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1.
The influence of different leaf-to-fruit (l-t-f) ratios on leaf net photosynthetic rate (P N) and fruit characteristics in Olea europaea L. cv. Frantoio was evaluated in 2001 and 2002. In both years, at the end of June, at the end of July, and in mid-September (first, second, and third time of treatment, respectively), defoliation or fruit thinning were performed to give l-t-f ratios of 1/1, 3/1, 5/1, and 7/1 (about 5.1, 15.3, 25.6, and 35.8 cm2 of leaf area per fruit, respectively) on girdled and ungirdled peripheral shoots. P N showed substantial seasonal and diurnal variations. In ungirdled shoots, no differences due to the different l-t-f ratios were observed, whereas in girdled shoots P N tended to be lower in shoots with a high l-t-f ratio. In general, the values of leaf transpiration rate (E), stomatal conductance (g s), sub-stomatal CO2 concentration (C i), and dark respiration rate (R D) were associated with those of P N. The starch and reducing sugar contents and area leaf dry mass (ADM) tended to be higher in leaves on girdled shoots with high l-t-f ratio, whereas in ungirdled shoots no differences related to the different l-t-f ratios were observed. The higher saccharide content in the leaves and the lower P N, in the presence of a high C i, observed in girdled shoots with a high l-t-f ratio suggests that the depression in P N in these shoots may be the result of a feedback inhibition of the photosynthetic mechanism that regulates such a process. The l-t-f ratio did not have a substantial effect on fruit drop. In ungirdled shoots, the different l-t-f ratios did not produce significant differences in terms of fruit growth and leaf dry matter and saccharide contents, whereas in girdled shoots fruit growth increased as the l-t-f ratio increased, particularly when treatments were applied at the initial stage of fruit development. The percentage of oil in the pulp, on a dry matter basis, was not substantially influenced by girdling and l-t-f ratio. The abundant availability of assimilates seemed to cause earlier fruit ripening and, at the same time, retard fruit senescence (fruit detachment force). Shoot growth was slightly reduced by girdling. The abundant availability of assimilates, induced by girdling associated with high l-t-f ratio, stimulated flower induction.  相似文献   

2.
综述了苹果(Malus domestica Borkh.)、草莓(Fragaria ananassa Duch.)、香蕉(Musa paradisiaca)、甜瓜(Cucumis melon L.)和番茄(Lycopersicon esculentum L.)等果实香气的化学成分、主要合成途径及其影响因素。果实的香气物质主要包括酯类、醇类、酮类、醛类、萜类和挥发性酚类物质等,这些物质主要由脂肪酸、氨基酸和次生代谢产生。品种、成熟度、乙烯、环境和栽培措施(光照、砧木、套袋和灌溉等)以及采后贮藏条件均影响果实香气的形成。  相似文献   

3.
果实香气形成及其影响因素   总被引:45,自引:0,他引:45  
综述了苹果(Malus domestica Borkh.)、草莓(Fragaria ananassa Duch.)、香蕉(Musa paradisiaca)、甜瓜(Cucumis melon L.)和番茄(Lycopersicon esculentum L.)等果实香气的化学成分、主要合成途径及其影响因素.果实的香气物质主要包括酯类、醇类、酮类、醛类、萜类和挥发性酚类物质等,这些物质主要由脂肪酸、氨基酸和次生代谢产生.品种、成熟度、乙烯、环境和栽培措施(光照、砧木、套袋和灌溉等)以及采后贮藏条件均影响果实香气的形成.  相似文献   

