共查询到20条相似文献,搜索用时 31 毫秒
2.
Jasmonates are a class of oxylipins that induce a wide variety of higher-plant responses. To determine if jasmonates play
a role in the regulation of climacteric fruit ripening, the effects of exogenous jasmonates on ethylene biosynthesis and color,
as well as the endogenous concentrations of jasmonates were determined during the onset of ripening of apple ( Malus domestica Borkh. cv. Golden Delicious) and tomato ( Lycopersicon esculentum Mill. cv. Cobra) fruit. Transient (12 h) treatment of pre-climacteric fruit discs with exogenous jasmonates at low concentration
(1 or 10 μM) promoted ethylene biosynthesis and color change in a concentration-dependent fashion. Activities of both 1-aminocyclopropane-1-carboxylic
acid (ACC) oxidase and ACC synthase were stimulated by jasmonate treatments in this concentration range. The endogenous concentration
of jasmonates increased transiently prior to the climacteric increase in ethylene biosynthesis during the onset of ripening
of both apple and tomato fruit. The onset of tomato fruit ripening was also preceded by an increase in the percentage of the
cis-isomer of jasmonic acid. Inhibition of ethylene action by diazocyclopentadiene negated the jasmonate-induced stimulation
of ethylene biosynthesis, indicating jasmonates act at least in part via ethylene action. These results suggest jasmonates
may play a role together with ethylene in regulating the early steps of climacteric fruit ripening.
Received: 14 August 1997 / Accepted: 4 October 1997 相似文献
4.
Seedless avocado fruit are produced alongside seeded fruit in the cultivar Arad, and both reach maturity at the same time. Using this system, it was possible to show that avocado seed inhibits the ripening process: seedless fruits exhibited higher response to exogenous ethylene already at the fruitlet stage, and also at the immature and mature fruit stages. They produced higher CO 2 levels, and the ethylene peak was apparent at the fruitlet stage of seedless fruit, but not of seeded ones. The expression levels of PaETR, PaERS1 and PaCTR1 on the day of harvest at all developmental stages were very similar between seeded and seedless fruit, except that PaCTR1 was higher in seedless fruit only at very early stages. This expression pattern suggests that the seed does not have an effect on components of the ethylene response pathway when fruits are just picked. The expression of MADS-box genes, PaAG1 and PaAGL9, preceded the increase in ethylene production of mature seeded fruit, but not at earlier stages. However, only PaAGL9 was induced in seedless fruit at early stages of development. Taken together, these data suggest that these genes are perhaps involved in climacteric response in seeded fruit, and the seed is responsible for their induction at normal fruit ripening. 相似文献
5.
Fruit ripening involves complex biochemical and physiological changes. Ethylene is an essential hormone for the ripening of
climacteric fruits. In the process of ethylene biosynthesis, cyanide (HCN), an extremely toxic compound, is produced as a
co-product. Thus, most cyanide produced during fruit ripening should be detoxified rapidly by fruit cells. In higher plants,
the key enzyme involved in the detoxification of HCN is β-cyanoalanine synthase (β-CAS). As little is known about the molecular
function of β-CAS genes in climacteric fruits, we identified two homologous genes, MdCAS1 and MdCAS2, encoding Fuji apple β-CAS homologs. The structural features of the predicted polypeptides as well as an in vitro enzyme
activity assay with bacterially expressed recombinant proteins indicated that MdCAS1 and MdCAS2 may indeed function as β-CAS
isozymes in apple fruits. RNA gel-blot studies revealed that both MdCAS1 and MdCAS2 mRNAs were coordinately induced during the ripening process of apple fruits in an expression pattern comparable with that
of ACC oxidase and ethylene production. The MdCAS genes were also activated effectively by exogenous ethylene treatment and mechanical wounding. Thus, it seems like that,
in ripening apple fruits, expression of MdCAS1 and MdCAS2 genes is intimately correlated with a climacteric ethylene production and ACC oxidase activity. In addition, β-CAS enzyme
activity was also enhanced as the fruit ripened, although this increase was not as dramatic as the mRNA induction pattern.
