree and during postharvest in a non-destructive way, through the absorbance of chlorophyll (IAD), the compression strength of the intact fruit, and the traditional parameters associated with ripening. Fruit were harvested at commercial ripeness and “tree-ripe”, and were stored for 10 d at 22 °C and 75-80% RH. The IAD decreased during the last phase of development of the fruit on-tree, and it was related to the common indexes used for plums. ‘Angeleno’ showed a decrease of the IAD 24% lower than that observed for ‘Autumn beaut’. The IAD versus time showed the highest coefficients of determination when compared with the soluble solids concentration (SSC), flesh firmness, hue (H°) and chroma (C*) of the skin. The compression strength of the intact fruit was associated with flesh firmness, and to a lesser extent with the SSC for ‘Angeleno’, whereas for ‘Autumn beaut’ higher correlations for both the SSC and flesh firmness were observed. The C* of the skin on ‘Autumn beaut’ showed an erratic change during ripening; by contrast, for ‘Angeleno’, this index showed a clear trend. During postharvest it was observed that for ‘Angeleno’ fruit picked at commercial ripeness, the rate of change of the IAD was practically the same as observed on-tree, while for ‘Autumn beaut’ the rates of change on-tree and at postharvest were 0.075 IAD d−1 and 0.024 IAD d−1, respectively. For the “tree-ripe” fruit, the rate of change was practically the same for both cultivars. Similar trends were observed for the compression strength.  相似文献   

18.
Capsaicinoids are pungent compounds used for industrial and medical purposes including food, medicine and cosmetics. The Indian local variety ‘Bhut Jolokia’ (Capsicum chinense Jacq.) is one of the world's hottest chilli peppers. It produces more than one million Scoville heat units (SHUs) in total capsaicinoids. In this study, our goal was to identify quantitative trait loci (QTLs) responsible for the high content of capsaicin and dihydrocapsaicin in ‘Bhut Jolokia’. Capsicum annuum ‘NB1’, a Korean pepper inbred line containing 14 000 SHUs, was used as a maternal line. An F2 population derived by crossing between ‘NB1’ and ‘Bhut Jolokia’ was generated to map QTLs for capsaicinoids content. A total of 234 markers, including 201 HRM, 21 SSR, 2 CAPS and 10 gene‐based markers of the capsaicinoid synthesis pathway, were mapped. The final map covered a total distance of 1175.2 cM and contained 12 linkage groups corresponding to the basic chromosome number of chilli pepper. Capsaicin and dihydrocapsaicin content were analysed in 175 F2 pepper fruits using the HPLC method. The maximum total capsaicinoids content was 1389 mg per 100g DW (dry weight), and the minimum content was 11 mg per 100g DW. Two QTLs (qcap3.1 and qcap6.1) for capsaicin content were identified on LG3 and LG6, and two QTLs (qhdc2.1 and qdhc2.2) for dihydrocapsaicin content were located on LG2. We did not detect QTLs for total capsaicinoids content. The QTL positions for capsaicin content were different from those for dihydrocapsaicin content. These results indicate that the complexity of selecting for more pungent chilli peppers must be considered in a chilli pepper breeding programme. The QTL‐linked markers identified here will be helpful to develop more pungent pepper varieties from ‘Bhut Jolokia’, a very hot pepper.  相似文献   

19.
The effects of temperature, scan interval and rate of oxygen (O2) decline on pulse frequency modulation (PFM)-based minimum fluorescence (Fα) and the Fα-based lower oxygen limit (LOL) were investigated using ‘Honeycrisp’ apples (Malus × domestica Borkh). The effects of temperature and hypoxic stress on pulse amplitude modulation (PAM) fluorescence parameters were also investigated. The PFM scan interval had no effect on the Fα baseline, but increases in the scan interval decreased the low-O2-induced fluorescence spike intensity (ΔFα). Temperature negatively correlated with the Fα baseline while ΔFα °C−1 was greater at lower than at higher temperatures. When using a PAM fluorometer, the minimum fluorescence (Fo), and to a lesser extent the maximum fluorescence (Fm), were similarly affected by temperature as was Fα. Temperature altered the LOL in fruit. Apples stored at 20, 10, 3.5 and 0 °C spiked at 0.72, 0.33, 0.22 and 0.08 kPa O2, respectively, under a rapid O2 decline (i.e., 20.9 to <1 kPa O2 in ≈5–6 h). Although the low-O2 Fα spike apex values did not change with temperature, the spike intensity increased with temperature due to a reduced fluorescence baseline. A slower O2 decline rate produced slightly higher LOL and lower spike intensity values. In conclusion, temperature and rate of O2 decline affected the low-O2-induced PFM fluorescence spike intensity as well as the LOL, while the PFM scan interval affected the spike intensity.  相似文献   

20.
Four expansin cDNA fragments, EjEXPA1, EjEXPA2, EjEXPA3 and EjEXPA4, were isolated and characterized from loquat (Eriobotrya japonica Lindl.) fruit. EjEXPA1 mRNA accumulated consistently with the increase in fruit firmness in 0 °C storage of ‘Luoyangqing’ (LYQ) fruit, where chilling injury with increased fruit firmness due to lignification was observed. EjEXPA1 mRNA levels were lower in fruit that underwent low temperature conditioning (LTC, 6 d at 5 °C then 4 d at 0 °C), and in 1-methylcyclopropene (1-MCP) treated fruit, in both cases where chilling injury was alleviated. Fruit of the ‘Baisha’ (BS) cultivar soften after harvest rather than increase in firmness, and high expression levels of EjEXPA1 and EjEXPA4 accompanied the softening of BS fruit stored at 20 °C; such mRNA accumulation was much lower when fruit were stored at 0 °C, where softening was significantly inhibited by the low temperature. Very low expression of EjEXPA2 and EjEXPA3 was observed during storage of both LYQ and BS fruit under the different storage conditions. Our results showed that of the four genes characterized, EjEXPA1 might be associated with chilling-induced lignification while both EjEXPA1 and EjEXPA4 were closely related to softening of loquat fruit during the postharvest period.  相似文献   

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