4.
Two genes (CM-AAT1 and CM-AAT2) with strong sequence homology (87% identity at the protein level) putatively involved in the formation of aroma volatile esters have been isolated from Charentais melon fruit. They belong to a large and highly divergent family of multifunctional plant acyl-transferases and show at most 21% identity to the only other fruit acyl-transferase characterized so far in strawberry. RT-PCR studies indicated that both genes were specifically expressed in fruit at increasing rates in the early and mid phases of ripening. Expression was severely reduced in ethylene-suppressed antisense ACC oxidase (AS) fruit and in wild-type (WT) fruit treated with the ethylene antagonist 1-MCP. Cloning of the two genes in yeast revealed that the CM-AAT1 protein exhibited alcohol acyl-transferase activity while no such activity could be detected for CM-AAT2 despite the strong homology between the two sequences. CM-AAT1 was capable of producing esters from a wide range of combinations of alcohols and acyl-CoAs. The higher the carbon chain of aliphatic alcohols, the higher the activity. Branched alcohols were esterified at differential rates depending on the position of the methyl group and the nature of the acyl donor. Phenyl and benzoyl alcohols were also good substrates, but activity varied with the position and size of the aromatic residue. The cis/trans configuration influenced activity either positively (2-hexenol) or negatively (3-hexenol). Because ripening melons evolve the whole range of esters generated by the recombinant CM-AAT1 protein, we conclude that CM-AAT1 plays a major role in aroma volatiles formation in the melon.  相似文献   

5.
研究了苹果果实成熟期间香气和乙烯的产生动态,以及游离氨基酸、游离脂肪酸含量和脂氧合酶(LOX)、醇-酰基转移酶(AAT)活性的变化.结果表明,果实香气物质是随着乙烯释放的增加而产生和增加的.在此过程中,异亮氨酸大量积累.游离脂肪酸在果实香气很少时呈增加趋势;随着香气产生的增多而迅速下降;乙烯高峰过后又有增加.脂氧合酶活性随着果实成熟而提高,其活性在乙烯释放达到高峰时达到最大值,之后迅速下降.醇-酰基转移酶活性在果实开始产生香气时迅速增加,之后保持较高活性.  相似文献   

6.
Short-chain esters contribute to the blend of volatiles that define the strawberry aroma. The last step in their biosynthesis involves an alcohol acyltransferase that catalyses the esterification of an acyl moiety of acyl-CoA with an alcohol. This study identified a novel strawberry alcohol acyltransferase gene (FaAAT2) whose expression pattern during fruit receptacle growth and ripening is in accordance with the production of esters throughout strawberry fruit ripening. The full-length FaAAT2 cDNA was cloned and expressed in Escherichia coli and its activity was analysed with acyl-CoA and alcohol substrates. The semi-purified FaAAT2 enzyme had activity with C1-C8 straight-chain alcohols and aromatic alcohols in the presence of acetyl-CoA. Cinnamyl alcohol was the most efficient acyl acceptor. When FaAAT2 expression was transiently downregulated in the fruit receptacle by agroinfiltration, the volatile ester production was significantly reduced in strawberry fruit. The results suggest that FaAAT2 plays a significant role in the production of esters that contribute to the final strawberry fruit flavour.  相似文献   

7.
Influence of Sink-Source Interaction on Dry Matter Production in Tomato   总被引:4,自引:0,他引:4  
Sink-source ratio in tomato was manipulated, in six glasshouseexperiments, by fruit pruning (trusses pruned to two to sevenfruits immediately after fruit set of each truss), truss pruning(removal of every other truss at anthesis) and truss pruningin plants with two shoots. Periodic destructive harvest wereconducted for about 100 d after flowering of the first truss.Dry matter production was not influenced by sink-source ratio,whereas dry matter distribution between fruits and vegetativeparts was greatly affected. The fraction of dry matter distributedto the fruits at the end of the fruit pruning experiments (Ffruits)could be described accurately as a saturation-type functionof number of fruits retained per truss (Nf): Ffruits = 0.660(l-e-0.341Nf). Specific leaf area and internode length decreasedand plant leaf area increased when sink-source ratio was reduced.Removal of every other truss at anthesis did reduce dry matterpartitioning into the fruits, but it did not influence internodelength. Plant development (number of visible leaves at the endof the experiments) was not influenced by sink-source ratio.In four experiments some plants were pruned to one fruit pertruss. Final dry matter production was 8-24% lower for theseplants, compared with plants with more than one fruit per truss.This was, at least party, the result of less light interceptionby these plants, which had strongly curled leaves pointing downwards. Results indicate that effects of sink demand on dry matter productionper unit of intercepted radiation and probably on leaf photosyntheticrate in commercial tomato production can be ignored.Copyright1995, 1999 Academic Press Dry matter production, feedback control, glasshouse, growth analysis, Lycopersicon esculentum, pruning, sink demand, sink-source ratio, tomato  相似文献   