Overall, these results suggest that MdCAS may play a role in cyanide detoxification in ripening apple fruits. 相似文献
6.
Woolliness is a chilling injury phenomenon occurring in nectarines held at low temperatures for extended periods. It is a disorder marked by altered cell wall metabolism during ripening leading to a dry, woolly texture in the fruit. Two treatments were found to alleviate this disorder. One was holding the fruits for 2 days at 20 °C before 0 °C storage (delayed storage) and the second was having ethylene present during cold storage (ethylene). Immediately stored fruit (control) had 88 percnt; woolliness while 7 percnt; of delayed storage and 15 percnt; of ethylene fruit showed woolliness. The severity of the injury in individual fruits was closely related to inhibition of ethylene evolution. Woolly fruit had higher levels of 1-aminocyclopropane-1-carboxylic acid (ACC) and less 1-aminocyclopropane-1-carboxylic acid oxidase (ACO, EC 1.4.3) activity than healthy fruit. It is suggested that ethylene is essential for promoting the proper sequence of cell wall hydrolysis necessary for normal fruit softening. This is in contrast to chilling injury in other fruits, whereby ethylene is often a sign of incipient damage. Respiration was also found to be associated with chilling injury, in that fruit with woolliness had a depressed respiration. 相似文献
7.
Purpose of work Melons have short shelf-lives due to fruit ripening caused by ethylene production. The 1-aminocyclopropane-1-carboxylic acid
(ACC) oxidase gene is essential for ethylene biosynthesis. As fruit ripening in other fruit crops can be deterred by down-regulation
of ACC oxidase expression, we have carried out similar work to improve fruit quality and shelf-life of the melon Cucumis melo. 相似文献
8.
The association of the level of ACC and the ethylene concentration in ripening apple fruit ( Malus sylvestris Mill, var. Ben Davis) was studied. Preclimacteric apple contained small amounts of ACC and ethylene. With the onset of the climacteric and a concomitant decrease in flesh firmness, the level of ACC and ethylene concentration both increased markedly. During the postclimacteric period, ethylene concentration started to decline, but the level of ACC continued to increase. Ethylene production and loss of flesh firmness of fruits during ripening were greatly suppressed by treatments with low O 2 (O 2 1–3%, CO 2 O%) or high CO 2 (CO 2 20–30%, O 2 15–20%) at the preclimacteric stage. However, after 4 weeks an accumulation of ACC was observed in treated fruits when control fruit was at the postclimacteric stage. Treatment of fruit with either low O 2 or high CO 2 at the climacteric stage resulted in a decrease of ethylene production. However, the ACC level in fruit treated with low O 2 was much higher than both control and high CO 2 treated fruit; it appears that low O 2 inhibits only the conversion of ACC to ethylene, resulting in an accumulation of ACC. Since CO 2 inhibits ethylene production but does not result in an accumulation of ACC, it appears that high CO 2 inhibits both the conversion of ACC to ethylene and the formation of ACC. 相似文献
10.
Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylene during ripening but respond to exogenous ethylene by ripening-related pigment changes and accelerated respiration. In the present study we show that young citrus fruitlets attached to the tree produce high levels of ethylene, which decrease dramatically towards maturation. Upon harvest, fruitlets exhibited a climacteric-like rise in ethylene production, preceded by induction of the genes for 1-aminocyclopropane-1-carboxylate (ACC) synthase 1 ( CsACS1), ACC oxidase 1 ( CsACO1) and the ethylene receptor CsERS1. This induction was advanced and augmented by exogenous ethylene or propylene, indicating an autocatalytic system II-like ethylene biosynthesis. In mature, detached fruit, very low rates of ethylene production were associated with constitutive expression of the ACC synthase 2 ( CsACS2) and ethylene receptor
CsETR1 genes (system I). CsACS1
gene expression was undetectable at this stage, even following ethylene or propylene treatment, and CsERS1 gene expression remained constant, indicating that no autocatalytic response had occurred. The transition from system II-like behavior of young fruitlets to system I behavior appears to be under developmental control.Abbreviations ACC
1-Aminocyclopropane-1-carboxylate
- CsACS1, CsACS2
ACC synthase
- CsACO1
ACC oxidase
- CsERS1, CsETR1
Ethylene receptors
- DAFB
Days after full bloom
- 1-MCP
1-Methylcyclopropene 相似文献
11.
