采后荔枝果实冷害过程中多胺含量的变化

以桂味荔枝果实为材料,研究冷害及外源亚精胺(Spd)处理对果实膜透性和内源多胺含量变化的影响。结果表明,在0℃下贮藏时果实发生冷害过程中,荔枝果皮中腐胺(Put)、Spd、精胺(Spm)含量在14d后明显增加,膜透性快速增大,21d时果皮出现明显的冷害褐变,Put进一步积累,而Spm含量下降,Spd保持较高水平。非冷害温度(3℃)下贮藏时,果皮多胺含量变化相对较小。0℃下果肉的多胺含量和变化幅度低于3℃果实,并延迟7d衰老。外源Spd处理明显提高果实内源多胺含量的同时,延缓了果皮相对膜透性增加,减轻了冷害。这表明果皮中Put的积累可能是荔枝果实冷害的结果,冷藏初期Spm含量的上升可能是果实对冷害的防卫反应。

Changes of polyamines contents during chilling injury of litchi fruit

Litchi(Litchi chinensis Sonn.cv.Guiwei)fruits stored at 0℃ and 3℃ and postharvest spermidine(Spd)treated fruits stored at 0℃ were respectively used to investigate the relationship between changes in polyamines and chilling injury. The content of putrescine(Put),Spd and spermine(Spm)in pericarp stored at 0℃ increased at the 14th day with a rapid increase in cell membrane permeability. After the fruits showed symptom of chilling injury as pericarp browning at the 21st day, Put accumulated further associated with the decrease of Spm.However,no significant content change of polyamines in pericarp was detected during storage at the non-chilling injury temperature(3℃). The levels of the three polyamines in pulp stored at 0℃ were lower than those at 3℃ and the senescence of the pulp was retarded about 7 days. Exogenous Spd alleviated the chilling injury symptoms of the fruits stored at 0℃ through elevation levels of endogenous polyamines. These results suggested that the accumulation of Put in litchi pericarp could be a consequence of the chilling injury while the increase in Spm level might served as a defense response.