Knock-down of a member of the isoflavone reductase gene family impairs plant growth and nodulation in Phaseolus vulgaris

• Published in: Plant physiology and biochemistry 2013-07, Vol.68, p.81-89
• Main Authors: Rípodas, Carolina, Via, Virginia Dalla, Aguilar, O. Mario, Zanetti, María Eugenia, Blanco, Flavio Antonio
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; auxins; Bacteria; beans; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Gene Knockdown Techniques; genes; Indoleacetic Acids - metabolism; isoflavones; Isoflavonoids; Lateral root; Legume; meristems; messenger RNA; Molecular Sequence Data; Multigene Family; nitrogen; Nitrogen fixation; nodulation; Oxidoreductases Acting on CH-CH Group Donors - genetics; Oxidoreductases Acting on CH-CH Group Donors - metabolism; Phaseolus - genetics; Phaseolus - physiology; Phaseolus vulgaris; Phylogeny; plant growth; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Shoots - genetics; Plant Shoots - growth & development; Plants, Genetically Modified; Rhizobium; Rhizobium etli; Rhizobium etli - physiology; RNA Interference; Root Nodules, Plant - genetics; Root Nodules, Plant - growth & development; Root Nodules, Plant - microbiology; roots; shoots; starvation; symbiosis; Symbiosis - physiology
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2013.04.003

Flavonoids and isoflavonoids participate in the signaling exchange between roots of legumes and nitrogen-fixing rhizobia and can promote division of cortical cells during nodule formation by inhibiting auxin transport. Here, we report the characterization of a member of the common bean isoflavone reductase (EC 1.3.1.45, PvIFR1) gene family, an enzyme that participates in the last steps of the biosynthetic pathway of isoflavonoids. Transcript levels of PvIFR1 were detected preferentially in the susceptible zone of roots, augmented upon nitrogen starvation and in response to Rhizobium etli inoculation at very early stages of the interaction. Knockdown of PvIFR1 mediated by RNA interference (RNAi) in common bean composite plants resulted in a reduction of shoot and root length. Furthermore, reduction of PvIFR1 mRNAs also affected growth of lateral roots after emergence, a stage in which auxins are required to establish a persistent meristem. Upon inoculation, the number of nodules formed by different strains of R. etli was significantly lower in IFR RNAi than in control roots. Transcript levels of two auxin-regulated genes are consistent with lower levels of auxin in PvIFR1 silenced roots. These results suggest a complex role of PvIFR1 during plant growth, root development and symbiosis, all processes in which auxin transport is involved. •PvIFR1 is a member of the isoflavone reductase gene family in common bean.•This gene is induced by N deficiency and expressed in the root susceptible zone.•Silencing of PvIFR1 affects shoot and root growing.•Lateral root elongation after emergence and nodule formation was also compromised.•Knockdown of PvIFR1 altered the expression of auxin regulated genes.