Triplett E W, Heitholt J J, Evensen K B, Blevins D G
Agronomy Department, University of Missouri-Columbia, Columbia, Missouri 65211.
Plant Physiol. 1981 Jan;67(1):1-4. doi: 10.1104/pp.67.1.1.
Dramatic differences in the height of lima beans (Phaseolus lunatus L.) treated with two different Rhizobium strains were studied. Lima beans were grown in Perlite in the greenhouse or in a minus-N culture solution in the growth chamber. The plants were inoculated with either Rhizobium sp. (lima bean) strain 127E15, which contains the constitutive nitrate reductase activity, or strain 127E14, which lacks that activity. For up to 3 weeks, no growth differences were observed in the plants inoculated with either strain. Five weeks after inoculation, however, those plants inoculated with strain 127E14 were significantly taller and had a larger number of leaves than those inoculated with strain 127E15. The difference in plant height was the result of increased internode elongation caused by inoculation with Rhizobium sp. 127E14. This response was observed with all lima bean cultivars tested, including Henderson, Fordhook, Allgreen, and Early Thorogreen. The growth difference occurred in plants cultured in the greenhouse or in the growth chamber.No differences were observed in fresh weights of nodules, roots, axes, leaves, or flowers. The number of nodules, pods, or flowers also did not differ. Acetylene reduction rates and total N content were equal in plants inoculated with strains 127E14 or 127E15.Inasmuch as only internode length and leaf number differed between Rhizobium treatments, the response appeared to be hormone-mediated. Application of gibberellic acid to the apex of plants inoculated with strain 127E15 caused an increase in plant height similar to that observed in untreated plants inoculated with strain 127E14. Conversely, the height of plants infected with strain 127E14 was decreased by application of gibberellin synthesis inhibitors to the root system. These data suggest that the increased growth caused by inoculation with strain 127E14 could be the result of increased gibberellin synthesis in lima bean nodules infected with that strain. Whether this response was related to the absence of nitrate reductase activity in strain 127E14 is unknown.
研究了用两种不同根瘤菌菌株处理的利马豆（菜豆属利马豆）高度的显著差异。利马豆在温室中的珍珠岩里或生长室内的缺氮培养液中种植。给植株接种含有组成型硝酸还原酶活性的根瘤菌（利马豆）菌株127E15，或缺乏该活性的菌株127E14。在长达3周的时间里，接种这两种菌株的植株未观察到生长差异。然而，接种后5周，接种菌株127E14的植株比接种菌株127E15的植株显著更高，且叶片数量更多。株高差异是接种根瘤菌127E14导致节间伸长增加的结果。在所有测试的利马豆品种中都观察到了这种反应，包括亨德森、福特胡克、奥尔格林和早托罗格林。在温室或生长室培养的植株中都出现了生长差异。在根瘤、根、茎、叶或花的鲜重上未观察到差异。根瘤、豆荚或花的数量也没有差异。接种菌株127E14或127E15的植株中乙炔还原率和总氮含量相等。由于根瘤菌处理之间仅节间长度和叶片数量不同，这种反应似乎是由激素介导的。将赤霉素施用于接种菌株127E15的植株顶端，导致株高增加，类似于未处理的接种菌株127E14的植株中观察到的情况。相反，通过向根系施用赤霉素合成抑制剂，降低了感染菌株127E14的植株高度。这些数据表明，接种菌株127E14导致的生长增加可能是该菌株感染的利马豆根瘤中赤霉素合成增加的结果。这种反应是否与菌株127E14中缺乏硝酸还原酶活性有关尚不清楚。
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