Endogenous Factors Controlling Photoperiodism of Crop Plants.

作物（高等植物）的各种发育变化，如开花、结瘤和茎生长的终止，都受到光周期的控制。马铃薯植株的块茎形成和大豆植株茎生长的终止都是由短日照诱导的。我们以前曾发现短日照条件下叶片中形成的块茎酸（TA）及其糖苷诱导马铃薯结薯。茉莉酸（JA）与块茎酸结构相似，对植物生长具有多种抑制作用，如抑制幼苗生长。在大豆[Glycine max（L.）梅里尔湾在有限株系茎生长终止前20天，两个株系叶片中的类茉莉酸活性都很低。此后活性迅速增加，并在接近终止时达到最大值。虽然两个等值线叶片中的活性波动方式相似，但有限等值线中的活性远高于无限等值线。确定的等值线的叶子中的JA的存在下，通过高效液相色谱法和质谱法纯化确认。叶片中JA的水平为0.18 mg/kg鲜重（接近10 μ <-6>M），平均4个不同时间收获的样品。JA在浓度超过10 μ M时，对不定等长线的培养茎尖的外源施用<-7>强烈抑制生长。在高于10 μ M的浓度<-6>下，观察到一些芽根本没有任何生长。这些结果表明，JA是一个主要的内源因子，控制大豆植株的生长习性。JA和TA的水平可能受光周期的控制。

Various developmental changes in crop plants (higher plants), such as flowering, tuberization and termination of stem growth, are under the control of photoperiods. Both tuberization in potato plants and termination of stem growth of soybean plants are induced by short days. We have previously found that potato tuberization is induced by tuberonic acid (TA) and its glucoside which seem to be formed in the leaves under the short days. Jasmonic acid (JA) which is structually related to tuberonic acid has various inhibitory effects on plant growth, for example, it inhibits the growth of seedlings. The possible involvement of JA in the termination of stem growth of soybean plants was examined in indeterminate and determinate isolines of soybean [Glycine max (L.) Merril cv. Harosoy].JA-like activities in leaves of both isolines were very low 20 days before the termination of stem growth of determinate isoline. The activity increased rapidly thereafter and reached a maximum near the time of the termination. Although the activities in leaves of both isolines fluctuated in a similar manner, the activity in the determinate isoline was much higher than that in the indeterminate isoline. The presence of JA in the leaves of the determinate isoline was confirmed by purification by high-performance liquid chromatography and by mass spectrometry. The level of JA in the leaves was 0.18 mg/kg fresh weight (nearly 10^<-6> M), on an average of four samples harvested different times. Exogenous application of JA to cultured shoot apices of the indeterminate isoline at concentrations above 10^<-7> M strongly inhibited growth. Above a concentration of 10^<-6> M, some shoots without any growth at all were observed. These results suggest that JA is a major endogenous factor that controls the growth habit of soybean plants. It is possible that the levels of JA and TA are under the control of photoperiod.