Starrett D A, Laties G G
Department of Biology, University of California, Los Angeles, California 90024.
Plant Physiol. 1991 Mar;95(3):921-7. doi: 10.1104/pp.95.3.921.
When early-season avocado fruit (Persea americana Mill. cv Hass) were treated with ethylene or propylene for 24 hours immediately on picking, the time to the onset of the respiratory climacteric, i.e. the lag period, remained unchanged compared with that in untreated fruit. When fruit were pulsed 24 hours after picking, on the other hand, the lag period was shortened. In both cases, however, a 24 hour ethylene or propylene pulse induced a transient increase in respiration, called the pulse-peak, unaccompanied by ethylene production (IL Eaks [1980] Am Soc Hortic Sci 105: 744-747). The pulse also caused a sharp rise in ethylene-forming enzyme activity in both cases, without any increase in the low level of 1-aminocyclopropane-1-carboxylic acid synthase activity. Thus, the shortening of the lag period by an ethylene pulse is not due to an effect of ethylene on either of the two key enzymes in ethylene biosynthesis. A comparison of two-dimensional polyacrylamide gel electrophoresis polypeptide profiles of in vitro translation products of poly(A(+)) mRNA from control and ethylene-pulsed fruit showed both up- and down-regulation in response to ethylene pulsing of a number of genes expressed during the ripening syndrome. It is proposed that the pulse-peak or its underlying events reflect an intrinsic element in the ripening process that in late-season or continuously ethylene-treated fruit may be subsumed in the overall climacteric response. A computerized system that allows continuous readout of multiple samples has established that the continued presentation of exogeneous ethylene or propylene to preclimacteric fruit elicits a dual respiration response comprising the merged pulse-peak and climacteric peak in series. The sequential removal of cores from a single fruit has proven an unsatisfactory sampling procedure inasmuch as coring induces wound ethylene, evokes a positive respiration response, and advances ripening.
当采摘后立即对早熟鳄梨果实（Persea americana Mill. cv Hass）用乙烯或丙烯处理24小时时，与未处理的果实相比，呼吸跃变开始的时间即滞后期保持不变。另一方面，当果实采摘24小时后进行脉冲处理时，滞后期缩短。然而，在这两种情况下，24小时的乙烯或丙烯脉冲均会引起呼吸的短暂增加，称为脉冲峰，且不伴有乙烯生成（IL Eaks [1980] Am Soc Hortic Sci 105: 744 - 747）。在这两种情况下，脉冲还会导致乙烯形成酶活性急剧上升，而1 - 氨基环丙烷 - 1 - 羧酸合酶活性的低水平没有任何增加。因此，乙烯脉冲使滞后期缩短并非由于乙烯对乙烯生物合成中两种关键酶的任何一种产生作用。对对照果实和乙烯脉冲处理果实的聚（A(+)）mRNA体外翻译产物的二维聚丙烯酰胺凝胶电泳多肽图谱进行比较，结果显示，在成熟综合征期间表达的许多基因对乙烯脉冲有上调和下调反应。有人提出，脉冲峰或其潜在事件反映了成熟过程中的一个内在因素，在晚熟或持续用乙烯处理的果实中，该因素可能包含在整体呼吸跃变反应中。一个允许对多个样品进行连续读数的计算机系统已经证实，向呼吸跃变前的果实持续施加外源乙烯或丙烯会引发双重呼吸反应，包括串联的合并脉冲峰和呼吸跃变峰。从单个果实中依次去除果核已被证明是一种不令人满意的采样方法，因为去核会诱导伤乙烯，引发积极的呼吸反应并促进成熟。