8.
以'粉红女士'苹果为试验材料,研究了1 μL/L 1-MCP(1-甲基环丙烯)对苹果冷藏期间乙烯释放速率、呼吸速率、果实硬度以及香气成分和相对含量的影响.结果表明,1-MCP处理可显著抑制'粉红女士'苹果冷藏期间呼吸作用和乙烯释放,有效延缓果实硬度的下降.冷藏期内'粉红女士'苹果香气物质主要有醇类、醛类、酯类、烯类、酸类和烷烃类等,并以酯类香气为主(占46.15%);1-MCP能显著减少果实贮藏期间酯类、醇类和烷烃类香气成分种类和相对含量,处理果中酯类和醇类香气成分种类比同期对照分别减少了50%和78%,主要香气成分丁酸己酯在处理和对照果实的相对含量分别为1.12%~1.73%和1.87%~5.18%.可见,1-MCP处理对'粉红女士'苹果具有良好保鲜效果,也显著地抑制了贮藏期间香气的形成.  相似文献   

9.
Changes in yield and quality of fresh tomatoes in response toair vapour pressure deficit (VPD) and plant fruit load werestudied under Mediterranean summer conditions. Plants thinnedto three or six fruits per truss were grown in two compartments,one at a VPD below 1.5 kPa, the other without VPD control. Theseasonal trend in fruit yield and quality was assessed fromApril to September by weekly measurement of number, fresh weightand dry matter content of harvested fruits, together with theoccurrence of blossom-end-rot (BER) and cracking. On two occasions,in July and September, sugar and acid content was measured atthree ripening stages. The seasonal decrease in fresh yieldwas attenuated at low VPD, because of higher individual fruitfresh weight, especially at low fruit load. Low VPD decreasedoccurrence of BER but like low fruit load, it increased fruitcracking. Fruit dry matter content was lower at low VPD, butwas unaffected by fruit load. Sugar content and the ratio ofsugars:acids was increased at high VPD and low fruit load, withinteractive effects depending on season and ripening stage.The influence of VPD on acid content differed with fruit loadand also changed during ripening and between seasons. Resultsshowed that water was the main limiting factor for growth offruits picked in July; at this time, reducing fruit load topromote mean fruit size had negative effects on BER and cracking.Reducing VPD reduced BER but had a negative effect on crackingand diluted both the dry matter and sugar content. For fruitsharvested later in summer, these negative effects were attenuatedbecause fruit growth was also carbon limited. Copyright 2000Annals of Botany Company Lycopersicon esculentum Mill., tomato, water and carbon stress, yield, quality, dry matter, sugar, acid, BER, volatile composition  相似文献   