Progress in ethylene regulating fruit ripening concerning itsperception and signal transduction and expression of ACC synthaseand ACC oxidase genes is reviewed. ACC synthase and ACC oxidasehave been characterized and their genes cloned from various fruittissues. Both ACC synthase and ACC oxidase are encoded bymultigene families, and their activities are associated withfruit ripening. In climacteric fruit, the transition toautocatalytic ethylene production appears to be due to a seriesof events in which ACC sythase and ACC oxidase genes have beenexpressed developmentally. Differential expression of ACCsynthase and ACC oxidase gene family members is probably involvedin such a transition that ultimately controls the onset of fruitripening.In comparison to ACC synthase and ACC oxidase, less is knownabout ethylene perception and signal transduction because of thedifficulties in isolating and purifying ethylene receptors orethylene-binding proteins using biochemical methods. However, theidentification of the Nr tomato ripening mutant as anethylene receptor, the applications of new potent anti-ethylenecompounds and the generation of transgenic fruits with reducedethylene production have provided evidence that ethylenereceptors regulate a defined set of genes which are expressedduring fruit ripening. The properties and functions of ethylenereceptors, such as ETR1, are being elucidated.Application of molecular genetics, in combination withbiochemical approaches, will enable us to better understand theindividual steps leading from ethylene perception and signaltransduction and expression of ACC synthase and ACC oxidase genefamily member to the physiological responses. 相似文献
14.
The “Nanguo” pear is a typically climacteric fruit and ethylene is the main factor controlling the ripening process of climacteric fruit. Ethylene biosynthesis has been studied clearly and ACC synthase (ACS) is the rate-limited enzyme. ACO (ACC oxidase) is another important enzyme in ethylene biosynthesis. By exploring the pear genome, we identified 13 ACS genes and 11 ACO genes, respectively, and their expression patterns in fruit and other organs were investigated. Among these genes, 11 ACS and 8ACO genes were expressed in pear fruits. What’s more, 4 ACS and 3ACO genes could be induced by Ethephon and inhibited by 1-MCP treatment. This study is the first time to explore ACS and ACO genes at genome-wide level and will provide new data for research on pear fruit ripening. 相似文献
15.
Mango ( Mangifera indica L. cv. Tainong) fruits were harvested at the green-mature stage in Hainan and air-freighted to the laboratory at Peking.
The fruits were treated with either 1 μl l −1 1-MCP or 5 μl l −1 ethylene for 24 h and stored at 20°C for up to 16 days. 1-MCP maintained fruit firmness, whereas exogenous ethylene decreased
fruit firmness. Exogenous ethylene accelerated the increase in ethylene and 1-aminocyclopropane-1-carboxylate (ACC) oxidase,
whereas 1-MCP reduced both. Exogenous ethylene stimulated and 1-MCP inhibited the production of H 2O 2 of mango fruit during storage. Ascorbic acid was maintained at a high concentration in 1-MCP-treated fruit but was low in
ethylene-treated fruit. 1-MCP inhibited activities of antioxidant enzymes including catalase, superoxide dismutase and ascorbate
peroxidase. These results suggest that 1-MCP could play a positive role in regulating the activated oxygen metabolism balance.
Baogang Wang and Jianhui Wang contributed equally to this work. 相似文献
17.
