Effects Of Pre - Harvest ALA / GNT Treatment And Modified Atmosphere Storage On Anthocyanin And Related Gene Expression Of Apple

Consumers are highly interested in purchasing apples with red color. However, the early-ripening apples always show poor color and apple are liable to suffer discoloration in their storage which led to commodity value reducing and bad appearance quality, and seriously affect the market competitiveness of Chinese apple. Therefore, study the effects of different treatments on anthocyanin and regulatory mechanism, to improving the apple red color and inhibit’skin burning’, enhance the competitiveness of Chinese apple market is particularly important. To solve the above problems, this study included two experiments.The experiment one was conducted with ten-year-old trees of’Qinyang’apple (Malus x domestica Borkh.) on the Farm of Northwest Agriculture & Forestry University, Baishui County, Shannxi Province, China in 2013.300 mg·L-1 ALA and/or 21.62 μug·L-1 GNT were sprayed on’Qinyang’apples every five days after debagging. The concentrations of anthocyanin and total polyphenol were analyzed by spectrophotometer, and the concentrations of anthocyanin and polyphenol component were investigated by HPLC. Additionally, RT-PCR was also used to test the relative expressions of six structural genes(PAL、CHS、DFR、F3H、UFGT and LDOX) related to anthocyanin synthesis transcription and regulation factor MYB10. The main results are as followed:(1) spraying ALA and/or GNT had a significant promotion effect on the accumulation of anthocyanin of’Qinyang’apple peels, improving appearance quality. (2) The contents of anthocyanin in ALA treatments (AT), GNT treatments (GT), and ALA plus GNT treatments (AGT) were 1.12,1.37, and 3.00 times more than it in control (CT), respectively. (3) ALA and/or GNT played an important role in promoting total polyphenol accumulation of the apple peel, and the flavonoids concentrations of the apple peels were significantly improved. (4) The RT-PCR results were revealed that ALA and/or GNT up-regulated the expressions of PAL, CHS, DFR, F3H, UFGT, LDOX and MYB10. In a word, spraying ALA and/or GNT by promoting anthocyanin-related genes expression to promote anthocyanin accumulation, which further improving the ’Qinyang’apple red color.The experiment two was collected fruits of ten-year-old trees of’red Fuji’{Malus Xdomestica’Red Fuji’) in the HUASH orchards located in Luochuan of Shaanxi, China during the optimum commercial harvest period of the variety (October 6,2013) and visually stored them in terms of their skin colors, keeping the apple fruits>80% of their surface red. Using four different treatments of CA-storage: ① CA (treatment with CA-storage put into operation in the harvesting day); ② CAM (treatment with CA-storage put into operation in the harvesting day and the fruits treated with 1.01 PPM 1-MCP); ③ DEC A (treatment with CA-storage put into operation 20 days after the harvesting day); ④ DECAM (treatment with CA-storage put into operation 20 days after the harvesting day and the fruits treated with 1.01 PPM 1-MCP). The main results are as followed:(1) Lightness value and red value become lower, yellow value increasing, and seriously’skin burning’of the fruits of’Fuji’apple during the storage period,1-MCP and/or the postponed CA could significantly inhibit anthocyanin degradation. (2) The stored fruits had significantly lower concentrations of anthocyanin and certain polyphenols than those at harvest time, and the certain polyphenols included cyaniding-3-galactoside, cyaniding-3-glucoside, cyanidin-3-arabinoside, chlorogenic acid and phloridzin,1-MCP and/or the postponed CA could significantly inhibit the above-mentioned degradation. (3) During storage,1-MCP and/or the postponed CA could significantly inhibit PPO and POD activity, and delay anthocyanin degradation. The cell membrane integrity declin with the storage time, a large amount of phenolic substances contact with PPO and POD, anthocyanin eventually was degradation. (4) The expressions of phenylalanine ammonia lyase (MdPAL), chalcone synthase (MdCHS), chalcone isomerase (MdCHl), leucoanthocyanidin dioxygenase (MdLDOX), anthocyanidin reductase (MdANR), and UDP-glucose: flavonoid-3-O-glucosyltransferase (MdUFGT), were significantly higher after four storage months than after eight storage months. The treatments involving 1-MCP and/or postponed CA significantly inhibited the expression levels of chalcone isomerase (MdCHl), flavanone-3-hydroxylase (MdF3H), dihydroflavonol-4-reductase (MdDFR), and anthocyanidinreductase (MdANR), UDP-glucose: flavonoid-3-O-glucosyltransferase (MdUFGT), which probably indicated that the contents of anthocyanin was increased in the treatments involving 1-MCP and/or postponed CA storage.