Regulation And Expression Of Chilling Injury Related FAD Genes In Peach Fruit

Melting peach (Prunus persica L. cv.'YL' and 'HJML') fruit were used as materials to investigate changes in fatty acid compositions and FAD genes expression in response to different temperatures. Results were as following:1. CI symptoms were mainly developed within 2 weeks during storage at 5℃, and expressed as flesh browning, mealy and woolly (lack of juice). There were significant higher levels in electrical conductivity and reduced ethylene production in CI fruit. Fruit firmness of'YL'peach declined normally during the low temperature storage, while'HJML'peach fruit maintain high level. LTC treatment significantly alleviate chilling injury of peach fruit and maintained good quality.2. Palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid were five major fatty acids detected in'YL'and'HJML'peach fruit. Fatty acid compositions changed differently in the'YL'and'HJML'.'YL' peach fruit stored at 5℃contained lower linoleic acid compared with LTC treatment, however'HJML'peach showed lower linolenic acid. At the same time, peach with LTC treatment performed higher DBI to keep membrane fluidity.3. Six FAD genes were cloned from peach, named PpFADl, PpFAD2, PpFAD3, PpFAD4, PpFAD5 and PpFAD6. Full-length of the above six FAD genes was 1146 bp,1113 bp,1347 bp,1323 bp,1359 bp and 1152 bp, respectively. Sequence analysis showed that PpFAD2, PpFAD3, PpFAD5 and PpFAD6 were clustered as co-3 FAD group, while PpFAD1 and PpFAD4 belong to co-6 FAD group.4. Expression patterns of six members of PpFAD gene family during low temperature storage were studied by QPCR. PpFAD2 and PpFAD6 were induced by low temperature, while PpFAD3 was not sensitive to low temperature. PpFAD5 expression was relative higher at 5℃for 'YL' fruit, while transcripts levels was higher in 'HJML' peach treated with LTC. PpFAD4 had similar expression patterns in 'YL' and 'HJML' peach fruit. Transcript levels of PpFAD1 were relative higher in 'YL' peach treated with LTC, and were redcued by LTC in 'YL' fruit.In this research, expression patterns of FAD gene family was studied in peach fruit during low temperature storage. Enhancement of PpFAD1 expression increased the content of linoleic acid in endoplasmic reticulum, accordingly raised the chilling resistant of'YL'peach, while in'HJML'peach, linolenic acid was accumlated by increasing the expression of PpFAD5 in plastid to alleviate chilling injury.