Imperlini Esther, Bianco Carmelina, Lonardo Enza, Camerini Serena, Cermola Michele, Moschetti Giancarlo, Defez Roberto
Institute of Genetics and Biophysics "Adriano Buzzati Traverso", Naples, Italy.
Appl Microbiol Biotechnol. 2009 Jun;83(4):727-38. doi: 10.1007/s00253-009-1974-z. Epub 2009 Apr 3.
We evaluated the effects of the main auxin phytohormone, indole-3-acetic acid (IAA), on the central metabolism of Sinorhizobium meliloti 1021. We either treated S. meliloti 1021 wild-type cells with 0.5 mM IAA, 1021+, or use a derivative, RD64, of the same strain harboring an additional pathway for IAA biosynthesis (converting tryptophan into IAA via indoleacetamide). We assayed the activity of tricarboxylic acid cycle (TCA) key enzymes and found that activity of citrate synthase and alpha-ketoglutarate dehydrogenase were increased in both 1021+ and RD64 as compared to the wild-type strain. We also showed that the intracellular acetyl-CoA content was enhanced in both RD64 and 1021+ strains when compared to the control strain. The activity of key enzymes, utilizing acetyl-CoA for poly-beta-hydroxybutyrate (PHB) biosynthesis, was also induced. The PHB level measured in these cells were significantly higher than that found in control cells. Moreover, 4-week-long survival experiments showed that 80% of 1021 cells died, whereas 50% of RD64 cells were viable. Medicago truncatula plants nodulated by RD64 (Mt-RD64) showed an induction of both acetylene reduction activity and stem dry weight production.
我们评估了主要生长素植物激素吲哚 - 3 - 乙酸（IAA）对苜蓿中华根瘤菌1021中心代谢的影响。我们用0.5 mM IAA处理苜蓿中华根瘤菌1021野生型细胞（1021 +），或者使用同一菌株的衍生物RD64，其具有额外的IAA生物合成途径（通过吲哚乙酰胺将色氨酸转化为IAA）。我们测定了三羧酸循环（TCA）关键酶的活性，发现与野生型菌株相比，1021 +和RD64中柠檬酸合酶和α - 酮戊二酸脱氢酶的活性均增加。我们还表明，与对照菌株相比，RD64和1021 +菌株中的细胞内乙酰辅酶A含量均有所提高。利用乙酰辅酶A进行聚β - 羟基丁酸酯（PHB）生物合成的关键酶的活性也被诱导。在这些细胞中测得的PHB水平明显高于对照细胞中的水平。此外，为期4周的存活实验表明，80%的1021细胞死亡，而50%的RD64细胞仍存活。由RD64结瘤的蒺藜苜蓿植株（Mt - RD64）显示出乙炔还原活性和茎干重产量均有所诱导。