10.
Alcohol dehydrogenases (ADH) participate in the biosynthetic pathway of aroma volatiles in fruit by interconverting aldehydes to alcohols and providing substrates for the formation of esters. Two highly divergent ADH genes (15% identity at the amino acid level) of Cantaloupe Charentais melon (Cucumis melo var. Cantalupensis) have been isolated. Cm-ADH1 belongs to the medium-chain zinc-binding type of ADHs and is highly similar to all ADH genes expressed in fruit isolated so far. Cm-ADH2 belongs to the short-chain type of ADHs. The two encoded proteins are enzymatically active upon expression in yeast. Cm-ADH1 has strong preference for NAPDH as a co-factor, whereas Cm-ADH2 preferentially uses NADH. Both Cm-ADH proteins are much more active as reductases with K ms 10–20 times lower for the conversion of aldehydes to alcohols than for the dehydrogenation of alcohols to aldehydes. They both show strong preference for aliphatic aldehydes but Cm-ADH1 is capable of reducing branched aldehydes such as 3-methylbutyraldehyde, whereas Cm-ADH2 cannot. Both Cm-ADH genes are expressed specifically in fruit and up-regulated during ripening. Gene expression as well as total ADH activity are strongly inhibited in antisense ACC oxidase melons and in melon fruit treated with the ethylene antagonist 1-methylcyclopropene (1-MCP), indicating a positive regulation by ethylene. These data suggest that each of the Cm-ADH protein plays a specific role in the regulation of aroma biosynthesis in melon fruit. Daniel Manríquez and Islam El-Sharkawy contributed equally to the work. Accession numbers for Cm-ADH1 (ABC02081), and Cm-ADH2 (ABC02082).  相似文献   

11.
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  相似文献   

12.
The volatile compounds produced by Debaryomyces hansenii NRRL Y-7426 during the fermentation of detoxified concentrated distilled grape marc hemicellulosic hydrolysates was analysed by GC?CMS. Thirty-five compounds corresponding to ten groups of volatile compounds: terpenes, higher alcohols, C6 alcohols, aldehydes, volatile acids, acetates, ethyl esters, volatile phenols, sulphur compounds and hydrocarbons were identified. The supplementation with commercial nutrients increased the concentration of 2-phenylethanol, a commercial flavour and fragrance compound, with a rose-like odour, employed in cosmetics and food industries; and other positive compounds to the aroma such as terpenes and ethyl esters. Non-supplemented media produced the highest content in higher alcohols, volatile acids, sulphur compounds and in the majority of hydrocarbons detected, meanwhile supplementation with vinasses hardly produced volatile compounds. Only four volatile compounds contributed directly to the aroma according to the OAVs values higher than 1. Finally, a PCA analysis allowed accounting for 100?% of the variance.  相似文献   

13.
The effects of water fogging and reducing plant fruit load werestudied in a tomato crop grown in a glasshouse under Mediterraneansummer conditions. The objective of these treatments was toreduce competition between leaves and fruits for carbohydratesand water. Flower pruning increased plant leaf area and increasedfruit, stem, lamina and petiole dry mass (DM). This indicatesthat leaf area growth was limited during the summer due to competitionbetween fruits and leaves for assimilates. In contrast, reducingthe air vapour pressure deficit (VPD) by water fogging had noeffect on plant leaf area or aerial plant DM. Interestingly,there was a significant interaction between plant fruit loadand VPD: the higher the leaf[ratio]fruit ratio the greater theresponses to a reduction in VPD (increase in fruit DM, fruitdiameter, fruit and leaf expansion rate). The data suggest thatunder high fruit loads, water and carbohydrates limit growthunder Mediterranean summer conditions. However, reducing VPDwas not always sufficient to enhance fruit and leaf growth.This might be due to the lower leaf area under high fruit load.In contrast, reducing VPD under low fruit load triggered higherrates of leaf and fruit expansion; this is probably linked toa greater availability of water and carbohydrates. Copyright2001 Annals of Botany Company Assimilate competition, assimilate supply, flower pruning, fruit load, fruit growth, generative/vegetative growth, leaf growth, Lycopersicon esculentum, specific leaf weight, tomato, vapour pressure deficit, water stress  相似文献   

14.
Quinyl esters of hydroxycinnamic acids usually occur in greater abundance than their corresponding glucose esters in tomato fruits. During fruit growth and ripening, the predominant derivatives of hydroxycinnamic acids were found to be chlorogenic acid (76%) and the glucosides (84%) respectively. The variations in the ratio of Benedict-reactive (chlorogenic acid) and non-reactive compounds (mainly caffeic acid glucoside) are discussed in relation to their possible role in the regulation of fruit growth and maturation.  相似文献   

