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Rhizogenesis in in vitro shoot cultures of passion fruit (Passiflora edulis f. flavicarpa Deg.) is affected by ethylene precursor and by inhibitors
47-54.Views:167The effects of the ethylene precursor ACC and two inhibitors, AgNO3 and AVG, on root formation were tested in in vitro shoots of passion fruit (Passiflora Midis f.flavicalpa Deg.). The organogenic response was assessed on the basis of percentage of shoot-forming. roots, root number and length. The time course of ethylene production was also monitored. ACC inhibited root formation by delaying root emergence and increasine, callus formation at the basis of the shoots. In addition, ACC caused a marked increase in ethylene production, coupled to leaf chlorosis and senescence with lower rooting frequencies, number and length of roots. IAA supplementation increased ethylene production. Both ethylene inhibitors, AgNO3 and AVG, at appropriate concentrations reduced callus formation at the basis of shoots. AVG increased the number of roots per shoot, but drastically reduced length of differentiated roots. Regarding to leaf pigments, ACC promoted a marked reduction on carotenoids and total chlorophyll, whereas AVG and AgNO3 delayed explant senescence and pigments degradation, not differing from IAA supplemented and non-supplemented control treatments. The results confirm previous reports on the beneficial effects of ethylene inhibitors on in vitro rooting and suggest its reliability to be used as an alternative approach to evaluate sensitivity of Passiflora species to ethylene.
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The effects of ACS (1-aminocyclopropane-l-carboxylate synthase) gene down regulation on ethylene production and fruit softening in transgenic apple
65-70.Views:113A detailed examination of the production of ethylene and other ripening parameters during storage period has been undertaken in transgenic apple fruits, where the ethylene biosynthesis was inhibited by antisense ACS (l-aminocyclopropane-l-carboxylate synthase) gene. Data indicate down regulation of ethylene production, softening and spoilage in some transgenic lines. In some cases ethylene production was inhibited for over 90 percent, considerable reduction of softening and spoilage was observed probably due to the reduced activity of cell wall degradable enzymes. ACS activity was also monitored during ripening. The fruits of the best transgenic lines could be stored for minimum 4-5 months longer under 5 °C cold room storage conditions and one month longer at normal room temperature. This molecular approach can provide an alternative way to replace the commonly used and costly atmospheric storage of fruits.
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Production of transgenic carnation with antisense ACS (1-aminocyclopropane44-carboxy late synthase) gene
104-107.Views:167Dianthus chinensis and Dianthus caryophyllus varieties were tested for shoot regeneration from leaf and petal explants and transformed with Agrobacterium tuniefaciens strains (EHA 105 and LBA 4404) harbouring an apple derived ACS cDNA in antisense orientation in order to reduce ethylene production and influence the ethylene dependant traits in carnation. After transformation regenerating shoots were selected on MS medium containing 50-75-100-125-150 mg/1 kanamycin and supplemented with 1 mg/1 BA, 0.2 mg/1 NAA. Transgene integration was proved by PCR analysis with npt II spcific primers followed by Southern hybridisation of DNA isolated from green shoots on medium containing 150 mg/1 kanamycin. Several putative transformants were subjected to RT-PCR in order to examine the npt 11 expression at mRNA level. Both the transformant and the non-transformant plants were potted into glasshouse to observe the effect of changed ethylene production on flowering time, petal senescence and vase life.
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1-MCP and STS as ethylene inhibitors for prolonging the vase life of carnation and rose cut flowers
101-107.Views:210The effect of STS and 1-MCP on the postharvest quality of carnation and rose cut flowers was studied. Cut flowers of Dianthus c..aryophyllus L. cv. Asso and Rosa hybritia cv. Baroness were treated with silver thiosulfate (STS) at 0.4 mM with sucrose at 50 g 1-t and 1-methylcyclopropene ( I -MCP) at 0.5 g m-3 for 611.
Pretreatment with STS and 1-MCP significantly extended the vase life and minimized the % loss of initial weight of carnation and rose cut flowers comparing to the untreated control. The two chemicals applied inhibited the chlorophyll degradation and carbohydrate loss and hence, significantly improved the postharvest quality of carnation and rose cut flowers comparing to the control. Ethylene production by cut flowers was inhibited as a result of using these chemicals. In general, there were no differences between STS and (-MCP but the later does not have the heavy metal implications of STS treatment, and hence, using 1-MCP pretreatment for extending the vase life of carnation and rose cut flowers was recommended.
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Down-regulation of ethylene production in carnation (Dianthus Caryphyllus L.) by an apple derived ACC-cDNA
101-104.Views:128Transgenic carnations were produced with an apple derived antisense ACC-synthase cDNA. Transgenic carnation regenerants were potted in glasshouse. All transformed plants showed normal growth and were true-to-type. Ethylene production — measured at full opening stage — lowered by 30-60 %, no plant with 100 % decrease was identified. The vase-life has been observed for 5 years. 38 % of the transformant carnations showed a higher a relative value in days by more than 2 days to 6 days. Twenty six plants were found exhibiting the most marked alterations in the tested trait. In these plants ethylene production decreased by 37-67 %, they have longer vase-life (by 4 days or more). Since the fragrance variety 'Bíbor' was the plant material for genetic modification of vase-life, this trait has been conserved after transformation in spite of the fact that the position of transgene integration cannot be directed.