When one leaf of a tomato plant is electrically-stimulated or heat-wounded, proteinase inhibitor genes are rapidly up-regulated in distant leaves. The identity of the systemic wound signal(s) is not yet known, but major candidates include hormones transmitted via the phloem or the xylem, the electrically-stimulated self-propagating electrical signal in the phloem (the action potential, AP), or the heat-wound-induced surge in hydraulic pressure in the xylem evoking a local change in membrane potential in adjacent living cells (the variation potential, VP). In order to discriminate between these signals we have adopted two approaches. The first approach involves applying stimuli that evoke known signals and determining whether these signals have similar effects on the "model" transcripts for proteinase inhibitors (pin) and calmodulin (cal). Here we show that a heat wound almost invariably evokes a VP, while an electrical stimulation occasionally evokes an AP, and both of these signals induce accumulation of transcripts encoding proteinase inhibitors. The second approach involves identifying the array of genes turned on by heat-wounding. To this end, we have constructed a subtractive library for heat-wounded tissue, isolated over 800 putatively up-regulated clones, and shown that all but two of the fifty that we have analyzed by Northern hybridization are, indeed, up-regulated. Here we show the early kinetics of up-regulation of three of these transcripts in the terminal (4th) leaf in response to heat-wounding the 3rd leaf, about 5 cm away. Even though these transcripts show somewhat different time courses of induction, with one peaking at 30 min, another at 15 min, and another at 5 min after flaming of a distant leaf, they all exhibit a similar pattern, i.e., a transient period of transcript accumulation preceding a period of transcript decrease, followed by a second period of transcript accumulation.

中文翻译：

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热伤和电刺激后基因的快速系统上调。

当番茄植株的一片叶子被电刺激或热伤时，蛋白酶抑制剂基因在远处的叶子中会迅速上调。全身性伤口信号的身份尚不清楚，但主要候选药物包括通过韧皮部或木质部传输的激素，韧皮部中的电刺激自传播电信号（动作电位，AP）或热伤口在木质部中引起的液压激增引起邻近活细胞中膜电位的局部变化（变异电位，VP）。为了区分这些信号，我们采用了两种方法。第一种方法涉及施加激发已知信号的刺激，并确定这些信号是否对蛋白酶抑制剂（pin）和钙调蛋白（cal）的“模型”转录物具有相似的作用。在这里，我们显示出热伤几乎总是引起VP，而电刺激有时引起AP，并且这两个信号均会诱导编码蛋白酶抑制剂的转录物积聚。第二种方法涉及鉴定通过热伤打开的基因阵列。为此，我们构建了一个用于热伤组织的消减文库，分离了800个可能被上调的克隆，并表明，我们通过Northern杂交分析的五十个克隆中，除两个之外的所有克隆实际上都被上调了。在这里，我们显示了在末端（第4片）叶片中响应于约5厘米远的第3片叶片热伤后，这些转录物中的三种转录物上调的早期动力学。即使这些笔录显示出不同的诱导时间，其中一个在30分钟达到峰值，另一个在15分钟达到峰值，