15.
Sink activity of fruits had been suggested to vary depending on transpiration of fruits. In this study, the effect of transpiration on dry matter accumulation was evaluated in tomato ( Lycopersicon esculentum Mill.). Fruits of cv. Saturn at 14 days after anthesis were enclosed in chambers and aerated with dried (<15% RH) or moistened (>90% RH) air. These treatments did not cause any significant differences in fruit fresh weight, dry weight, percentage of dry matter, and concentration of soluble sugars within 5 days of the treatment, or the import of 14C within 18 h after the application of 14CO2 to the source leaves. However, displacement transducer measurement of each fruit showed a 40% reduction in growth rate in response to exchange of moistened air with dried air. When fruits of cv. Momotaro were exposed to transpiration treatments from the beginning of visible fruit enlargement until the ripening stage, the fruits exhibited 20% reduction in growth and lower accumulation of dry matter at harvest following treatment with dried air. These results suggested that higher transpiration reduced both water accumulation and dry matter accumulation. In contrast, when fruit growth was mechanically restricted by enclosing the fruits in a chamber packed with glass beads, and dried or moistened air was passed through the spaces between the glass beads, fruits exhibited higher dry matter accumulation under dried air treatment conditions. The results show that only under artificial conditions would transpiration of fruits potentially drive carbohydrate transport; it does not serve as a limiting step of carbohydrate transport to tomato fruits under normal circumstances.  相似文献   

16.
Almost all terrestrial plants produce green leaf volatiles (GLVs), consisting of six-carbon (C6) aldehydes, alcohols and their esters, after mechanical wounding. C6 aldehydes deter enemies, but C6 alcohols and esters are rather inert. In this study, we address why the ability to produce various GLVs in wounded plant tissues has been conserved in the plant kingdom. The major product in completely disrupted Arabidopsis leaf tissues was (Z)-3-hexenal, while (Z)-3-hexenol and (Z)-3-hexenyl acetate were the main products formed in the intact parts of partially wounded leaves. (13)C-labeled C6 aldehydes placed on the disrupted part of a wounded leaf diffused into neighboring intact tissues and were reduced to C6 alcohols. The reduction of the aldehydes to alcohols was catalyzed by an NADPH-dependent reductase. When NADPH was supplemented to disrupted tissues, C6 aldehydes were reduced to C6 alcohols, indicating that C6 aldehydes accumulated because of insufficient NADPH. When the leaves were exposed to higher doses of C6 aldehydes, however, a substantial fraction of C6 aldehydes persisted in the leaves and damaged them, indicating potential toxicity of C6 aldehydes to the leaf cells. Thus, the production of C6 aldehydes and their differential metabolisms in wounded leaves has dual benefits. In disrupted tissues, C6 aldehydes and their α,β-unsaturated aldehyde derivatives accumulate to deter invaders. In intact cells, the aldehydes are reduced to minimize self-toxicity and allow healthy cells to survive. The metabolism of GLVs is thus efficiently designed to meet ecophysiological requirements of the microenvironments within a wounded leaf.  相似文献   

