Lipe J A, Morgan P W
Department of Plant Sciences, Texas A&M University, College Station, Texas 77843.
Plant Physiol. 1972 Dec;50(6):759-64. doi: 10.1104/pp.50.6.759.
Two peaks of ethylene production occur during the development of cotton fruitz (Gossypium hirsutum L.). These periods precede the occurrence of young fruit shedding and mature fruit dehiscence, both of which are abscission phenomena and the latter is generally assumed to be part of the total ripening process. Detailed study of the dehiscence process revealed that ethylene production of individual, attached cotton fruits goes through a rising, cyclic pattern which reaches a maximum prior to dehiscence. With detached pecan fruits (Carya illinoensis [Wang.] K. Koch), ethylene production measured on alternate days rose above 1 microliter per kilogram fresh weight per hour before dehiscence began and reached a peak several days prior to complete dehiscence. Ethylene production by cotton and pecan fruits was measured just prior to dehiscence and then the internal concentration of the gas near the center of the fruit was determined. From these data a ratio of production rate to internal concentration was determined which allowed calculation of the approximate ethylene concentration in the intact fruit prior to dehiscence and selection of appropriate levels to apply to fruits. Ethylene at 10 microliters per liter of air appears to saturate dehiscence of cotton, pecan, and okra (Hibiscus esculentus L.) fruits and the process is completed in 3 to 4 days. In all cases some hastening of dehiscence was observed with as little as 0.1 microliter of exogenous ethylene per liter of air. The time required for response to different levels of ethylene was determined and compared to the time course of ethylene production and dehiscence. We concluded that internal levels of ethylene rose to dehiscence-stimulating levels a sufficience time before dehiscence for the gas to have initiated the process. Since our data and calculations indicate that enough ethylene is made a sufficient time before dehiscence, to account for the process, we propose that ethylene is one of the regulators of natural fruit dehiscence, an important component of ripening in some fruits. Our data also suggest a possible involvement of ethylene in young fruit abscission.
在棉花果实（陆地棉）发育过程中会出现两个乙烯生成高峰。这两个时期分别先于幼果脱落和成熟果实开裂的发生，这两种现象均为脱落现象，且一般认为后者是整个成熟过程的一部分。对开裂过程的详细研究表明，单个附着的棉花果实的乙烯生成呈现出上升的循环模式，在开裂前达到最大值。对于分离的山核桃果实（伊利诺伊胡桃），每隔一天测量的乙烯生成量在开裂开始前每千克鲜重每小时超过1微升，并在完全开裂前几天达到峰值。在开裂前测量棉花和山核桃果实的乙烯生成量，然后测定果实中心附近气体的内部浓度。根据这些数据确定了生成速率与内部浓度的比值，从而能够计算出开裂前完整果实中的近似乙烯浓度，并选择适用于果实的合适水平。每升空气中10微升的乙烯似乎能使棉花、山核桃和秋葵（黄秋葵）果实的开裂达到饱和，且该过程在3至4天内完成。在所有情况下，每升空气中低至0.1微升的外源乙烯都能观察到开裂有一定程度的加速。确定了对不同水平乙烯响应所需的时间，并与乙烯生成和开裂的时间进程进行了比较。我们得出结论，乙烯的内部水平在开裂前足够长的时间上升到刺激开裂的水平，以使气体启动该过程。由于我们的数据和计算表明，在开裂前足够长的时间内产生了足够的乙烯来解释该过程，我们提出乙烯是天然果实开裂的调节因子之一，而果实开裂是某些果实成熟的重要组成部分。我们的数据还表明乙烯可能参与了幼果脱落。
