Campbell A D, Labavitch J M
Department of Pomology, University of California at Davis, Davis, California 95616.
Plant Physiol. 1991 Oct;97(2):699-705. doi: 10.1104/pp.97.2.699.
Pectic oligomers induced a rapid, transient increase in ethylene biosynthesis when added to pear cells in suspension culture. The rate of ethylene biosynthesis increased within 30 to 40 minutes after oligomer addition, reached a maximum between 90 and 120 minutes after addition, and then decreased to basal rates of synthesis. Both the rapid increase and decrease in biosynthesis appear to be precisely regulated components of the ethylene response to oligomers. Induction of ethylene biosynthesis by pectic oligomers resulted in a reduced sensitivity of cells to further ethylene induction. This reduction in sensitivity occurred within 90 minutes after an oligomer treatment, slightly preceding the decline in ethylene synthesis. The degree of insensitivity induced was proportional to the concentration of oligomer in the first treatment. Induced insensitivity to elicitors appears to represent a novel mechanism which may limit continued ethylene biosynthesis after ethylene induction. Ethylene was produced by pear cells throughout the cell growth cycle, as cells increased in density over a 6 day period. Endogenous ethylene biosynthesis was at a maximum during the first 4 days of rapid cell growth, then declined to half the peak rate through day 10. Pectic oligomers could induce an increase in ethylene biosynthesis above this background rate only after day 5, as endogenous biosynthesis declined. Changes in sensitivity to added oligomer during the growth cycle may result from insensitivity to elicitors induced by growth processes.
将果胶低聚物添加到悬浮培养的梨细胞中时，会引起乙烯生物合成的快速、短暂增加。添加低聚物后30至40分钟内，乙烯生物合成速率增加，添加后90至120分钟达到最大值，然后降至基础合成速率。生物合成的快速增加和减少似乎都是乙烯对低聚物反应的精确调节成分。果胶低聚物诱导乙烯生物合成导致细胞对进一步乙烯诱导的敏感性降低。这种敏感性降低在低聚物处理后90分钟内发生，略早于乙烯合成的下降。诱导的不敏感程度与第一次处理中低聚物的浓度成正比。对诱导子的诱导不敏感似乎代表了一种新机制，可能会限制乙烯诱导后乙烯的持续生物合成。在整个细胞生长周期中，随着细胞在6天内密度增加，梨细胞都会产生乙烯。内源性乙烯生物合成在细胞快速生长的前4天达到最大值，然后在第10天降至峰值速率的一半。随着内源性生物合成下降，只有在第5天后，果胶低聚物才能诱导乙烯生物合成高于此背景速率。生长周期中对添加低聚物敏感性的变化可能是由生长过程诱导的对诱导子的不敏感引起的。