17.
18.
Aroma and flavor are important factors of fruit quality and consumer preference. The specific pattern of aroma is generated during ripening by the accumulation of volatiles compounds, which are mainly esters. Alcohol acyltransferase (AAT) (EC 2.3.1.84) catalyzes the esterification reaction of aliphatic and aromatic alcohols and acyl-CoA into esters in fruits and flowers. In Fragaria x ananassa, there are different volatiles compounds that are obtained from different alcohol precursors, where octanol and hexanol are the most abundant during fruit ripening. At present, there is not structural evidence about the mechanism used by the AAT to synthesize esters. Experimental data attribute the kinetic role of this enzyme to 2 amino acidic residues in a highly conserved motif (HXXXD) that is located in the middle of the protein. With the aim to understand the molecular and energetic aspects of volatiles compound production from F. x ananassa, we first studied the binding modes of a series of alcohols, and also different acyl-CoA substrates, in a molecular model of alcohol acyltransferase from Fragaria x ananassa (SAAT) using molecular docking. Afterwards, the dynamical behavior of both substrates, docked within the SAAT binding site, was studied using routine molecular dynamics (MD) simulations. In addition, in order to correlate the experimental and theoretical data obtained in our laboratories, binding free energy calculations were performed; which previous results suggested that octanol, followed by hexanol, presented the best affinity for SAAT. Finally, and concerning the SAAT molecular reaction mechanism, it is suggested from molecular dynamics simulations that the reaction mechanism may proceed through the formation of a ternary complex, in where the Histidine residue at the HXXXD motif deprotonates the alcohol substrates. Then, a nucleophilic attack occurs from alcohol charged oxygen atom to the carbon atom at carbonyl group of the acyl CoA. This mechanism is in agreement with previous results, obtained in our group, in alcohol acyltransferase from Vasconcellea pubescens (VpAAT1).  相似文献   

19.
Glycosides are an important potential source of aroma and flavour compounds for release as volatiles in flowers and fruit. The production of glycosides is catalysed by UDP‐glycosyltransferases (UGTs) that mediate the transfer of an activated nucleotide sugar to acceptor aglycones. A screen of UGTs expressed in kiwifruit (Actinidia deliciosa) identified the gene AdGT4 which was highly expressed in floral tissues and whose expression increased during fruit ripening. Recombinant AdGT4 enzyme glycosylated a range of terpenes and primary alcohols found as glycosides in ripe kiwifruit. Two of the enzyme's preferred alcohol aglycones, hexanol and (Z)‐hex‐3‐enol, contribute strongly to the ‘grassy‐green’ aroma notes of ripe kiwifruit and other fruit including tomato and olive. Transient over‐expression of AdGT4 in tobacco leaves showed that enzyme was able to glycosylate geraniol and octan‐3‐ol in planta whilst transient expression of an RNAi construct in Actinidia eriantha fruit reduced accumulation of a range of terpene glycosides. Stable over‐expression of AdGT4 in transgenic petunia resulted in increased sequestration of hexanol and other alcohols in the flowers. Transgenic tomato fruit stably over‐expressing AdGT4 showed changes in both the sequestration and release of a range of alcohols including 3‐methylbutanol, hexanol and geraniol. Sequestration occurred at all stages of fruit ripening. Ripe fruit sequestering high levels of glycosides were identified as having a less intense, earthier aroma in a sensory trial. These results demonstrate the importance of UGTs in sequestering key volatile compounds in planta and suggest a future approach to enhancing aromas and flavours in flowers and during fruit ripening.  相似文献   

20.
Aims:  To investigate the impact of Proteus vulgaris growth on a multispecies ecosystem and on volatile aroma compound production during cheese ripening.
Methods and Results:  The microbial community dynamics and the production of volatile aroma compounds of a nine-species cheese ecosystem were compared with or without the presence of P. vulgaris in the initial inoculum. Proteus vulgaris was able to colonize the cheese surface and it was one of the dominant species, representing 37% of total isolates at the end of ripening with counts of 9·2 log10 CFU g−1. In the presence of P. vulgaris , counts of Arthrobacter arilaitensis , Brevibacterium aurantiacum and Hafnia alvei significantly decreased. Proteus vulgaris influenced the production of total volatile aroma compounds with branched-chain aldehydes and their corresponding alcohols being most abundant.
Conclusions:  Proteus vulgaris was able to successfully implant itself in a complex cheese ecosystem and significantly contributed to the organoleptic properties of cheese during ripening. This bacterium also interacted negatively with other bacteria in the ecosystem studied.
Significance and Impact of the Study:  This is the first time that the impact of a Gram-negative bacterium on cheese microbial ecology and functionality has been described.  相似文献   

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