The shelf life of Japanese pear fruit is determined by its level of ethylene production. Relatively high levels of ethylene
reduce storage potential and fruit quality. We have identified RFLP markers tightly linked to the locus that determines the
rate of ethylene evolution in ripening fruit of the Japanese pear. The study was carried out using sequences of two types
of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase genes (PPACS1 and pPPACS2) and a ACC oxidase gene (PPAOX1) as probes
on 35 Japanese pear cultivars expressing different levels of ethylene (0.0∼300 μl/kg fresh weight/h) in ripening fruit. When
total DNA was digested with HindIII and probed with pPPACS1, we identified a band of 2.8 kb which was specific to cultivars having very high ethylene levels
(≧10 μ1/kg f.w./h) during fruit ripening. The probe pPPACS2 identified a band of 0.8 kb specific to cultivars with moderate
ethylene levels (0.5 μl/kg f.w./h–10 μl/kg f.w./h) during fruit ripening. The cultivars that produce high levels of ethylene
possess at least one additional copy of pPPACS1 and those producing moderate levels of ethylene have at least one additional
copy of pPPACS2. These results suggest that RFLP analysis with different ACC synthase genes could be useful for predicting
the maximum ethylene level during fruit ripening in Japanese pear.
Received: 1 July 1998 / Accepted: 6 October 1998 相似文献
18.
Ethylene initiates the ripening and senescence of climacteric fruit, whereas polyamines have been considered as senescence inhibitors. Ethylene and polyamine biosynthetic pathways share S-adenosylmethionine as a common intermediate. The effects of 1-methylcyclopropene (1-MCP), an inhibitor of ethylene perception, on ethylene and polyamine metabolism and associated gene expression was investigated during ripening of the model climacteric fruit, tomato (Solanum lycopersicum L.), to determine whether its effect could be via polyamines as well as through a direct effect on ethylene. 1-MCP delayed ripening for 8 d compared with control fruit, similarly delaying ethylene production and the expression of 1-aminocyclopropane-1-carboxylic acid (ACC)-synthase and some ethylene receptor genes, but not that of ACC oxidase. The expression of ethylene receptor genes returned as ripening was reinitiated. Free putrescine contents remained low while ripening was inhibited by 1-MCP, but increased when the fruit started to ripen; bound putrescine contents were lower. The activity of the putrescine biosynthetic enzyme, arginine decarboxylase, was higher in 1-MCP-treated fruit. Activity of S-adenosylmethionine-decarboxylase peaked at the same time as putrescine levels in control and treated fruit. Gene expression for arginine decarboxylase peaked early in non-treated fruit and coincident with the delayed peak in putrescine in treated fruit. A coincident peak in the gene expression for arginase, S-adenosylmethionine-decarboxylase, and spermidine and spermine synthases was also seen in treated fruit. No effect of treatment on ornithine decarboxylase activity was detected. Polyamines are thus not directly associated with a delay in tomato fruit ripening, but may prolong the fully-ripe stage before the fruit tissues undergo senescence. 相似文献
19.
Aminoethoxyvinylglycine (AVG) inhibits 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, and thus blocks ethylene synthesis. Preharvest foliar application of AVG to apple ( Malus domestica Borkh.) fruit retards several key events of maturation including climacteric ethylene production, starch conversion to sugars, fruit softening, and abscission zone development. Although the impact of AVG on apple fruit maturation is well known, the biochemical basis of these effects is not well understood. The effects of AVG application on Redchief Delicious apple fruit maturation were studied. AVG applied four weeks prior to harvest significantly reduced internal ethylene levels, amylose degradation, and accumulation of sucrose, glucose, and sorbitol. Because AVG application coincidentally inhibited starch degradation and the increase in internal ethylene, we investigated the enzymatic basis of starch mobilization in apple fruit. Amylase activity was somewhat reduced in AVG-treated fruit. Amylase activity was less in AVG-treated fruit during the early stages of starch mobilization. Starch phosphorylase activity increased dramatically during the later stages of starch mobilization, but was not affected by AVG treatment. Soluble starch synthase activity was also unaffected by AVG treatment and remained constant throughout the eight-week harvest period. Moreover, AVG did not affect the levels of amylopectin, fructose, malate, ascorbate, citrate, or anthocyanin. These results suggest that apple fruit ripening has both ethylene-dependent and -independent processes occurring simultaneously. 相似文献
|