Sanchez-Ballesta M T, Zacarias L, Granell A, Lafuente M T
Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Apdo Correos 73, Burjassot, 46100 Valencia, Spain.
J Agric Food Chem. 2000 Jul;48(7):2726-31. doi: 10.1021/jf991141r.
The effects of different periods of heating at 37 degrees C on phenylalanine ammonia-lyase (PAL) and how this relates to chilling tolerance was investigated in fruits of the chilling-sensitive Fortune mandarin. All effective heat-conditioning treatments caused an early and transient increase in PAL mRNA and PAL activity. Conditioning fruits at 37 degrees C for 1 or 2 days prevented the manifestation of chilling symptoms but not the accumulation of PAL mRNA and PAL activity observed in untreated fruits. In fruits conditioned for 3 days, cold-induced damage and PAL activity were also suppressed but not the accumulation of PAL transcript upon subsequent storage at 2 degrees C. Storage of 3-day-heated fruits at a nonchilling temperature (12 degrees C) induced an early and transient increase in both PAL mRNA and PAL activity. High levels of PAL transcript and PAL activity were detected in freshly harvested fruits of a chilling-resistant mandarin (Hernandina) that decreased upon cold storage at 2 degrees C in heat-treated and nontreated fruits. These results indicate that sensitivity of mandarins to chilling correlates with low constitutive levels of PAL mRNA and PAL activity and with the inducibility of both upon exposure to low temperatures.
研究了在37摄氏度下不同加热时长对苯丙氨酸解氨酶（PAL）的影响，以及这与冷敏型福橘果实耐冷性的关系。所有有效的热预处理均导致PAL信使核糖核酸（mRNA）和PAL活性提前且短暂增加。在37摄氏度下对果实进行1天或2天预处理可防止冷害症状出现，但无法阻止未处理果实中观察到的PAL mRNA积累和PAL活性增加。在经过3天预处理的果实中，冷害损伤和PAL活性也受到抑制，但在随后2摄氏度储存时，PAL转录本的积累并未受到抑制。将经过3天加热处理的果实置于非冷害温度（12摄氏度）下储存，会导致PAL mRNA和PAL活性提前且短暂增加。在耐冷性柑橘品种（ Hernandina）的新鲜采收果实中检测到高水平的PAL转录本和PAL活性，在经过热处理和未处理的果实中，于2摄氏度冷藏时二者均会降低。这些结果表明，柑橘对冷害的敏感性与PAL mRNA和PAL活性的低组成水平以及低温暴露后二者的诱导性相关。
